JP4091271B2 - Photomask manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photomask manufacturing method, and more particularly to pass / fail judgment of a manufactured photomask.
[0002]
[Prior art]
A semiconductor device manufacturing process includes a pattern forming process for forming various patterns on a semiconductor wafer, a so-called lithography process, and a mask such as a photomask or a phase shift mask is used in this lithography process.
[0003]
In recent years, with the miniaturization of semiconductor devices, the dimensional accuracy required for this type of photomask is rapidly becoming strict, and for example, the dimensional uniformity within the mask surface is required to be 10 nm or less.
[0004]
Conventionally, in a photomask manufacturing method, after a mask pattern is formed on a mask substrate based on specifications, it is determined whether the mask is a good product or a defective product. There are many judgment items, and if one of the items does not satisfy the specification value, it has been regarded as a defective product. For example, in the halftone phase shift mask, there are 11 typical specification items and specification values as shown in the table of FIG. 32. Conventionally, even one of these items exceeds the specification value. The mask was defective.
[0005]
For this reason, the mask yield is extremely low, although the mask manufacturing technique has been improved in accuracy.
[0006]
In this way, in the conventional mask manufacturing method, since there are many items that do not satisfy the specifications among the determination items of whether the product is non-defective or defective, the mask yield is extremely low. There was a situation.
[0007]
In order to solve this situation, the inventors of the present invention have found the following facts as a result of various analyzes of conventional defective masks.
[0008]
That is, in general, the specifications of the photomask are necessary for obtaining a desired exposure margin in pattern exposure on a semiconductor wafer, and even if each item is almost the specification value, the desired exposure margin is achieved. However, in an actual photomask, it is extremely rare for all items to be close to the specification value, and most photomasks have certain items exceeding the specification value. , Other items are often included in the specification value with a margin, and even if there are items that exceed the specification value, other items are within the specification value with a margin. If the decrease in exposure tolerance due to an item exceeding the specified value is less than the increase in exposure tolerance of the item within the specified value with a margin, the desired exposure tolerance can be obtained as a whole. it can. For example, as shown in the table of FIG. 33, in the measurement example of the halftone type phase shift mask that has been regarded as a defective product in the past, for example, the deviation from the target value of the average pattern dimension value of the completed mask is 13 nm. Even if the value exceeds ± 10 nm, if the in-plane uniformity of the pattern dimension of the mask is 4 nm (3σ), which is smaller than the specified value of 8 nm (3σ), this mask is actually used. It was confirmed that the desired exposure latitude was obtained when the wafer was exposed and the defocus tolerance and the exposure tolerance were measured. There is Japanese Patent Application No. 2000-260285 (filed on Aug. 30, 2000) as a prior application by the applicant regarding this.
[0009]
[Problems to be solved by the invention]
In this prior application, in the case of a photomask, the main items that determine the exposure margin are the average value of pattern dimensions and in-plane uniformity, and the average value of these pattern dimensions and in-plane uniformity are measured. An exposure margin is calculated from the measurement data, and a mask having a desired exposure margin is determined as a non-defective product.
[0010]
Further, in the case of a phase shift mask, for example, a halftone type phase shift mask, in addition to the average value of the pattern dimension and the in-plane uniformity, the average value of the transmissivity of the semi-light-shielding portion and the in-plane uniformity The average value and the in-plane uniformity of the phase shift amount of the light shielding part are measured, the exposure margin is calculated from these measurement data, and a mask having a desired exposure margin is judged as a good product.
[0011]
However, the items that determine the exposure latitude include the average value of pattern dimensions and in-plane uniformity. If this item is newly measured and the exposure margin is obtained using the measurement data, the average value of the pattern dimensions, and the measurement data of the in-plane uniformity, it becomes possible to make a pass / fail judgment with higher accuracy.
[0012]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photomask manufacturing method that can improve yield and has high accuracy of pass / fail judgment.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, according to one aspect of the present invention, after a pattern is formed on a photomask, the dimension of the pattern is measured, the drawing position of the pattern is measured, and the pattern dimension measurement result is measured. The exposure margin 1 due to dimensional accuracy when the photomask is used, and the exposure margin 2 due to the drawing position accuracy when the photomask is used from the pattern drawing position measurement result of the pattern, For each. Further, from the exposure margin 1 caused by the dimensional accuracy and the exposure margin 2 caused by the drawing position accuracy, an exposure margin when the photomask is used is obtained, and the obtained exposure margin is desired. It is characterized in that whether the photomask is acceptable or not is determined based on whether or not the exposure margin is satisfied.
[0014]
In order to achieve the above object, in another aspect of the present invention, after forming a pattern including a phase shift film on a photomask, the dimension of this pattern is measured, and the drawing position of the pattern is measured. The characteristics of the phase shift film are measured, and from the dimension measurement result of the pattern, when the photomask is used, the exposure margin 1 due to dimensional accuracy and the pattern drawing position measurement result are used to calculate the photomask. Exposure margin 2 due to the drawing position accuracy when using the photomask, and exposure margin 3 due to the property of the phase shift film when the photomask is used, based on the measurement result of the property of the phase shift film. For each. Further, when the photomask is used from the exposure margin 1 due to the dimensional accuracy, the exposure margin 2 due to the drawing position accuracy, and the exposure margin 3 due to the property of the phase shift film. An exposure margin is obtained, and whether the photomask is acceptable or not is determined based on whether or not the obtained exposure margin satisfies a desired exposure margin.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the description, common parts are denoted by common reference symbols throughout the drawings.
[0016]
(First embodiment)
A photomask manufacturing method according to the first embodiment of the present invention will be described below with reference to FIGS.
[0017]
FIG. 1 is a flowchart showing a method for manufacturing a photomask according to the first embodiment of the present invention, FIGS. 2A and 2B are plan views showing a Cr mask, FIGS. 3A and 3B are views showing a dimension measuring method, and FIG. FIG. 5 is a diagram illustrating a drawing position measuring method, and FIG. 5 is a diagram illustrating a relationship between focus latitude and exposure tolerance.
[0018]
First, a mask pattern is formed on a mask blank (ST. 1).
[0019]
In this example, a 0.60 μm line and space pattern (hereinafter referred to as L / S pattern) was drawn and developed on a Cr mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, the Cr film was etched using this resist pattern as an etching mask to form a Cr pattern (mask pattern). FIG. 2A shows a plan view of the Cr mask after forming the Cr pattern, and FIG. 2B shows an enlarged view inside the broken line frame 2B in FIG. 2A.
[0020]
Next, the dimension of the mask pattern is measured (ST.2).
[0021]
Further, the drawing position of the mask pattern is measured (ST.3).
[0022]
In this example, as a dimension measurement item, the difference between the average value of the Cr pattern dimension and the target dimension value and the in-plane uniformity of the Cr pattern dimension were obtained. As a result, the difference between the average value and the target dimension value was 10 nm, and the in-plane uniformity was 20 nm (3σ).
[0023]
As a specific example of the dimension measuring method, as shown in FIG. 3A, the dimension measuring points 10 are set in a matrix on the surface of the Cr mask. Then, as shown in FIG. 3B, for example, the line width dimension of the Cr pattern is measured for each of these points 10. In this way, the dimension measurement data is obtained for each point 10, and the difference between the average value of the Cr pattern dimension and the target dimension value and the in-plane uniformity of the Cr pattern dimension are obtained from the obtained dimension measurement data.
[0024]
Further, in this example, the average value of the positional deviation of the Cr pattern and the variation of the positional deviation were obtained as the drawing position measurement items. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0025]
As a specific example of this drawing position measuring method, as shown in FIG. 4, for example, cross-shaped position measuring marks 11 are arranged in a matrix on the surface of the Cr mask, and the drawing position 12 as a target is The deviation component from the actually drawn drawing position 13 is measured for each position measuring mark 11. In this way, drawing position measurement data is obtained for each mark 11, and the average value of the positional deviation of the Cr pattern and the deviation of the positional deviation are obtained from the obtained drawing position measurement data.
[0026]
Next, from the dimensional measurement result, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this mask is obtained (ST. 4).
[0027]
In this example, the exposure margin resulting from the dimensional accuracy is assumed to be 1, and the degree of deterioration from the exposure amount margin of a complete mask (hereinafter referred to as a complete mask) having no deviation from the target is calculated.
[0028]
The exposure conditions used for this calculation were the exposure conditions that actually use the mask, KrF stepper (exposure wavelength 248 nm), NA = 0.68, σ = 0.75, and annular zone shielding rate 2/3.
[0029]
First, the exposure tolerance of the complete mask was calculated. As a result of this calculation, the exposure tolerance of the complete mask was 15% as the exposure tolerance when the pattern tolerance was within 10% and the focus tolerance was secured to 0.5 μm (FIG. 5, ▲). 1 ▼: Refer to exposure tolerance curve (complete mask)).
[0030]
Further, the exposure margin 1 of the Cr mask is calculated from the calculation result, when the pattern dimension variation is within 10% and the focus margin is 0.5 μm, the exposure tolerance of the Cr mask is calculated from the exposure tolerance of the complete mask. It was 9.4% deteriorated (ΔELcd) (see FIG. 5, (2): exposure tolerance 1 curve).
[0031]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when the pattern is transferred onto the wafer using the mask is obtained (ST. 5).
[0032]
In this example, the exposure margin is 2 due to the drawing position accuracy, and the degree of deterioration from the exposure tolerance of the complete mask is calculated. The exposure conditions are the same as in the case of an exposure margin of 1.
[0033]
As a result of the calculation, the exposure margin 2 of the Cr mask is calculated as follows: when the pattern dimension variation is within 10% and the focus margin is 0.5 μm, the exposure tolerance of the Cr mask is 2. 6% deterioration (ΔELpos) (see FIG. 5, (3): exposure margin 2 curve).
[0034]
Next, from the exposure margins 1 and 2, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST. 6).
[0035]
In this example, the exposure degree of the formed Cr mask was used, and the total deterioration degree ΔEL was calculated from the deterioration degrees ΔELcd and ΔELpos. An example of this calculation formula is as follows.
[0036]
ΔEL = √ ((ΔELcd) ² + (ΔELpos) ² )
As a result of the calculation, the exposure tolerance of the Cr mask is 9.75% from the exposure tolerance of the complete mask when the pattern tolerance is within 10% and the focus tolerance is 0.5 μm. % Deterioration.
