JP2000029202A - Production of mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a transfer pattern with high accuracy in a short time by using a second substrate from which a part of an absorbing layer is removed as a reflection type mask. SOLUTION: In the first step, a master pattern 36 is formed by magnifying the pattern to be formed on a mask, and the master pattern 36 is drawn on a first substrate which transmits UV rays in 100 to 400 nm wavelength region to produce master masks P1 to PN. In the second step, a reflection layer which reflects ultra UV rays and an absorbing layer which absorbs the ultra UV rays are formed on a specified second substrate. In the third step, reduced images of the patterns of the master masks P1 to PN are projected on the second substrate by using a reduction stepper which reduces and projects an image with UV rays of 100 to 400 nm wavelength as exposure beams so as to remove a part of the absorbing layer. The second substrate from which a part of the absorbing layer is removed is used as a reflection type mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as an original pattern when manufacturing a micro device such as a semiconductor integrated circuit, an image pickup device (CCD or the like), a liquid crystal display device, or a thin film magnetic head by using a lithography technique. In particular, a method of manufacturing a mask that uses extreme ultraviolet light (EU
V light) as an exposure beam when used in manufacturing a mask for an exposure apparatus.

[0002]

2. Description of the Related Art When a device such as a semiconductor integrated circuit is manufactured, a circuit pattern to be formed is enlarged by, for example, about 4 to 5 times. A transfer method is used in which the image is projected onto a substrate to be exposed such as a wafer or a glass plate via a reduction projection optical system. An exposure apparatus is used for transferring such a photomask pattern, and a photomask used in a step-and-repeat type reduction projection exposure apparatus is also called a reticle.

Conventionally, such a reticle has been manufactured by drawing an original pattern on a predetermined substrate (blank) using an electron beam drawing apparatus or a laser beam drawing apparatus. That is, after a mask material (light shielding film) is formed on the substrate and a resist is applied, the original pattern is drawn using an electron beam drawing apparatus or a laser beam drawing apparatus. Thereafter, the original pattern was formed by the mask material by developing the resist and performing an etching process or the like. In this case, if the reduction magnification of the reduction projection type exposure apparatus using the reticle is 1 / β times, the original pattern drawn on the reticle may be a pattern obtained by enlarging the device pattern by β times. The drawing error by the apparatus is reduced to approximately 1 / β times on the device. Therefore, a device pattern can be formed with a resolution substantially equal to 1 / β times the resolution of the drawing apparatus.

[0004]

As described above, conventionally, an original pattern of a reticle has been drawn by an electron beam drawing apparatus or a laser beam drawing apparatus. In this regard, the minimum line width (resolution) of a projected image required for an exposure apparatus has been gradually narrowed in accordance with the progress of lithography technology. In 2005, a pattern having a minimum line width of about 100 nm or less was required. It is predicted that exposure is required. Exposure methods for exposing such a pattern include (a) an optical reduction projection type exposure method, (b) reduction transfer using an electron beam, (c) reduction transfer using an ion beam, and (d). A proximity type exposure method using X-rays, and (e) a lithography technique for projecting a reduced image of a reflective reticle using extreme ultraviolet light (EUV light) composed of soft X-rays having a wavelength of about 5 to 20 nm as an exposure beam. (EUV
L: Extreme Ultraviolet Lithography)
Some are actually being developed. Among these, the most prominent exposure method is EUVL of (e).

[0005] All of these exposure methods, except for the exposure method of the proximity method using X-rays (d),
A common point is that the projection exposure method uses a reduction ratio of about 1/4 to 1/10. In order to expose a pattern with a minimum line width of, for example, about 100 nm on a wafer at a reduction magnification of 1/4, it is necessary to form an original pattern having a minimum line width of about 400 nm on a corresponding reticle. is there. At this time, the required line width control accuracy is set to ±
If it is about 5%, a line width control accuracy of about ± 20 nm or less is required.

Further, the overlay accuracy required for the exposure apparatus is about 1/3 of the minimum line width. Therefore, the overlay accuracy required for an exposure apparatus having a minimum line width of about 100 nm is about 30 nm. It is as follows. Factors that determine the overlay accuracy include the alignment accuracy of the stage system of the exposure apparatus and the distortion of the reduction projection system in addition to the positional accuracy of the original pattern on the reticle. The positional accuracy is at most about 10 nm.

