JP4160239B2 - Exposure amount measuring method and exposure amount measuring apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exposure amount measurement technique in exposure using a mask, and more particularly to an exposure amount measurement method for measuring an exposure amount in photolithography using a projection exposure apparatus and an exposure amount measurement apparatus using the exposure amount measurement method.
[0002]
[Prior art]
In recent years, the minimum dimension of an LSI approaches the limit resolution of an optical exposure apparatus, and process margins (depth of focus, exposure margin) in optical lithography cannot be obtained sufficiently. In order to raise these process margins, various devices such as a phase shift mask (PSM) and modified illumination have been made.
[0003]
On the other hand, in order to perform optical lithography with a small process margin, accurate analysis and error distribution (error budget) that consumes the process margin have been regarded as important. For example, even if you intend to expose a large number of chips on the wafer with the same set exposure amount, effective proper exposure is possible due to non-uniformity in the wafer surface of PEB, development, and film thickness variation in the wafer surface of resist. The amount varies.
[0004]
Conventionally, when measuring fluctuations in the appropriate exposure amount within the wafer surface, the pattern is transferred to the wafer surface with the focus and exposure amount set values in the exposure apparatus kept constant, and the pattern dimensions are measured. The wafer in-plane exposure dose non-uniformity was calculated by converting the exposure dose. However, in this method, since the finally formed pattern dimension is measured, it is impossible to eliminate the influence of the fine focus fluctuation on the resolution dimension. In addition, it takes an enormous amount of time for dimension measurement.
[0005]
Japanese Laid-Open Patent Application No. 10-171345 discloses a technique for measuring an appropriate exposure amount fluctuation in a wafer surface without receiving a focus fluctuation. A pitch P ≦ λ / (1 + σ) NA (P: pitch, λ: exposure wavelength, NA: wafer side numerical aperture, σ: illumination coherence factor) having a resolution limit or less, and the ratio of the space width to the line width is A mask including a plurality of different line and space patterns is exposed to a resist film by a projection exposure apparatus and developed. Depending on the ratio of the space width to the line width, the transmittance changes and the exposure amount changes. The exposure amount through which the resist pattern corresponding to each line and space pattern is removed is obtained in advance. Then, the resist pattern is observed, and the exposure amount is determined according to the pattern from which the resist pattern is missing.
[0006]
However, since the exposure amount obtained by this method is obtained when the resist pattern is missing, there is a problem that it is discrete and the accuracy is poor.
[0007]
[Problems to be solved by the invention]
As described above, there has been a problem that the exposure amount measured from the pattern from which the conventional resist pattern is missing is discrete and the accuracy is poor.
[0008]
An object of the present invention is to provide an exposure dose measuring method and an exposure dose measuring apparatus capable of continuously and accurately measuring an exposure dose without being affected by focus fluctuations.
[0009]
[Means for Solving the Problems]
[Constitution]
The present invention is configured as follows to achieve the above object.
[0011]
In the exposure amount measuring method according to the present invention, a mask on which a mask pattern is formed is set in an exposure apparatus having an exposure wavelength λ, a wafer-side numerical aperture NA, an illumination coherence factor σ, and a mask pattern magnification M with respect to the pattern on the wafer. An exposure measurement method that measures the effective exposure on the wafer by exposing the mask pattern to the resist applied on the wafer and observing the state of the resist on the wafer corresponding to the mask pattern. The mask pattern is a pattern in which the light-transmitting part and the light-shielding part are repeated at a period p, and a plurality of types having different transmittances according to the ratio of the light-transmitting part and the light-shielding part are formed on the same mask. The period p is set to satisfy p / M ≦ λ / (1 + σ) NA, and corresponds to the resist film thickness on the wafer corresponding to a specific mask pattern. A measurement step for measuring the physical quantity, a comparison step for comparing the physical quantity measured in this measurement step with a preset setting range value, and the physical quantity measured in the measurement step as a result of the comparison in this comparison step is If within the set range value, the step of measuring the effective exposure amount on the wafer corresponding to the measured physical amount based on the relationship between the physical amount and the exposure amount obtained in advance, and the comparison in this comparison step As a result, when the physical quantity measured in the measurement step is outside the set range value, the physical quantity corresponding to the film thickness of the resist corresponding to a different mask pattern from the mask pattern corresponding to the resist used for the measurement is measured. If the physical quantity measured in the remeasurement step and the remeasurement step is within the set range value, the physical quantity and the exposure amount obtained in advance And measuring an effective exposure amount on the wafer corresponding to the measured physical quantity.