[0037]
From this, the exposure tolerance of the Cr mask was determined to be 5.25% in the exposure dose tolerance when the pattern dimension variation was within 10% and the focus tolerance was secured to 0.5 μm. (See FIG. 5, (4): exposure tolerance curve).
[0038]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0039]
In the case of this example, when the pattern dimension variation is within 10% and the focus tolerance is secured to 0.5 μm, the reference exposure margin is 5% or more (FIG. 5, FIG. 5). (5): Refer to exposure tolerance curve (good / bad line).
[0040]
The exposure tolerance of the formed Cr mask is ST. As determined in 6, it is 5.25%. For this reason, as shown in FIG. 5, the Cr mask satisfies the standard. Therefore, it was determined that the present Cr mask is a non-defective product. Incidentally, conventionally, the specification value of this Cr mask has an in-plane uniformity of pattern dimension within 16 nm (3σ). Therefore, the in-plane uniformity of the pattern dimension does not satisfy the specification, and is disposed as a defective product.
[0041]
According to this embodiment, there are the following effects.
[0042]
Conventionally, an average value of pattern dimensions and a specification value of in-plane uniformity are determined, and if either of them does not satisfy the specification value, it is regarded as a defective mask.
[0043]
However, in this embodiment, the exposure margin of the formed mask is obtained from the exposure margin 1 caused by the dimensional accuracy and the exposure margin 2 caused by the drawing position accuracy, and the obtained exposure margin is determined as the reference. A pass / fail judgment is made based on whether or not a desired exposure margin is satisfied. For this reason, masks that have been regarded as defective products, for example, the average value satisfies the specification value with a margin, but the in-plane uniformity does not satisfy the specification value. The filling mask can be newly relieved as a non-defective product, and the yield of the mask can be improved.
[0044]
Furthermore, according to the present embodiment, compared with the prior application (Japanese Patent Application No. 2000-260285 (filed on Aug. 30, 2000)) filed by the applicant of the present application, the exposure tolerance of the mask is measured based on the measurement data of the drawing position, for example, Cr. Since the average value of the positional deviation of the pattern and the deviation of the positional deviation are obtained by further taking into consideration, it is possible to make a pass / fail judgment with higher accuracy.
[0045]
(Second Embodiment)
The difference between the second embodiment and the first embodiment is that the ST. In the pass / fail judgment in FIG. 6, instead of the exposure tolerance of the complete mask, a pattern with good dimensional accuracy, for example, a pattern with a small deviation of the dimensional average value, was extracted from the formed Cr mask, and this pattern was actually exposed on the wafer That is, the exposure tolerance obtained from the result is used.
[0046]
FIG. 6 is a flowchart showing a photomask manufacturing method according to the second embodiment of the present invention, and FIG. 7 is a diagram showing the relationship between the focus tolerance and the exposure tolerance.
[0047]
First, as shown in FIG. 6, a mask pattern is formed on a mask blank (ST. 1).
[0048]
In this example, a 0.60 μm L / S pattern was drawn and developed on a Cr mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, the Cr film was etched using this resist pattern as an etching mask to form a Cr pattern (mask pattern).
[0049]
Next, the dimension of the mask pattern is measured (ST.2).
[0050]
Further, the drawing position of the mask pattern is measured (ST.3).
[0051]
In this example, as a dimension measurement item, the difference between the average value of the Cr pattern dimension and the target dimension, and the in-plane uniformity of the Cr pattern dimension were obtained. As a result, the difference between the average value and the target dimension was 10 nm, and the in-plane uniformity was 20 nm (3σ).
[0052]
In this example, the average value of the positional deviation of the Cr pattern and the variation of the positional deviation were obtained as items for measuring the drawing position. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0053]
Next, from the dimensional measurement result, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this mask is obtained (ST. 4).
[0054]
In this example, the exposure margin due to the dimensional accuracy is assumed to be 1, and the degree of deterioration from the exposure margin of the complete mask is calculated.
[0055]
The exposure conditions used for this calculation are the exposure conditions that actually use the mask, KrF stepper, NA = 0.68, σ = 0.75, and annular zone shielding ratio 2/3.
[0056]
First, the exposure tolerance of the complete mask was calculated. As a result of this calculation, the exposure tolerance of the complete mask was 15% of the exposure tolerance when the pattern tolerance was within 10% and the focus tolerance was secured to 0.5 μm (FIG. 7, ▲ 1 ▼: Refer to exposure tolerance curve (complete mask)).
[0057]
As a result of the calculation, the exposure tolerance 1 of the Cr mask indicates that the exposure tolerance of the Cr mask is the exposure tolerance of the complete mask when the pattern tolerance is within 10% and the focus tolerance is 0.5 μm. 9.4% (ΔELcd) (see FIG. 7, (2): exposure tolerance 1 curve).
[0058]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when the pattern is transferred onto the wafer using the mask is obtained (ST. 5).
[0059]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 resulting from the drawing position accuracy is the exposure tolerance of the Cr mask when the pattern margin is within 10% and the focus margin is 0.5 μm. Was deteriorated by 2.6% from the exposure tolerance of the complete mask (ΔELpos) (refer to (3) in FIG. 7, exposure tolerance 2 curve).
[0060]
Next, from the exposure margins 1 and 2, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST. 6).
[0061]
In this example, the exposure tolerance of the formed Cr mask was used, and first, the total deterioration degree ΔEL was calculated from the deterioration degrees ΔELcd and ΔELpos.
[0062]
As a result of the calculation, the exposure tolerance of the formed Cr mask is that when the pattern dimension fluctuation is within 10% and the focus tolerance is secured to 0.5 μm, the exposure tolerance is 9. It was 75% deteriorated.
[0063]
Further, a pattern with a small deviation between the average value of the Cr pattern dimension and the target dimension value is extracted from the Cr mask, and this pattern is extracted as a KrF stepper, NA = 0.68, σ = 0.75, and annular zone shielding. The wafer was actually exposed under the condition of a rate of 2/3. Subsequently, the dimension of the pattern formed on the wafer through the development and etching processes was measured. As a result of the actual exposure as described above, the exposure margin of this Cr mask with a small deviation between the average value of the Cr pattern dimension and the target dimension value is obtained when the focus margin is 0.5 μm. It was found that a tolerance of 17% was obtained (see FIG. 7, (6): exposure tolerance curve (pattern with good dimensional accuracy)).
[0064]
From this, the exposure margin of this Cr mask was determined to be 7.25% when the focus margin was secured to 0.5 μm (FIG. 7, (4): (See exposure tolerance curve).
[0065]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0066]
In the case of this example, the reference desired exposure latitude is 4% or more when the focus tolerance is secured to 0.5 μm (FIG. 7, (5): exposure tolerance curve). (See the pass / fail line).
[0067]
The exposure tolerance of the formed Cr mask is ST. As determined in 6, it is 7.25%. For this reason, as shown in FIG. 7, the present Cr mask satisfies the criteria. Therefore, it was determined that the present Cr mask is a non-defective product. Incidentally, conventionally, the specification value of this Cr mask has an in-plane uniformity of pattern dimension within 13 nm (3σ). Therefore, the in-plane uniformity of the pattern dimension does not satisfy the specification, and is disposed as a defective product.
[0068]
According to the second embodiment, the same effects as those of the first embodiment can be obtained.
[0069]
Furthermore, according to the second embodiment, compared to the first embodiment, ST. In the pass / fail judgment in step 6, since the exposure tolerance obtained from the result of actual exposure on the wafer is used, it is possible to make a pass / fail judgment that is more suitable for actual exposure.
[0070]
(Third embodiment)
The third embodiment is an example in which the present invention is applied to a phase shift mask, particularly a halftone phase shift mask.
[0071]
8 is a flowchart showing a photomask manufacturing method according to the third embodiment of the present invention, and FIG. 4 shows a step ST. FIG. 11 is a diagram showing the relationship between the focus latitude and the exposure tolerance.
[0072]
First, as shown in FIG. 8, a mask pattern is formed on a mask blank (ST. 1).
[0073]
In this example, an isolated space line of 0.70 μm in which a distance between an L / S pattern of 0.52 μm and an adjacent pattern is 2.0 μm on a halftone mask blank coated with a positive chemically amplified resist. Was drawn and developed to form a resist pattern. Next, using this resist pattern as an etching mask, the Cr film and the halftone film were etched to form a mask pattern.
[0074]
Next, the dimension of the mask pattern is measured (ST.2).
[0075]
Further, the drawing position of the mask pattern is measured (ST.3).
[0076]
Furthermore, the property of the phase shift film, in this example, the property of the halftone phase shift film is measured (ST. 8).
[0077]
In this example, as a dimension measurement item, the space width of the formed mask pattern was measured, and the difference between the average value of the space width and the target dimension value and the in-plane uniformity of the space width were obtained. As a result, the difference between the average value of the space width and the target dimension value is −4 nm for the L / S pattern of 0.52 μm, +4 nm for the isolated space pattern of 0.70 μm, and the in-plane uniformity of the space width is 14 nm (3σ )Met.
[0078]
Further, in this example, the variation of the positional deviation of the mask pattern was obtained as a drawing position measurement item. As a result, the positional deviation variation was 3 nm (3σ).
[0079]
In addition, in this example, the properties of the halftone phase shift film are measured, and the difference between the average value of the transmittance of the phase shift film and the target transmittance value, the dispersion of the transmittance, the average value of the phase difference and the target The difference from the phase difference value and the variation in the phase difference were obtained. As a result, the deviation of the average value of the transmittance from the target value is 0.05%, the dispersion of the transmittance is 0.1%, the deviation of the average value of the phase difference from the target value is 6 °, and the dispersion of the phase difference is Was 5 ° (3σ).
[0080]
Next, from the dimensional measurement results, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this halftone phase shift mask is obtained (ST.4).
[0081]
In this example, as shown in FIG. 9, of the dimensional accuracy, the exposure margin 1A due to the difference between the average value of the space width and the target dimension value, and the exposure margin due to the in-plane uniformity of the space width. 1B is obtained (ST.4A, ST.4B). Then, assuming that the exposure margin was 1A, the degree of deterioration from the exposure margin of the complete mask was calculated. The exposure conditions used for this calculation are exposure conditions when the mask is actually used, for example, KrF stepper, NA = 0.68, σ = 0.75, and annular zone shielding rate 2/3.