As described above, the minimum line width on the wafer is 1
At about 00 nm, that is, about 1/2 of the current minimum line width, the integration degree of the original pattern on the corresponding reticle becomes about 4
Double. At this time, the electron beam writing apparatus (the same applies to the laser beam writing apparatus) is a so-called single-stroke writing method, and the writing time is increased substantially in proportion to the integration degree of the original pattern (inversely proportional to the square of the minimum line width). Therefore, the writing time of the original pattern having the minimum line width of about 100 nm increases to about four times the current writing time. However, it is difficult to keep the drawing apparatus in a stable state continuously during such a long drawing time (for example, half a day to one day), and the position exceeding the allowable value of the original pattern during the drawing time is difficult. There was a risk of displacement. Further, for example, when a plurality of reticles (working reticles) are manufactured for a plurality of manufacturing lines, the time required for manufacturing increases in proportion to the number of reticles.

Further, use of a silicon wafer itself as a substrate of a reflective reticle for EUVL has been studied. However, quartz, which has been generally used in the past, has a small linear expansion coefficient, whereas the linear expansion coefficient of a silicon wafer is about 5 times as large as that. Therefore, if the writing time by an electron beam writing apparatus becomes longer, the writing time becomes longer. The displacement of the original pattern due to the thermal expansion of the silicon wafer inside cannot be ignored.

At present, it is not always easy to suppress the positional accuracy of the original pattern to about 10 nm by the electron beam drawing apparatus as described above. In view of the above, it is a first object of the present invention to provide a method for manufacturing a mask which can form a transfer pattern with high accuracy and in a short time. Also, the present invention relates to, for example, extreme ultraviolet light (EU).
V light) as an exposure beam,
A highly accurate mask that can be used as a reflective mask
A second object is to provide a method for manufacturing a mask which can be formed in a short time.

[0010]

According to the method of manufacturing a mask according to the present invention, an extreme ultraviolet light (E) having a wavelength of 1 to 50 nm is used.
A method of manufacturing a reflective mask (34) for an exposure apparatus using (UV light) as an exposure beam, wherein the first original pattern (3) is obtained by enlarging a pattern formed on the mask.
6), and the first original pattern is set to a wavelength of 100
A first mask for manufacturing parent masks (P1, P2,..., PN) by drawing on a first substrate that transmits ultraviolet light of 400 nm
A second step of laminating a reflective layer (31) for reflecting the extreme ultraviolet light and an absorbing layer (32) for absorbing the extreme ultraviolet light on a predetermined second substrate (4); Using a projection exposure apparatus that performs reduction projection using ultraviolet light having a wavelength of 100 to 400 nm as an exposure beam, a reduced image of the pattern of the parent mask (P1, P2,..., PN) manufactured in the first step is formed. The second substrate (4) manufactured in the second step
A third step of projecting and exposing the second substrate (4) from which a part of the absorbing layer has been removed to a reflection type. Is used as a mask.

According to the present invention, when the first original pattern is drawn on the first substrate, for example, an electron beam drawing apparatus is used to reduce the reduced image of the first original pattern. When projecting on the second substrate, KrF
(Wavelength 248 nm) or a projection exposure apparatus using excimer laser light such as ArF (wavelength 193 nm) or other ultraviolet light as exposure light, that is, an optical projection exposure apparatus. The first original pattern is a pattern obtained by enlarging the pattern of the finally manufactured mask by α times, and the influence of the writing error of the electron beam writing apparatus is reduced to 1 / α.
The pattern of the mask (transfer pattern) is formed with high precision. In addition, when a plurality of such masks are manufactured, the first original pattern is transferred by the optical projection exposure apparatus, so that the time required for manufacturing the masks is greatly reduced.

Further, the reflection layer (3) of the reflection type mask is provided.
1) is formed, for example, by alternately laminating two or more thin films of a substance in a predetermined number or more, and the absorption layer (3) is formed.
2) is formed of, for example, a thin film of one kind of substance. Therefore, by removing a part of the absorption layer (32) on the reflection layer (31), the pattern of the reflection type mask is formed with high precision. Further, by using a substrate such as a semiconductor wafer as the substrate of the reflection type mask, the optical projection exposure apparatus can use a normal semiconductor exposure apparatus almost as it is, thereby reducing the manufacturing cost. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a manufacturing process of a reticle as a mask of this embodiment. In FIG. 1, a reticle to be manufactured in this embodiment is a reflective working reticle 34 used when manufacturing a semiconductor device. . The working reticle 34 is obtained by forming an original pattern 27 on one surface of a substantially circular thin substrate made of a wafer such as a silicon wafer using a reflection film and an absorption layer. The two alignment marks 24A, 24A are sandwiched between the original pattern 27.
4B is formed. In addition, as the material of the substrate, low expansion glass, quartz, metal or the like can be used.