[0012]
In the present invention, in the re-measurement step, when the physical quantity on the wafer corresponding to the specific mask pattern is a predetermined range value or more, the transmittance is higher than that of the specific mask pattern corresponding to the measured resist pattern. When the physical quantity of the resist corresponding to a high-type mask pattern is measured and the physical quantity on the wafer corresponding to the specific mask pattern is equal to or less than a predetermined range value, the specific mask corresponding to the measured resist pattern It is preferable to measure the physical quantity of the resist corresponding to a mask pattern having a lower transmittance than the pattern.
[0013]
The exposure amount measuring apparatus according to the present invention sets a mask on which a mask pattern is formed in an exposure apparatus having an exposure wavelength λ, a wafer-side numerical aperture NA, an illumination coherence factor σ, and a mask pattern magnification M with respect to the pattern on the wafer. The exposure dose measuring device measures the effective exposure dose on the wafer by exposing the mask pattern to the resist applied on the wafer and observing the resist state on the wafer corresponding to the mask pattern. The mask pattern is a pattern in which the light-transmitting part and the light-shielding part are repeated at a period p, and a plurality of types having different transmittances according to the ratio of the light-transmitting part and the light-shielding part are formed on the same mask. The period p is set to satisfy p / M ≦ λ / (1 + σ) NA, and the physical quantity according to the film thickness of the resist on the wafer corresponding to the mask pattern When the physical quantity is outside the set range value as a result of comparison between the measurement unit to measure, the comparison unit that compares the physical quantity measured by the measurement unit, and a preset set range value, and the comparison unit, A control unit that causes the measurement unit to measure a physical quantity corresponding to a resist film thickness corresponding to a mask pattern different from the mask pattern corresponding to the resist used for the measurement, and the physical quantity measured by the measurement unit is predetermined. An exposure amount calculation unit that calculates an effective exposure amount on the wafer corresponding to the measured physical quantity based on the relationship between the physical quantity and the exposure quantity obtained in advance when within the range value; It is characterized by that.
[0014]
In the present invention, the control unit has a higher transmittance than the specific mask pattern corresponding to the measured resist pattern when the physical quantity on the wafer corresponding to the specific mask pattern is not less than a predetermined range value. When the physical quantity of the resist corresponding to the type of mask pattern is measured and the physical quantity on the wafer corresponding to the specific mask pattern is less than or equal to a predetermined range value, the specific mask pattern corresponding to the measured resist pattern It is preferable to measure the physical quantity of the resist corresponding to a mask pattern having a lower transmittance.
[0015]
[Action]
The present invention has the following operations and effects by the above configuration.
[0016]
In the present invention, a mask including a plurality of repetitive patterns in which the area ratio (opening ratio) of the opening area to the light shielding area is slightly different is exposed and developed by the projection exposure apparatus. At this time, by setting the repetition period p of the light transmitting portion and the light shielding portion as in claims 1, 2, and 4, diffracted light (first-order or higher order diffracted light) in the mask pattern does not enter the pupil of the projection lens Only the straight light (0th order diffracted light) enters the pupil. That is, the pitch of the mask pattern is below the resolution limit. If the mask pattern has a pitch less than the resolution limit, the pattern is not resolved.
[0017]
The resist is exposed using such a mask pattern, the physical quantity according to the resist film thickness is measured, and the relationship between the measured physical quantity and the physical quantity according to the resist film thickness obtained in advance and the exposure amount Based on the above, the exposure amount can be measured continuously and accurately.
[0018]
Furthermore, although there is a measurement area where it is difficult to measure the exposure amount in the above measurement, in the measurement area where it is difficult to measure the exposure amount, a physical quantity corresponding to the resist film thickness corresponding to the mask pattern with different transmittance should be measured. Thus, the exposure amount can be continuously and accurately measured based on the measured physical amount and the relationship between the physical amount determined in advance and the exposure light.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0020]
[First Embodiment]
FIG. 1 is a diagram showing a schematic configuration of a mask including an exposure amount monitor pattern according to the first embodiment of the present invention and a resist pattern formed using the mask. 1A is a plan view of the mask, FIG. 1B is a cross-sectional view of the mask, and FIG. 1C is a cross-sectional view of a resist pattern formed using the mask for exposure.