[0082]
As a result of the calculation, the exposure margin 1A indicates that the exposure tolerance of the halftone phase shift mask is 0 from the exposure tolerance of the complete mask when the pattern tolerance is within 10% and the focus margin is secured to 0.4 μm. .39% deterioration.
[0083]
Similarly, when the exposure tolerance 1B is within 10% of the pattern dimension variation and the focus margin is secured to 0.4 μm, the exposure tolerance of the halftone phase shift mask is 6.5 from the exposure tolerance of the complete mask. % Deterioration.
[0084]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST. 5).
[0085]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 is a complete exposure dose margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. The exposure amount tolerance of the mask deteriorated by 0.8%.
[0086]
Further, from the measurement results of the properties of the halftone film, an exposure margin 3 resulting from the properties of the halftone phase shift film when a pattern is transferred onto the wafer using the same halftone phase shift mask is obtained ( ST.9).
[0087]
In this example, as shown in FIG. 10, among the properties of the phase shift film, the exposure margin is 3A due to the difference between the average value of the transmittance of the phase shift film and the target transmittance value, and the variation in the transmittance. An exposure margin 3C resulting from the difference between the resulting exposure margin 3B, the target phase difference value of the average value of the phase differences, and an exposure margin 3D resulting from the variation in the phase differences are obtained (ST.9A to ST). .9D).
[0088]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 3A is a complete exposure dose margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It was degraded by 0.055% from the exposure tolerance of the mask.
[0089]
Similarly, the exposure margin 3B is such that when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, the exposure tolerance of the halftone phase shift mask is 0.33 from the exposure tolerance of the complete mask. % Deterioration.
[0090]
Similarly, when the pattern margin is within 10% and the focus margin is 0.4 μm, the exposure margin 3C is 0.017 from the exposure tolerance of the complete mask when the exposure tolerance of the halftone phase shift mask is secured. % Deterioration.
[0091]
Similarly, the exposure margin 3D is such that when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, the exposure tolerance of the halftone phase shift mask is 0.12 from the exposure tolerance of the complete mask. % Deterioration.
[0092]
Next, from the exposure margins 1A and 1B, the exposure margin 2 and the exposure margins 3A to 3D, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6).
[0093]
In this example, the total deterioration degree was calculated from the exposure margins 1A and 1B, the exposure margin 2 and the exposure margins 3A to 3D as the exposure margin of the formed Cr mask.
[0094]
As a result of calculation, when the pattern dimension variation is within 10% and the focus margin is 0.5 μm, the exposure tolerance of the halftone phase shift mask is deteriorated by 7.24% from the exposure tolerance of the complete mask. Met.
[0095]
In this example, similarly to the second embodiment, a pattern with a small deviation between the average value of the Cr pattern dimension and the target dimension value is extracted from the halftone phase shift mask, and this pattern is extracted as a KrF stepper. , NA = 0.68, σ = 0.75, and annulus shielding rate 2/3, the wafer was actually exposed to light, and the dimension of the pattern formed on the wafer was measured. As a result of the actual exposure, the exposure margin of the pattern in which the deviation between the average value of the Cr pattern dimension of the halftone phase shift mask and the target dimension value is small is obtained when the focus margin is secured to 0.4 μm. It was found that 12% could be obtained as the amount tolerance.
[0096]
From this, the exposure tolerance of the halftone phase shift mask was determined to be 4.76% as the exposure tolerance when the focus tolerance was secured to 0.4 μm.
[0097]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0098]
In the case of this example, the reference desired exposure latitude is 4% or more as the exposure tolerance when the focus tolerance is 0.4 μm.
[0099]
The exposure tolerance of the formed halftone phase shift mask is ST. As obtained in FIG. 6, it is 4.76%, and as shown in FIG. 11, this halftone phase shift mask satisfies the standard. Therefore, it was determined that this halftone phase shift mask was a non-defective product. Incidentally, conventionally, the specification value of this halftone type phase shift mask has an in-plane uniformity of pattern dimension within 13 nm (3σ). Therefore, the in-plane uniformity of the pattern dimension does not satisfy the specification, and is disposed as a defective product.
[0100]
According to the third embodiment, the same effect as that of the first embodiment can be obtained.
[0101]
(Fourth embodiment)
FIG. 12 is a flowchart showing a photomask manufacturing method according to the fourth embodiment of the present invention, and FIG. 13 is a diagram showing the relationship between focus latitude and exposure tolerance.
[0102]
First, as shown in FIG. 12, a mask pattern is formed on a mask blank (ST. 1).
[0103]
In this example, a 0.60 μm L / S pattern was drawn and developed on a Cr mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, the Cr film was etched using this resist pattern as an etching mask to form a Cr pattern (mask pattern).
[0104]
Next, the dimension of the mask pattern is measured (ST.2).
[0105]
Further, the drawing position of the mask pattern is measured (ST.3).
[0106]
In this example, as a dimension measurement item, the difference between the average value of the Cr pattern dimension and the target dimension, and the in-plane uniformity of the Cr pattern dimension were obtained. As a result, the difference between the average value and the target dimension value was 10 nm, and the in-plane uniformity was 20 nm (3σ).
[0107]
Also, in this example, as the items for measuring the drawing position, the average value of the Cr pattern displacement, the variation in displacement, the expansion / contraction component of the entire photomask, the orthogonal displacement component of the entire photomask, and the local displacement of the entire photomask The amount was determined. As a result, the average value of misalignment was 5 nm, the misalignment variation was 10 nm (3σ), the expansion and contraction components and the orthogonal misalignment component were both 1.5 ppm, and the local misalignment amount was 15 nm (3σ).
[0108]
Next, from the dimensional measurement result, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this Cr mask is obtained (ST. 4).
[0109]
In this example, among the dimensional accuracy, an exposure margin 1A caused by the difference between the average value of the Cr pattern size and the target dimensional value and an exposure margin 1B caused by the in-plane uniformity of the Cr pattern size were obtained. . Then, the degree of deterioration from the exposure tolerance of the complete mask was calculated as the exposure tolerance 1A. The exposure conditions used for this calculation are the exposure conditions when actually using the mask, for example, KrF stepper, NA = 0.68, σ = 0.75, and annular zone shielding rate 2/3.
[0110]
As a result of the calculation, when the pattern tolerance is 10% or less and the focus margin is 0.5 μm, the exposure tolerance of the Cr mask deteriorates by 9.4% from the exposure tolerance of the complete mask. It was.
[0111]
Similarly, as a result of the calculation, when the pattern tolerance is 10% or less and the focus tolerance is 0.5 μm, the exposure tolerance of the Cr mask is 0.3% from the exposure tolerance of the complete mask. % Deterioration.
[0112]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when the pattern is transferred onto the wafer using the mask is obtained (ST. 5).
[0113]
As a result of calculation under the same conditions as the exposure margins 1A and 1B, the exposure margin 2 resulting from the drawing position accuracy is the exposure amount of the Cr mask when the pattern dimension variation is within 10% and the focus margin is 0.5 μm. The tolerance deteriorated by 2.6% from the exposure tolerance of the complete mask.
[0114]
Next, from the exposure margins 1A and 1B and the exposure margin 2, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6).
[0115]
In this example, the total deterioration degree was calculated from the three deterioration degrees obtained as the exposure margins 1A and 1B and the exposure margin 2 as the exposure margin of the formed Cr mask.
[0116]
As a result of calculation, the exposure tolerance of the Cr mask is 10% lower than the exposure tolerance of the complete mask when the pattern tolerance is within 10% and the focus tolerance is secured to 0.5 μm. It was.
[0117]
In this example, similarly to the second embodiment, a pattern with a small deviation between the average value of the Cr pattern dimensions and the target dimension value is extracted from the Cr mask, and this pattern is extracted as a KrF stepper, NA = 0. The exposure was actually performed on the wafer under the conditions of .68, σ = 0.75, and annulus shielding rate of 2/3, and the dimensions of the pattern formed on the wafer were measured. From the actual exposure result, the exposure margin of the pattern with little deviation between the average value of the Cr pattern dimension and the target dimension value of this Cr mask is the exposure margin when the focus margin is 0.5 μm. It was found that 17% was obtained.
[0118]
From this, it was determined that the exposure tolerance of the Cr mask can be obtained as 7% as the exposure tolerance when the focus tolerance is secured to 0.5 μm.
[0119]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0120]
In the case of this example, the reference desired exposure latitude is 5% or more as the exposure tolerance when the focus tolerance is secured to 0.5 μm.
[0121]
The exposure tolerance of the formed Cr mask is ST. As obtained in FIG. 6, it is 7%, and this Cr mask satisfies the standard as shown in FIG. Therefore, this Cr mask was determined to be a good product.
[0122]
In the fourth embodiment, the same effect as that of the first embodiment can be obtained.
[0123]
(Fifth embodiment)
FIG. 14 is a flowchart showing a photomask manufacturing method according to the fifth embodiment of the present invention, and FIG. 15 is a diagram showing the relationship between the focus latitude and the exposure tolerance.
[0124]
First, as shown in FIG. 14, a mask pattern is formed on a mask blank (ST. 1).
[0125]
In this example, a 0.70 μm isolated line pattern was drawn and developed on halftone mask blanks coated with a positive chemically amplified resist to form a resist pattern. Next, using this resist pattern as an etching mask, the halftone film was etched to form a mask pattern.
[0126]
Next, the dimension of the mask pattern is measured (ST.2).
[0127]
Further, the drawing position of the mask pattern is measured (ST.3).
[0128]
Further, the properties of the phase shift film, in this example, the properties of the halftone phase shift film are measured (ST. 8).
[0129]
In this example, as a dimension measurement item, the difference between the average value of the formed mask pattern dimensions and the target dimension value, and the in-plane uniformity of the mask pattern dimensions were obtained. As a result, the difference between the average value of the mask pattern dimension and the target dimension value was 10 nm, and the in-plane uniformity was 13 nm (3σ).
[0130]
Further, in this example, the average value of the positional deviation of the mask pattern and the variation of the positional deviation were obtained as the items for measuring the drawing position. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0131]
In this example, the properties of the halftone phase shift film are measured, and the difference between the average value of the transmittance of the phase shift film and the target transmittance value, the in-plane uniformity of the transmittance (from the target transmittance). Deviation), the difference between the average value of the phase difference and the target phase difference value, and the in-plane uniformity of the phase difference. As a result, the difference between the average transmittance value and the target transmittance value is −0.5%, the in-plane uniformity of the transmittance is 0.7% (3σ), and the target retardation value is the average value of the phase difference. The in-plane uniformity of the phase difference was 7 °.
