JP3513124B2 - Film formation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method which can be used in a process for repairing a convex defect or a concave defect of a structure, and more particularly to a film forming method suitable for use in a defect correcting process of a phase shift mask. Membrane method.

[0002]

2. Description of the Related Art In recent years, as a mask for transferring an LSI pattern onto a wafer, a phase shift mask having a resolution improved by utilizing a phase shift effect has been used. In such a phase shift mask, if there is a defect in the shifter, good pattern transfer cannot be performed, so it is necessary to surely correct the defect when it occurs.

When the shifter of the phase shift mask has a convex defect, a method has been proposed in which the convex defect is etched by irradiating the defect with a focused ion beam (hereinafter abbreviated as FIB) to correct the defect. ing. However, since the phase shifter and the mask substrate are often made of the same material, it is difficult to detect the etching end point of the convex defect by this method. Further, it is extremely difficult to etch only the convex defects, and even if only the convex defects can be etched, the shape of the shifter after etching depends on the shape of the convex defects.

In order to solve this, the convex defect is covered with a deposited film so that the upper surface of the film becomes flat, and the convex defect is included in the FIB under the condition that the convex defect and the deposited film have the same etching rate. A method is conceivable in which the deposited film is etched to remove the convex defects together with the deposited film. However,
In the case of assist deposition using FIB,
For some types, flatten the top surface of the film when covering the convex defect.
It is difficult to form. To some extent the thickness of the deposited film
As the film thickness of the deposited film covering the edge of the convex defect increases,
Although the steps are small, even if a thicker film is formed,
The step of the laminated film is unlikely to be zero. And a film with steps
When etching, the shape after etching is the shape of the step
Depending on the shape, it is difficult to remove the convex defect and make it flat
Becomes On the other hand, when repairing concave defects,
Modifying the surface to be flush with other shifter surfaces
It's extremely difficult. In this way, the conventional phase shift mask
To use FIB to fix defects in
However, it is difficult to form a deposited film flat on the defect.
From that, the defect should be corrected flatly to the substrate surface.
It is difficult.

[0005]

By the way, tetrameth
SiO obtained using a mixed gas of xysilane and oxygen
_The light transmittance of the _x film for light with a wavelength of 436 nm is over 40%.
I'm sorry. 80.6% or higher light transmittance for repairing concave defects
is necessary.

[0006]

[0007]

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a silicone having a high light transmittance.
An object of the present invention is to provide a film forming method capable of forming an oxide film .

[0009]

In order to solve the above problems, the present invention adopts the following configuration.

That is, the first aspect of the present invention is Si-O-
Forming a silicon oxide film by FIB-assisted deposition in which a material having Si bonds and Si-H bonds is supplied to the surface of the structure and a desired portion of the surface supplied with the material is irradiated with a focused ion beam. Including
Only has the Si-O-Si bond and the Si-H bond.
There is provided a film forming method, wherein the material has a ring structure .

The second invention of the present invention is Si-O-
A FIB assist device that supplies a material having a Si bond and a Si-H bond and a gas containing an oxygen element-containing material to the surface of the structure and irradiates a desired portion of the surface supplied with the material with a focused ion beam. look including a step of forming a silicon oxide film by position, the Si-O-S
The material having i-bond and Si-H bond has a cyclic structure.
To provide a film forming method characterized by that.

In the film forming method according to the first aspect of the present invention, before the step of forming the silicon oxide film, the energy of the focused ion beam, the current density of the focused ion beam, and the FIB assisted deposition are used. The method may further include determining at least one set point for gas pressure. In this case, the FIB assist deposition is
At least one of the energy of the focused ion beam, the current density of the focused ion beam, and the gas pressure during the FIB assist deposition may be adjusted to the set value.

Further, in the film forming method according to the second invention, before the step of forming the silicon oxide film, the energy of the focused ion beam, the current density of the focused ion beam, and the FIB assisted deposition are performed. And the step of determining at least one set value of the gas partial pressure during the FIB-assisted deposition. In this case, the FIB assist deposition is performed by at least the energy of the focused ion beam, the current density of the focused ion beam, the gas pressure during the FIB assist deposition, and the gas partial pressure during the FIB assist deposition. You may perform one according to the said setting value.

Preferred embodiments of the present invention include, for example, the following. (1) S i-O-Si bonds and materials having a Si-H bond is 1,3,5,7-tetramethylcyclotetrasiloxane. (2) Use Ga beam or Si beam as the focused ion beam. (3) The oxygen-containing material should be a material selected from the group consisting of O ₂ , O ₃ , and N ₂ O.

The film forming method of the present invention can be used, for example, in the first and second defect correction processes described below. That is, the first defect repairing process is a defect repairing method for a structure, which repairs a convex defect generated in a structure having a substrate and a desired pattern provided on the substrate,
Forming a first thin film made of a material different from the material forming the underlayer of the convex defect around the convex defect or close to the convex defect; the convex defect and the first thin film; A step of forming a second thin film on the thin film and flattening its upper surface; the convex defect and portions of the first and second thin films located above and around the convex defect are charged particle beam; And a step of removing portions of the first and second thin films remaining in the removing step at the same time, and a defect repairing method for a structure body.

The second defect repairing process is a structure defect repairing method for repairing a concave defect generated in a structure having a substrate and a desired pattern provided on the substrate. A step of embedding an embedding material in the concave defect and forming a protrusion protruding from the surface where the concave defect is generated, a region including the protrusion is made of a material different from the material forming the surface region where the concave defect is generated. Covering with a planarizing film and flattening the upper surface thereof; simultaneously removing the protrusion and the portion of the planarizing film located above and around the protrusion using a charged particle beam; And a step of removing a portion of the oxide film remaining in the removing step, the defect repairing method of the structure.

Here, the flattening film in the second defect repairing process may have a laminated structure of the first and second thin films as in the first defect repairing process.

The following are examples of implementations of these defect correction processes.

(1) The first and second thin films are made of a substance containing carbon deposited by FIB assist. This assisted deposition should be performed using hydrocarbon gas. This hydrocarbon-based gas is methyl methacrylate gas, 2,4,4-trimethyl-1-pentene gas, or isoprene gas.

(2) The first and second thin films are made of a material containing tungsten deposited by FIB assist. This assist deposition should be performed using W (CO) ₆ or WF ₆ .

(3) The flattening film is made of a photosensitive resin or a resin which is crosslinked or decomposed by charged particles.

(4) In the simultaneous removal step, the convex defect or protrusion and the first and second thin films are removed at the same processing rate by controlling the processing conditions.

(5) In the simultaneous removal step, the convex defect or protrusion and the first and second thin films are removed by FIB sputtering and / or assisted etching of charged particles. This assisted etching should be performed using XeF ₂ gas and / or gas containing oxygen element. The gas containing oxygen element is O _2, ozone, or N ₂ O.

(6) In the simultaneous removal step, determine the processing end points of the convex defect or protrusion and the first and second thin films by measuring the secondary particles emitted from both.

(7) The first and second thin films remaining in the simultaneous removal step are subjected to thermal etching using laser light, O ₃ or O ₂
Reactive etching using laser light in an atmosphere, O ₂ plasma asher, CF ₄ , H ₂ , H ₂ O, N ₂ , N ₂ O, and chemical dry in which at least one of NO is added to O ₂ gas. Etching (hereinafter abbreviated as CDE),
C using hydrogen gas or a gas containing hydrogen atoms in the molecule
Removal by DE or RIE or FIB assisted etching using O ₃ or O ₂ .

(8) Removal of the photosensitive resin remaining in the simultaneous removal step or the resin which is crosslinked or decomposed by charged particles by using a stripping solution.

(9) Removing the damaged layer on the surface of the substrate after the removing step using the charged particle beam.

(10) After the removal step using the charged particle beam,
Removing the damaged layer on the substrate surface by assist etching using a gas containing at least XeF ₂ or thermal etching using a laser beam.

(11) The embedding material should be the same material as the substrate.

(12) The embedding material must have the optical characteristics, especially the transmittance and the refractive index, which match those of the substrate material.

(13) Embedding the concave defect should be performed in two or more steps.

(14) Embedding the concave defect is performed by charged particle beam (FI).
B or electron beam) assist deposition.

(15) The gas having Si—O bond and / or Si—H bond in assisted deposition for embedding a concave defect is 1,3,5,7-tetramethylcyclotetrasiloxane. The gas containing oxygen element is oxygen, ozone, or N ₂ O. FIB is Ga
Beam or Si beam.

(16) A gas having a Si--N bond and / or a Si--H bond and a gas containing nitrogen as a main component were used for assisted deposition for embedding a concave defect. The gas containing this nitrogen element is nitrogen or ammonia.

Among the above defect repair processes, the feature of the convex defect repair process is that FIB processing conditions in which a flat film is formed on the convex defect and the deposited film and the convex defect are simultaneously at the same etching rate. Then, remove it by etching,
Also, the end point of processing is determined by detecting the inflection point of the ratio of secondary ions emitted from the deposited film and the convex defect at that time.

Here, if the film formed on the convex defect is not flat, there arises a problem that the surface shape after simultaneous etching of both depends on the shape of the deposited film and the convex defect cannot be corrected to be flat. Therefore, in the present invention, when forming a film on a convex defect, first, a desired gap is provided from the convex defect to facilitate flattening of the upper surface of the film covering the convex defect.
Is formed, and then a second thin film is formed so as to cover the convex defect and the first thin film, thereby performing a two-step thin film formation.

Among the above defect repair processes, the feature of the recess defect repair process is that the embedding material is deposited so as to slightly protrude from the defect depending on the shape of the recess defect, and then the above convex defect is deposited. It is to be able to apply the correction process.

By applying the above defect repair process, it is possible to repair even a convex defect or a concave defect to be flat according to the substrate surface, which is extremely useful for repairing a defect such as a phase shift mask. It is valid.

The film forming method of the present invention is suitable for forming the first thin film, the second thin film and the like in the above defect correction process. The film forming method of the present invention is suitable for use in the above defect repair process, but can also be used in other defect repair processes. The film forming method of the present invention can also be used for purposes other than defect correction. In particular, the film forming method of the present invention is useful for forming a fine thin film pattern.

[0040]

The details of the present invention will be described below with reference to the illustrated embodiments. Reference Example 1 In this example , a method of correcting a convex defect of silicon oxide generated on a mask substrate of a phase shift mask will be described.

(Example 1) In the first example, a method of correcting a convex defect of silicon oxide generated on the mask substrate of the phase shift mask will be described.

The feature of the convex defect repairing process is that a flat film is formed on the convex defect using an FIB apparatus, and the deposited film and the convex defect are simultaneously removed by etching under the FIB processing conditions that have the same etching rate. And to determine the end point of the processing by detecting the inflection point of the ratio of the secondary ions emitted from the deposited film and the convex defect at that time. Therefore, if the film formed on the convex defect is not flat, the surface shape after etching both of them at the same time depends on the deposited film shape, which causes a problem that the convex defect cannot be corrected to be flat. The formation of the planarization film is the most important in the process.

FIG. 1 shows a schematic configuration of the FIB device used in the method of this example. This device has a well-known configuration, 1 is an ion source, 2 is a magnifying lens, 3 is a mass separation mechanism, 4 is a deflector, 5 is an objective lens, 6 is a charge neutralizer, and 7
Is a secondary ion detector, 8 is a sample, 9 is a sample stage, 1
Reference numeral 1 is a gas cylinder, 12 is a capacitance type pressure gauge (baratron), and 13 is a nozzle.

2 and 3 are process flows for correcting the convex defect 102 of the phase shifter formed on the quartz substrate 101, and FIGS. 2A and 3A are sectional views. 2B and 3B are plan views.

As shown in FIGS. 2 (A1) and 2 (B1), the phase shift mask is a shifter edge type phase shift mask in which a phase shifter pattern 103 made of silicon oxide is formed on a quartz substrate 101, for example. . The film thickness t of the phase shifter for inverting the phase is t = λ / {2 (n−, where λ is the wavelength of the exposure light source and n is the refractive index.
1)}. Here, KrF is used as a light source (λ = 248 nm), and the phase shifter is a silicon oxide film (n
= 1.508), t = 244 nm.

First, based on information such as the size, shape (convex or concave), and position of a defect obtained by using a general defect inspection device, the defect is corrected by using the FIB device shown in FIG. Recognize the flaws that should be. As a result, it is assumed that the convex defect 102 is recognized.

After the defect is confirmed, as shown in FIGS.
As shown in (B2), the first thin film 104 is formed into a doughnut-shaped defect 10 with a slight space around the convex defect 102.
Deposit to the same height as 2. This deposited film 104 is, for example, GaFI accelerated to 20 keV at room temperature (25 ° C.).
B is formed by assisted deposition in which pyrene gas is decomposed to deposit carbon (C). Here, since the first deposited film 104 needs to be finally removed, the substrate 10
It is essential that the selection ratio with respect to 1 is sufficiently large.

Next, as shown in FIGS. 2A3 and 2B3, a second deposited film 105 is formed in a region covering the convex defect 102 and the first deposited film 104. The formation of the second deposited film 105 is performed by the assist deposition like the formation of the first deposited film 104.

Here, the convex defect 102 and the first deposited film 1
04, and the second deposited film 105 has a thickness of 1.0 μm.
There is a relationship as shown in FIG. 4 with the depth y of the surface depression that occurs when the film is formed by m. That is, as x decreases, y decreases. This is because, in assisted deposition using an ion beam and gas, the deposition proceeds due to multiply scattered ions and secondary electrons inside the narrow groove, so that the convex defect 102 or the first deposited film 104 causes the inside of the groove to grow. This is because the film formation rate is faster, y is smaller, and a flat film can be obtained. In the two-step carbon film deposition method described above, only one step of forming the carbon film may be performed when the convex defect is small or the pattern is close to the defect to be repaired.

Then, as shown in FIGS. 3 (A4) and 3 (B4), the flat film (10) thus formed is formed.
4, 105) and the convex defect 102 are simultaneously etched back at the same rate (planarization and the planarization film and the etching target are simultaneously etched). For example, the above-mentioned 2
Carbon film 1 formed with 0 keV GaFIB and pyrene gas
04, 105 and a convex defect 102 composed of a silicon oxide film
When and are sputter-etched with GaFIB at room temperature, the etching rate ratio of C / SiO ₂ changes depending on the acceleration voltage of GaFIB as shown in FIG.
At V, the C / SiO ₂ etch rate ratio is about 1. Therefore, under this condition, the beam 106 narrowed down can be used to raster scan a region slightly larger than the convex defect 102 to simultaneously remove carbon and SiO ₂ at the same etching rate.