Further, the working reticle 34 includes 1 to 5
1 / β times (β is an integer greater than 1 or a half integer, etc.) through a projection optical system of a projection exposure apparatus using extreme ultraviolet light (EUV light) in a soft X-ray region of about 0 nm as exposure light. For example, 4, 5, or 6) is used in reduced projection. That is, in FIG. 1, after exposing a reduced image 27W of 1 / β times the original pattern 27 of the working reticle 34 to each shot area 48 on the wafer W coated with the resist,
By performing development, etching, and the like, a predetermined circuit pattern 35 is formed in each shot region 48. Hereinafter, an example of a manufacturing process of the working reticle 34 of the present embodiment will be described.

In FIG. 1, first, a circuit pattern 35 of a certain layer of a semiconductor device to be finally manufactured is designed. The width of the orthogonal side of the circuit pattern 35 is dX, dY.
Various line-and-space patterns and the like are formed in the rectangular area of FIG. In this example, the circuit pattern 35 is enlarged by β times so that the width of the orthogonal side is β · d
An original pattern 27 composed of X, β and dY rectangular areas is created on computer design data (including image data). β times is the reciprocal of the reduction ratio (1 / β) of the projection exposure apparatus in which the working reticle 34 is used.

Next, the original pattern 27 is multiplied by α (α is an integer greater than 1 or a half-integer, such as 4, 5, or 6 as an example), and the width of the orthogonal side is α · β.・ D
Parent pattern 36 consisting of rectangular areas of X, α, β, dY
Is created on design data (including image data), and its parent pattern 36 is divided vertically and horizontally into α pieces, respectively, so that α × α
, PN (N =
α ² ) is created on the design data. FIG. 1 shows a case where α = 4. Note that the division number α of the parent pattern 36 is not necessarily the original pattern 27 to the parent pattern 36.
It is not necessary to match the magnification α to. Thereafter, an electron beam writing apparatus (or a laser beam writing apparatus or the like can also be used) based on the parent patterns Pi (i = 1 to N).
Is generated, and the parent pattern Pi is transferred at the same magnification to a master reticle Ri as a parent mask.

For example, when manufacturing the first master reticle R1, a light-transmitting substrate such as quartz glass, quartz glass mixed with fluorine, or fluorite (corresponding to the first substrate of the present invention) A thin film of a mask material such as chromium (Cr) or molybdenum silicide (MoSi ₂ or the like) is formed thereon, and an electron beam resist is applied thereon. An equal-magnification image of the first parent pattern P1 is drawn. Thereafter, after the electron beam resist is developed, etching, resist stripping, and the like are performed to form the parent pattern P1 in the pattern region 20 on the master reticle R1. At this time, alignment marks 21A and 21B composed of two two-dimensional marks are formed on master reticle R1 in a predetermined positional relationship with respect to parent pattern P1. Similarly, for the other master reticle Ri, the parent pattern Pi and the alignment mark 21 are respectively formed by using an electron beam drawing apparatus or the like.
A and 21B are formed. This alignment mark 21
A and 21B are used for positioning when screen joining is performed later.

As described above, in this embodiment, since each parent pattern Pi to be drawn by the electron beam drawing apparatus (or laser beam drawing apparatus) is a pattern obtained by enlarging the original pattern 27 by α times, the amount of each drawing data is , Is reduced to about 1 / α ^{2 as} compared with the case where the original pattern 27 is directly drawn.
Furthermore, the minimum line width of the parent pattern Pi is
.Times. (For example, 5 times, 4 times, or the like) as compared with the minimum line width of each of the parent patterns Pi. Can be drawn. In addition, each parent pattern Pi
Is projected after being reduced to 1 / α, the drawing error of the electron beam drawing apparatus is also substantially reduced to 1 / α. Further, once the N master reticles R1 to RN are manufactured, the required number of working reticles 34 can be manufactured by repeatedly using them as described later. Time is not a big burden.

Next, the above-mentioned N master reticles Ri
Reduced image PIi of 1 / α times the parent pattern Pi (i = 1 to 1)
The working reticle 34 is manufactured by transferring N) while performing screen splicing. Therefore, as shown in FIG. 2A, a substrate for the working reticle 34 has a diameter of about 300 mm and a thickness of 1 mm.
The substrate 4 (corresponding to the second substrate of the present invention) of a silicon wafer of about mm is prepared, and the multilayer reflective film 31 is formed on the substrate 4.
Are laminated. FIG. 2B which is an enlarged view of part B of FIG. 2A.
As shown in FIG. 7, the reflection film 31 is composed of a molybdenum (Mo) thin film 31a having a thickness d1 and silicon (Si) having a thickness d1.
Are laminated at a pitch d2 (= 2 · d1). The thickness d1 is 3.25 as an example.
In this case, the pitch d2 is 6.5 nm, and the entire thickness of the reflection film 31 is about 325 nm (0.325 μm). Thus, the reflection film 31 in which the thin film 31a of molybdenum and the thin film 31b of silicon are laminated has a wavelength of 13 nm.
The wavelength of the EUV light for the working reticle 34 of this example is 13 nm because the extreme ultraviolet light (EUV light) is reflected. When EUV light having a wavelength of 11 nm is used, the reflection film 31 may be formed by alternately laminating a thin film of molybdenum and a thin film of beryllium (Be).