[0132]
Next, from the dimensional measurement results, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this halftone phase shift mask is obtained (ST.4).
[0133]
In this example, of the dimensional accuracy, the exposure margin 1A resulting from the difference between the average value of the mask pattern dimension and the target dimension value and the exposure margin 1B resulting from the in-plane uniformity of the mask pattern dimension were obtained. . Then, assuming that the exposure margin was 1A, the degree of deterioration from the exposure margin of the complete mask was calculated. The exposure conditions used for this calculation are exposure conditions when the mask is actually used, for example, ArF stepper, NA = 0.55, σ = 0.75, and annular zone shielding rate 2/3.
[0134]
As a result of the calculation, the exposure margin 1A is 3% from the exposure margin of the complete mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, and the exposure margin of the halftone phase shift mask is 3%. .2% deterioration.
[0135]
Similarly, when the pattern tolerance is within 10% and the focus margin is 0.4 μm, the exposure margin 1B is 3.3% from the exposure amount margin of the complete mask when the exposure tolerance of the halftone phase shift mask is secured. % Deterioration.
[0136]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST. 5).
[0137]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 is a complete exposure dose margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.6% from the exposure tolerance of the mask.
[0138]
Further, from the measurement results of the properties of the phase shift film, an exposure margin 3 resulting from the properties of the phase shift film when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST.9). ).
[0139]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 3 is a complete exposure amount margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.1% from the exposure dose tolerance of the mask.
[0140]
Next, from the exposure margins 1A, 1B, the exposure margin 2, and the exposure margin 3, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6).
[0141]
In this example, the total deterioration degree was calculated from the exposure margins 1A and 1B, the exposure margin 2 and the exposure margin 3 as the exposure margin of the formed halftone phase shift mask.
[0142]
As a result of calculation, when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, the exposure tolerance of the halftone phase shift mask is deteriorated by 8.1% from the exposure tolerance of the complete mask. Met.
[0143]
Moreover, the exposure margin of the complete mask was 9.6% as the exposure margin when the pattern margin was within 10% and the focus margin was 0.4 μm as a result of calculation.
From this, it was determined that the exposure margin of the halftone phase shift mask can be obtained as an exposure margin of 1.5% when a focus margin of 0.4 μm is secured.
[0144]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0145]
In the case of this example, the reference desired exposure latitude is 4% or more as the exposure tolerance when the focus tolerance is 0.4 μm.
[0146]
The exposure tolerance of the formed halftone phase shift mask is ST. As found in FIG. 6, it is 1.5%, and as shown in FIG. 15, this halftone phase shift mask does not satisfy the standard. Therefore, this halftone phase shift mask was determined to be a defective product.
[0147]
(Sixth embodiment)
FIG. 16 is a flowchart showing a photomask manufacturing method according to the sixth embodiment of the present invention, and FIG. 17 is a diagram showing the relationship between focus latitude and exposure tolerance.
[0148]
First, as shown in FIG. 16, a mask pattern is formed on a mask blank (ST. 1).
[0149]
In this example, a 0.52 μm L / S pattern was drawn and developed on a Cr mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, using this resist pattern as an etching mask, the Cr film is etched to form a Cr pattern (mask pattern). Further, adjacent Cr patterns were processed so as to ideally have a phase difference of 180 ° to form a so-called Levenson type phase shift mask.
[0150]
Next, the dimension of the mask pattern is measured (ST.2).
[0151]
Further, the drawing position of the mask pattern is measured (ST.3).
[0152]
Further, the properties of the phase shift film are measured. In this example, the properties of the Levenson type phase shift film are measured (ST. 8).
[0153]
In this example, as a dimension measurement item, the difference between the average value of the Cr pattern dimension and the target dimension, and the in-plane uniformity of the Cr pattern dimension were obtained. As a result, the difference between the average value and the target dimension was 10 nm, and the in-plane uniformity was 20 nm (3σ).
[0154]
Further, in this example, the average value of the positional deviation of the Cr pattern and the variation of the positional deviation were obtained as the drawing position measurement items. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0155]
Further, in this example, as an item for measuring the properties of the Levenson type phase shift film, the average value of the phase difference of the phase shift film, the target phase difference value, and the in-plane uniformity of the phase difference were obtained. As a result, the difference between the average value of the phase difference and the target phase difference value was 5 °, and the in-plane uniformity of the phase difference was 7 °.
[0156]
Next, the exposure margin 1 resulting from the dimensional accuracy when the pattern is transferred onto the wafer using the Levenson type phase shift mask is obtained from the dimensional measurement result (ST. 4).
[0157]
In this example, of the dimensional accuracy, an exposure margin 1A caused by the difference between the average value of the Cr pattern and the target dimension value and an exposure margin 1B caused by the in-plane uniformity of the Cr pattern were obtained. Then, assuming that the exposure margin was 1A, the degree of deterioration from the exposure margin of the complete mask was calculated. The exposure conditions used for this calculation are the exposure conditions when the mask is actually used, for example, ArF stepper, NA = 0.60, σ = 0.30, and no annular zone shielding.
[0158]
As a result of the calculation, the exposure margin 1A indicates that the exposure tolerance of the Levenson-type phase shift mask is 2. from the exposure tolerance of the complete mask when the pattern tolerance is 10% or less and the focus margin is 0.4 μm. It deteriorated by 5%.
[0159]
Similarly, when the pattern tolerance is 10% or less and the focus margin is 0.4 μm, the exposure margin of the Levenson-type phase shift mask deteriorates by 3.3% from the exposure margin of the complete mask. It was.
[0160]
Further, from the drawing position measurement result, the exposure margin 2 resulting from the drawing position accuracy when the pattern is transferred onto the wafer using the Levenson type phase shift mask is obtained (ST. 5).
[0161]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 is that the exposure tolerance of the Levenson-type phase shift mask is a complete mask when the pattern tolerance is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.6% from the exposure dose tolerance.
[0162]
Further, from the measurement results of the properties of the phase shift film, an exposure margin 3 resulting from the properties of the phase shift film when a pattern is transferred onto the wafer using the Levenson type phase shift mask is obtained (ST.9). .
[0163]
As a result of the calculation under the same conditions as the exposure margin 1, the exposure margin 3 is that the exposure margin of the Levenson-type phase shift mask is a complete mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.1% from the exposure tolerance.
[0164]
Next, from the exposure margins 1A, 1B, the exposure margin 2, and the exposure margin 3, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6).
[0165]
In this example, the total deterioration degree was calculated from the exposure margins 1A and 1B, the exposure margin 2 and the exposure margin 3 as the exposure margin of the formed Levenson type phase shift mask.
[0166]
As a result of calculation, when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, the exposure amount margin of the Levenson type phase shift mask is deteriorated by 7.6% from the exposure amount margin of the complete mask. there were.
[0167]
Further, the exposure margin of the complete mask was calculated to be 16% as the exposure margin when the variation in pattern dimensions was within 10% and the focus margin was secured to 0.4 μm.
From this, it was determined that the exposure margin of the Levenson-type phase shift mask can be obtained as 8.4% as the exposure margin when the focus margin is secured to 0.4 μm.
[0168]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0169]
In the case of this example, the reference desired exposure latitude is 4% or more as the exposure tolerance when the focus tolerance is 0.4 μm.
[0170]
The exposure tolerance of the formed Levenson type phase shift mask is ST. As found in FIG. 6, it is 8.4%, and as shown in FIG. 17, this Levenson type phase shift mask satisfies the standard. Therefore, this Levenson type phase shift mask was determined to be a non-defective product.
[0171]
Also in the sixth embodiment, the same effect as that of the first embodiment can be obtained.
[0172]
(Seventh embodiment)
FIG. 18 is a flowchart showing a photomask manufacturing method according to the seventh embodiment of the present invention, and FIG. 19 is a diagram showing the relationship between the focus latitude and the exposure tolerance.
[0173]
First, as shown in FIG. 18, a mask pattern is formed on a mask blank (ST. 1).
[0174]
In this example, a 0.6 μm L / S pattern was drawn and developed on a Cr mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, the Cr film was etched using this resist pattern as an etching mask to form a Cr pattern (mask pattern).
[0175]
Next, the dimension of the mask pattern is measured (ST.2).
[0176]
Further, the drawing position of the mask pattern is measured (ST.3).
[0177]
Further, in this example, the formed Cr mask is inspected for defects (ST. 10).
In this example, as a dimension measurement item, the difference between the average value of the Cr pattern dimension and the target dimension, and the in-plane uniformity of the Cr pattern dimension were obtained. As a result, the difference between the average value and the target dimension was 10 nm, and the in-plane uniformity was 20 nm (3σ).
[0178]
Further, in this example, the average value of the positional deviation of the Cr pattern and the variation of the positional deviation were obtained as the drawing position measurement items. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0179]
In this example, in the defect inspection, the area is 10,000 nm. ² An opaque foreign object was found. An opaque foreign substance is a defect that is different from the desired mask shape and shape.
[0180]
Next, from the dimensional measurement result, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this mask is obtained (ST. 4).
[0181]
In this example, the exposure margin due to the dimensional accuracy is assumed to be 1, and the degree of deterioration from the exposure margin of the complete mask is calculated.
[0182]
The exposure conditions used for this calculation are the exposure conditions that actually use the mask, KrF stepper, NA = 0.68, σ = 0.75, and annular zone shielding ratio 2/3.
[0183]
As a result of the calculation, the exposure tolerance 1 of the Cr mask is 9% from the exposure tolerance of the complete mask when the pattern tolerance is within 10% and the focus tolerance is 0.5 μm. .4% deterioration.
[0184]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when the pattern is transferred onto the wafer using the mask is obtained (ST. 5).
[0185]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 resulting from the drawing position accuracy is the exposure tolerance of the Cr mask when the pattern margin is within 10% and the focus margin is 0.5 μm. Was 2.6% lower than the exposure tolerance of the complete mask.
[0186]
Further, an exposure margin 4 resulting from the defect is obtained (ST. 11).
[0187]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 4 resulting from the defect is that the exposure tolerance of the Cr mask is complete when the pattern dimension variation is within 10% and the focus margin is 0.5 μm. The exposure amount tolerance of the mask deteriorated by 1%.