When the ratio of carbon and secondary ions of Si generated during this processing is measured by using the mass spectrometer 107, the moment when carbon around the convex defect 102 disappears in the beam scanning region. Since the secondary ion ratio of C / Si greatly changes, it can be determined that the convex defect 102 is cut to the same height as the surface of the substrate 101. It is also possible to use the C / O secondary ion ratio instead of the C / Si secondary ion ratio to determine the end point. A method of determining the end point of the process by using such secondary ion measurement is disclosed in, for example, Japanese Patent Laid-Open No. 58-106750. It is also possible to detect carbon and SiO ₂ by detecting secondary electrons.
It is possible to distinguish the interface between and.

However, in GaFIB sputtering, a damaged layer 108 having a depth of about 15 nm remains on the surface of the sputtered substrate 101, and the transmittance of light used for exposure is reduced. Therefore, the convex defect 102
After the removal is completed, for example, XeF ₂ gas and GaFIB are used to assist-etch the damaged layer 108 at room temperature as shown in FIGS. 3 (A5) and 3 (B5). Since the damaged layer cannot be formed by the assist etching using this gas, the damaged layer 108 can be removed. When the sample temperature is lower than room temperature, gas adsorption advances and etching can be performed more effectively. It should be noted that this processing produces a recess of about 15 nm, but such a recess does not transfer to the wafer and does not affect the surrounding pattern. Note that assist etching can be similarly performed by using an electron beam instead of GaFIB.

Finally, as shown in FIGS. 3 (A6) and 3 (B6), the carbon remaining in the periphery during the removal of the convex defect is replaced with O ₂
Remove by plasma asher. For example, when ashing is performed by flowing O ₂ gas so that the inside of the chamber becomes 0.9 Torr and applying high-frequency power of 500 W,
Carbon can be removed without damage. Removal of carbon, O ₂
Not plasma asher only, it is possible to perform even CDE using O ₂ gas or CF ₄ O ₂ gas was added. Further, it is effective to keep the substrate temperature at 150 to 400 ° C. Further, this removal can also be performed by laser light irradiation or FIB irradiation in an O ₂ or O ₃ atmosphere.

It should be noted that the removal of the residual carbon is more efficient if it is carried out collectively after the correction of all the defects. Further, the order of the last two steps, that is, the carbon removing step and the damage removing step can be exchanged.

Here, the steps formed on the surface of the substrate when the convex defect is repaired by using the above repair process will be described. The step formed by the correction is the sum of the depression amount y of the flattening film and the depression amount Dy capable of removing the damaged layer, and the convex or concave step De formed by the difference in etching rate between the flattening film and the defect is added. Amount.
Therefore, the step difference thus formed must be naturally suppressed to be equal to or less than the step difference that causes the line width variation that is allowed in the transfer pattern.

Taking the Levenson-type phase shift mask as an example, if the allowable value is 10% of the minimum resolution dimension, the wavelength is 2
48 nm, minimum dimension 0.25 μm, stepper NA = 0.
45, coherence factor indicating exposure wavelength coherence: Approximately 40 nm, wavelength 365 nm, minimum size 0.35 μm, stepper NA = 0.46, coherence factor indicating exposure wavelength coherence when σ = 0.3 It becomes about 80 nm when σ = 0.3. That is, if the amount of step difference is less than or equal to these steps, there is no problem in the transfer performance of the phase shift mask. In other words, the processing conditions of each step can be relaxed until (y + Dy + De) becomes the step. That is, if y = 10 nm and Dy = 15 nm at the wavelength KrF, the etching rate ratio (0.94 to 1.06) can be relaxed until De reaches a maximum of 15 nm.

As described above, if the convex defect is corrected according to the correction process flow of this example, the following effects can be obtained.

(1) The convex defect 102 has a flattening film (first deposited film 104, second deposited film 105) in a wider range than that.
Since it is covered with, it is possible to suppress the occurrence of damage to the periphery of the defect region caused by Ga beam irradiation during defect removal as much as possible.

(2) Flattening films (104, 10) made of different materials
5) and the convex defect 102 are processed at the same time, and a planarizing film (C) is formed.
It is easy to detect the end point of processing by measuring the secondary ions emitted from the defects (SiO ₂ ) or their secondary ion ratio or secondary electrons.

(3) By flattening the convex defect 102 having a non-uniform thickness using the flattening film (104, 105), it is possible to easily obtain a flat shape after correction.

(4) Damage layer 108 remaining on the substrate 101
Can be easily removed by assisted etching using XeF ₂ and GaFIB or an electron beam.

(5) Carbon film used for defect removal (10
4, 105) can also be easily removed by the O ₂ plasma asher without damaging others.

(6) Since most of the correction can be performed by using the GaFIB apparatus and changing the type of gas introduced into the apparatus, extremely efficient defect correction is possible.

Although the process of repairing a convex defect has been described above, this repair process is not limited to the above example.

In the above example, the carbon film formed of pyrene gas as a raw material is described as the flattening film for covering the convex defects, but a carbon film formed of another hydrocarbon gas as a raw material or W (CO) ₆ is used. You may use the tungsten film formed using it. The coverage of the tungsten film was almost the same as that of the carbon film, and when the above-described two-step deposition was performed at room temperature, a flat film with small dents on the surface could be obtained as with the carbon film. Furthermore, when the defect (SiO ₂ ) and the tungsten film are simultaneously processed, the etching rate ratio is about 1
Is in the acceleration voltage range of a general FIB device.

As the flattening film for covering the convex defects,
Not only the film formed by FIB, but also a film made of a photosensitive resin or a resin that is crosslinked or decomposed by charged particles may be used. In this case, after applying these resins on the reticle by spin coating, use a microscope or the coordinates obtained in the inspection process to narrow down only the area containing the desired defect using laser light and a slit. The light, FIB, or electron beam is emitted. By developing this, a flattening film is formed. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) when exposing the resist or the resist concentration. If the convex defect is small or the pattern is close to the defect to be repaired, it is sufficient to form the flattening film once.
After that, the same processing as the carbon film formed by using the FIB using the pyrene gas as a raw material can be performed. Also,
When a photosensitive resin or a resin that is crosslinked or decomposed by charged particles is used, it can be removed using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Further, although the simultaneous etching of carbon and SiO ₂ is performed by GaFIB in the above example, it is also possible to use FIB using gas or electron beam assisted etching. In this case, the etching rate of the deposited film and the shifter can be controlled by selecting or combining the gases.
Furthermore, if a mixed gas of XeF _{2 is used} as a gas, a damaged layer does not remain on the surface of the substrate during defect removal, and the step of removing the damaged layer in the above-described process flow can be reduced, thereby eliminating the need for additional digging. it can. in this case,
There is a point where the etching rate of carbon and SiO ₂ becomes about 1 within a general acceleration voltage range, and the absolute etching rate becomes higher than that in the case of sputter etching, so that the throughput can be improved.

In the GaFIB sputtering process, for example, the sputtering yield of a quartz substrate becomes saturated with time (FIG. 6). This is because in sputtering, the sputtered substance redeposits around the processing area and the sputtering yield becomes saturated over time. On the other hand, in the assisted etching using XeF ₂ gas and GaFIB or electron beam, the etching yield of the quartz substrate is always constant because there is no effect of redeposition (FIG. 7), and the controllability of the processing is very good. can get.

Further, although the carbon remaining after removing the defects was removed by the O ₂ asher in the above, for example, a laser may be used. This method uses the evaporation of carbon due to the absorption of laser light.When the laser light is narrowed down using a slit and the residual carbon is irradiated, the laser energy is absorbed by the carbon and becomes heat, which causes the carbon to sublime and scatter. To do.
Moreover, at this time, laser energy is also absorbed in the damaged layer, and the damaged layer is removed similarly to carbon. The two steps of removing the residual carbon and removing the damaged layer will be shortened to one step, and the repair process will be carried out more efficiently.

Another method is to react C with O ₂ or O ₃ by laser beam irradiation in an O ₂ or O ₃ atmosphere to remove CO and CO ₂ . In this case, since the chemical reaction is used, the power of the laser light can be reduced, and even if the light shield near the defect is irradiated with the laser light, the light shield does not evaporate and only carbon is removed. There are conditions that can be achieved. Therefore, there is an advantage that the tolerance of the beam diameter of the laser light and the tolerance of alignment are increased, and the process margin is widened. Further, when a laser is used, heating can be locally performed, so that pattern distortion due to heat can be suppressed. Further, similar effects can be expected by using FIB instead of laser light under O ₂ or O ₃ atmosphere. In this case, light ions are used or acceleration energy is set to 10 in order to obtain a selective ratio between the substrate and carbon.
It is necessary to use FIB with a keV or less.

Further, although the deposition of carbon, the simultaneous etching of carbon and SiO ₂ , and the removal of the damaged layer are all carried out by GaFIB, the present invention is not limited to this ion. For example, it is obvious that the process of each of the above steps may be performed using other ions such as Au and Si.

( Example 1 ) In this example , a method of correcting a shifter concave defect will be described in detail with reference to FIG. First, the defect to be repaired is recognized using the FIB device based on the information such as the size, shape (whether convex or concave) and position of the defect obtained by using a general defect inspection device. As shown in FIG. 8A, after the concave defect 202 is confirmed in the phase shifter 201, the concave defect 202 is detected at room temperature.
Si-O bond and / or Si-H from the nozzle 203 on top
A gas having a bond or a mixed gas containing it, eg 1,
While spraying a mixed gas 204 (mixing ratio = 1: 3) of 3,5,7-tetramethylcyclotetrasiloxane and oxygen, S of 50 keV was applied to a region slightly wider than the concave defect 202.
Irradiate i ²⁺ FIB205. As a result, FIG. 8 (B)
As shown in, S slightly protruding from the surface of the shifter 201
An iO ₂ film (embedding material) 206 is deposited. The diameter of the nozzle used here was 0.2 mm, and the pressure in the capacitance type pressure gauge shown in FIG. 1 was 4 Torr. At this time, the total flow rate of gas at the nozzle outlet was 0.05 sccm.

The 0.4 μm thick S deposited in this way
The light transmittance of the TiO ₂ film for light with a wavelength of 436 nm is 100.
%, And the light transmittance of a film (SiO _x ) formed using a conventional mixed gas of tetramethoxysilane and oxygen is 40%.
The optical characteristics are better than those described above. Further, the SiO ₂ film formed by the method of this example has a light transmittance of 90.6% with respect to light having a wavelength of 248 nm (light used in the Levenson-type phase shift mask method), which is the light transmission required for the correction of concave defects. It has a value equal to or higher than the rate (80.6%).

When it is necessary to improve the light transmittance of the deposited film, the following post-treatment may be performed. After the film deposition, UV light having a power density of 200 mW / cm ^{2 on} the surface of the deposited film is irradiated for 1 hour. Also, instead of such UV light treatment, a deposited film having a similar light transmittance can be obtained by performing film formation while irradiating UV light, and the other formed film is subjected to 350 ° C. in an O ₂ atmosphere at 350 ° C. The same effect can be obtained by performing the annealing treatment for 1 hour.

Here, the above-mentioned two kinds of gas may be sprayed from different nozzles respectively, and instead of oxygen, O ₃ ,
A gas containing oxygen as a main component such as N ₂ O may be used. The gas mixture ratio is not only 1: 7, but also the type of gas used, FI
The mixing ratio may be such that the deposit is transparent according to the ion species and energy of B and the concave defect is filled with a good shape. For example, T
When EOS (tetraethoxysilane) is used, at the room temperature, "su" can be formed inside the deposit, but when the mask temperature is lowered to about -70 degrees, "su" cannot be formed and the concave defect can be filled. . The energy and ion species of FIB are not only Si ²⁺ FIB of 50 keV but also 25 keV.
It is possible to select other energies and ion species such as V Ga ⁺ FIB. An electron beam may be used instead of the FIB.

However, when the charge neutralizer is near the gas nozzle and the radiant heat from the electron emitting filament in the neutralizer affects the gas, black contamination made of carbon adheres to the mask substrate. Therefore, it is desirable to place the charge neutralizer away from the gas nozzle.

Then, as shown in FIG.
₂ Make a small gap around the protrusion of the membrane 206
Thin film 207 is formed into a donut shape to the same height as the SiO ₂ film 206. This deposited film 207 is, for example, 20 ke
It is formed by assist deposition in which pyrene gas is decomposed by GaFIB accelerated to V and carbon (C) is deposited.

Then, as shown in FIG.
_{A second} deposited film 208 is formed in a region that covers the protruding portion of the _second film 206 and the first deposited film 207. SiO _{2 at} this time
Between the distance x between the protruding portion of the film and the first deposited film 207 and the depth y of the surface depression that occurs when the second deposited film 208 is formed to a thickness of 1.0 μm, There is a relationship as shown in 4. That is, as x decreases, y decreases.
This is because, in assisted deposition using an ion beam and a gas, the deposition proceeds due to multiple scattering ions and secondary electrons inside the narrow groove, so that the protrusions of the SiO ₂ film 206 and the first deposited film 207 are deposited. This is because the film formation rate becomes faster inside the groove and y becomes smaller, so that a flat film can be obtained.

Then, as shown in FIG. 8E, the flat films (207, 208) thus formed and Si are formed.
The protruding portion of the O ₂ film 206 is simultaneously etched at the same rate. For example, the above-mentioned carbon film (207, 208) formed of 20 keV GaFIB and pyrene gas and SiO
_When the projection of the ₂ film 206 is sputter-etched with GaFIB, the etching rate ratio of C / SiO ₂ changes depending on the acceleration voltage of GaFIB as shown in FIG. The etching rate ratio of ₂ is about 1. Therefore, the beam 20 narrowed down under these conditions
By using 9 to scan a region slightly larger than the protruding portion, carbon and SiO ₂ can be simultaneously removed at the same etching rate.

When the ratio of the secondary ions of carbon and Si generated during this processing is measured by using the mass spectrometer 210, the carbon around the protrusion of the SiO ₂ film 206 in the beam scanning region is measured. Since the secondary ion ratio of C / Si changes greatly at the moment of disappearance, it can be determined that the protruding portion of the SiO ₂ film 206 is cut to the same height as the surface of the shifter 201.
It is also possible to determine the end point by using the secondary ion ratio of C / O instead of the secondary ion ratio of C / Si.