Next, as shown in FIG. 2C, an absorption layer 32 made of nickel (Ni) for absorbing EUV light is formed on the reflection film 31 on the substrate 4 to a thickness of about 1 μm. At this time, an alignment mark may be formed as necessary. Further, a photoresist layer 33 sensitive to light having a wavelength of 248 nm is applied on the absorption layer 32 to a thickness of about 1 μm. In addition, as a material of the absorption layer 32, another metal or the like may be used. Then, as shown in FIG.
The photoresist layer 33 on the substrate 4 is exposed to the pattern image of the master reticle while performing screen joining using the exposure light IL.

FIG. 3 shows an optical reduction projection type exposure apparatus used when performing exposure on the substrate 4. In FIG. 3, an exposure light source and a fly-eye for uniformizing the illuminance distribution are used at the time of exposure. Exposure light IL is applied to a reticle on a reticle stage 2 from an illumination optical system 1 including a lens, an illumination system aperture stop, a reticle blind (variable field stop), and a condenser lens system. On the reticle stage 2 of this example, the i-th (i = 1 to N) master reticle R
i is placed. In this example, K is used as the exposure light.
rF excimer laser light (wavelength 248 nm) is used, but other than that, ArF excimer laser light (wavelength 193 nm) is used.
m), F ₂ laser light (wavelength 157 nm), harmonics of a solid-state laser, or ultraviolet light having a wavelength of about 100 to 400 nm, such as a mercury lamp i-line (wavelength 365 nm).

The image of the pattern in the illumination area of the master reticle Ri is reduced via the projection optical system 3 by a reduction ratio of 1 / α (1
(/ Α is ４ in this example), which is projected onto the photoresist layer on the surface of the substrate 4. The numerical aperture of the projection optical system 3 is about 0.7
And the resolution is about 200 nm. Projection optical system 3 of this example
Is a double-sided telecentric refraction system, but a catadioptric system or the like including a concave mirror may be used. In the following, the Z axis is taken parallel to the optical axis AX of the projection optical system 3, the X axis is taken parallel to the plane of FIG. 3 in a plane perpendicular to the Z axis, and the Y axis is taken perpendicular to the plane of FIG. I do.

First, reticle stage 2 positions master reticle Ri on the reticle stage 2 in the XY plane. The position of the reticle stage 2 is measured by a laser interferometer (not shown), and the operation of the reticle stage 2 is controlled by the measured value and control information from the main control system 9. On the other hand, the substrate 4 is a disk-shaped substrate holder 2 as a holding member.
2 is held on the substrate holder 22 by electrostatic attraction.
Is fixed on a sample stage 5, and the sample stage 5 is fixed on an XY stage 6. The sample stage 5 adjusts the surface of the substrate 4 to the image plane of the projection optical system 3 by controlling the focus position (position in the optical axis AX direction) and the tilt angle of the substrate 4 by an autofocus method. XY stage 6
On the base 7 in the X direction, Y
The sample stage 5 (substrate 4) is positioned in the direction.

In this example, the substrate 4 and the substrate holder 22
For example, it is integrally attached to and detached from the sample table 5 by an electromagnetic adsorption method. Then, when the substrate 4 is later mounted on an exposure apparatus using EUV light as the working reticle 34, the substrate 4 and the substrate holder 22 are integrally attached to and detached from the exposure apparatus. This prevents foreign matter from being mixed between the substrate 4 and the substrate holder 22 during the processing step of the substrate 4 to prevent the flatness of the substrate 4 from deteriorating. Further, the surface of the substrate holder 22 is, for example, 0.1 mm to 100 mm square.
It is finished to have a flatness of about 0.3 μm or less. Thus, the substrate 4 is held on the substrate holder 22 while maintaining a very high flatness. Note that, instead of the substrate holder 22, a vacuum suction type substrate holder 22A fixed to the sample table 5 may be used.

An X coordinate, a Y coordinate, and a rotation angle of the sample table 5 are measured by a movable mirror 8m fixed on the upper portion of the sample table 5 and a laser interferometer 8 disposed opposite thereto. Is supplied to the stage control system 10 and the main control system 9. The movable mirror 8m, as shown in FIG. 4, represents an X-axis movable mirror 8mX and a Y-axis movable mirror 8mY. The stage control system 10 controls the operation of the linear motor and the like of the XY stage 6 based on the measured values and the control information from the main control system 9.