[0188]
Next, from the exposure margin 1, the exposure margin 2, and the exposure margin 4, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST. 6).
[0189]
In this example, the total deterioration degree was calculated from the three deterioration degrees obtained as the exposure margin 1, the exposure margin 2, and the exposure margin 3 as the exposure margin of the formed Cr mask.
[0190]
As a result of the calculation, the exposure tolerance of the formed Cr mask is such that when the pattern dimension variation is within 10% and the focus tolerance is 0.5 μm, the exposure tolerance of the Cr mask is determined from the exposure tolerance of the complete mask. It deteriorated by 10.5%.
[0191]
Further, as a result of calculation, the exposure tolerance of the complete mask was 15% as the exposure tolerance when the pattern tolerance was within 10% and the focus tolerance was secured to 0.5 μm.
From this, it was determined that the exposure tolerance of the Cr mask can be obtained as 4.3% as the exposure tolerance when the focus tolerance is secured to 0.5 μm.
[0192]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0193]
In the case of this example, the reference desired exposure latitude is 5% or more as the exposure tolerance when the focus tolerance is secured to 0.5 μm.
[0194]
The exposure tolerance of the formed Cr mask is ST. As obtained in FIG. 6, it is 4.3%, and as shown in FIG. 19, this Cr mask does not satisfy the standard. Therefore, this Cr mask was determined to be a defective product.
[0195]
(Eighth embodiment)
FIG. 20 is a flowchart showing a photomask manufacturing method according to the eighth embodiment of the present invention, and FIG. 21 is a diagram showing the relationship between focus latitude and exposure tolerance.
[0196]
First, as shown in FIG. 20, a mask pattern is formed on a mask blank (ST. 1).
[0197]
In this example, a 0.7 μm isolated line pattern was drawn and developed on a halftone mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, using this resist pattern as an etching mask, the halftone film was etched to form a mask pattern.
[0198]
Next, the dimension of the mask pattern is measured (ST.2).
[0199]
Further, the drawing position of the mask pattern is measured (ST.3).
[0200]
Further, the properties of the phase shift film, in this example, the properties of the halftone phase shift film are measured (ST. 8).
[0201]
Further, a defect inspection of the formed halftone phase shift mask is performed (ST. 10).
[0202]
In this example, as a dimension measurement item, the difference between the average value of the formed mask pattern dimensions and the target dimension value, and the in-plane uniformity of the mask pattern dimensions were obtained. As a result, the difference between the average value of the mask pattern dimension and the target dimension value was 10 nm, and the in-plane uniformity was 5 nm (3σ).
[0203]
Further, in this example, the average value of the positional deviation of the mask pattern and the variation of the positional deviation were obtained as the items for measuring the drawing position. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0204]
In this example, the properties of the halftone phase shift film are measured, and the difference between the average value of the transmittance of the phase shift film and the target transmittance value, the in-plane uniformity of the transmittance (from the target transmittance). Deviation), the difference between the average value of the phase difference and the target phase difference value, and the in-plane uniformity of the phase difference. As a result, the difference between the average transmittance value and the target transmittance value is −0.5%, the in-plane uniformity of the transmittance is 0.7% (3σ), and the target retardation value is the average value of the phase difference. The in-plane uniformity of the phase difference was 7 °.
[0205]
In this example, the area is 40000 nm in the defect inspection process. ² A pinhole was discovered. For this reason, the defect, in this example, the pinhole was corrected by the defect correcting device (ST. 12).
[0206]
Next, the area and transmittance of the corrected portion are measured (ST.13).
[0207]
In this example, when the area and transmittance of the corrected pinhole part were measured, the area of the corrected pinhole part was 44000 nm. ² The transmittance was 0%.
[0208]
Next, from the dimensional measurement results, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this halftone phase shift mask is obtained (ST.4).
[0209]
In this example, the exposure margin 1A resulting from the difference between the average value of the dimension and the target dimension value and the exposure margin 1B resulting from the in-plane uniformity of the dimension were obtained from the dimensional accuracy. Then, assuming that the exposure margin was 1A, the degree of deterioration from the exposure margin of the complete mask was calculated. The exposure conditions used for this calculation are the exposure conditions when the mask is actually used, for example, ArF stepper, NA = 0.60, σ = 0.75, and annular zone shielding rate 2/3.
[0210]
As a result of the calculation, when the pattern tolerance is 10% or less and the focus margin is 0.4 μm, the exposure margin of the halftone phase shift mask is 1 from the exposure margin of the complete mask. .7% deterioration.
[0211]
Similarly, when the exposure tolerance 1B is within 10% of the pattern dimension variation and the focus margin is 0.4 μm, the exposure tolerance of the halftone phase shift mask is 1.1 from the exposure tolerance of the complete mask. % Deterioration.
[0212]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST. 5).
[0213]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 is a complete exposure dose margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.6% from the exposure tolerance of the mask.
[0214]
Further, from the measurement results of the properties of the phase shift film, the exposure margin 3 resulting from the properties of the phase shift film when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST.9). ).
[0215]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 3 is a complete exposure amount margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.1% from the exposure dose tolerance of the mask.
[0216]
Further, an exposure margin 5 resulting from defect correction is obtained (ST.14).
[0217]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 5 resulting from defect correction is the exposure of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. The amount tolerance deteriorated by 1% from the exposure amount tolerance of the complete mask.
[0218]
Next, from the exposure margins 1A, 1B, the exposure margin 2, the exposure margin 3, and the exposure margin 5, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6). ).
[0219]
In this example, the total deterioration degree was calculated from the exposure margins 1A and 1B, the exposure margin 2, the exposure margin 3 and the exposure margin 5 as the exposure margin of the formed halftone phase shift mask. .
[0220]
As a result of calculation, when the pattern dimension variation is within 10% and the focus margin is secured to 0.4 μm, the exposure tolerance of the halftone phase shift mask is deteriorated by 5.4% from the exposure tolerance of the complete mask. Met.
[0221]
Further, as a result of calculation, the exposure tolerance of the complete mask was 11% as the exposure tolerance when the pattern dimension variation was within 10% and the focus tolerance was secured to 0.4 μm.
From this, the exposure tolerance of the halftone phase shift mask was determined to be 5.6% as the exposure tolerance when the focus tolerance was secured to 0.4 μm.
[0222]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0223]
In the case of this example, the reference desired exposure latitude is 4% or more as the exposure tolerance when the focus tolerance is 0.4 μm.
[0224]
The exposure tolerance of the formed halftone phase shift mask is ST. As obtained in FIG. 6, it is 5.6%, and this halftone phase shift mask satisfies the standard as shown in FIG. Therefore, it was determined that this halftone phase shift mask was a non-defective product.
[0225]
In the eighth embodiment, the same effect as that of the first embodiment can be obtained.
[0226]
(Ninth embodiment)
FIG. 22 is a flowchart showing a photomask manufacturing method according to the ninth embodiment of the present invention, and FIG. 23 is a diagram showing the relationship between focus latitude and exposure tolerance.
[0227]
First, as shown in FIG. 22, a mask pattern is formed on a mask blank (ST. 1).
[0228]
In this example, a 0.7 μm isolated line pattern was drawn and developed on a halftone mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, using this resist pattern as an etching mask, the halftone film was etched to form a mask pattern.
[0229]
Next, the dimension of the mask pattern is measured (ST.2).
[0230]
Further, the drawing position of the mask pattern is measured (ST.3).
[0231]
Further, the properties of the phase shift film, in this example, the properties of the halftone phase shift film are measured (ST. 8).
[0232]
Further, a defect inspection of the formed halftone phase shift mask is performed (ST. 10).
[0233]
In this example, as a dimension measurement item, the difference between the average value of the formed mask pattern dimensions and the target dimension value, and the in-plane uniformity of the mask pattern dimensions were obtained. As a result, the difference between the average value of the mask pattern dimension and the target dimension value was 10 nm, and the in-plane uniformity was 5 nm (3σ).
[0234]
Further, in this example, the average value of the positional deviation of the mask pattern and the variation of the positional deviation were obtained as the items for measuring the drawing position. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0235]
In this example, the properties of the halftone phase shift film are measured, and the difference between the average value of the transmittance of the phase shift film and the target transmittance value, the in-plane uniformity of the transmittance (from the target transmittance). Deviation), the difference between the average value of the phase difference and the target phase difference value, and the in-plane uniformity of the phase difference. As a result, the difference between the average transmittance value and the target transmittance value is −0.5%, the in-plane uniformity of the transmittance is 0.7% (3σ), and the target retardation value is the average value of the phase difference. The in-plane uniformity of the phase difference was 7 °.
[0236]
In this example, a pinhole having a length of 200 nm and a width of 200 nm was found in the defect inspection process. For this reason, the defect was corrected by the defect correcting device, and in this example, the pinhole was corrected (ST. 12).
[0237]
Next, the size and transmittance of the corrected part are measured (ST.13).
[0238]
In this example, when the size and transmittance of the corrected pinhole portion were measured, the size of the corrected pinhole portion was 200 nm in length, the width was 220 nm, and the transmittance was 0%.
[0239]
Next, from the dimensional measurement results, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this halftone phase shift mask is obtained (ST.4).
[0240]
In this example, the exposure margin 1A resulting from the difference between the average value of the dimension and the target dimension value and the exposure margin 1B resulting from the in-plane uniformity of the dimension were obtained from the dimensional accuracy. Then, assuming that the exposure margin was 1A, the degree of deterioration from the exposure margin of the complete mask was calculated. The exposure conditions used for this calculation are the exposure conditions when the mask is actually used, for example, ArF stepper, NA = 0.60, σ = 0.75, and annular zone shielding rate 2/3.
[0241]
As a result of the calculation, when the pattern tolerance is 10% or less and the focus margin is 0.4 μm, the exposure margin of the halftone phase shift mask is 1 from the exposure margin of the complete mask. .7% deterioration.
[0242]
Similarly, when the exposure tolerance 1B is within 10% of the pattern dimension variation and the focus margin is 0.4 μm, the exposure tolerance of the halftone phase shift mask is 1.1 from the exposure tolerance of the complete mask. % Deterioration.
[0243]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST. 5).
[0244]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 is a complete exposure dose margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.6% from the exposure tolerance of the mask.