However, the GaFIB sputtering process leaves a damaged layer 211 having a depth of about 15 nm on the processed substrate surface, and reduces the transmittance of light used for exposure. Therefore, after the removal of the protruding portion of the SiO ₂ film 206 is completed, as shown in FIG. 8F, the damage layer 211 is assist-etched by using, for example, XeF ₂ gas and GaFIB. Since the damaged layer 211 does not remain in the assisted etching using this gas, the damaged layer 2
11 can be removed. In addition, about 1
Although a recess of 5 nm can be formed, such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG. 8G, SiO
₂ When removing the protrusion of the film 206, the carbon remaining around is removed by O ₂
Remove by plasma asher. For example, when ashing is performed by flowing O ₂ gas so that the inside of the chamber becomes 0.9 Torr and applying high-frequency power of 500 W,
Carbon can be removed without damage. Carbon is removed not only by O ₂ plasma asher but also by O ₂ gas or C
It is also possible to perform CDE using O ₂ gas to which F ₄ is added. Further, it is more effective to keep the substrate temperature at 150 to 400 ° C. Further, it is possible to remove carbon also by laser light irradiation in an O ₂ or O ₃ atmosphere or FIB irradiation.

It is more efficient to remove the residual carbon if it is carried out collectively after the correction of all the defects. Further, the order of the last two steps, the carbon removing step and the damage removing step can be exchanged.

As described above, when the concave defect is corrected according to the correction process flow of this example, the following effects can be obtained.

(1) Since it is not necessary to fill the concave defect 202 with the SiO ₂ film 206 in the same manner as the concave shape, the process becomes extremely simple.

(2) Since the protruding portion formed by the filling of the concave defect 202 is covered with the planarizing film (first deposited film 207, second deposited film 208) in a wider range than that, the protruding portion is projected. At the time of removing the portion, it is possible to suppress the occurrence of damage to the periphery of the defective region due to Ga beam irradiation as much as possible.

(3) Flattening films (207, 20) made of different materials
8) and the protrusions of the SiO ₂ film 206 are processed at the same time, and the secondary ions emitted from the flattening film (C) and the protrusions (SiO ₂ ) or their secondary ion ratios are measured to process the protrusions. It is easy to detect the end point of.

(4) Since the protrusions having a non-uniform thickness are also flattened by using the flattening film (207, 208), the correction surface is easily flattened.

(5) The damaged layer 211 remaining on the surface of the corrected concave defect can be easily removed by assist etching using XeF ₂ and GaFIB.

(6) Carbon film (20) used for defect repair
7, 208) can be easily removed by the O ₂ plasma asher without damaging others.

(7) Since most of the repair can be performed by using the GaFIB device and only changing the type of gas introduced into the device, extremely efficient defect repair is possible.

Although the process of repairing a concave defect has been described above, this repair process is not limited to the above example.

In the above example, the carbon film formed by using pyrene gas as a raw material was used as the flattening film for covering the protrusions remaining after the concave defects were filled with SiO ₂ , but the carbon film formed by using another hydrocarbon gas as a raw material was described. Membrane or W (C
A tungsten film formed using O) ₆ can also be used. The coverage of the tungsten film is almost the same as that of the carbon film, and when the above-mentioned two-step deposition was performed, a flat film with small dents on the surface could be obtained as with the carbon film. Furthermore, in the simultaneous processing of the protrusion (SiO ₂ ) and the tungsten film, the point that the etching rate ratio becomes about 1 exists in the acceleration voltage range of a general FIB device.

As the flattening film for covering the convex defect,
Not only the film formed by FIB but also a film made of a photosensitive resin or a resin that is crosslinked or decomposed by charged particles. When forming these films, after coating these resins on the reticle by spin coating, use a microscope or use the coordinates obtained in the inspection process to laser light and slit only the area containing the desired defect. To irradiate light, FIB or electron beam that has been squeezed. Then
This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) when exposing the resist or the resist concentration. If the convex defect is small or the pattern is close to the defect to be repaired, it is sufficient to form the flattening film once. Thereafter, F using the above pyrene gas as a raw material
The same processing as the carbon film formed using IB can be performed. When a photosensitive resin or a resin that is crosslinked or decomposed by charged particles is used, it can be removed by using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Further, the same modification as in the first example is possible as the simultaneous etching of carbon and SiO ₂ . further,
The removal of the flattening film remaining after the removal of the protruding portion can be modified in the same manner as in the first example. Also, carbon deposition, carbon,
The ion source used for simultaneous etching of SiO ₂ and removal of the damaged layer can be modified in the same manner as in the first example.

Further, in the above process, the shape of the concave defect is formed.
Although I did not describe it, the process was saved depending on the shape.
It can be abbreviated. That is, a concave shape with a large aspect ratio
In case of defects, 1,3,5,7-tetramethylcycloteto
SiO using Lasiloxane ₂The stacking shape of Fig. 9 (A)
become that way. In such a case, unevenness on the surface is a defect
As it fits within the size of the step allowed by the modification,
It is not necessary to proceed with the steps after (C).

In the above example, the concave defect is filled with the silicon oxide film, but the filling material is not limited to silicon oxide. The burying material should be selected depending on the material of the shifter, and the above modification can be similarly performed with silicon nitride, chromium oxide or the like.

Other than the above, various modifications can be made without departing from the scope of the present invention.

( Embodiment 2 ) In this embodiment , a shifter of a shifter edge type phase shift mask is used.
FIG. 11 shows a method of repairing the concave defect in the edge portion.
And FIG. 12 will be described. Here, FIGS. 11A and 12A are cross-sectional views, and FIGS.
(B) shows a plan view.

First, the FIB device is used to recognize the defect to be corrected based on the information such as the size, shape (whether convex or concave) and position of the defect obtained by using a general defect inspection device. As shown in FIG. 11 (A1) and FIG. 11 (B1),
After the concave defect 303 is confirmed at the edge portion of the phase shifter 302 formed on the SiO ₂ substrate 301, the gas having the Si—O bond and / or the gas having the Si—H bond from the nozzle 304 on the concave defect 303. , Or a mixed gas containing the same, for example, a mixed gas 305 of 1,3,5,7-tetramethylcyclotetrasiloxane and oxygen (mixing ratio = 1:
While spraying 7), a region slightly wider than the concave defect region is irradiated with 50 keV Si ²⁺ FIB306. As a result, as shown in FIGS. 11 (A2) and 11 (B2),
Protruding SiO ₂ 307 is deposited in a region wider than the concave defect 303.

Here, the above-mentioned two kinds of gas may be sprayed from different nozzles respectively, and instead of oxygen, O ₃ ,
A gas containing oxygen as a main component such as N ₂ O may be used. The mixing ratio of gases is not only 1: 7, but also the type of gas used, FI
The mixing ratio may be such that the deposit becomes transparent according to the ion species and energy of B. The energy and ion species of FIB are not only Si ²⁺ FIB of 50 keV but also 25 keV.
It is possible to select other energies and ion species such as V Ga ⁺ FIB. An electron beam may be used instead of the FIB.

Next, FIG. 11 (A3) and FIG. 11 (B3)
As shown in FIG.
Thin films (carbon films) 308 and 308 'are formed. At this time, the protruding SiO ₂ 307 and the first carbon film 308, 308 '
The distance between and is 0.4 μm or less.

Next, FIG. 11 (A4) and FIG. 11 (B4)
The second thin film (carbon film) 309 is formed by projecting Si
It is formed on the O ₂ 307 and the first carbon films 308 and 308 ′ by the same method as described above. The film thickness is about 1 μm.
By doing so, the surface of the second carbon film 309 becomes flat.

Next, FIG. 12 (A5) and FIG. 12 (B5)
As shown in FIG. 3, the flat film 309 thus formed is formed.
And the protrusion 307 are simultaneously etched at the same rate.
For example, when the carbon films 308, 308 ′ and 309 formed by using the above-mentioned 20 keV GaFIB and pyrene gas and the protrusion 307 made of a silicon oxide film are sputter-etched by GaFIB, as shown in FIG. Si
The etching rate ratio of O ₂ changes depending on the acceleration voltage of GaFIB, and the etching rate ratio of C / SiO ₂ becomes about 1 at about 30 kV. Therefore, by using the beam 310 narrowed down under this condition, a region slightly larger than the protrusion 307 can be raster-scanned to remove carbon and SiO ₂ at the same etching rate at the same time.

When the ratio of the secondary ions of carbon and Si generated during this processing is measured using the mass spectrometer 311,
At the moment when carbon around the convex defect disappears in the beam scanning region, the secondary ion ratio of C / Si changes greatly and the protrusion 30
It can be determined that 7 is ground to the same height as the surface of the shifter 302. Also, instead of the secondary ion ratio of C / Si,
It is also possible to determine the end point by using the secondary ion ratio of C / O.

Further, in the concave defect at the edge portion, it is necessary to remove the extra protrusion generated for correction in accordance with the edge. First, the edge position is detected using the FIB. Next, the protrusion S protruding from the extension line of the edge portion
The beam scan area is determined so that all of the iO ₂ 313 can be removed. One side of the scanning area is aligned with the edge position previously obtained, and the narrowed beam is raster-scanned to project 31
3, that is, carbon and SiO2 are removed at the same etching rate at the same time. At the end point of the processing of the protrusion 313, the ratio of carbon and Si secondary ions generated during this processing is measured using a mass spectrometer. That is, the protrusion 313 in the beam scanning area
It is determined that the secondary ion ratio of C / Si is greatly changed and the protrusion 313 is cut to the same height as the surface of the quartz substrate 301 at the moment when the carbon around is disappeared.

However, with GaFIB sputtering, a depth of 15 nm is formed on the surface of the sputtered substrate.
The damaged layer 312 remains to some extent, which reduces the light transmittance used for exposure. Therefore, after the removal of the protrusions 307 and 313 is completed, the damage layer 312 is assisted etched by using, for example, XeF ₂ gas and GaFIB.
Since the damaged layer does not remain in the assist etching using this gas, the damaged layer 312 can be removed as shown in FIGS. 12 (A7) and 12 (B7). By this processing, a recess of about 15 nm can be formed, but such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, FIG. 12 (A8) and FIG. 12 (B8)
As shown in Fig. 3, when the protrusions 307 and 313 are removed, the
Carbon₂Remove with plasma asher.
For example, O₂So that the gas in the chamber is 0.9 Torr
And apply high-frequency power of 500 W to
Singing can remove carbon without damage. carbon
Removal of O₂Not only plasma asher, but also O₂gas
Or CF_FourO added₂You can also do CDE using gas
And are possible. Note that removal of residual carbon is
It is more efficient if you do it all at once after the correction of the pitfalls is completed.
It Also, the last step, carbon removal step and damage removal step
It is also possible to change the order. Furthermore, the substrate
It is more effective to keep the temperature at 150 to 400 ° C. It
In addition, O ₂Or O₃Laser irradiation or FIB in the atmosphere
Irradiation can also remove carbon.

As described above, the following effects can be obtained by repairing the concave defect at the edge portion according to the repair process flow of this embodiment.

(1) Since it is not necessary to fill the concave defect 302 with SiO ₂ in the same manner as the concave shape, the process becomes extremely simple.

(2) The protrusion 307 caused by the filling of the concave defect 302 is covered with the flattening film (the first carbon film 308 and the second C film 309) in a wider range than that, and therefore the protrusion At the time of removal, it is possible to suppress the occurrence of damage to the periphery of the defective area caused by Ga beam irradiation as much as possible.

(3) Flattening films (308, 30) made of different materials
9) and the protrusion 307 are processed at the same time, and secondary ions or those 2 emitted from the flattening film (C) and the protrusion (SiO ₂ ) are processed.
By measuring the secondary ion ratio, the end point of protrusion processing can be easily detected.

(4) Since the protrusion 307 having a non-uniform thickness is also flattened by using the flattening film (308, 309), the correction surface is easily flattened.

(5) The damaged layer 312 remaining on the surface of the corrected concave defect can be easily removed by the assist etching using XeF ₂ and GaFIB.

(6) The carbon film used for defect correction is also O
₂ It can be easily removed with the plasma asher without damaging others.

(7) Since most of the correction can be performed by using the GaFIB apparatus and changing the kind of gas introduced into the apparatus, extremely efficient defect correction is possible.

Although the process of repairing a concave defect has been described above, this repair process is not limited to the above example.

In the above example, the carbon film formed by using pyrene gas as a raw material is described as the flattening film for covering the protrusions remaining after the concave defects are filled with SiO ₂ , but the carbon film formed by using another hydrocarbon gas as a raw material. Or for example W (C
You may use the tungsten film formed using O) ₆ . The coverage of the tungsten film is almost the same as that of the carbon film, and when the above-mentioned two-step deposition was performed, a flat film with small dents on the surface could be obtained as with the carbon film. Further, in the simultaneous processing of the defects (SiO ₂ ) and the tungsten film, there is a tendency as shown in FIG. It exists in the acceleration voltage range.

As the flattening film for covering the convex defects,
Not only the film formed by FIB but also a film made of a photosensitive resin or a resin that is crosslinked or decomposed by charged particles. When forming these films, after coating these resins on the reticle by spin coating, use a microscope or use the coordinates obtained in the inspection process to laser light and slit only the area containing the desired defect. To irradiate light, FIB or electron beam that has been squeezed. Then
This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) when exposing the resist or the resist concentration. If the convex defect is small or the pattern is close to the defect to be repaired, it is sufficient to form the flattening film once. Thereafter, F using the above pyrene gas as a raw material
The same processing as the carbon film formed using IB can be performed. When a photosensitive resin or a resin that is crosslinked or decomposed by charged particles is used, it can be removed by using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Further, as for the simultaneous etching of carbon and SiO ₂ , the same modification as in Reference Example 1 is possible. further,
The removal of the carbon remaining after the removal of the protruding portion can be modified in the same manner as in Reference Example 1 . Also, carbon deposition, carbon, Si
The ion source used for simultaneous etching of O ₂ and removal of the damaged layer can also be modified in the same manner as in Reference Example 1 .

In the above example, the concave defect is filled with the silicon oxide film, but the filling material is not limited to silicon oxide. The burying material should be selected depending on the material of the shifter, and the above modification can be similarly performed with silicon nitride, chrome oxide or the like.

In addition, various modifications can be made without departing from the scope of the present invention.

Reference Example 2 In this example , the shifter of the shifter edge type phase shift mask is used.
A method of correcting a convex defect in the edge portion will be described with reference to FIG. Here, FIG. 13A is a cross-sectional view and FIG. 13B is a plan view, where 401 is a substrate, 402 is a phase shifter, and 403 is a convex defect.