[0021]
In FIG. 1, 101 is a mask, 102 is an exposure amount monitor pattern formed on the mask 101, 103 is a transparent substrate, 104 is a light shielding film such as Cr, 105 is a translucent portion, 106 is a wafer, and 107 is an exposure amount monitor pattern. This is a resist pattern formed corresponding to 102.
[0022]
Assuming an exposure apparatus having an exposure wavelength λ, a wafer-side numerical aperture NA, an illumination coherence factor σ, and a mask pattern magnification M with respect to the pattern on the wafer, the exposure amount monitor pattern 102 is the same as the light shielding film 104 at a pitch p. It is a line and space pattern in which the translucent part 105 is repeated, and the pitch p is
p / M ≦ λ / (1 + σ) NA (1)
It is set to satisfy.
[0023]
By setting the period p of the light shielding film 104 and the light transmitting portion 105 of the exposure amount monitor mark to the condition of the expression (1), the diffracted light (first-order or higher order diffracted light) at the exposure amount monitor mark is We focused on the fact that only the straight light (0th order diffracted light) enters the pupil without entering. By satisfying the above conditions, the monitor mark pattern is below the resolution limit. If the exposure dose monitor mark pattern has a pitch less than or equal to the resolution limit, the pattern is not resolved, resulting in flat exposure with different exposure amounts reaching the wafer surface according to the aperture ratio. For this reason, even if the set exposure amount of the exposure apparatus is the same, the effective exposure amount changes according to the aperture ratio. In this case, since the exposure amount monitor mark pattern is not resolved, the influence of the focus fluctuation can be completely eliminated.
[0024]
First, conditional exposure was performed using the above mask. On the Si wafer 106, a coating-type antireflection film 60 nm was spin-coated, and a chemically amplified positive resist was spin-coated with a thickness of 0.4 μm. Then, the prebaking process was performed at 100 degreeC and 90 second. A series of processing was performed on a track connected to an exposure apparatus.
[0025]
The wafer after these processes was transferred to an exposure apparatus, and the mask was exposed. The reduction ratio of the projection optical system was 1/4, the exposure wavelength was 248 nm, NA was 0.6, the illumination coherence factor σ was 0.75, and the annular zone shielding ratio ε was 0.67. Exposure amount set value of the exposure apparatus was carried out is increased from 3 mJ / cm ² to 10 mJ / cm ^2. The exposed wafer was transported to the track again, post-exposure bake (PEB) at 100 ° C. for 90 seconds, and then developed for 60 seconds with a 0.21 normal alkaline developer.
[0026]
The residual film of the resist pattern 107 on the wafer 106 thus processed was measured with a film thickness meter. The measurement results are shown in FIG. As shown in FIG. 2, it can be seen that the remaining resist pattern film decreases as the exposure dose increases.
[0027]
Therefore, the relationship between the exposure amount shown in FIG. 2 and the thickness of the resist pattern formed by exposing the mask pattern set by equation (1) to the resist film is obtained in advance, and the thickness of the resist pattern is measured. By doing so, the effective exposure amount on the wafer can be measured.
[0028]
Further, since the repetition pitch p between the light transmitting portion and the light shielding portion in the mask pattern is set as shown in the equation (1) and the mask pattern is not resolved, the influence of the focus variation can be completely removed. .
[0029]
[Second Embodiment]
The remaining film amount T of the resist pattern 107 formed corresponding to the exposure amount monitor pattern is measured in the exposure amount range where the resist remains, and the effective exposure amount d is grasped using the conversion curve shown in FIG. Follow the procedure. However, if the process fluctuations such as illuminance unevenness of the exposure apparatus, temperature unevenness of the PEB, and development unevenness are large and the effective exposure amount fluctuation is large, the residual film amount of the resist formed corresponding to one exposure amount monitor pattern Then, the measurement range may be exceeded, and measurement may not be possible. For example, in the case of the conversion curve shown in FIG. 2, when the effective exposure amount becomes 4 mJ due to process variations, the resist pattern hardly decreases, and it is difficult to measure the effective exposure amount. There is.