In this embodiment, a reticle library 16 having a shelf shape is arranged on the side of the reticle stage 2, and the master reticle R 1 is mounted on N support plates 17 sequentially arranged in the Z direction in the reticle library 16. RN are mounted. These master reticles R1 to RN
Is a reticle (parent mask) on which parent patterns P1 to PN obtained by dividing the parent pattern 36 of FIG. 1 are respectively formed. The reticle library 16 is supported by a slide device 18 so as to be movable in the Z direction. A reticle loader 19 provided between the reticle stage 2 and the reticle library 16 and having an arm that is rotatable and movable in a predetermined range in the Z direction. Is arranged. After the main control system 9 adjusts the position of the reticle library 16 in the Z direction via the slide device 18, the main control system 9 controls the operation of the reticle loader 19,
Between the desired support plate 17 in the reticle library 16 and the reticle stage 2, the desired master reticle R1
It is configured to be able to deliver RNs.

Further, a storage device 11 such as a magnetic disk device is connected to the main control system 9, and the storage device 11 stores an exposure data file. The exposure data file records data such as the mutual positional relationship of the master reticles R1 to RN, alignment information, and the like. When exposing the first shot area on the substrate 4 to the reduced image of the first master reticle R1 at the time of exposing the substrate 4 in this example, the XY stage 6 moves the next shot area on the substrate 4 by stepping. Moves to the exposure area of the projection optical system 3. In parallel with this, the master reticle R1 on the reticle stage 2 is returned to the reticle library 16 via the reticle loader 19, and the next master reticle R2 to be transferred next is transferred from the reticle library 16 via the reticle loader 19 to the reticle stage 2. Placed on top. Then, after the alignment is performed, the reduced image of the master reticle R2 is projected and exposed on the shot area on the substrate 4 via the projection optical system 3, and the remaining image on the substrate 4 is thereafter subjected to a step-and-repeat method. Exposure of the reduced images of the corresponding master reticles R2 to RN is sequentially performed on the shot areas.

The projection exposure apparatus shown in FIG. 2 is a batch exposure type. Instead, a scanning exposure type reduction projection type exposure apparatus (scanning exposure apparatus) such as a step-and-scan method is used. Is also good. In the scanning exposure type, at the time of exposure, the master reticle and the substrate 4 are synchronously scanned with respect to the projection optical system 3 at a reduction ratio. By using an optical scanning exposure apparatus, the influence of distortion or the like of the projection optical system can be reduced.

Now, as described above, the master reticle R1
When exposing the reduced image of the RN on the substrate 4, it is necessary to perform screen joining (joining) between adjacent reduced images with high accuracy. For this purpose, each master reticle Ri (i =
1 to N) and the corresponding shot area (referred to as Si) on the substrate 4 must be aligned with high accuracy. For this alignment, the projection exposure apparatus of this example is provided with an alignment mechanism for a reticle and a substrate.

FIG. 4 is a perspective view showing a main part of the projection exposure apparatus shown in FIG. 3. In FIG.
A pair of reference marks 13A and 13B having, for example, a cross shape are formed on the reference mark member 12 at predetermined intervals in the X direction.
Exposure light I is provided at the bottom of the reference marks 13A and 13B.
An illumination system that illuminates the reference marks 13A and 13B with the illumination light branched from L on the projection optical system 3 side is provided. At the time of alignment of the master reticle Ri, XY in FIG.
By driving the stage 6, the reference mark member 1
2 so that the centers of the reference marks 13A and 13B on the optical axis AX substantially coincide with the optical axis AX of the projection optical system 13.
A and 13B are positioned.

As an example, two cross-shaped alignment marks 21A and 2A are arranged so as to sandwich the pattern region 20 on the pattern surface (lower surface) of the master reticle Ri in the X direction.
1B is formed. The interval between the reference marks 13A and 13B is set substantially equal to the interval between the reduced images of the alignment marks 21A and 21B by the projection optical system 3, and the center of the reference marks 13A and 13B is almost aligned with the optical axis AX. The exposure light I from the bottom side of the reference mark member 12.
By illuminating with the illumination light having the same wavelength as L, enlarged images of the reference marks 13A and 13B by the projection optical system 3 are formed near the alignment marks 21A and 21B, respectively.

These alignment marks 21A, 21
Mirrors for reflecting illumination light from the projection optical system 3 side in the ± X direction are disposed above B, and a TTR (through-the-reticle) system is provided so as to receive the illumination light reflected by these mirrors. And the imaging type alignment sensor 14
A and 14B are provided. Alignment sensor 14
A, 14B, the alignment marks 21A, 21
B and the images of the corresponding reference marks 13A and 13B are captured, and the captured signals are output to the alignment signal processing system 1 shown in FIG.
5 is supplied.