First, the defect to be corrected is recognized by using the FIB device based on the information such as the size, shape (whether convex or concave) and position of the defect obtained by using a general defect inspection device. In this case, since the defect protrudes from the edge, it corresponds to a state in which the steps of the correction method shown in FIGS. 11A2 and 11B2 are completed. Therefore, after that, if the process is advanced according to the following steps, the correction of the convex defect at the edge portion is completed. Although it protrudes from the edge, if it is thinner than the shifter film thickness, it is shown in FIGS. 11 (A3) and 11 (B3).
12 (A5) and 12 (B5) among the steps shown below
The step shown in can be omitted.

Reference Example 3 In this example , a method for correcting an irregular convex defect which is not a rectangular parallelepiped and is formed of silicon oxide on the mask substrate of the phase shift mask will be described. The occurrence of such defects is caused by adhesion of dust during etching, resist residue, pinholes, etc., and many defects occur.

The feature of the convex defect repairing process is that a flat film is formed on the convex defect by using the FIB apparatus, and the deposited film and the convex defect are simultaneously removed by etching under the FIB processing conditions with the same etching rate. And to try to determine the processing end point by detecting the inflection point of the ratio of the secondary ions emitted from the deposited film and the convex defect at that time. Therefore, if the film formed on the convex defect is not flat, the surface shape after etching both of them at the same time depends on the shape of the deposited film, which causes a problem that the convex defect cannot be corrected to be flat. Therefore, the formation of the flattening film becomes the most important.

FIG. 14 is a process flow for correcting the convex defect 502 of the phase shifter formed on the quartz substrate 501. This phase shift mask is, for example, a shifter edge type phase shift mask in which a phase shift pattern of silicon oxide is formed on a quartz substrate 501. The film thickness t of the phase shifter for inverting the phase is t = λ / {2 (n−, where λ is the wavelength of the exposure light source and n is the refractive index.
1)}. Here, KrF is used as a light source (λ = 248 nm), and the phase shifter is a silicon oxide film (n = n).
1.508), so t = 244 nm.

First, the FIB device is used to recognize the defect to be corrected based on the information such as the size, shape, film thickness and position of the defect obtained by using a general defect inspection device. As a result, it is assumed that the convex defect 502 is recognized.

Next, a film is formed so as to flatly cover the convex defects. This deposited film is, for example, at room temperature (25 ° C.) 20
It is formed by assist deposition in which pyrene gas is decomposed by GaFIB accelerated to KeV and carbon (C) is deposited.

In the case of correcting the defect as shown in FIG. 14 (A), the same method as in the reference example 1 , that is, FIG. 15 (A), FIG.
As shown in (B), the first deposited film 503 is formed in a donut shape to the same height as the defect 502 with a slight space around the defect 502, and then the convex defect 502 and the first deposited film 503 are formed. If only the second deposited film 504 is formed so as to cover it, the result is as shown in FIG. as a result,
The second deposited film 504 needs to be deposited very thickly for planarization, which is not practical.

Therefore, based on the information about the defect shape obtained by the defect inspection apparatus, as shown in FIG. 14B, an appropriate distance is set so that the height is the same as the highest portion of the convex defect 502. To form a first deposited film 503. Then, as shown in FIG.
2 and the first deposited film 503 in a region covering the second deposited film 50.
4 is formed.

The distance x between the first deposited films 503 can be determined from the relationship between the distance x and the depth y of the recess of the plane when the thickness of the second deposited film 504 is constant. For example, when the second deposited film 504 is formed with a thickness of 1.0 μm, there is the relationship as shown in FIG. That is, as x decreases, y decreases. This is because, in assisted deposition using an ion beam and a gas, the deposition proceeds due to multiple scattered ions and secondary electrons inside the narrow groove, so that the film formation rate inside the groove is higher than that on the first deposited film 503. Is faster and y is smaller to obtain a flat film.

In the above description, the convex defect is flattened in two steps. However, when the convex defect is highly uneven as shown in FIG. As shown, it is effective to use a multi-step process to fill the convex defects with the first, second, and third deposited films 503, 504, and 508.

Then, as shown in FIG.
Flat films (503, 504) formed in this way and convex
Back defects 502 at the same rate at the same time
It For example, the above-mentioned 20 keV GaFIB and pyrene
Carbon film (503, 504) formed by gas and silicon acid
The convex defects 502 made of a chemical film at room temperature (25 ° C.)
When performing sputter etching with FIB, please refer to FIG.
Sea urchin C / SiO₂Etch rate ratio is GaFIB acceleration
It changes depending on the voltage, and C / SiO at about 30 kV ₂D
The crate rate is about 1. Therefore, under this condition
Slightly larger than the convex defect 502 using
Raster scan the threshold area to simultaneously scan carbon and SiO2.
Can be scraped off at one etching rate.

When the ratio of the secondary ions of C and Si generated during this processing is measured using the mass spectrometer 506,
At the moment when carbon around the convex defect 502 disappears in the beam scanning region, the secondary ion ratio of C / Si changes greatly,
It can be determined that the convex defect 502 is cut to the same height as the surface of the substrate 501. It is also possible to use the C / O secondary ion ratio instead of the C / Si secondary ion ratio to determine the end point. A method of determining the end point of the process by using such secondary ion measurement is disclosed in, for example, Japanese Patent Laid-Open Publication No.
No. 8-106750.

However, in the GaFIB sputtering, the damaged layer 507 having a depth of about 15 nm remains on the surface of the sputtered substrate 501, which lowers the transmittance of light used for exposure. Therefore, after the removal of the convex defect 502 is completed, for example, using XeF ₂ gas and GaFIB at room temperature (25 ° C.), as shown in FIG.
The damaged layer 507 is assist-etched. Since a damaged layer cannot be formed by the assist etching using this gas, the substrate surface can be brought into a good state without damage. By this processing, a recess of about 15 nm can be formed, but such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG.
The carbon remaining in the surroundings when removing ₂Plasma asher
To remove. For example, O₂Gas in the chamber
Flow at 0.9 Torr and apply high frequency power of 500W.
Carbon without damage when ashed by adding
Can be removed. Removal of carbon is O₂plasma
Not only asher₂Gas or CF_FourO added
₂It is also possible to use CDE using gas. Furthermore
Better than keeping the substrate temperature at 150-400 ℃
Target. Furthermore, O₂Or O₃Laser illumination in the atmosphere
This can also be removed by irradiation or FIB irradiation.

It should be noted that the removal of the residual carbon is efficient if it is carried out collectively after the correction of all the defects is completed. Also,
The order of the last two steps, the carbon removing step and the damage removing step can be interchanged.

The step formed on the surface of the substrate when the convex defect is repaired by the above repair process will be described below. The step formed by the correction is the sum of the depression amount y of the flattening film and the depression amount Dy caused by the removal of the damaged layer, and the convex or concave step De formed by the difference in etching rate between the flattening film and the defect is added. It will be Therefore, the step formed in this manner must be suppressed to be equal to or less than the step that causes the line width variation allowed in the transfer pattern.

Taking the Levenson type phase shift mask as an example, if the allowable value is 10% of the minimum resolution dimension, the wavelength 2
48 nm, minimum dimension 0.25 μm, stepper NA = 0.
45, coherence factor σ = 0.3 indicating exposure wavelength coherence, wavelength 365 nm, minimum size 0.35 μm, stepper NA = 0.46, coherence factor σ indicating exposure wavelength coherence In the case of = 0.3, it becomes about 80 nm. That is, if the amount of step difference is less than or equal to these steps, there is no problem in the transfer performance of the phase shift mask.
In other words, the processing conditions of each step can be made softer until (y + Dy + De) becomes the step. That is, if y = 10 nm and Dy = 15 nm at the wavelength KrF, the etching rate ratio (0.94 to 1.06) can be relaxed until De reaches a maximum of 15 nm.

When the convex defect is corrected according to the correction process flow of this embodiment, the following effects can be obtained.

(1) The convex defect 502 has a flattening film (first deposited film 503, second deposited film 504) in a wider range than that.
Since it is covered with, it is possible to suppress the occurrence of damage to the periphery of the defect region caused by Ga beam irradiation during defect removal as much as possible.

(2) Flattening films (503, 50) made of different materials
4) and the convex defect are processed at the same time, and the secondary ions emitted from the flattening film (C) and the defect (SiO ₂ ) or the ratio of these secondary ions are measured, so that the processing end point can be easily detected. .

(3) By flattening the convex defect 502 having a non-uniform thickness by using the flattening film (503, 504), the corrected flat shape can be easily obtained.

(4) Damage layer 507 remaining on the substrate 501
Can be easily removed by assisted etching using XeF ₂ and GaFIB.

(5) Carbon film used for defect removal (50
3, 504) can be easily removed by O ₂ plasma asher without damaging others.

(6) Since most of the correction can be performed by using the GaFIB apparatus and changing the kind of gas introduced into the apparatus, extremely efficient defect correction is possible.

Although the process of repairing a convex defect has been described above, this repair process is not limited to the above example.

In the above example, the carbon film formed of pyrene gas as a raw material is described as the flattening film for covering the convex defects, but a carbon film formed of another hydrocarbon gas as a raw material or W (CO) ₆ is used. It may be a tungsten film formed as described above. The coverage of the tungsten film was almost the same as that of the carbon film, and when the above-described two-step deposition was performed at room temperature (25 ° C.), a flat film with small depressions on the surface could be obtained as with the carbon film. Further, in the simultaneous processing of defects (SiO ₂ ) and the tungsten film, the point that the etching rate ratio becomes about 1 exists in the acceleration voltage range of a general FIB device.

Further, as a flattening film for covering the convex defect, F is used.
Not only the film formed of IB, but also a film made of a photosensitive resin or a resin that is crosslinked or decomposed by charged particles may be used. After applying these resins on the reticle by spin coating, laser light only in the region containing the desired defect using the microscope or using the coordinates obtained in the inspection process, the light squeezed using the slit, Irradiate with FIB or electron beam. This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) when exposing the resist or the resist concentration. If the convex defect is small or the pattern is close to the defect to be repaired, it is sufficient to form the flattening film once. After that, the same processing as the carbon film formed by using FIB using the above-mentioned pyrene gas as a raw material can be performed. When a photosensitive resin or a resin that is crosslinked or decomposed by charged particles is used, it can be removed by using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Further, although the simultaneous etching of carbon and SiO ₂ is performed by GaFIB in the above example, it is also possible to use FIB assisted etching using gas. In this case, the etching rate of the deposited film and the shifter can be controlled by selecting or combining the gases. Furthermore, if a mixed gas of XeF _{2 is used} as a gas, no damage layer remains on the substrate surface when removing defects, and the damage layer removal process in the above-mentioned process flow can be reduced, eliminating the need for extra digging. it can. In this case, there is a point where the etching rate of carbon and SiO ₂ becomes about 1 within a general voltage range, and the absolute etching rate becomes larger than that in the case of sputter etching, so that the throughput can be improved. .

In GaFIB sputtering, for example, the sputtering yield of a quartz substrate becomes saturated with time (FIG. 6). This is because in sputtering, the sputtered substance redeposits around the processing area and the sputtering yield becomes saturated over time. On the other hand, in the assisted etching using XeF ₂ gas and GaFIB, the etching yield of the quartz substrate is always constant because there is no effect of redeposition (FIG. 7), and there is an advantage that the controllability of processing is extremely good.

Further, although the carbon remaining after removing the defects is removed by the O ₂ asher in the above, laser light may be used, for example. One method uses evaporation of carbon by absorption of laser light.When the laser light is narrowed using a slit and irradiated to residual carbon, the laser energy is absorbed by carbon and becomes heat, and carbon sublimes and scatters. . At this time, laser energy is also absorbed in the damaged layer, and the damaged layer is removed similarly to carbon. The two steps of residual carbon removal and damaged layer removal will be shortened to one step, and the repair process will be carried out more efficiently.

As another method, O₂Or O₃Atmosphere
Carbon and O by laser light irradiation under air ₂Or O₃React
CO, CO₂It is to remove as. This
In the case of using a chemical reaction, the laser
The power of light can be reduced, and the light shield near the defect can be recorded.
The light shield does not evaporate when exposed to laser light, and only carbon is removed.
There are conditions that can be left. Therefore, the beam diameter of the laser light
Tolerance, alignment tolerance, process
This has the advantage of increasing the margin. In addition, laser light
When used, heating can be performed locally, so the pattern is
Distortion can be suppressed. Furthermore, O₂Or O₃Atmosphere
The same effect can be obtained by using FIB instead of laser light under air.
The fruit can be expected. In this case, the choice of substrate material and carbon
Use light ions or acceleration energy to take the ratio
It is necessary to use an FIB with a voltage of 10 keV or less.

Further, although the deposition of carbon, the simultaneous etching of carbon and SiO ₂ , and the removal of the damaged layer are all carried out by GaFIB, the present invention is not limited to this ion. For example, it is obvious that the process of each of the above steps may be performed using other ions such as Au and Si.

Besides, various modifications can be made without departing from the scope of the present invention. In addition, in the above-mentioned example, the correction method for the shifter made of silicon oxide has been described, but the application targets of the first and second defect correction methods are not limited to the shifter made of silicon oxide. It is also applicable to a shifter made of an organic material such as a resist, a shifter made of silicon, a silicon nitride, and the like. Further, it can be applied to the correction of a normal Cr mask or an X-ray mask.

( Embodiment 3 ) In this embodiment , a method of correcting an irregular shape shifter concave defect which is not a rectangular parallelepiped by reducing unevenness on the surface will be described in detail with reference to FIG.

First, on the basis of information such as the size, shape (whether convex or concave), film thickness, and position of a defect obtained by using a general defect inspection device, a defect to be corrected by the FIB device. Recognize. After the concave defect 602 is confirmed in the phase shifter 601, a silicon oxide film is formed so as to slightly project from the surface of the shifter 601 by using gas blown from a nozzle and FIB.

At this time, the FIB is formed so as to cover the entire concave defect.
17A, it is necessary to project and deposit the recessed defect having a complicated shape as shown in FIG. 17A so as to be considerably larger than the surface of the shifter. is not. Therefore, multi-stage deposition is performed to reduce surface irregularities. Based on the information about the defect shape obtained by the defect inspection apparatus, the first silicon oxide films 603 are formed at appropriate intervals so that the height is almost the same as the surface of the substrate as shown in FIG. 17B. Form.

Next, as shown in FIG. 17C, a second silicon oxide film 604 is formed in a region covering the concave defect 602 and the first silicon oxide film 603. In assisted deposition using an ion beam and a gas, since the deposition proceeds due to multiple scattering ions and secondary electrons inside the narrow groove, the film formation rate inside the groove is higher than that on the first silicon oxide film 603. It becomes faster, and the unevenness of the surface becomes smaller, so that a flat film can be obtained.