[0245]
Further, from the measurement results of the properties of the phase shift film, the exposure margin 3 resulting from the properties of the phase shift film when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST.9). ).
[0246]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 3 is a complete exposure amount margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.1% from the exposure dose tolerance of the mask.
[0247]
Further, an exposure margin 5 resulting from defect correction is obtained (ST.14).
[0248]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 5 resulting from defect correction is the exposure of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. The amount tolerance deteriorated by 1% from the exposure amount tolerance of the complete mask.
[0249]
Next, from the exposure margins 1A, 1B, the exposure margin 2, the exposure margin 3, and the exposure margin 5, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6). ).
[0250]
In this example, the total deterioration degree was calculated from the exposure margins 1A and 1B, the exposure margin 2, the exposure margin 3 and the exposure margin 5 as the exposure margin of the formed halftone phase shift mask. .
[0251]
As a result of calculation, when the pattern dimension variation is within 10% and the focus margin is secured to 0.4 μm, the exposure tolerance of the halftone phase shift mask is deteriorated by 5.4% from the exposure tolerance of the complete mask. Met.
[0252]
Further, as a result of calculation, the exposure tolerance of the complete mask was 11% as the exposure tolerance when the pattern dimension variation was within 10% and the focus tolerance was secured to 0.4 μm.
From this, the exposure tolerance of the halftone phase shift mask was determined to be 5.6% as the exposure tolerance when the focus tolerance was secured to 0.4 μm.
[0253]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0254]
In the case of this example, the reference desired exposure latitude is 4% or more as the exposure tolerance when the focus tolerance is 0.4 μm.
[0255]
The exposure tolerance of the formed halftone phase shift mask is ST. As found in FIG. 6, it is 5.6%, and as shown in FIG. 23, this halftone phase shift mask satisfies the standard. Therefore, it was determined that this halftone phase shift mask was a non-defective product.
[0256]
In the ninth embodiment, the same effect as that of the first embodiment can be obtained.
[0257]
(10th Embodiment)
FIG. 24 is a flowchart showing a photomask manufacturing method according to the tenth embodiment of the present invention, and FIG. 25 is a diagram showing the relationship between focus latitude and exposure tolerance.
[0258]
First, as shown in FIG. 24, a mask pattern is formed on a mask blank (ST. 1).
[0259]
In this example, a 0.70 μm isolated line pattern was drawn and developed on halftone mask blanks coated with a positive chemically amplified resist to form a resist pattern. Next, using this resist pattern as an etching mask, the halftone film was etched to form a mask pattern.
[0260]
Next, the dimension of the mask pattern is measured (ST.2).
[0261]
Further, the drawing position of the mask pattern is measured (ST.3).
[0262]
Further, the properties of the phase shift film, in this example, the properties of the halftone phase shift film are measured (ST. 8).
[0263]
Further, a defect inspection of the formed halftone phase shift mask is performed (ST. 10).
[0264]
In this example, as a dimension measurement item, the difference between the average value of the formed mask pattern dimensions and the target dimension value, and the in-plane uniformity of the mask pattern dimensions were obtained. As a result, the difference between the average value of the mask pattern dimension and the target dimension value was 10 nm, and the in-plane uniformity was 5 nm (3σ).
[0265]
Further, in this example, the average value of the positional deviation of the mask pattern and the variation of the positional deviation were obtained as the items for measuring the drawing position. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0266]
In this example, the properties of the halftone phase shift film are measured, and the difference between the average value of the transmittance of the phase shift film and the target transmittance value, the in-plane uniformity of the transmittance (from the target transmittance). Deviation), the difference between the average value of the phase difference and the target phase difference value, and the in-plane uniformity of the phase difference. As a result, the difference between the average transmittance value and the target transmittance value is −0.5%, the in-plane uniformity of the transmittance is 0.7% (3σ), and the target retardation value is the average value of the phase difference. The in-plane uniformity of the phase difference was 7 °.
[0267]
In this example, the area is 50000 nm in the defect inspection process. ² An opaque foreign object was found. For this reason, the defect, in this example, the opaque foreign matter was corrected by the defect correcting device (ST. 12).
[0268]
Next, the area and transmittance of the corrected portion are measured (ST.13).
[0269]
When the area and transmittance were measured, the area of the corrected portion was 30000 nm. ² The transmittance was 96%.
[0270]
Next, from the dimensional measurement results, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this halftone phase shift mask is obtained (ST.4).
[0271]
In this example, the exposure margin 1A resulting from the difference between the average value of the dimension and the target dimension value and the exposure margin 1B resulting from the in-plane uniformity of the dimension were obtained from the dimensional accuracy. Then, assuming that the exposure margin was 1A, the degree of deterioration from the exposure margin of the complete mask was calculated. The exposure conditions used for this calculation are exposure conditions when the mask is actually used, for example, ArF stepper, NA = 0.55, σ = 0.75, and annular zone shielding rate 2/3.
[0272]
As a result of the calculation, the exposure margin 1A is 3% from the exposure margin of the complete mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, and the exposure margin of the halftone phase shift mask is 3%. .2% deterioration.
[0273]
Similarly, when the pattern tolerance is within 10% and the focus margin is secured to 0.4 μm, the exposure margin of the halftone phase shift mask is 1.3% from the exposure margin of the complete mask. % Deterioration.
[0274]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST. 5).
[0275]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 is a complete exposure dose margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.6% from the exposure tolerance of the mask.
[0276]
Further, from the measurement results of the properties of the phase shift film, the exposure margin 3 resulting from the properties of the phase shift film when a pattern is transferred onto the wafer using the halftone phase shift mask is obtained (ST.9). ).
[0277]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 3 is a complete exposure amount margin of the halftone phase shift mask when the pattern dimension variation is within 10% and the focus margin is 0.4 μm. It deteriorated by 2.1% from the exposure dose tolerance of the mask.
[0278]
Further, an exposure margin 5 resulting from defect correction is obtained (ST.14).
[0279]
As a result of calculation under the same conditions as exposure margin 1, exposure margin 5 resulting from defect correction is the exposure of the halftone phase shift mask when the pattern margin is within 10% and the focus margin is 0.4 μm. The amount tolerance deteriorated by 1.5% from the exposure amount tolerance of the complete mask.
[0280]
Next, from the exposure margins 1A, 1B, the exposure margin 2, the exposure margin 3, and the exposure margin 5, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST.6). ).
[0281]
In this example, the total deterioration degree was calculated from the exposure margins 1A and 1B, the exposure margin 2, the exposure margin 3 and the exposure margin 5 as the exposure margin of the formed halftone phase shift mask. .
[0282]
As a result of calculation, when the pattern dimension variation is within 10% and the focus margin is 0.4 μm, the exposure tolerance of the halftone phase shift mask is deteriorated by 7.6% from the exposure tolerance of the complete mask. Met.
[0283]
Moreover, the exposure margin of the complete mask was 9.6% as the exposure margin when the pattern margin was within 10% and the focus margin was 0.4 μm as a result of calculation.
From this, the exposure margin of the halftone phase shift mask was determined to be 2.0% as the exposure margin when the focus margin was secured to 0.4 μm.
[0284]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0285]
In the case of this example, the reference desired exposure latitude is 4% or more as the exposure tolerance when the focus tolerance is 0.4 μm.
[0286]
The exposure tolerance of the formed halftone phase shift mask is ST. As found in FIG. 6, it is 2.0%, and as shown in FIG. 25, this halftone phase shift mask does not satisfy the standard. Therefore, this halftone phase shift mask was determined to be a defective product.
[0287]
However, a customer who uses this halftone type phase shift mask has a process control condition when using this mask, for example, the number of times of managing the exposure amount of the exposure apparatus used in the process of transferring the pattern from this mask to the wafer, etc. Tightening is performed such that the number of times is once every two lots, for each lot (ST.15).
[0288]
By stricting the process management conditions such as the number of times of exposure amount management as described above, the required exposure amount may be 2% as shown in FIG.
[0289]
Therefore, this halftone type phase shift mask satisfies the standard by tightening the customer's process control conditions, and was judged to be a non-defective product (ST.16).
[0290]
(Eleventh embodiment)
FIG. 27 is a flowchart showing a photomask manufacturing method according to the eleventh embodiment of the present invention, and FIG. 28 is a diagram showing the relationship between the focus latitude and the exposure dose latitude.
[0291]
First, as shown in FIG. 27, a mask pattern is formed on a mask blank (ST. 1).
[0292]
In this example, a 0.60 μm L / S pattern was drawn and developed on a Cr mask blank coated with a positive chemically amplified resist to form a resist pattern. Next, the Cr film was etched using this resist pattern as an etching mask to form a Cr pattern (mask pattern).
[0293]
Next, the dimension of the mask pattern is measured (ST.2).
[0294]
Further, the drawing position of the mask pattern is measured (ST.3).
[0295]
Further, in this example, the formed Cr mask is inspected for defects (ST. 10).
In this example, as a dimension measurement item, the difference between the average value of the Cr pattern dimension and the target dimension, and the in-plane uniformity of the Cr pattern dimension were obtained. As a result, the difference between the average value and the target dimension was 10 nm, and the in-plane uniformity was 25 nm (3σ).
[0296]
Further, in this example, the average value of the positional deviation of the Cr pattern and the variation of the positional deviation were obtained as the drawing position measurement items. As a result, the average value of misalignment was 5 nm and the variation in misalignment was 10 nm (3σ).
[0297]
In this example, in the defect inspection, the area is 100 nm. ² An opaque foreign object was found.
[0298]
Next, from the dimensional measurement result, an exposure margin 1 resulting from dimensional accuracy when a pattern is transferred onto the wafer using this mask is obtained (ST. 4).
[0299]
In this example, the exposure margin due to the dimensional accuracy is assumed to be 1, and the degree of deterioration from the exposure margin of the complete mask is calculated.
[0300]
The exposure conditions used for this calculation are the exposure conditions that actually use the mask, KrF stepper, NA = 0.68, σ = 0.75, and annular zone shielding ratio 2/3.
[0301]
As a result of the calculation, the exposure tolerance 1 of the Cr mask is 9% from the exposure tolerance of the complete mask when the pattern tolerance is within 10% and the focus tolerance is 0.5 μm. .4% deterioration.
[0302]
Further, from the drawing position measurement result, an exposure margin 2 resulting from the drawing position accuracy when the pattern is transferred onto the wafer using the mask is obtained (ST. 5).