[0030]
Therefore, in the present embodiment, an exposure amount measuring method that can avoid this problem and an exposure amount measuring apparatus using the exposure amount measuring method will be described.
[0031]
FIG. 3 is a diagram showing a schematic configuration of a mask including an exposure amount monitor pattern according to the second embodiment of the present invention and a resist pattern formed using this mask. 3A is a plan view of the mask, FIG. 3B is a cross-sectional view of the mask, and FIG. 3C is a cross-sectional view of a resist pattern formed using the mask for exposure. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0032]
As shown in FIG. 3, in the exposure amount monitor patterns 102 _{0 to} 102 ₃ formed on the mask 101, the light shielding film 104 and the translucent portion 105 are repeated at a pitch p satisfying the above-described equation (1). The light shielding film 104 and the translucent portion 105 are of a plurality of types having different ratios. The transmittances Tr _{0 to} Tr ₃ of the exposure amount monitor patterns 102 _{0 to} 102 ₃ are different.
[0033]
In this embodiment, resist patterns 107 _{0 to} 107 ₂ are formed by exposing a plurality of types of exposure amount monitor patterns 102 _{0 to} 102 ₃ having different ratios between the light shielding film 104 and the light transmitting portion 105. When measuring the film thickness T of a certain resist pattern 107, if it is difficult to measure the exposure amount, the thickness of the resist pattern formed by the exposure of the next adjacent exposure amount monitor pattern is measured again, and the transmittance The effective exposure is calibrated based on the data.
[0034]
Next, the exposure amount measuring method of the present embodiment will be described with reference to FIGS. FIG. 4 is a block diagram showing a schematic configuration of an exposure amount measuring apparatus according to the second embodiment of the present invention. FIG. 5 is a flowchart showing an exposure dose measuring method using the exposure dose measuring apparatus shown in FIG. The configuration of the exposure dose measuring apparatus shown in FIG. 4 will be described while explaining the exposure method.
[0035]
First, the sample 40 in which the resist patterns 107 _{0 to} 107 ₂ are formed using the exposure dose monitor patterns 102 _{0 to} 102 ₃ described above is set in the film thickness measuring unit 402.
[0036]
The conditions for forming the sample 400 will be described below. A coating type antireflection film of 60 nm was spin-coated on a Si wafer, and a chemically amplified positive resist was spin-coated at a thickness of 0.4 μm. Then, the prebaking process was performed at 100 degreeC and 90 second. A series of processing was performed on a track connected to an exposure apparatus. The wafer after these processes was transferred to an exposure apparatus, and the mask was exposed. The reduction ratio of the projection optical system was 1/4, the exposure wavelength was 248 nm, NA was 0.6, the illumination coherence factor σ was 0.75, and the annular shielding rate ε was 0.67.
[0037]
Next, the transmittance of each exposure amount monitor pattern 102 _{0 to} 102 ₃ and the resist pattern 107 _{0 to} 107 ₂ coordinate D ₁ , the coordinates of the resist pattern 107 used for measurement, and the resist film residual film with respect to the exposure amount in the resist pattern used for measurement A conversion curve D ₃ composed of a graph of quantity values and a measurement allowable range value D ₂ are input. Here, enter the resist pattern 107 ₁ as a metric resist pattern used for measurement.
[0038]
Then, depending on the metric resist pattern 107 ₁ of coordinates set, the film thickness measurement control unit 401 causes the measured thickness of the metrics resist pattern 107 ₁ in the film thickness measuring unit 402 (step S101). Then, comparison section 403 compares the measured thickness value D ₄ of the measured metric resist pattern 107 ₁ (here, a thickness T ₁ of the metric resist pattern 107 ₁₎ and the measured tolerance value D ₂ Then, it is determined whether the measured film thickness value D ₄ (T ₁ ) is within the allowable range value D ₂ (step S102).