In the above, the concave defect is filled with the silicon oxide film in two steps. However, when the concave defect has a large unevenness as shown in FIG. 18A, as shown in FIGS. 18B to 18D. The multi-step process is used to remove the concave defects from the first, second, third and fourth silicon oxide films (deposited films) 603, 6
The method of embedding with 04,610,612 is effective.

The silicon oxide film is a gas having a Si--O bond and / or a Si--H bond, or a mixed gas containing the same, for example, a mixed gas of 1,3,5,7-tetramethylcyclotetrasiloxane and oxygen. 50 keV Si ²⁺ FIB at room temperature (25 ° C) while spraying (mixing ratio = 1: 7)
Is formed by irradiation. The diameter of the nozzle used here is 0.2
mm, and the pressure measured by the capacitance type pressure gauge shown in FIG. 1 was 4 Torr. At this time, the total flow rate of gas at the nozzle outlet is 0.
It was 05 sccm.

The thus-formed silicon oxide film having a thickness of 0.4 μm has a light transmittance of 10 at a wavelength of 436 nm.
It is 0%, which is excellent in optical characteristics as compared with the conventional film formed using a mixed gas of tetramethoxysilane and oxygen having a light transmittance of 40%. Further, the light transmittance of the silicon oxide film formed by the method of this example for light having a wavelength of 248 nm (light used in the Levenson type phase shift mask method) is 90.6%, which is the light required for repairing the concave defect. It has a value equal to or higher than the transmittance (80.6%).

If it is necessary to improve the light transmittance of the deposited film, the following post-treatment may be performed. UV with a power density of 200 mW / cm ^{2 on} the surface of the deposited film after film formation
A process of irradiating with light for 1 hour is performed. Also, such UV
A deposited film having the same light transmittance can be obtained by performing film formation while irradiating UV light instead of light treatment, and the other formed film is annealed at 350 ° C. for 1 hour in an O ₂ atmosphere. However, the same effect can be obtained.

Here, the above-mentioned two kinds of gas may be sprayed from different nozzles respectively, and instead of oxygen, O ₃ ,
A gas containing oxygen as a main component such as N ₂ O may be used. The gas mixture ratio is not only 1: 7, but also the type of gas used, FI
The mixing ratio may be set so that the deposit is transparent according to the ion species and energy of B and no void is formed inside. For example TEO
When S is used, "su" is formed inside the deposit at room temperature, but when the mask temperature is lowered to about -70 degrees, "su" cannot be formed and the concave defect can be filled. FI
B energy and ion species are 50 keVSi ²⁺ FIB
Not only that, other energies and ion species such as 25 keV Ga ⁺ FIB can be selected. Also,
An electron beam may be used instead of the FIB.

However, when the charge neutralizer is near the gas nozzle and the radiant heat from the electron emission filament in the neutralizer affects the gas, black contamination made of carbon adheres to the mask substrate. Therefore, it is desirable to place the charge neutralizer away from the gas nozzle.

Next, as shown in FIG. 17D, the first flattening film 605 is formed into a donut-shaped silicon oxide film (donut shape) with a slight space around the protrusions of the silicon oxide film (603, 604). 603, 604). The flattening film 605 is formed by assist deposition in which carbon (C) is deposited by decomposing pyrene gas with GaFIB accelerated to 20 keV, for example.

Next, as shown in FIG. 17E, the silicon oxide films (603, 604) and the first flattening film 605 are formed.
A second flattening film 606 is formed in a region covering the. At this time, the distance x between the protruding portion of the silicon oxide film and the first flattening film 605 and the depth y of the surface depression that occurs when the second flattening film 606 is formed with a thickness of 1.0 μm. There is a relationship between them as shown in FIG. That is, as x decreases, y decreases. This is because, in assisted deposition using an ion beam and gas, the deposition proceeds due to multiply scattered ions and secondary electrons inside the narrow groove, so the protrusions of the silicon oxide film (603, 604) and the first flattening are performed. Membrane 6
This is because the film formation rate in the inside of the groove is higher than that in the above 05, y is small, and a flat film can be obtained.

In the above description, the concave defect portion was flattened in two steps. However, when the concave defect has a large unevenness, the concave defect is buried in one step or two steps, and then a multi-step process as shown in FIG. It is also effective to flatten the concave defect portion by using.

Next, as shown in FIG. 17F, the flat films (605, 606) thus formed and the silicon oxide films (603, 604) are simultaneously etched back at the same rate. For example, the above-mentioned 20 keV G
Carbon film formed by using aFIB and pyrene gas (60
5, 606) and a protrusion (60
3, 604) with GaFIB by sputter etching, the etching rate ratio of C / SiO ₂ changes depending on the acceleration voltage of GaFIB as shown in FIG.
The etching rate ratio of C / SiO ₂ is about 1 at 0 kV. Therefore, under this condition, the beam 607 narrowed down can be used to raster scan a region slightly larger than the protrusions (603, 604) made of the silicon oxide film to simultaneously remove the carbon and the silicon oxide film at the same etching rate. it can.

When the ratio of the secondary ions of C and Si generated during this processing is measured using the mass spectrometer 608,
Silicon oxide film (603, 604) in the beam scanning area
Since the secondary ion ratio of C / Si changes greatly at the moment when the carbon around the silicon disappears, the silicon oxide film shifts to the shifter 601.
It can be determined that it has been cut to the same height as the surface. Also C
Instead of the / Si secondary ion ratio, the C / O secondary ion ratio can be used to determine the end point. A method of determining the end point of the process by using such secondary ion measurement is disclosed in, for example, Japanese Patent Laid-Open No. 58-106750.

However, with GaFIB sputtering, a depth of 15 nm is formed on the surface of the sputtered substrate.
The damaged layer 609 remains to some extent, which reduces the light transmittance used for exposure. Therefore, the silicon oxide film (603,
After the removal of 604) is completed, as shown in FIG. 17G, the damaged layer 609 is assisted by using, for example, XeF ₂ gas and GaFIB. Since the damaged layer does not remain in the assist etching using this gas, the substrate surface can be in a good state without damage. By this processing, a recess of about 15 nm can be formed, but such a recess does not transfer to the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG. 17H, the carbon remaining in the periphery when removing the silicon oxide films (603, 604) is removed by an O ₂ plasma asher.
For example, if O ₂ gas is caused to flow in the chamber at 0.9 Torr and high-frequency power of 500 W is applied to perform ashing, carbon can be removed without damage. Carbon can be removed not only by the O ₂ plasma asher, but also by CDE using O ₂ gas or CF ₄ -added O ₂ gas. Further, it is effective to keep the substrate temperature at 150 to 400 ° C. Further, carbon can be removed by laser irradiation or FIB irradiation in an O ₂ or O ₃ atmosphere.

It is more efficient to remove the remaining carbon if it is collectively performed after all the defects have been repaired. Further, the order of the last two steps, the carbon removing step and the damage removing step can be exchanged.

As described above, if the defect is corrected according to this correction process flow, the following effects can be obtained.

(1) The concave defect 602 is formed on the silicon oxide film (6
03, 604), it is not necessary to embed the dented shape exactly, so the process is extremely simple.

(2) The protrusion formed by filling the concave defect 602 has a flattening film (60
5, 606), so when removing the protrusion, Ga
It is possible to minimize the occurrence of damage around the defect area caused by the beam irradiation.

(3) Flattening films (605, 60) made of different materials
6) and the silicon oxide film (603, 604) are processed at the same time, and the secondary ions or their secondary ion ratios emitted from the flattening film (C) and the protruding portion (silicon oxide film) are measured. It is easy to detect the end point of machining.

(4) Since the protrusions having a non-uniform thickness are also flattened by using the flattening films (605, 606), the correction surface is easily flattened.

(5) The damaged layer 609 remaining on the surface of the corrected concave defect can be easily removed by the assist etching using XeF ₂ and GaFIB.

(6) The carbon film used for defect correction is also O
₂ It can be easily removed with the plasma asher without damaging others.

(7) Since most of the repair can be performed by using the GaFIB device and only changing the kind of gas introduced into the device, extremely efficient defect repair is possible.

Although the process of repairing a concave defect has been described above, this repair process is not limited to the above example.

[0184] While the above example has been described carbon film to the pyrene as a flattening material covering the protruding portion left after embedding the concave defects with a silicon oxide film as a raw material in Reference Example 1
The same modification as is possible.

Further, as for simultaneous etching of carbon and SiO ₂ , the same modification as in Reference Example 1 is possible. Furthermore, the removal of the carbon remaining after the removal of the protrusion is also performed in Reference Example 1
The same modification as is possible. Also, carbon deposition, carbon,
The ion source used for simultaneous etching of SiO ₂ and removal of the damaged layer can be modified in the same manner as in Reference Example 1 .

The process can be omitted depending on the shape of the concave defect. That is, FIGS.
After the silicon oxide film is formed in multiple steps as shown in (C), the unevenness on the surface is within the step allowed by the defect correction depending on the shape of the concave defect. Therefore, steps shown in FIG. There is no need to proceed.

In the above example, the concave defect is filled with the silicon oxide film, but the filling material is not limited to silicon oxide. The filling material should be selected depending on the material of the shifter, and the above modification can be similarly performed with silicon nitride, chromium oxide or the like.

( Embodiment 4 ) In this example , a method of repairing a shifter concave defect will be described, particularly including a film quality improving effect of an embedding material deposited on the concave defect.

This example is basically the same as the first example , and the SiO ₂ film 706 is formed in the same manner as the steps shown in FIGS. 20A to 20D, and the first and second steps are performed. Deposited films 707 and 708 are formed. Thereafter, the region covered with the first and second deposited films 707 and 708 is irradiated with laser light, and the SiO ₂ film 706 under the deposited films 707 and 708 is locally heated by heat generation due to energy absorption of the carbon film. To do. The SiO ₂ film 706 is improved in defects of the SiOx structure due to the annealing effect by heating, and the light transmittance of the SiO ₂ film is improved. By doing so, an improvement in light transmittance as shown in FIG. 19 is recognized. From this point onward, FIG.
8 (G), the SiO ₂ film 706 and the deposited films 707 and 708 are etched back, and the damaged layer 2 is formed.
11 is removed.

As described above, when the concave defect is repaired according to the repair process flow of this embodiment, it is described in the first embodiment (1).
In addition to the effects (7) to (7), the structural defects of the SiO ₂ film 706 are improved by laser annealing, and the light transmittance of the SiO ₂ film 706 can be improved.

First, a defect to be corrected is recognized by using the FIB device based on information such as the size, shape (whether convex or concave) and position of the defect obtained by using a general defect inspection device. . As shown in FIG. 20A, after the concave defect 702 is confirmed in the phase shifter 701, the gas having the Si—O bond and / or the Si—H bond from the nozzle 703 on the concave defect 702 at room temperature, or A mixed gas containing, for example, 1,
While blowing a mixed gas 704 (mixing ratio = 1: 7) of 3,5,7-tetramethylcyclotetrasiloxane and oxygen, the GaFIB 70 was formed in a region slightly wider than the concave defect 702.
Irradiate 5. As a result, as shown in FIG. 20B, a SiO ₂ film (embedding material) 706 slightly protruding from the surface of the shifter 701 is formed. The diameter of the nozzle used was 0.2 mm, and the pressure in the capacitance type pressure gauge shown in Fig. 1 was 4 Torr. At this time, the total flow rate of gas at the nozzle outlet was 0.05 sccm.

FIG. 23 shows the relationship between the energy of GaFIB to be irradiated and the light transmittance of the formed SiO ₂ film (thickness 0.3 μm) with respect to the light of 248 nm (light used for the Levenson type phase shift mask). The light transmittance increases as the energy of GaFIB decreases. This is S
Ga ⁺ ions are implanted into the deposited film during the formation of the iO ₂ film to cause defects that cause a decrease in light transmittance. However, the smaller the Ga ⁺ ion energy, the more defects that are generated per ion. This is because the number will decrease. Here, Ga
Since the FIB energy was set to 5.5 keV, the light transmittance of the formed film was 91%, which was a value equal to or higher than the light transmittance (80.6%) required for the correction of concave defects.
The beam current of GaFIB was 20 pA. Here, since the FIB device in the retarding mode, that is, the device capable of setting the voltage of the sample stage to 19.5 kV at the acceleration voltage of 25 kV, Ga ⁺ ion irradiation energy [(acceleration voltage)-(sample stage voltage) is used. ] Xe (elementary charge) is 5.5 keV, the beam diameter is 0.05 μmφ, and film formation on a fine region is possible. The acceleration voltage is 5.5 in a normal FIB device instead of the retarding mode.
kV must be set, and the beam diameter in this case is ~
It becomes 1 μm, which makes it difficult to form a film on a fine region.

Note that here, Ga ⁺ FI of 5.5 keV is used.
Although B was used, other energies can be selected in consideration of the relationship between the Ga ⁺ ion energy and the light transmittance shown in FIG. 23, and other ion species can also be selected. The two kinds of gas may be sprayed from different nozzles, and a gas containing oxygen as a main component such as O ₃ or N ₂ O may be used instead of oxygen. The mixing ratio of the gas is not limited to 1: 7, but the mixing ratio may be such that the deposit is transparent and the concave defect is filled with a good shape depending on the gas species used, the FIB ion species, and the energy.

When the charge neutralizer is near the gas nozzle and the radiant heat from the electron emission filament in the neutralizer affects the gas, black contamination made of carbon adheres to the mask substrate. Therefore, it is desirable to place the charge neutralizer away from the gas nozzle.

Then, as shown in FIG.
A first thin film 707 is formed in a donut shape around the protruding portion of the O ₂ film 706 in a donut shape to the same height as the SiO ₂ film 706. This deposited film 707 is, for example, 20 k
It is formed by assist deposition in which pyrene gas is decomposed by GaFIB accelerated to eV and carbon (C) is deposited.

Then, as shown in FIG.
A _second deposited film 708 is formed in a region that covers the protruding portion of the O ₂ film 706 and the first deposited film 707. SiO _{2 at} this time
Between the distance x between the protrusion of the film and the first deposited film 707 and the depth y of the surface depression formed when the second deposited film 708 is formed with a thickness of 1.0 μm, There is a relationship as shown in 4. That is, as x decreases, y decreases.
This is because, in assisted deposition using an ion beam and a gas, deposition proceeds due to multiply scattered ions and secondary electrons inside the narrow groove, so that the protrusion of the SiO ₂ film 706 and the first deposited film 707 are deposited. This is because the film formation rate becomes faster inside the groove, and y becomes smaller, so that a flat film can be obtained.