The alignment signal processing system 15 performs image processing on the image pickup signal to make the X and Y directions of the alignment marks 21A and 21B with respect to the images of the reference marks 13A and 13B.
The amount of displacement in the direction is obtained, and these two sets of displacements are supplied to the main control system 9. The main control system 37 positions the reticle stage 2 so that the two sets of positional deviation amounts are symmetrical to each other and each falls within a predetermined range. As a result, the alignment marks 21A and 21B and the parent pattern Pi of the master reticle Ri (see FIG. 1) are positioned with respect to the reference marks 13A and 13B.

In this state, the main control system 9 shown in FIG. 2 stores the coordinates of the sample stage 5 in the X and Y directions measured by the laser interferometer 8, thereby completing the alignment of the master reticle Ri. Thereafter, any point on the sample stage 5 (substrate 4) can be moved to the exposure center of the parent pattern Pi. Further, in FIG. 4, the position of the mark on the substrate 4 is detected by turning off the side of the projection optical system PL.
An Axis type image processing type alignment sensor (not shown) is also provided, and, for example, two cross-shaped alignment marks 24A and 24B are formed on the end of the substrate 4 in the X direction. Then, for example, before performing exposure of the first master reticle R1, the position of the alignment marks 24A, 24B is detected by the alignment sensor, and the reference marks 13A, 13B are determined based on the detection results.
, The exposure center of the master reticle Ri can be adjusted to a desired position on the substrate 4. Since only a single exposure is performed on the substrate 4, the alignment marks 24
Instead of using A and 24B, for example, alignment of the initial state of the substrate 4 may be performed based on the outer shape of the substrate 4, and thereafter, only the positioning of the substrate 4 may be performed based on the measurement value of the laser interferometer 8.

By performing the alignment in this manner, as shown in FIG. 4, the i-th master reticle Ri
Image PIi of the parent pattern Pi by the projection optical system 3
Is exposed on an i-th shot area Si in a rectangular pattern area 25 surrounded by sides parallel to the X axis and the Y axis on the substrate 4. In FIG. 4, a reduced image of the parent pattern already exposed in the pattern area 25 of the substrate 4 is shown by a solid line,
The unexposed reduced image is indicated by a dotted line. In this manner, the reduced images of the parent patterns P1 to PN of the N master reticles R1 to RN in FIG. The reduced images of the PN are exposed while performing screen joining with the reduced images of the adjacent parent patterns.
Thereby, the parent pattern 36 of FIG.
The projection image reduced by α times is exposed.

Thereafter, as shown in FIG.
When the upper photoresist layer 33 is developed, if the photoresist is a positive type, a dark portion of the projected image is left as a resist pattern 33a. Next, as shown in FIG. 2F, after the absorption layer 32 is etched using the resist pattern 33a as a mask, the remaining resist pattern 33a is peeled off as shown in FIG. 2G. As a result, the absorbing layer 32a is left in the region corresponding to the dark portion of the reduced image of the parent mask on the reflective film 31 on the substrate 4, and the working reticle 34 of the present example is completed.

Note that, as described above, the master reticle Ri
When the parent pattern is connected to the substrate 4 and reduced and transferred, predetermined marks (for example, alignment marks 21A and 21B) on each master reticle Ri are also reduced and transferred, and a reduced image of the parent pattern of the adjacent master reticle is reduced. The transfer of the reduced image of the parent pattern of the adjacent master reticle may be corrected based on the detection result when the mark is transferred.

When, for example, a dense pattern and an isolated pattern are formed on the original pattern 27 in FIG. 1, only one dense pattern is formed on one of the master reticles Ra among the master reticles R1 to RN. Only one isolated pattern may be formed on one master reticle Rb. At this time, the exposure condition such as the best illumination condition and the image formation condition is different between the dense pattern and the isolated pattern. Therefore, each time the master reticle Ri is exposed, the exposure condition, that is, the illumination optical system 1 is adjusted according to the parent pattern Pi. The shape and size of the aperture stop, the coherence factor (σ value), the numerical aperture of the projection optical system 3, and the like may be optimized. In order to optimize the exposure condition, a predetermined optical filter (so-called pupil filter) is inserted / removed near the pupil plane of the projection optical system 3, or when the exposure of an isolated pattern is performed, the projection optical system A so-called progressive focus method (flex method) in which the image plane 3 and the surface of the substrate 4 are relatively vibrated in the Z direction within a predetermined range may be used together.