[0039]
First, the case where it is determined in step S102 that the measured film thickness value D ₄ (T ₁ ) is within the allowable range value D ₂ will be described. When it is determined that the measured film thickness value D ₄ (T ₁ ) is within the allowable range value D ₂ , it is determined whether the measured film thickness value D ₄ (T ₁ ) is a measured value of the measurement reference resist pattern 107 ₁ (step) S103). Here, since the measured film thickness value D ₄ (T ₁ ) is the measured value of the measurement reference resist pattern 107 ₁ , the exposure amount calculation unit 404 calculates the measured film thickness value D ₄ (T ₁ ) and the conversion curve D ₃ . calculating an exposure amount D ₅ from (step S104), and stores the calculated exposure amount as measurement data (step S105).
[0040]
Next, the case where it is determined in step S102 that the measured film thickness value D ₄ is not within the allowable range value D ₂ will be described. If the measured thickness value D ₄ in step S102 is determined not within the allowable range values D _2, comparing unit 403, measured thickness by comparing the measured thickness value D ₄ and measured tolerance value D ₂ It determines the value D ₄ is the allowable range values D ₂ or more (step S106).
[0041]
In step S106, the measurement membrane if thickness value D ₄ is determined to be allowable range values D ₂ or more, the comparison unit 403 is formed of a high transmittance dose monitor mass pattern in the film thickness measurement control unit 401 Instructed to re-measure the thickness of the resist pattern. Then, the film thickness measurement control unit 401 reads the transmission and the coordinate data D _1, transmittance than the measured dose monitor pattern prior to the film thickness measuring unit 402 is formed at a high dose monitor pattern resist pattern The film thickness is measured (step S107). The film thickness measurement control unit 401 measures the re-thickness of the resist pattern and transmits the exposure amount monitor pattern transmittance to the comparison unit 403. This re-measurement is sequentially repeated until the measured film thickness falls within the measurement allowable range value.
[0042]
Further, in step S106, measuring membrane if the thickness value D ₄ is determined not to be allowable range values D ₂ or more, the comparison unit 403 is formed of a low transmittance dose monitor pattern in the film thickness measurement control unit 401 Instructed to measure the thickness of the resist pattern again. Then, the film thickness measurement control unit 401 reads the transmission and the coordinate data D _1, measured dose monitor pattern than the transmittance before the film thickness measuring unit 402 is formed at a lower dose monitor pattern resist pattern The film thickness is measured (step S108). The film thickness measurement control unit 401 measures the re-thickness of the resist pattern and transmits the exposure amount monitor pattern transmittance to the comparison unit 403. This re-measurement is sequentially repeated until the measured film thickness falls within the measurement allowable range value.
[0043]
Next, the resist film thickness is measured again, and when the measured film thickness value D ₄ falls within the allowable range value D ₂ , it is determined whether the measured film thickness value D ₄ is that of the measurement reference resist pattern (step S103).
[0044]
In the following, the film thickness of the resist pattern 107 ₂ is measured instead of the measurement reference resist pattern 107 ₁ , the measurement film thickness T ₂ is within the measurement allowable range value D ₂ , and the measurement film thickness value D ₄ is the measurement reference resist pattern. A case that is not 107 ₁ will be described.
[0045]
If it is determined that the measured film thickness value D ₄ is not that of the measurement reference resist pattern 107 ₁ , the effective exposure amount d ₂ corresponding to the measured film thickness value D ₄ (T ₂ ) is obtained using the conversion curve D _3. (Step S109). Furthermore, from the ratio of the transmittance Tr ₂ metrics resist pattern 107 transmittance Tr ₁ of dose monitor pattern 102 ₁ corresponding to ₁ and the resist pattern 107 ₂ dose monitor pattern corresponding to 102 _1, the effective exposure dose d ₁ ,
d ₁ = d ₂ × Tr ₁ / Tr ₂ (2)
(Step S110). Then, the calculated exposure amount is stored as measurement data.