Then, as shown in FIG. 20E, the flat films (707, 708) thus formed and S are formed.
The protruding portion of the iO ₂ film 706 is simultaneously etched at the same rate. For example, the above-mentioned 20 keV GaFIB
And carbon film formed by using pyrene gas (707, 70
8) and the protruding portion of the SiO ₂ film 706 are sputter-etched with GaFIB, as shown in FIG.
The etching rate ratio of O ₂ changes depending on the acceleration voltage of GaFIB, and the etching rate ratio of C / SiO ₂ becomes about 1 at about 30 kV. Therefore, under this condition, the beam 709 narrowed down can be used to raster scan a region slightly larger than the protruding portion to simultaneously remove C and SiO ₂ at the same etching rate.

When the ratio of carbon and secondary ions of Si generated during this processing is measured by using the mass spectrometer 710, carbon around the protrusion of the SiO ₂ film 706 in the beam scanning region is measured. Since the secondary ion ratio of C / Si changes greatly at the moment of disappearance, it can be determined that the protruding portion of the SiO ₂ film 706 is cut to the same height as the surface of the shifter 701.
It is also possible to determine the end point by using the secondary ion ratio of C / O instead of the secondary ion ratio of C / Si.

However, with GaFIB sputtering, a depth of 15 nm is formed on the surface of the sputtered substrate.
The damaged layer 711 to some extent remains, and the light transmittance used for exposure is reduced. Therefore, after the removal of the protruding portion of the SiO ₂ film 706 is completed, as shown in FIG. 20F, the damage layer 7 is formed by using, for example, XeF ₂ gas and GaFIB.
11 is assisted etched. Since the damaged layer 711 does not remain in assisted etching using this gas,
The damage layer 711 can be removed. It should be noted that this processing produces a recess of about 15 nm, but such a recess does not transfer onto the wafer and does not affect the surrounding pattern.

Finally, as shown in FIG.
The carbon remaining in the periphery when removing the protruding portion of the O ₂ film 706 is removed by the O ₂ plasma asher. For example, O ₂
When the gas is flowed so that the inside of the chamber becomes 0.9 Torr and the high frequency power of 500 W is applied to perform the ashing, the carbon can be removed without damage. Removal of carbon
O ₂ not plasma asher only, it is possible to perform even CDE using O ₂ gas or CF ₄ O ₂ gas was added. Further, it is more effective to keep the substrate temperature at 150 to 400 ° C. Further, it is possible to remove carbon also by laser light irradiation in an O ₂ or O ₃ atmosphere or FIB irradiation.

It is more efficient to remove the residual carbon if it is collectively performed after all the defects have been repaired. Further, the order of the last two steps, the carbon removing step and the damage removing step can be exchanged.

As described above, when the concave defect is corrected according to the correction process flow of this example, the following effects can be obtained.

(1) Since it is not necessary to fill the recessed defect 702 with the SiO ₂ film 706 according to the recessed shape, the process becomes extremely simple.

(2) Since the protruding portion formed by filling the concave defect 702 is covered with the planarizing film (first deposited film 707 and second deposited film 708) in a wider range than that, At the time of removing the portion, it is possible to suppress the occurrence of damage to the periphery of the defective region due to Ga beam irradiation as much as possible.

(3) Flattening films (707, 70) made of different materials
8) and the protrusions of the SiO ₂ film 706 are processed at the same time, and the secondary ions emitted from the flattening film (C) and the protrusions (SiO ₂ ) or their secondary ion ratios are measured to process the protrusions. It is easy to detect the end point of.

(4) Since the protrusions having a non-uniform thickness are also flattened by using the flattening films (707, 708), the correction surface is easily flattened.

(5) The damaged layer 711 remaining on the surface of the modified concave defect can be easily removed by assist etching using XeF ₂ and GaFIB.

(6) Carbon film (70) used for defect repair
7, 708) can be easily removed by the O ₂ plasma asher without damaging others.

(7) Since most of the correction can be performed by using the GaFIB apparatus and only changing the type of gas introduced into the apparatus, extremely efficient defect correction is possible.

(8) Since the acceleration energy of Ga ⁺ ions is lowered, the light transmittance of the SiO ₂ film 706 deposited in the recess can be sufficiently increased even for a short wavelength (248 nm), It can be applied to the modification of the Levenson type phase shift mask used in the above wavelength range.

Although the concave defect repairing process has been described above, this repairing process is not limited to the above example.

In the above example, the carbon film formed from pyrene gas as a raw material is used as the flattening film for covering the protrusions remaining after the concave defects are filled with SiO _2. However, carbon formed from another hydrocarbon gas as a raw material has been described. Membrane or W (C
A tungsten film formed using O) ₆ can also be used. The coverage of the tungsten film is almost the same as that of the carbon film, and when the above-mentioned two-step deposition was performed, a flat film with small dents on the surface could be obtained as with the carbon film. Furthermore, in the simultaneous processing of the protrusion (SiO ₂ ) and the tungsten film, the point that the etching rate ratio becomes about 1 exists in the acceleration voltage range of a general FIB device.

As the flattening film for covering the convex defects,
Not only the film formed by FIB but also a film made of a photosensitive resin or a resin that is crosslinked or decomposed by charged particles. When forming these films, after coating these resins on the reticle by spin coating, use a microscope or use the coordinates obtained in the inspection process to laser light and slit only the area containing the desired defect. To irradiate light, FIB or electron beam that has been squeezed. Then
This is developed to form a flattening film. The formation of the first thin film and the second thin film is performed by repeating the above steps, and the film thickness is adjusted by adjusting the exposure amount (irradiation light amount) when exposing the resist or the resist concentration. If the convex defect is small or the pattern is close to the defect to be repaired, it is sufficient to form the flattening film once. Thereafter, F using the above pyrene gas as a raw material
The same processing as the carbon film formed using IB can be performed. When a photosensitive resin or a resin that is crosslinked or decomposed by charged particles is used, it can be removed by using a stripping solution such as a mixed solution of sulfuric acid and hydrogen peroxide.

Further, as for the simultaneous etching of carbon and SiO ₂ , the same modification as in Reference Example 1 is possible. further,
The removal of the carbon remaining after the removal of the protruding portion can be modified in the same manner as in Reference Example 1 . Also, carbon deposition, carbon, Si
The ion source used for simultaneous etching of O ₂ and removal of the damaged layer can also be modified in the same manner as in Reference Example 1 .

Further, in the above process, the shape of the concave defect is formed.
Although I did not describe it, the process was saved depending on the shape.
It can be abbreviated. That is, a concave shape with a large aspect ratio
In case of defects, 1,3,5,7-tetramethylcycloteto
SiO using Lasiloxane ₂Figure 21 shows the stacking shape of
It becomes like (A). In such a case, unevenness on the surface
20 is within the step allowed for defect correction, so that
(C) It is not necessary to proceed with the steps shown below.

On the other hand, FIG. 21 (B) and FIG. 21 (C)
In the case of a defect as shown in (4), since the unevenness of the surface after depositing SiO ₂ does not fall within the allowable step, all the steps shown in FIG. 20 are required. Furthermore, if defects such as FIG. 21 (C), the slightly apart by depositing SiO ₂ from the side wall in the previously recessed as shown in FIG. 22, the SiO ₂ followed completely cover the defect area By depositing
It is possible to deposit with small surface irregularities. In this case, it may not be necessary to proceed with the steps shown in FIG. 20C and the like as described above.

Further, although silicon oxide is described in the above example, the present invention is not limited to silicon oxide.
For example, by using silicon nitride, Cr oxide, or the like, by lowering the irradiation FIB energy during film formation,
It is possible to suppress a decrease in light transmittance due to ion irradiation.

Other than the above, various modifications can be made without departing from the scope of the present invention.

In each of the above-described examples, the correction method has been described by taking the phase shift mask as an example, but the application targets of the first and second defect correction methods are not limited to the phase shift mask. It can also be applied to correction of a normal Cr mask or X-ray mask. Further, it can be applied to the modification of the Fresnel zone plate and other optical components.

( Embodiment 5 ) In this example , a method of repairing a shifter concave defect, particularly, formation of an SiO ₂ film of a filling material deposited in a concave defect will be described.

This example is basically based on Japanese Patent Application No. 4-2945.
This is the same as the second embodiment in the specification No. 36. First, based on information such as the size, shape (whether convex or concave), position, etc. of the defect obtained using a general defect inspection device,
Recognize the defect to be repaired using the FIB device. After the concave defect is confirmed in the phase shifter, a gas having Si-O bond and / or Si-H bond from the nozzle on the concave defect at room temperature or a gas containing the same, for example, 1,3,5,7-tetra While spraying a mixed gas of methylcyclotetrasiloxane and oxygen, Ga ⁺ F over a region slightly larger than the concave defect
Irradiate IB. As a result, a SiO ₂ film (embedding material) slightly protruding from the surface of the shifter is formed. The diameter of the nozzle used here was 0.2 mm, and the total flow rate of the gas at the nozzle outlet was 0.05 sccm.

According to the specification of Japanese Patent Application No. 4-294536, in order to improve the light transmittance of the SiO ₂ film which is the embedding material, the deposited film is irradiated with UV light or is formed while being irradiated with UV light. Alternatively, the deposited film is annealed in an O ₂ atmosphere or is deposited by low energy ions. If the SiO ₂ film formed by using the Si ²⁺ FIB of 50 keV, although improvement in the light transmittance by annealing in an O ₂ atmosphere was seen, 25 keV of Ga ⁺
In the case of the SiO ₂ film formed by using FIB, the effect of improving the light transmittance due to the annealing treatment in the O ₂ atmosphere cannot be obtained. Further, the annealing treatment in the process of correcting the Levenson-type phase shift mask may cause a problem such as distortion of the mask pattern.

On the other hand, in the case of forming using low energy ions, if a retarding mode FIB apparatus is used, the beam diameter is 0.05 μmφ even if the ion energy is 5.5 keV. However, the ion energy is 5.
In the case of 5 keV, the beam diameter is ˜1 μmφ, and it is difficult to form a film on a fine region. Further, at 5.5 keV, the film forming efficiency is low, so that it is not very practical. In this example, G
An example of using a ⁺ FIB to form an SiO ₂ film having an ion energy other than 5.5 keV and having a light transmittance that can be used for modifying a phase shifter without post-treatment such as annealing or UV light irradiation is shown. .

In this example, a SiO ₂ film is formed by irradiating Ga ⁺ FIB using a mixed gas of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) and oxygen as a raw material gas for film formation. I went by. FIG. 24 shows the relationship between the beam current density when the ion energy is 25 keV and the light transmittance of the formed SiO ₂ film for KrF light (wavelength 248 nm).

As can be seen from FIG. 24, the light transmittance tends to increase as the beam current density decreases, but the light transmittance saturates when the beam current density becomes 11 mA / cm ² or less. This saturation tendency is the same regardless of the ion energy. Therefore, at each ion energy, film formation was performed using a beam having a beam current density at which the light transmittance was saturated.

Next, FIG. 25 shows the light transmittance of KrF light (wavelength 248 nm) of the SiO ₂ film (film thickness 250 nm) formed by changing the ion energy and the O ₂ partial pressure ratio. According to this, there is a tendency that the higher the O ₂ partial pressure ratio to TMCTS and / or the lower the ion energy, the higher the light transmittance.

In the Levenson type phase shift mask for KrF light, the film thickness t of the phase shifter for inverting the phase is t = λ / {2 where λ is the wavelength of the exposure light source and n is the refractive index.
It is represented by an odd multiple of (n-1)}. Here, since KrF is used as the light source (λ = 248 nm) and the phase shifter is the silicon oxide film (n = 1.508), t = 244 nm. According to simulations, it is known that the light transmittance for KrF light necessary for correcting the concave defect of the shifter of the Levenson-type phase shift mask for KrF light is 80% or more. Therefore, the SiO ₂ film may be formed under the condition that the partial pressure ratio is equal to or higher than the curve showing the light transmittance for KrF light of 80% in FIG.

According to this method, Si having a high transmittance can be obtained by using an ion of any energy in an ordinary FIB apparatus.
It is possible to form an O ₂ film. The light transmittance is 7
If it is 0%, may be performed deposition at curves or more O ₂ voltage dividing ratio showing 70% of 25, also in the case of other light transmission ratio O ₂ minutes in the light transmittance The SiO ₂ film may be formed in a region equal to or higher than the O ₂ partial pressure ratio calculated from the relation between the ion energy and

[0229] The subsequent steps are described in Japanese Patent Application No. 4-294536.
In the same manner as in the step shown in Example 2 of Pat, SiO ₂
Etch back of the film and the first and second thin films.

In this way, if the concave defect is repaired according to the repair process flow of this example, Japanese Patent Application No. 4-2945 is used.
In addition to the effects (1) to (7) described in the 36th embodiment, SiO ₂ having a high light transmittance that can be used for correcting the phase shifter concave defect of the phase shift mask can be efficiently formed without post-treatment. The effect of, is obtained.

The TMCT used in this example
S will be described. First of all, TMCTS is shown in FIG.
As shown in 7 (A), it is a cyclic molecule having a bond of -Si-O-Si-. TMCTS because of the ring-
SiO-Si- bonds are stable, it tends to SiO ₂ film shown in FIG. 26 to hold it. This is due to the relatively high reactivity of the ethoxy group O which is easily eliminated as ethanol.
Is significantly different from TEOS bonded to Si.

Second, in TMCTS, as shown in FIG. 27A, in addition to Si--O bond and Si--C bond, S
There is an i-H bond. As shown in FIG. 27B, this is an OMCT consisting of only Si-O bonds and Si-C bonds.
Unlike S (octamethylcyclotetrasiloxane), TMCT
When a film is formed using S, the steric hindrance due to the bulky CH ₃ group is small, so that the O atom easily reacts with the Si atom and Si-
O bond is likely to occur. Thus, the SiO ₂ film obtained by using TMCTS is the Si obtained by using OMCTS.
The light transmittance is higher than that of the O ₂ film.

Third, SiO by GaFIB₂Film formation
The film yield is 7 atom / ion when TMCTS is used.
In the case of using TEOS, it is 2 atom / ion. did
Therefore, when TMCTS is used, it is possible to achieve a specific film thickness.
Since the number of incident ions when forming a film is small,
Obtained SiO with little damage due to incident ions ₂
The light transmittance of the film is increased.

Reference Example 4 In this example , formation of a flattening film covering the convex defects and removal of the flattening film and the residual flattening film after etching the convex defects will be described. According to Japanese Patent Application No. 4-294536, the first and second films are planarized by using carbon films assisted by FIB deposition. In this example, an example in which Au remaining after FIB assist deposition is used as the flattening film and the residual flattening film is removed by wet etching is shown.