[0303]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 2 resulting from the drawing position accuracy is the exposure tolerance of the Cr mask when the pattern margin is within 10% and the focus margin is 0.5 μm. Was 2.6% lower than the exposure tolerance of the complete mask.
[0304]
Further, an exposure margin 4 resulting from the defect is obtained (ST. 11).
[0305]
As a result of calculation under the same conditions as the exposure margin 1, the exposure margin 4 resulting from the defect is that the exposure tolerance of the Cr mask is complete when the pattern dimension variation is within 10% and the focus margin is 0.5 μm. The exposure amount tolerance of the mask deteriorated by 1%.
[0306]
Next, from the exposure margin 1, the exposure margin 2, and the exposure margin 4, the exposure margin when a pattern is transferred onto the wafer using this mask is obtained (ST. 6).
[0307]
In this example, the total deterioration degree was calculated from the three deterioration degrees obtained as the exposure margin 1, the exposure margin 2, and the exposure margin 4 as the exposure margin of the formed Cr mask.
[0308]
As a result of the calculation, the exposure tolerance of the formed Cr mask is such that when the pattern dimension variation is within 10% and the focus tolerance is 0.5 μm, the exposure tolerance of the Cr mask is determined from the exposure tolerance of the complete mask. It deteriorated by 11.0%.
[0309]
Further, as a result of calculation, the exposure tolerance of the complete mask was 15% as the exposure tolerance when the pattern tolerance was within 10% and the focus tolerance was secured to 0.5 μm.
From this, it was determined that the exposure tolerance of the Cr mask can be obtained as 4% as the exposure tolerance when the focus tolerance is secured to 0.5 μm.
[0310]
Next, it is determined whether or not the exposure latitude of the mask satisfies the standard (ST. 7).
[0311]
In the case of this example, the reference desired exposure latitude is 5% or more as the exposure tolerance when the focus tolerance is secured to 0.5 μm.
[0312]
The exposure tolerance of the formed Cr mask is ST. As obtained in FIG. 6, it is 4.3%, and this Cr mask does not satisfy the standard as shown in FIG. Therefore, this Cr mask was determined to be a defective product.
[0313]
However, the part of the device corresponding to the defective part is cut by using, for example, a redundancy technique used in the field of semiconductor memory, and the part does not function as a device (ST. 17).
[0314]
As a result, the defect was not a problem with this Cr mask.
[0315]
Then, a pattern is transferred onto the wafer using this mask from the exposure margin 1 caused by dimensional accuracy and the exposure margin 2 caused by the drawing position accuracy, except for the exposure margin 4 caused by defects. Is again obtained (ST.18).
[0316]
As a result, it was determined that the exposure tolerance of the Cr mask can be obtained as an exposure tolerance of 5% when a focus tolerance of 0.5 μm is secured.
[0317]
Therefore, this Cr mask satisfies the standard by setting the part of the device corresponding to the defective part as a part that does not function as a device, and was judged to be a good product (ST. 19).
[0318]
(Twelfth embodiment)
FIG. 29 is a flowchart showing a photomask manufacturing method according to the twelfth embodiment of the present invention, and FIG. 31 is a diagram showing the relationship between focus latitude and exposure tolerance.
[0319]
First, as shown in FIG. 29, a mask pattern is formed on a mask blank (ST. 1).
[0320]
In this example, a rectangular figure of W = 520 nm, L = 480 nm, WPitch = 2080 nm, LPitch = 4800 nm as shown in FIG. 30 is drawn and processed on a halftone mask blank coated with a positive chemically amplified resist. Formed.
[0321]
Next, when the X direction of the formed pattern dimension was measured at the “L” portion, the in-plane uniformity in the X direction was 10 nm, and the difference between the average value of the dimension and the desired value was −10 nm. . Similarly, when the Y direction was measured at the “W” portion, the in-plane uniformity in the Y direction was 10 nm, and the difference between the average value of dimensions and the desired value was −10 nm (ST. 2).
[0322]
The in-plane uniformity of the transmittance of the phase shift film is 1.5% (range), the deviation of the average transmittance from the desired transmittance is -0.5%, and the in-plane uniformity of the phase difference is 1. 0.5 ° (range), and the deviation of the average value from the desired phase difference was 3 ° (ST. 8).
[0323]
Further, it was measured that the connecting error between unit drawing areas was 2.5 nm at the drawing connecting error occurrence position (ST.3).
[0324]
From these data, an exposure margin was calculated when the mask was exposed to a wafer under the conditions of NA = 0.68, σ = 0.75, and annular zone shielding ratio 2/3 using a KrF stepper. Pattern dimension variation When the focus margin is 0.4 μm within 15 nm on the X direction wafer and within 15 nm on the Y direction wafer, the exposure tolerance when using a complete mask with no deviation from the target The degree of deterioration is 7.75% due to in-plane uniformity, 0.28% due to the difference from the average value of the desired dimension, and the difference from the desired value of the average value of the HT phase difference. Due to the difference of 0.05% due to the uniformity of the phase difference, 0.13% due to the difference between the average value of the HT transmittance and the desired value of 0.19%, the uniformity of the transmittance It was demanded that deterioration was 2.88% due to the property, 0.71% due to the positional accuracy, and 8.83% as a total from the complete mask. In addition, it was calculated by calculation that the desired exposure margin when using a complete mask is 12.84% when the focus margin is 0.4 μm. From these facts, the exposure margin when the mask is used was determined to be 4.1% when the focus margin is 0.4 μm (ST. ST.6, ST.9).
[0325]
In the process of transferring the pattern to the wafer using this mask, the exposure tolerance when the focus tolerance is 0.4 μm is required to be 4%, so this mask clears it. Therefore, it was shipped as acceptable (ST.7).
[0326]
As mentioned above, although this invention was demonstrated by 1st-12th embodiment, this invention is not limited to each of these embodiment, In the implementation, it changes variously in the range which does not deviate from the summary of invention. It is possible.
[0327]
For example, in the above-described embodiment, the desired exposure latitude is not limited to the values shown in the embodiment, but may be changed as appropriate depending on the ease of manufacturing the device and the characteristics of the resist.
[0328]
In addition, for example, in the calculation for estimating the exposure margin, the exposure margin may be obtained purely from the optical image, but from the calculation including the characteristics of the resist and the characteristics of the etching process which is the subsequent process. It goes without saying that more accurate judgment can be made by obtaining the exposure margin.
[0329]
As for the pattern for which the exposure margin is obtained, it is desirable to estimate a pattern that seems to have the smallest exposure margin. Any part of the device may be selected as long as the exposure margin is considered to be the smallest. For example, taking a semiconductor memory as an example, it is of course possible to estimate a pattern that seems to have the smallest exposure margin not only from a cell pattern but also from a core circuit portion or the like.
[0330]
Also, in the case of a phase shift mask, when it is difficult to measure the phase and transmittance of the phase shift film, the specifications of phase and transmittance are included in the calculation of exposure tolerance, and only the pattern dimension value is actually used. It is also possible to calculate using the measured value of the mask.
[0331]
In addition, various modifications can be made without departing from the scope of the invention.
[0332]
In addition, each of the above embodiments can be carried out independently, but can be carried out in combination as appropriate.
[0333]
Further, the above embodiments include inventions at various stages, and the inventions at various stages can be extracted by appropriately combining a plurality of constituent elements disclosed in the embodiments.
[0334]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method of manufacturing a photomask that can improve the yield and has high accuracy of pass / fail judgment.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a photomask manufacturing method according to a first embodiment of the present invention.
FIGS. 2A and 2B are plan views showing Cr mask blanks, respectively. FIGS.
FIG. 3A and FIG. 3B are diagrams each showing a dimension measuring method.
FIG. 4 is a diagram showing a drawing position measuring method.
FIG. 5 is a view showing a relationship between a focus tolerance and an exposure tolerance according to the first embodiment of the present invention.
FIG. 6 is a flowchart showing a photomask manufacturing method according to the second embodiment of the present invention;
FIG. 7 is a view showing a relationship between a focus tolerance and an exposure tolerance according to the second embodiment of the present invention.
FIG. 8 is a flowchart showing a photomask manufacturing method according to a third embodiment of the present invention.
FIG. 9 shows a process ST. FIG.
FIG. 10 shows a process ST. FIG.
FIG. 11 is a view showing a relationship between a focus tolerance and an exposure tolerance according to a third embodiment of the present invention.
FIG. 12 is a flowchart showing a photomask manufacturing method according to the fourth embodiment of the present invention;
FIG. 13 is a view showing a relationship between a focus tolerance and an exposure tolerance according to the fourth embodiment of the present invention.
FIG. 14 is a flowchart showing a photomask manufacturing method according to the fifth embodiment of the present invention;
FIG. 15 is a view showing a relationship between a focus tolerance and an exposure tolerance according to a fifth embodiment of the present invention.
FIG. 16 is a flowchart showing a photomask manufacturing method according to the sixth embodiment of the present invention;
FIG. 17 is a view showing a relationship between a focus latitude and an exposure latitude according to the sixth embodiment of the present invention.
FIG. 18 is a flowchart showing a photomask manufacturing method according to the seventh embodiment of the present invention;
FIG. 19 is a view showing the relationship between focus latitude and exposure tolerance according to the seventh embodiment of the present invention.
FIG. 20 is a flowchart showing a photomask manufacturing method according to the eighth embodiment of the present invention;
FIG. 21 is a view showing a relationship between a focus latitude and an exposure latitude according to the eighth embodiment of the present invention.
FIG. 22 is a flowchart showing a photomask manufacturing method according to the ninth embodiment of the present invention;
FIG. 23 is a view showing a relationship between a focus tolerance and an exposure tolerance according to the ninth embodiment of the present invention.
FIG. 24 is a flowchart showing a photomask manufacturing method according to the tenth embodiment of the invention.
FIG. 25 is a view showing the relationship between the focus latitude and the exposure tolerance according to the tenth embodiment of the present invention.
FIG. 26 is a view showing the relationship between the focus latitude and the exposure tolerance after strict process control conditions according to the tenth embodiment of the present invention.
FIG. 27 is a flowchart showing a photomask manufacturing method according to the eleventh embodiment of the present invention;
FIG. 28 is a view showing a relationship between a focus latitude and an exposure latitude according to the eleventh embodiment of the present invention.