In the above-described embodiment, the number of master reticles P1 to PN shown in FIG. 1 is not fixed to 16, but the master reticle P1 to PN of the original pattern formed on the reflective working reticle 34 to be manufactured. It increases or decreases depending on the size or the like. The original pattern is D
If it is a regular pattern like a RAM, a predetermined plurality of reticles of the master reticles P1 to PN are
One reticle can be shared. In this case, the number of master reticles to be drawn by the electron beam drawing apparatus is reduced, so that the time required for manufacturing the master reticle can be reduced.

Further, in the above embodiment, a silicon wafer is used as the substrate 4 of the working reticle 34. However, the projection lithography apparatus shown in FIG. Can be performed. Further, as a processing apparatus for etching or the like, a conventional processing apparatus for silicon wafers (thin film forming apparatus, resist coater, resist developing apparatus, etching apparatus, etc.) can be used as it is, so that it is necessary to prepare new manufacturing equipment. In addition, the manufacturing cost of the reflective working reticle 34 can be reduced. Further, N master reticles P1 to P in FIG.
Once N is manufactured, the same number of reticles as the working reticle 34 can be manufactured in the required number of times in a short time and with the same accuracy by simply repeating exposure using an optical projection exposure apparatus. The time required for manufacturing can be reduced, and the overall manufacturing cost can be reduced.

Next, an example of the operation when performing exposure using the reflective working reticle 34 of FIG. 1 manufactured as described above will be described. FIG. 5 shows a reduction projection type step-and-scan type (scanning exposure type) exposure apparatus (hereinafter, referred to as an "EUVL exposure apparatus") in which the working reticle 34 is mounted and exposure is performed using EUV light as an exposure beam. In FIG. 5, an X axis is taken in a horizontal plane perpendicular to the plane of FIG. 5, a Y axis is taken parallel to the plane of FIG. 5, and a Z axis is taken in the vertical direction. At this time, the reticle stage 41 is mounted on the reticle base 42 so as to be movable in the Y direction, the substrate holder 22 is held on the bottom surface of the reticle stage 41 by electromagnetic adsorption or the like, and the working reticle is placed on the upper surface (vertically below) of the substrate holder 22. 34 are held by electrostatic attraction. Working reticle 3
4 and the substrate holder 22 are integrally transferred from the projection exposure apparatus of FIG.

Then, for example, SOR (Synchrotron Orbi)
tal Radiation) A wavelength 1 as an exposure beam emitted from an X-ray source 43 such as a ring or a laser / plasma light source
The soft X-ray IL1 of 3 nm is transmitted to the mirror 5 in the projection optical system 46.
The light is reflected at 1 and illuminates the arc-shaped illumination area of the pattern area of the working reticle 34 obliquely with respect to the normal direction. Then, the soft X reflected by the working reticle 34
The line IL1 passes through the first concave mirror 52, the convex mirror 53, the plane mirror 54, and the second concave mirror 55 in the projection optical system 46,
An image in which the pattern of the illumination area is reduced to 1 / β (1 / β is 1/4 in this example) is formed on a wafer W to be exposed. An opening is formed in a portion of the concave mirror 52 or the like through which the soft X-ray IL1 passes. Since there is no suitable transparent glass material for EUV light having a wavelength of, for example, about 1 to 50 nm such as soft X-rays, the projection optical system 46 of the present example is constituted by a reflection system, and is also used as a reticle. A working reticle 34 of the type is used.

The numerical aperture of the projection optical system 46 is 0.08.
The above is set, for example, to about 0.1 to 0.2. Since the wavelength of the soft X-ray IL1 is 13 nm, a resolution of about 100 to 50 nm can be obtained by the projection optical system 46. For example, when it is desired to obtain a resolution (minimum line width) of 100 to 50 nm, the working reticle 3
The minimum line width of the pattern No. 4 is 400 to 200 nm, but with this line width, the optical projection exposure apparatus of FIG.

The wafer W is held on a wafer stage 49 via a wafer holder (not shown). The wafer stage 49 continuously moves the wafer W on the surface plate 50 in the Y direction, and also moves the wafer W in the X and Y directions. The step movement of the wafer W is performed. Further, the wafer stage 49 also controls the focus position and the tilt angle of the wafer W so that the surface of the wafer W is adjusted to the image plane of the projection optical system 46 by an autofocus method. Reticle stage 41 and wafer stage 4
The position of 9 is measured by a laser interferometer in the reticle stage drive system 44 and the wafer stage drive system 47, respectively, and based on these measured values, the main control system 45 passes through the reticle stage drive system 44 and the wafer stage drive system 47. Reticle stage 41 and wafer stage 49
Drive synchronously.