First, the defect to be corrected is recognized by using the FIB device based on the information such as the size, shape (whether convex or concave) and position of the defect obtained by using a general defect inspection device. To do. After confirming the concave defect, Ga of 15 keV
⁺ FIB and source gas for Au film formation, such as dimethyl gold hexafluoroacetylacetonate (C
Assist deposition using ( ₇ H ₇ F ₆ O ₂ Au) deposits Au so that the upper portion of the convex defect becomes flat. At this time, as shown in Japanese Patent Application No. 4-294536, flattening is performed by two-step or multi-step deposition depending on the shape and position of the defect.

After depositing the flattening film, Japanese Patent Application No. 4-29453
Similar to the process shown in the specification No. 6, Ga of 30 keV is obtained.
FIB and XeF ₂ gas are used to remove the flat region of the Au film including the convex defect. Where Au is GaFIB
Removed by sputtering with a convex defect (Si
O ₂ ) is removed by the assisted etching of GaFIB and XeF ₂ without reducing the light transmittance. At this time, XeF ₂
The etching rates of Au and SiO ₂ are made equal by adjusting the gas pressure of.

Excessive Au film peeling after etchback is
It is performed by wet etching with aqua regia. Au dissolves in aqua regia, whereas Si, which is the material of the mask shifter,
Since O2 and chromium or chromium oxide as the light shield are insoluble in aqua regia, only Au can be peeled off without damaging the light shield and the shifter.

As a substance soluble in aqua regia, Pt in addition to Au
Therefore, instead of the Au film, a flattening film that covers the convex defects is used.
Then, the source gas for FIB and Pt film deposition, for example,
(Methylcyclopentadimethyl) trimethylplatinum
[(MeCp) PtMe₃] To deposit a Pt film
You may use it. Others, mask light shields and shifters
Uses a material that dissolves in a chemical solution that is insoluble as a flattening film
It is also possible to do so. In addition, the method of this example is
SiO deposited slightly protruding from the surface of the shifter ₂film
It can also be used in the process of flattening (embedded material)
it is obvious.

Reference Example 5 In this example , removal of the planarization film covering the convex defect will be described. In particular, the use of a mixed gas of hydrocarbon gas and hydrogen gas as the source gas for the flattening film will be described.

In Japanese Patent Application No. 4-294536, pyrene, styrene, methyl methacrylate, 2, and 3 are used as a source gas of a planarizing material made of carbon for covering convex defects.
Although it has been described that a hydrocarbon gas such as 4,4-trimethyl-1-pentene or isoprene is used, a mixed gas of a hydrocarbon gas and a hydrogen gas may be used as a raw material gas. By mixing the hydrogen gas, the amount of hydrogen in the carbon film increases, and the carbon film is polymerized. Thereby, the removal of the carbon film can be facilitated. This can be understood from the fact that the resist can be removed more easily by asher, CDE, laser, etc. when comparing the carbon film produced by sputtering or the like with the polymer resist.

For example, hydrocarbon gas 2,4,4-
The case of using trimethyl-1-pentene gas and hydrogen gas will be described below.
4,4-Trimethyl-1-pentene gas and hydrogen gas were put in the gas cylinder 11, and 2,4,4-trimethyl-1-pentene 1.0 Torr and hydrogen gas 1.0 Torr were introduced in the gas introduction system.
Are mixed and sprayed from the nozzle 13 onto the surface of the sample 8. A beam current of 10p extracted from the Ga ion source 1
A carbon film was formed by irradiating FIB with A and an acceleration voltage of 25 keV. The deposition efficiency of the carbon film thus formed is 18
atom / ion, which was 1.6 times that of 2,4,4-trimethyl-1-pentene alone. In addition, this carbon film was used at a power of 1 using 20 sccm of water and 200 sccm of oxygen gas.
When it was removed by CDE at 00 W, the removal rate was improved by 5 times as compared with the carbon film formed using only 2,4,4-trimethyl-1-pentene gas as the source gas. Here, the mixing ratio of 2,4,4-trimethyl-1-pentene gas and hydrogen gas was set to 1: 1. However, when the total pressure is constant, the removal rate of the carbon film formed by the increase in the hydrogen gas partial pressure is removed. On the other hand, when the gas partial pressure becomes too high, the film forming efficiency is lowered. Therefore, it is desirable to select an appropriate condition for the hydrogen gas partial pressure.

Reference Example 6 In this example , removal of the planarization film covering the convex defect will be described. In particular, the Ga removal step will be described.

In the step of removing the carbon film in Japanese Patent Application No. 4-294536, O was added in order to oxidize carbon.
₂ alone, O ₃ alone, or O ₂ and N ₂ , H ₂ O, CF ₄ ,
CDE using mixed gas of H ₂ , N ₂ O, or NO
Alternatively, when removing carbon by laser irradiation or the like in an O ₂ or O ₃ atmosphere, it is desirable to include a Ga removing step.

The carbon film formed by FIB assisted deposition contains not only carbon but also Ga and O. Therefore, in the above method of oxidizing and removing carbon, carbon is removed as CO and CO ₂ , but Ga is not removed by oxidation and remains as gallium oxide in the surface layer. Therefore, as the etching of the carbon film progresses, the concentration of Ga on the surface of the carbon film increases and the etching rate decreases. If the carbon film whose etching rate has decreased is left for 5 minutes together with the reticle in a 1N nitric acid aqueous solution, the gallium oxide remaining on the surface of the carbon film is removed. Then, by performing CDE or laser irradiation utilizing the oxidation of carbon, it is possible to perform good etching. In this case, the quartz substrate is insoluble in nitric acid,
Cr, which is a light shield, and CrOx, which is an antireflection film, were also insoluble because they made passivation with respect to nitric acid, and did not cause damage to the reticle. For removing gallium oxide by such wet etching, not only nitric acid but also concentrated sulfuric acid, alkali such as KOH or NaOH can be used.

Reference Example 7 In this example , deposition of a flattening film covering a convex defect and removal of a residual flattening film after etching back will be described. That is, in this example, a film that is easy to remove with a solution is thinly formed as a flattening film, a carbon film is formed on the thin film to form a film having a two-layer structure, and the carbon remaining along with the lower layer film in the solution after etchback is formed. An example in which the film is removed will be described.

First, based on information such as the size, shape (whether concave or convex), and position of a defect obtained by using a general defect inspection apparatus, PIBM (polyisobutyl) is formed in an area including a convex defect. A LB (Langmuir-Blodgett) film of methacrylate is formed (18 layers, 200 Å thick). Next, the defect to be corrected is recognized by using the FIB device based on the defect information. After the convex defect was recognized, using GaFIB of 5 keV using pyrene gas,
A carbon film having a thickness of 200 angstrom is formed on the LB film including a region for forming a planarization film. Next, in order to form a flattening film with high accuracy, as shown in Japanese Patent Application No. 4-294536, pyrene gas is used to achieve a G of 20 keV.
With aFIB, two-stage or multi-stage deposition is performed depending on the shape and position of the defect, and thereby planarization is performed. Where 5
Since the range of keV Ga ions in the LB film is within 100 Å, the Ga ion implantation into the LB film does not destroy the entire structure of the LB film. In addition, by forming a carbon film with 5 keV GaFIB, G in the subsequent carbon film formation with 20 keV GaFIB
The a ion does not completely destroy the structure of the LB film.

After forming the flattening film, Japanese Patent Application No. 4-294
Similar to the process described in Japanese Patent No. 536, the flatly formed region of the carbon film including the convex defect is removed. After the etch back, the residual carbon film on the LB film is removed by melting the LB film with metaclen. Since the substrate of the mask and SiO ₂ which is the shifter material and Cr which is the light shielding film material cannot be dissolved in methacrene, only the carbon film and the LB film can be removed without damaging the light shielding member and the shifter. .

The flattening film having a two-layer structure is PI
Not only a combination of the BM LB film and the carbon film, but also a lower layer film that can be dissolved in a solution in which SiO ₂ and Cr are insoluble, and an upper layer film that can etch back convex defects can be used. The lower layer film may be a film that can be mechanically removed with a brush or a film that can be removed by a method that does not damage the SiO ₂ film and the Cr film.

In addition to the flattening film having a two-layer structure,
It is obvious that at least the lowermost layer film may be a flattening film having a multi-layer structure composed of a film that is easily removed as described above.

Reference Example 8 In this example , the formation of a damaged layer in the FIB irradiation region of the substrate and the removal of the protrusion of the convex defect and the planarization film will be described.

When styrene or the like is used as the source gas for the flattening film, the film forming efficiency is low, and when a defect occurs, it takes a long time to correct it. In addition, since the film forming efficiency is low, the amount of ion irradiation during film forming is large, and chemical dry etching at a high temperature for a long time when removing the planarization film is more effective than chemical dry etching using O ₂ gas after the simultaneous removal process. Must be done.

Further, when the protruding portions of the convex defects and the flattening film are removed by sputter etching while making the etching rates the same, a damaged layer is formed in the FIB irradiation region of the substrate. To prevent the occurrence of this damage layer, X
If the assist etching using the gas containing eF ₂ or the thermal etching using the laser beam is performed, extra digging is performed and the processing margin is narrowed.

In order to solve the above problem, this example adopts the following means.

First, in repairing a convex defect or a concave defect, the first and second thin films made of a carbon-containing material are treated with methyl methacrylate gas, 2,4,4-trimethyl-.
1-to be formed by FIB assist deposition using pentene gas as a raw material gas.

As a result, the film formation efficiency of the planarization film can be improved, the time required for the correction can be shortened, and the ion irradiation amount at the time of film formation can be suppressed, so that it remains after the simultaneous removal step. The flattening film can be easily removed.

Second, at the time of repairing a convex defect or a concave defect, the protrusion and the first and second thin films are simultaneously subjected to FIB assist etching using XeF ₂ gas and O ₂ gas or O ₃ gas. To remove.

As a result, the etching rates of the flattening film and the shifter can be made equal to each other, and the correction can be performed without leaving any damage on the substrate surface. Therefore, the damage layer removing step can be reduced. Therefore, there is no extra digging that occurs during the damaged layer removal step.

Thirdly, when repairing a convex defect or a concave defect, the first and second thin films remaining after the simultaneous removal step are treated with CF ₄ , H ₂ , H ₂ O, N ₂ and N ₂ O. Alternatively, it is removed by chemical dry etching using a mixed gas in which at least one gas of NO is added to O ₂ gas.

As a result, when applying high frequency power,
The discharged atomic oxygen increases and the removal rate of carbon increases. Further, since carbon is removed from a low temperature, throughput can be improved.

Next, a specific example of the present invention will be described.

Methyl methacrylate (monomer), which is liquid at room temperature, (CH ₂ : C (CH ₃ ) COOCH ₃ ), 2,
4,4-trimethyl-1-pentene ((CH _{3) 3} CCH
₂ C (CH ₃ ): CH ₂ ), isoprene (CH ₂ : C (CH
₃ ) FIB assist deposition using CH: CH ₂ ) will be described with reference to FIG.

Gas cylinder 1 was charged with methyl methacrylate, 2,4,4-trimethyl-1-pentene, or isoprene.
1, the gas inside the gas cylinder 11 was evacuated and the resulting gas was blown onto the sample 8 from the nozzle 13. The gas pressure in the nozzle 13 at this time is 1 Torr. Then, a beam current of 10 pA was extracted from the ion source 1 onto the sample on which the gas was sprayed, and G of 25 keV was used.
A carbon film was formed on sample 8 by irradiating it with aFIB.

When the film formation efficiency of the carbon film was examined in this manner, it was 7.5 atom when methyl methacrylate was used.
/ ion, 11 atom / ion when 2,4,4-trimethyl-1-pentene was used, and 9 atom / ion when isoprene was used. In the specification of Japanese Patent Application No. 4-294536, it is described that the flattening film and the quartz substrate can be simultaneously etched by FIB assisted etching using a gas. At this time, the filament forming the charge neutralizer may react with the gas used. For example, when a gas serving as an oxidant is used, the tungsten filament and the gas react with each other to form a tungsten oxide, which is attached to the sample to be corrected and reduces the light transmittance. In order to prevent this, it is necessary to attach a cover to the tungsten filament so that the generated tungsten oxide adheres to the cover surface so that only electrons reach the sample surface. Further, in order to suppress the generation of tungsten oxide and extend the life of the filament, it is desirable to suppress the gas pressure near the filament by performing differential evacuation.

Further, in Japanese Patent Application No. 4-294536, by using a mixed gas containing XeF ₂ as a gas for the simultaneous etching of the flattening film and the quartz substrate, defect removal leaves damage on the substrate surface. I said that I can do without it. That is, although it depends on the film material of the flattening film to be used, in the case where the flattening film is a carbon film formed by FIB assisted deposition, most of the quartz have a higher etching rate in the XeF ₂ gas single atmosphere,
By adding a gas that functions as an oxidant to the XeF ₂ gas, it becomes possible to match the etching rates of the flattening film and the shifter.

For example, a case where FIB assist deposition is performed using a mixed gas of XeF ₂ gas and O ₂ gas will be described. FIG. 28 shows the etching rate when O ₂ gas is added to the XeF ₂ gas having a gas partial pressure of 0.15 Torr, and the etching rates of carbon and quartz are the same when the O ₂ gas partial pressure is about 4 Torr or more. Become. FIG. 29 shows the change in light transmittance at this time. As it can be seen from Figure 29, although the O ₂ partial pressure of the light transmittance decreases from the vicinity of 5 Torr, partial pressure of O ₂ indicates more than 93% even in the vicinity of 6 Torr. Actually, when an exposure experiment using a KrF excimer stepper was performed, even if the conditions such as the exposure amount, the depth of focus, and the development were changed, the transfer result was not affected by the correction.

By using the mixed gas of XeF ₂ gas and O ₂ gas as described above, the correction can be performed without leaving any damage on the substrate surface. Therefore, the damage layer removing step can be reduced, and the extra digging can be performed. Can be done without.

Here, since the allowable value of the etching rate difference between carbon and quartz changes depending on the use condition of the mask, it is necessary to appropriately determine the allowable value depending on the use condition of each mask.

For example, XeF ₂ having a gas partial pressure of 0.15 Torr
When a gas is used, the O ₂ gas partial pressure range in which the etching rate difference between carbon and quartz falls within the allowable range is wide,
The etching yield is reduced to less than twice that in the case of sputtering, and the throughput is not improved so much.