[0046]
Here, the measured film thickness value D ₄ is not that of the measurement reference resist pattern. Therefore, the exposure amount cannot be obtained immediately from the measured film thickness value D ₄ and the conversion curve D ₃ . Since the measurement reference resist pattern 107 ₁ and the resist pattern 107 ₂ have the same exposure conditions and development conditions other than the transmittance, the conversion curve of the resist pattern 107 ₂ is moved horizontally with respect to the conversion curve D ₃ of the measurement reference resist pattern 107 ₁ . It will be a thing. Therefore, determine the effective exposure dose d ₂ corresponding the conversion curve D ₃ to the measuring film thickness T _2, this effective exposure dose d _2, dose monitor pattern 102 ₁ of the transmittance Tr ₁ and the exposure dose monitor pattern 102 ₁ By multiplying the ratio with the transmittance Tr ₂ , the effective exposure amount d ₁ in the exposure amount monitor pattern 102 ₁ can be calculated.
[0047]
With the above configuration, the exposure amount can be accurately calculated even when the resist pattern film thickness variation is small relative to the exposure amount variation.
[0048]
Next, a resist pattern is formed on the wafer under the same conditions as the exposure conditions and development conditions described above, except that the set exposure amount of the exposure apparatus is set to 7.5 mJ / cm ^2. The film amount was measured over the entire wafer surface.
[0049]
FIG. 6A shows the result of measuring a specific floc on the entire surface of the wafer by the method shown in the first embodiment. Although the set exposure amount of the exposure apparatus is 7.5 mJ / cm ² , it can be seen that the effective exposure amount varies due to variations in the wafer surface such as PEB, development, and resist film thickness. In the figure, in the vicinity of the center, since any of the above-mentioned fluctuation factors fluctuated greatly, the effective exposure amount is greatly reduced, and the resist as a parameter to be measured is thinned. That is, since the effective exposure amount fluctuation exceeding the measurement range occurs, the value of the effective exposure amount fluctuation is large.
[0050]
Therefore, the next exposure dose monitor pattern was measured again for the part having an abnormal film thickness, the effective exposure amount was obtained using the conversion curve, and then calibrated using the transmittance ratio. As a result, as shown in FIG. 6B, there was no portion where the variation in effective exposure amount was extremely large, and the reliability of the data could be improved.
[0051]
The present invention is not limited to the above embodiment. Since the reflection intensity changes according to the film thickness of the resist pattern, the relationship between the reflected light intensity from the resist pattern and the exposure amount can be obtained in advance, and the exposure amount can be obtained from the reflection intensity from the resist pattern.
In addition to the line and space pattern, a repetitive hole pattern or a rhombus repetitive pattern can be used as the exposure amount monitor pattern.
In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.
[0052]
【The invention's effect】
As described above, according to the present invention, the repetitive pitch p between the light transmitting part and the light shielding part is set in the above-described range, and a plurality of types of mask patterns having different ratios of the light transmitting part and the light shielding part are exposed on the wafer. By measuring the physical quantity of the resist on the wafer corresponding to each mask pattern, it becomes possible to measure the exposure quantity continuously and accurately without being affected by the focus fluctuation.
[0053]
In the measurement area where it is difficult to measure the exposure amount, the measured physical amount, the physical amount obtained in advance, and the exposure light are measured by measuring the physical amount according to the resist film thickness corresponding to the mask pattern having different transmittance. The exposure amount can be continuously and accurately measured based on the relationship between
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a mask including an exposure amount monitor pattern according to the first embodiment and a resist pattern formed using the mask.
FIG. 2 is a characteristic diagram showing a relationship between a resist pattern film thickness and an exposure amount;
FIG. 3 is a diagram showing a schematic configuration of a mask including an exposure amount monitor pattern according to a second embodiment and a resist pattern formed using the mask.
FIG. 4 is a block diagram showing a schematic configuration of an exposure amount measuring apparatus according to a second embodiment.