FIG. 29 is a flowchart showing a photomask manufacturing method according to the twelfth embodiment of the present invention;
FIG. 30 is a plan view showing HT mask blanks.
FIG. 31 is a view showing the relationship between focus latitude and exposure latitude according to the twelfth embodiment of the present invention;
FIG. 32 is a diagram showing an example of specification values of a halftone phase shift mask.
FIG. 33 is a diagram showing an example of measurement results of a halftone phase shift mask.
[Explanation of symbols]
10 ... Dimension measurement point
11 ... Mark for position measurement
12: Drawing position

Claims (24)

In the photomask manufacturing method, after forming a pattern on the photomask, a step of measuring the dimension of the pattern;
Measuring the drawing position of the pattern;
From the dimensional measurement result of the pattern, a step of obtaining an exposure margin 1 due to dimensional accuracy when the photomask is used;
From the drawing position measurement result of the pattern, a step of obtaining an exposure margin 2 due to the drawing position accuracy when using the photomask;
Obtaining an exposure margin when the photomask is used from an exposure margin 1 resulting from the dimensional accuracy and an exposure margin 2 resulting from the drawing position accuracy;
And a step of judging whether or not the photomask is acceptable depending on whether or not the obtained exposure tolerance satisfies a desired exposure tolerance. In the photomask manufacturing method, after forming a pattern including a phase shift film on the photomask, measuring the dimension of the pattern;
Measuring the drawing position of the pattern;
Measuring the properties of the phase shift film;
From the dimensional measurement result of the pattern, a step of obtaining an exposure margin 1 due to dimensional accuracy when the photomask is used;
From the drawing position measurement result of the pattern, a step of obtaining an exposure margin 2 due to the drawing position accuracy when using the photomask;
From the property measurement result of the phase shift film, a step of obtaining an exposure margin 3 due to the property of the phase shift film when using the photomask;
From the exposure margin 1 due to the dimensional accuracy, the exposure margin 2 due to the drawing position accuracy, and the exposure margin 3 due to the nature of the phase shift film, the exposure margin when the photomask is used. The process of seeking
And a step of judging whether or not the photomask is acceptable depending on whether or not the obtained exposure tolerance satisfies a desired exposure tolerance. Inspecting whether or not the pattern is formed in a desired shape, and detecting a portion that is not formed in the desired shape as a defect;
Measuring the size of the detected defect portion;
Measuring the transmittance of the detected defect portion;
A step of obtaining an exposure margin 4 resulting from the defective portion when using a photomask including the defective portion from the size and transmittance measurement result of the defective portion,
The exposure margin is obtained from an exposure margin of 1 caused by the dimensional accuracy, an exposure margin of 2 caused by the drawing position accuracy, and an exposure margin of 4 caused by the defect portion. 2. A method for producing a photomask according to 1. Inspecting whether or not the pattern is formed in a desired shape, and detecting a portion that is not formed in the desired shape as a defect;
Measuring the size of the detected defect portion;
Measuring the transmittance of the detected defect portion;
A step of obtaining an exposure margin 4 resulting from the defective portion when using a photomask including the defective portion from the size and transmittance measurement result of the defective portion,
The exposure margin is caused by the exposure margin 1 caused by the dimensional accuracy, the exposure margin 2 caused by the drawing position accuracy, the exposure margin 3 caused by the property of the phase shift film, and the defect portion. The method for producing a photomask according to claim 2, wherein the photomask is obtained from an exposure margin of 4. Inspecting whether or not the pattern is formed in a desired shape, and detecting a portion that is not formed in the desired shape as a defect;
Correcting the detected defect portion;
Measuring the size of the correction portion;
Measuring the transmittance of the modified portion;
A step of obtaining an exposure margin 5 caused by the corrected portion when using a photomask including the corrected portion from the size and transmittance measurement result of the corrected portion; and
The exposure margin is obtained from an exposure margin of 1 caused by the dimensional accuracy, an exposure margin of 2 caused by the drawing position accuracy, and an exposure margin of 5 caused by the correction portion. 2. A method for producing a photomask according to 1. Inspecting whether or not the pattern is formed in a desired shape, and detecting a portion that is not formed in the desired shape as a defect;
Correcting the detected defect portion;
Measuring the size of the correction portion;
Measuring the transmittance of the modified portion;
A step of obtaining an exposure margin 5 caused by the corrected portion when using a photomask including the corrected portion from the size and transmittance measurement result of the corrected portion; and
The exposure margin is caused by the exposure margin 1 due to the dimensional accuracy, the exposure margin 2 due to the drawing position accuracy, the exposure margin 3 due to the property of the phase shift film, and the correction portion. The method for producing a photomask according to claim 2, wherein the photomask is obtained from an exposure margin of 5. 5. The method of manufacturing a photomask according to claim 3, wherein the size of the defect portion is defined by the area of the defect portion. 5. The size of the defect portion is defined by a dimension in the X direction of the defect portion and a dimension in the Y direction orthogonal to the X direction. 6. Photomask manufacturing method. 7. The method of manufacturing a photomask according to claim 5, wherein a size of the correction portion is defined by an area of the correction portion. The magnitude | size of the said correction part is prescribed | regulated by the dimension of the X direction of this correction part, and the dimension of the Y direction orthogonal to the said X direction, The Claim 5 and Claim 6 characterized by the above-mentioned. Photomask manufacturing method. The step of measuring the properties of the phase shift film includes:
Measuring the phase of the phase shift film,
The photomask manufacturing method according to claim 2, wherein the exposure margin 3 resulting from the properties of the phase shift film is obtained from the phase. The step of measuring the phase of the phase shift film,
Obtaining an average value of the phases;
Determining the phase variation,
The step of obtaining the exposure margin 3 resulting from the properties of the phase shift film is
A step of obtaining an exposure margin E resulting from the average value of the phase when the photomask is used from the average value of the phase;
The method of manufacturing a photomask according to claim 11, further comprising: determining an exposure margin F caused by the phase variation when the photomask is used from the phase variation. The step of measuring the properties of the phase shift film includes:
Measuring the phase of the phase shift film;
Measuring the transmittance of the phase shift film,
The photomask according to any one of claims 2, 4, and 6, wherein an exposure margin 3 resulting from the properties of the phase shift film is obtained from the phase difference and the transmittance. Manufacturing method. The step of measuring the phase of the phase shift film,
Obtaining an average value of the phases;
Determining the phase variation,
The step of measuring the transmittance of the phase shift film,
Obtaining an average value of the transmittance;
Obtaining a variation in the transmittance,
The step of obtaining the exposure margin 3 resulting from the properties of the phase shift film is
A step of obtaining an exposure margin E resulting from the average value of the phase when the photomask is used from the average value of the phase;
A step of obtaining an exposure margin F caused by the phase variation when the photomask is used from the phase variation;
Obtaining an exposure margin G resulting from the average value of transmittance when the photomask is used from the average value of the transmittance; and
The method of manufacturing a photomask according to claim 13 , further comprising: determining an exposure margin H resulting from the variation in transmittance when the photomask is used from the variation in transmittance. The step of measuring the dimension of the pattern includes:
Obtaining an average dimension of the pattern;
And determining the in-plane uniformity of the dimension of the pattern,
The step of obtaining the exposure margin 1 due to the dimensional accuracy is as follows:
A step of obtaining an exposure margin A resulting from the average dimension when the photomask is used from the average dimension;
The method of claim 1, further comprising: determining an exposure margin B resulting from in-plane uniformity when the photomask is used from the in-plane uniformity. The manufacturing method of the photomask as described. The step of measuring the drawing position of the pattern includes:
Obtaining an average value of positional deviation of the drawing position of the pattern;
Obtaining a variation in displacement of the drawing position of the pattern,
The method of manufacturing a photomask according to claim 1, wherein the exposure margin 2 resulting from the drawing position accuracy is obtained from an average value of the positional deviation and the variation. The step of measuring the dimension of the pattern includes:
Obtaining an average dimension in the X direction of the pattern;
Obtaining an average dimension in the Y direction of the pattern,
The step of obtaining the exposure margin 1 due to the dimensional accuracy is as follows:
Obtaining an exposure margin C resulting from the average dimension in the X direction when the photomask is used from the average dimension in the X direction;
7. A step of obtaining an exposure margin D resulting from the average dimension in the Y direction when the photomask is used from the average dimension in the Y direction. The manufacturing method of the photomask of claim | item. The step of measuring the drawing position of the pattern includes:
A step of obtaining a connecting error between unit drawing regions generated when forming the pattern, a step of obtaining an expansion / contraction component of the entire photomask, a step of obtaining an orthogonal deviation component of the entire photomask, and a local positional deviation of the entire photomask. Including at least one of the steps of determining the quantity,
The exposure margin 2 resulting from the drawing position accuracy is obtained from at least one of the splicing error, the expansion / contraction component, the orthogonal deviation component, and the local positional deviation amount. The manufacturing method of the photomask as described in any one of Claims 6. The said exposure tolerance is prescribed | regulated by the focus tolerance and the exposure tolerance in the process of transferring a pattern from the said photomask to a wafer, The Claim 1 thru | or 6 characterized by the above-mentioned. Photomask manufacturing method. As a result of the pass / fail judgment of the photomask, for the photomask that is determined not to satisfy the desired exposure tolerance, the process control condition of the process of transferring the pattern from the photomask to the wafer by the user of the photomask The method of manufacturing a photomask according to any one of claims 1 to 6, further comprising a step of determining whether the photomask is acceptable or not again. 21. The method of manufacturing a photomask according to claim 20, wherein the process management condition includes an item for designating an apparatus used in a process of transferring a pattern from the photomask to a wafer. 21. The photomask manufacturing method according to claim 20, wherein the process management condition includes an item for increasing the number of times of exposure amount management in a process of transferring a pattern from the photomask to a wafer. As a result of the pass / fail determination of the photomask, the user of the photomask determines again the pass / fail of the photomask according to the function of each part of the device for the photomask that is determined not to satisfy the desired exposure margin. The method of manufacturing a photomask according to claim 1, further comprising a step. The step of re-judging the pass / fail of the photomask according to the function of each part of the device corresponds to the local portion when the portion of the photomask that does not satisfy the desired exposure margin is local. the portion of the device, a manufacturing method of a photomask according to claim 23, the user, characterized in that it comprises a step so as not to function as a device.

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