When it is desired to improve the throughput, Xe
It is necessary to increase the pressure of F ₂ gas. For example, FIG. 30 shows a case where XeF ₂ gas having a gas partial pressure of 0.30 Torr is used.
Shown in. In this case, the etching rates of the two are the same at the intersection of the curve showing quartz and the curve showing carbon. The etching yields in this case are 7.3 times higher in the case of carbon and 5.6 times higher in the case of quartz than in the case of sputtering, and it can be expected that the throughput is improved. The change in light transmittance at this time is shown in FIG.
As can be seen from FIG. 31, the light transmittance is about 95%, and when an exposure experiment using a KrF excimer stepper was actually performed, the transfer was performed even when the conditions such as the exposure amount, the depth of focus, and the development were changed. The results were unaffected by the correction.

Also in this case, by using a mixed gas of XeF ₂ gas and O ₂ gas, the correction can be performed without leaving any damage on the substrate surface, and therefore, the damage layer removing step can be reduced, and an extra engraving can be performed. You can avoid doing it.

Here, the allowable value of the difference in etching rate between carbon and quartz varies depending on the usage conditions of the mask, so it is necessary to appropriately determine the allowable value depending on the usage conditions of each mask.

In this case, since the range of the O ₂ gas partial pressure within which the difference between the etching rates of carbon and quartz is within the allowable value range is narrow, it is necessary to precisely control both the gas partial pressure and the total gas pressure. A feedback control mechanism such as is required.

Further, as a gas functioning as an oxidizing agent, O
_No damage is left when using O ₃ gas as well as ₂ gas,
The etching rates of carbon and quartz can be matched. FIG. 32 shows a case where O ₃ gas + O ₂ gas is added to XeF ₂ gas having a gas partial pressure of 0.15 Torr. Normally, the concentration of O ₃ gas generated by an ozonizer is about 10% even for high concentration. In the ozonizer used in this experiment, the O ₃ concentration at the ozonizer outlet was 10%. XeF ₂ with O ₃ gas + O ₂ gas at a gas partial pressure of 2.1 Torr
When added to the gas, the etching rates of carbon and quartz match. The change in light transmittance at this time is shown in FIG. As can be seen from FIG. 33, this gas partial pressure is 95
% Is shown. Further, when an exposure experiment was actually conducted using a KrF excimer stepper, there was no correction effect on the transfer result even if the conditions such as the exposure amount, the depth of focus, and the development were changed.

As described above, XeF ₂ gas and O ₃ gas + O ₂
By using a mixed gas of gases, the substrate surface is damaged.
You can make corrections without leaving a gap. Therefore, the step of removing the damage layer can be reduced, and moreover, it is not necessary to carry out extra digging. Here, the allowable value of the etching rate difference between carbon and quartz changes depending on the usage conditions of the mask, and therefore the allowable value needs to be appropriately determined depending on the usage conditions of each mask.

In this case, since the range of the O ₂ gas partial pressure within which the difference between the etching rates of carbon and quartz falls within the allowable range is narrow, it is necessary to precisely control both the gas partial pressure and the total gas pressure. A feedback control mechanism such as is required.

When O ₃ is used as a gas functioning as an oxidant, O ₃ is easily thermally decomposed even at a low temperature (instantaneous decomposition into O ₂ at 250 ° C. or higher). It is not possible to use a pressure gauge that includes a different heat source inside. In the above example, a baratron was used, but it is necessary to use a pressure measuring means that does not include a heat source inside.

In the specification of Japanese Patent Application No. 4-294536, the carbon remaining around the CDE is removed by CDE when removing the convex defects.
It can be removed with. As the gas used at this time, an O2 mixed gas can be used. In particular CF ₄ ,
By adding H ₂ O, N ₂ , N ₂ O, and NO gas alone or in combination to O ₂ gas and applying high-frequency power, and discharging them together to increase oxygen radicals, the removal rate of carbon can be increased. It is even more effective because it can remove carbon from lower temperatures.

For example, when H ₂ O is added to O ₂ gas,
Depending on the material of the carbon film, O2 gas alone is 100 ° C
The etching starts from the vicinity, but by adding H ₂ O, the etching starts from around room temperature. Further, although it depends on the temperature of the substrate, the addition of H ₂ O increases the etching rate by one digit at the same substrate temperature. This H
The effect of improving the etching rate by the addition of ₂ O is only for carbon, and the etching rate is not improved for Cr and quartz. Therefore, the addition of H ₂ O does not adversely affect the mask.

Further, although the deposition of carbon, the simultaneous etching of carbon and SiO ₂ , and the removal of the damage layer are all carried out by GaFIB, the present invention is not limited to this ion. For example, it is obvious that other ions such as Au and Si may be used to perform the processes of the above steps.

Reference Example 9 In this example , the use of a gas containing hydrogen atoms in the molecule for removing the carbon film will be described.

In the above first and second defect repairing methods, it is possible to remove the carbon film by using hydrogen gas or a gas containing hydrogen atoms in its molecule.

For example, the flow rate of hydrogen gas is 20 sccm, the pressure is 0.
By applying high frequency power of 200W at 5 Torr,
When the flattening film formed by FIB using pyrene as a raw material gas was removed using a parallel plate type RIE device, only the flattening film could be removed without etching Cr and quartz. After removing the flattening film, no damage to the mask such as a decrease in light transmittance of the quartz substrate or reduction of the antireflection film on the surface of the light shield was observed, and the pattern using the modified mask was not observed. -There was no problem in the transcription test.

In the above example, dry etching was performed using the RIE apparatus, but the dry etching method is not limited to this. The carbon film can be removed by an etching method utilizing discharge of hydrogen gas or a gas containing hydrogen atoms in its molecule, such as CDE, ECR etching, and magnetron RIE. Further, the removal method is not limited to dry etching, but hydrogen gas,
The carbon film can also be removed by laser light irradiation in a gas atmosphere containing hydrogen atoms in the molecule.

The case where a carbon film formed by FIB using pyrene as a source gas is used as the flattening film has been described, but styrene, methyl methacrylate, 2,
A carbon film formed by FIB using a hydrocarbon gas such as 4,4-trimethyl-1-pentene or isoprene alone or a mixed gas of a hydrocarbon gas and hydrogen gas as a raw material, or a film containing carbon such as a resist film. It is also possible to apply to.

[0285]

As described above , according to the present invention,
A film formation method that can form a silicon oxide film with high light transmittance is
Provided.

[0286]

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a FIB device used in an embodiment method of the present invention.

FIG. 2 is a diagram showing the first half of a shifter convex defect repairing process according to Reference Example 1 ;

FIG. 3 is a diagram showing the latter half of the shifter convex defect repairing process according to Reference Example 1 ;

FIG. 4 is a diagram showing a result of measuring flatness by two-step film deposition.

FIG. 5 is a diagram showing FIB accelerating voltage dependence of an etching rate ratio of a carbon film and SiO ₂ .

FIG. 6 is a diagram showing the processing time dependence of the sputtering yield of a quartz substrate by GaFIB.

FIG. 7 is a diagram showing processing time dependence of etching yield of a quartz substrate by FIB-assisted etching.

FIG. 8 is a sectional view showing a process of correcting a shifter concave defect according to the first embodiment .

FIG. 9 is a cross-sectional view for explaining a SiO ₂ embedded shape in a concave defect.

FIG. 10 is a sectional view showing another example of embedding SiO _{2 in a} concave defect.

11 is a diagram illustrating the first half of the concave defect repair process in shifter edge portion of the shifter edge type phase shifting mask according to the second embodiment.

12 is a diagram illustrating the latter half of the concave defect repair process in shifter edge portion of the shifter edge type phase shifting mask according to the second embodiment.

FIG. 13 is a diagram showing a process of correcting a convex defect in a shifter-edge portion of a shifter-edge type phase shift mask according to Reference Example 2 .

FIG. 14 is a cross-sectional view showing a two-step correction process of an irregular convex defect of the phase shifter according to the reference example 3 ;

FIG. 15 is a cross-sectional view for explaining the problem of flattening an irregular convex defect.

FIG. 16 is a cross-sectional view showing a multi-step correction process of an irregular convex defect of the phase shifter according to Reference Example 3 .

FIG. 17 is a cross-sectional view showing a two-step correction process of an irregular concave defect of the phase shifter according to the third embodiment .

FIG. 18 is a cross-sectional view showing a multi-step correction process of an irregular concave defect of the phase shifter according to the third embodiment .

FIG. 19 is a view for explaining the example 4 , in which SiO _{2 is used.}
FIG. 6 is a characteristic diagram showing a change in transmittance before and after film annealing.

FIG. 20 is a sectional view showing a shifter concave defect repairing process according to a fourth embodiment .

FIG. 21 is a cross-sectional view for explaining a SiO ₂ embedded shape in a concave defect.

FIG. 22 is a cross-sectional view showing another example of embedding SiO _{2 in a} concave defect.

FIG. 23 is a characteristic diagram showing Ga ⁺ ion energy dependence of the transmittance of a SiO ₂ deposited film with respect to light having a wavelength of 248 nm.

FIG. 24: Beam current density and Kr of deposited SiO ₂ film
The graph which shows the relationship with the light transmittance with respect to F light (wavelength 248nm).

FIG. 25 is a graph showing the relationship between the ion energy and the O ₂ partial pressure ratio for each light transmittance with respect to KrF light (wavelength 248 nm).

FIG. 26 is a view showing an atomic bond state of TMCTS.

FIG. 27 is a schematic diagram showing an atomic bond state of TMCTS and OMCTS.

FIG. 28 is a graph showing the relationship between etching rate and O ₂ partial pressure.

FIG. 29 is a graph showing the relationship between light transmittance and O ₂ partial pressure.

FIG. 30 is a graph showing the relationship between etching rate and O ₂ partial pressure.

FIG. 31 is a graph showing the relationship between light transmittance and O ₂ partial pressure.

FIG. 32 is a graph showing the relationship between etching rate and O ₂ + O ₃ partial pressure.

FIG. 33 is a graph showing the relationship between light transmittance and O ₂ + O ₃ partial pressure.

[Explanation of symbols]

101, 301 ... Quartz substrate, 101 ... Convex defects of phase shifter, 103 ... Phase shifter pattern, 104, 207 ...
First deposited film, 105, 208 ... Second deposited film, 10
6, 205, 209, 306, 310 ... Focused ion beam, 107, 210, 311 ... Mass spectrometer (secondary ion detector), 108, 211, 312 ... Damage layer, 20
1, 302 ... Phase shifter, 202 ... Recessed defect of phase shifter, 203, 304 ... Nozzle, 204, 305 ... Gas,
206, 307 ... Protruding silicon oxide film, 303 ... Defects formed in phase shifter edge portion, 308 ... First
Carbon film, 309 ... Second carbon film, 313 ... Excessive protrusion of silicon oxide film.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inoue Soichi 1 Komukai Toshiba Town, Komukai-shi, Kawasaki City, Kanagawa Prefecture, Research & Development Center, Toshiba Corporation (72) Inventor Kazuka Sugihara Komukai Toshiba, Kawasaki-shi, Kanagawa Prefecture No. 1 in the Toshiba Research & Development Center, Ltd. (72) Inventor Ichiro Mori Komukai, Kouki, Kawasaki-shi, Kanagawa No. 1 in the Toshiba R & D Center, Toshiba (72) Inventor Keiji Horioka Small, Saiwai-ku, Kawasaki, Kanagawa Muko Toshiba-cho No. 1 In Toshiba Research and Development Center Co., Ltd. (72) Inventor Gensuke Miyoshi 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside the Horikawa-cho Plant, Toshiba Corporation (72) Toru Watanabe Yuuki-ku, Kawasaki-shi, Kanagawa Komukai Toshiba Town No. 1 Toshiba Research & Development Center Co., Ltd. (72) Inventor Haruo Okano No. 1 Komukai Toshiba Town, Kawasaki City, Kanagawa Prefecture Toshiba Research & Development Center Co., Ltd. (72) Inventor Katsuya Okumura 1 Komukai Toshiba Town, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Tama River Factory Co., Ltd. (72) Tadahiro Takigawa 1 Komukai Toshiba Town, Kouki-ku, Kawasaki City, Kanagawa Prefecture Address: Toshiba Research & Development Center, Inc. (72) Yuichiro Yamazaki, 72, Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa, Ltd., Horikawa-cho, Toshiba Corp. (56) Reference JP 3-16127 (JP, A) JP Flat 4-107270 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C23C 16/00-16/56 H01L 21/31-21/32 G03F 1/00-1/16 JSTP File (JOIS)

Claims (7)

(57) [Claims] 1. A FIB assist device for supplying a material having a Si—O—Si bond and a Si—H bond to a surface of a structure and irradiating a desired portion of the surface supplied with the material with a focused ion beam. look including a step of forming a silicon oxide film by position, the bond of Si-O-Si
And a material having a Si-H bond has a ring structure . 2. Before the step of forming the silicon oxide film, at least one set value of energy of the focused ion beam, current density of the focused ion beam, and gas pressure during the FIB assisted deposition is set. Further comprising the step of determining the FIB assisted deposition to match at least one of the energy of the focused ion beam, the current density of the focused ion beam, and the gas pressure during the FIB assisted deposition to the set value. The film forming method according to claim 1, wherein the film forming method is performed as follows. 3. A material having Si—O—Si bonds and Si—H bonds and a gas containing an oxygen element-containing material are supplied to the surface of the structure, and the material is supplied to a desired portion of the surface. look including a step of forming a silicon oxide film by FIB assisted deposition of irradiating the focused ion beam, closed the bond of Si-O-Si and Si-H bonds
The film forming method , wherein the material to be formed has a ring structure . 4. The energy of the focused ion beam, the current density of the focused ion beam, the gas pressure during the FIB assist deposition, and the FIB assist deposition prior to the step of forming the silicon oxide film. Further comprising the step of determining at least one set value of the gas partial pressure at the time, wherein the FIB assisted deposition is performed by the energy of the focused ion beam, the current density of the focused ion beam,
The film forming method according to claim 3, wherein at least one of a gas pressure during the FIB assist deposition and a gas partial pressure during the FIB assist deposition is performed in accordance with the set value. 5. The oxygen-containing material is O ₂ , O ₃ , and N.
The film forming method according to any one of claims 1 to 4, wherein the material is a material selected from the group consisting of ₂ O. 6. The method according to claim 1, wherein the material having the Si—O—Si bond and the Si—H bond is 1,3,5,7-tetramethylcyclotetrasiloxane. 4. The film forming method according to any one of 4 above. 7. A film forming method according to any one of claims 1 to 6, characterized by using a Ga beam or Si beam as the focused ion beam.