FIG. 5 is a flowchart showing an exposure dose measuring method using the exposure dose measuring apparatus shown in FIG. 4;
FIG. 6A is a diagram showing fluctuations in the effective exposure amount in the wafer surface measured by the method shown in the first embodiment, and FIG. 6B is a method shown in the second embodiment. The figure which shows the effective exposure amount fluctuation | variation in the measured wafer surface.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Mask 102 ... Exposure amount monitor pattern 104 ... Light shielding film 105 ... Light transmission part 106 ... Wafer 107 ... Resist pattern 400 ... Sample 401 ... Film thickness measurement control part 402 ... Film thickness measurement part 403 ... Comparison part 404 ... Exposure amount calculation Part

Claims (4)

The mask on which the mask pattern is formed is set in an exposure apparatus having an exposure wavelength λ, a wafer-side numerical aperture NA, an illumination coherence factor σ, and a mask pattern magnification M with respect to the pattern on the wafer. An exposure measurement method for measuring an effective exposure on a wafer by exposing a mask pattern and observing a state of a resist on the wafer corresponding to the mask pattern,
The mask pattern is a pattern in which a light-transmitting part and a light-shielding part are repeated at a period p, and a plurality of types having different transmittances according to the ratio of the light-transmitting part and the light-shielding part are formed on the same mask. But,
p / M ≦ λ / (1 + σ) NA
Is set to meet
A measurement step for measuring a physical quantity corresponding to a film thickness of the resist on the wafer corresponding to a specific mask pattern;
A comparison step for comparing the physical quantity measured in this measurement step with a preset setting range value;
As a result of the comparison in this comparison step, when the physical quantity measured in the measurement step is within the set range value, on the wafer corresponding to the measured physical quantity based on the relationship between the physical quantity obtained in advance and the exposure amount. Measuring the effective exposure amount of
As a result of the comparison in this comparison step, if the physical quantity measured in the measurement step is outside the set range value, the resist film thickness corresponding to a mask pattern of a different type from the mask pattern corresponding to the resist used for the measurement is used. A re-measurement step to measure the corresponding physical quantity;
When the physical quantity measured in this re-measurement step is within the set range value, the effective exposure amount on the wafer corresponding to the measured physical quantity is measured based on the relationship between the physical quantity and the exposure quantity obtained in advance. A step of measuring the exposure amount. In the re-measurement step,
When the physical quantity on the wafer corresponding to the specific mask pattern is equal to or greater than a predetermined range value, the resist corresponding to the type of mask pattern having a higher transmittance than the specific mask pattern corresponding to the measured resist pattern. Measure physical quantity,
When the physical quantity on the wafer corresponding to the specific mask pattern is equal to or less than a predetermined range value, the resist corresponding to the type of mask pattern having a lower transmittance than the specific mask pattern corresponding to the measured resist pattern. The exposure amount measuring method according to claim 1 , wherein a physical quantity is measured. The mask on which the mask pattern is formed is set in an exposure apparatus having an exposure wavelength λ, a wafer-side numerical aperture NA, an illumination coherence factor σ, and a mask pattern magnification M with respect to the pattern on the wafer. An exposure amount measuring apparatus that measures an effective exposure amount on a wafer by exposing a mask pattern and observing a resist state on the wafer corresponding to the mask pattern,
The mask pattern is a pattern in which a light-transmitting part and a light-shielding part are repeated at a period p, and a plurality of types having different transmittances according to the ratio of the light-transmitting part and the light-shielding part are formed on the same mask. But,
p / M ≦ λ / (1 + σ) NA is set to satisfy,
A measurement unit that measures a physical quantity according to the film thickness of the resist on the wafer corresponding to the mask pattern;
A comparison unit that compares the physical quantity measured by the measurement unit with a preset set range value;
When the physical quantity is outside the set range value as a result of the comparison by the comparison unit, the measurement unit has a film thickness of a resist corresponding to a different mask pattern from the mask pattern corresponding to the resist used for the measurement. A control unit for measuring the measured physical quantity;
When the physical quantity measured by the measurement unit is within a predetermined range value, the effective exposure amount on the wafer corresponding to the measured physical quantity is calculated based on the relationship between the physical quantity and the exposure quantity obtained in advance. An exposure amount measuring apparatus comprising: an exposure amount calculation unit. The controller is
When the physical quantity on the wafer corresponding to the specific mask pattern is equal to or greater than a predetermined range value, the resist corresponding to the type of mask pattern having a higher transmittance than the specific mask pattern corresponding to the measured resist pattern. Let me measure the physical quantity,
When the physical quantity on the wafer corresponding to the specific mask pattern is equal to or less than a predetermined range value, the resist corresponding to the type of mask pattern having a lower transmittance than the specific mask pattern corresponding to the measured resist pattern. The exposure amount measuring apparatus according to claim 3 , wherein a physical quantity is measured.

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