That is, at the time of exposure, after one shot area on the wafer W is step-moved to the approach start position, the working reticle 34 is moved via the reticle stage 41 with respect to the illumination area of the soft X-ray IL1 in the + Y direction (or By scanning the wafer W at a speed VR / β in the −Y direction (or + Y direction) via the wafer stage 49 in synchronization with the scanning at the speed VR in the −Y direction, the working reticle is provided in the shot area. 34 reduced images are exposed.

At this time, the optical axis A of the projection optical system 46 of this embodiment is
X1 is parallel to the vertical direction (Z direction), and the projection optical system 46 is telecentric on the wafer W side, but the telecentricity is lost on the reticle side. Therefore, if the surface of the working reticle 34 has irregularities, or if the surface hangs down in the Z direction,
The reduced image on the wafer W may be distorted. However, in this example, the working reticle 34 is transported integrally with the substrate holder 22, there is no possibility that foreign matter or the like will be pinched on the back surface of the working reticle 34, and the working reticle 34 is adsorbed on almost the entire surface. Therefore, the pattern surface of the working reticle 34 has a very high flatness (about 0.1 to 0.3 μm or less in a 100 mm square).
Has been maintained. Therefore, a reduced image of the pattern of the working reticle 34 is always transferred onto the wafer W with high accuracy.

The present invention is not limited to the above-described embodiment, but may take various configurations without departing from the spirit of the present invention.

[0048]

According to the method of manufacturing a mask of the present invention, the writing error of the first original pattern is reduced on the second substrate, and the pattern of the parent mask is formed by the second optical projection exposure apparatus. Any number of the same masks can be manufactured simply by transferring onto the substrate, and therefore, there is an advantage that the masks can be formed with high accuracy and in a short time.

Further, since the mask has a reflection layer that reflects extreme ultraviolet light, the mask can be used as a reflection type mask in an exposure apparatus that uses extreme ultraviolet light as an exposure beam. . Further, when the substrate is a circular substrate such as a semiconductor wafer, for example, an optical projection exposure apparatus for manufacturing a semiconductor can be used as it is, so that there is an advantage that the manufacturing cost of the reflective mask can be reduced. .

[Brief description of the drawings]

FIG. 1 is a view showing an entire manufacturing process for manufacturing a working reticle by exposing a reduced image of a master reticle in an example of an embodiment of the present invention.

FIG. 2 is an enlarged view, partially cut away, showing each manufacturing process for forming a master pattern by applying a photoresist to a working reticle substrate.

FIG. 3 is a configuration diagram showing an optical projection exposure apparatus used when performing reduction projection of a master reticle in an example of the embodiment.

4 is a perspective view of a main part showing a state in which a reduced image of a parent pattern on a master reticle is projected onto a substrate 4 in the projection exposure apparatus of FIG.

FIG. 5 is a cross-sectional view illustrating a part of an example of an exposure apparatus that mounts the working reticle manufactured in the embodiment and performs exposure using EUV light as an exposure beam.

[Explanation of symbols]

R1 to RN: Master reticle (parent mask), P1 to P
N: divided parent pattern, 3: projection optical system, 4: working reticle substrate, 5: sample stage, 6: XY stage, 16: reticle library, 18: slide device,
19: reticle loader, 22: substrate holder, 27: original pattern, 31: reflective film, 32: absorption layer, 33: photoresist layer, 34: working reticle, 43: X-ray source, 46: projection optical system

Claims (4)

[Claims] 1. A method of manufacturing a reflection type mask for an exposure apparatus using an extreme ultraviolet light having a wavelength in a range of 1 to 50 nm as an exposure beam, wherein a first original plate having an enlarged pattern formed on the mask is provided. A pattern is created, and the first original pattern has a wavelength of 10
A first step of manufacturing a parent mask by drawing on a first substrate that transmits 0 to 400 nm ultraviolet light, a reflective layer for reflecting the extreme ultraviolet light on a predetermined second substrate, and the extreme ultraviolet light A second step of laminating and forming an absorption layer that absorbs light, and a projection exposure apparatus that performs reduction projection using ultraviolet light having a wavelength of 100 to 400 nm as an exposure beam, and the parent device manufactured in the first step. The reduced image of the pattern of the mask is
A third step of projecting and exposing the second substrate manufactured in the step to remove a part of the absorbing layer, wherein the second substrate has a part of the absorbing layer removed. Is used as the reflective mask. 2. The method according to claim 1, wherein the second substrate is a substantially circular substrate. 3. The projection exposure apparatus used in the third step, wherein the holding member for holding the second substrate by suction and the second substrate are moved integrally. Item 3. The method for producing a mask according to Item 1 or 2. 4. The projection exposure apparatus used in the third step, wherein the second substrate has a surface of 100 mm square and maintains a flatness of substantially 0.1 to 0.3 μm. 4. The method according to claim 1, wherein the mask is held.