JP3069215B2 - Photomask pattern evaluation method and apparatus, and pattern transfer method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for evaluating a photomask pattern for evaluating the quality of a fine pattern formed on a photomask used as a mask for exposing a fine pattern in the manufacture of LSIs and the like, and an apparatus therefor. The present invention relates to a pattern transfer method using a photomask pattern evaluation method.

[0002]

2. Description of the Related Art Along with the high integration of a semiconductor device, a projection exposure technique used in a lithography process requires a finer pattern and a higher resolution of a transferable pattern.

[0003] A photomask used as a mask when performing this projection exposure is formed by forming an exposure fine pattern comprising a light-transmitting portion and a light-shielding portion on a transparent substrate. This fine pattern requires that the individual patterns have an exactly predetermined positional relationship with respect to the reference position. For the accuracy of the positional relationship, higher accuracy is required in proportion to finer patterns and higher resolution.

This fine pattern is usually formed by forming a resist film on a photomask blank having a light-shielding film formed on the surface of a light-transmitting substrate and subjecting the resist film to electron beam exposure for drawing a fine pattern with an electron beam. Then, it is formed by developing and etching. In this electron beam drawing, a photomask blank is held on a moving stage, a pattern to be drawn is stored in a computer as design coordinate data, and the irradiation position of the electron beam and the position of the moving stage are controlled based on the design coordinate data. Do it.

Here, exposure is performed by this electron beam drawing,
The fine pattern actually formed on the photomask by development and etching must exactly match the fine pattern indicated by the design coordinate data. If pattern transfer is performed using a photomask that does not match with a predetermined accuracy or more, a large number of defective semiconductor products will be manufactured. For this reason, about the manufactured photomask,
It is necessary to check whether or not the actually formed fine pattern and the fine pattern indicated by the design coordinate data match with a predetermined accuracy or more, and evaluate the photomask pattern.

[0006] For example, Japanese Patent Laid-Open No.
The method described in 206640 is known. In this method, alignment marks are provided at four corners outside the fine pattern region, and the distance from the reference position to the marks at the four corners is measured, and the measured values and the corresponding values obtained from the design coordinate data are obtained. The distance value is compared with the distance value, and a distance correction value in each direction is calculated from the difference. Next, the distance between each pattern of the fine pattern of the photomask is actually measured, and the measured value is corrected by the above-described correction value. Then, the corrected distance between the patterns and the corresponding distance between the patterns determined from the design coordinate data are calculated. In comparison, the quality of the pattern is evaluated based on the magnitude of the deviation.

[0007] However, the above-mentioned method is, so to speak, individually looking at the deviation of the distance between the patterns. Therefore, it is not necessarily the best method from the viewpoint of observing the deviation of the overall pattern arrangement. It's difficult. In addition, since the distance between each pattern is measured, the number of combinations between the patterns increases rapidly as the pattern becomes more complicated, so that the number of actual measurement points increases rapidly and processing becomes difficult. is there.

As a method of checking the overall pattern dislocation, a specific position of the pattern is set as a reference point, and then the measured pattern and the design coordinate data are made to coincide with each other and the two patterns are overlapped. Thereafter, a method of checking the shift amount of the corresponding individual pattern position can be considered. However, since this method is based on the assumption that there is no deviation between the reference points, if there is a deviation in the reference point itself, the deviation amount is the deviation of the other individual pattern positions. Will be added to the quantity. As a result, in some measured deviation amounts of the individual points, an apparent deviation amount larger than the true deviation amount is measured as the deviation amount. For this reason, a deviation that is originally within the allowable range is evaluated as exceeding the allowable range, and a product that should be evaluated as a good product may be evaluated as a defective product. In addition, this method has a drawback of lacking reliability because the shift amount of each point varies depending on where the reference point is set, and the evaluation may differ depending on the method of selecting the reference point.

Accordingly, the applicant of the present application has filed an earlier application (Japanese Patent Application No.
5-63816), the coordinate system of both data was superimposed and aligned so that the overall deviation between the measured coordinate data and the design coordinate data was statistically minimized, and the mutual position of both data was determined. A method for evaluating the quality of a photomask pattern based on whether the amount of deviation between the two data thus determined is within an allowable range has been proposed.

According to the method according to this proposal, since it is possible to statistically view the shift of the entire pattern, it is possible to perform an accurate evaluation and to obtain an advantage that the amount of data to be handled can be reduced.

[0011]

Incidentally, some recent exposure apparatuses have a transfer pattern correction function of detecting a deviation of a transfer pattern of a photomask to be used from a design pattern, correcting the deviation at the time of transfer, and transferring the pattern. Not a few. For example, in an apparatus of a method of transferring while scanning a photomask and an object to be transferred at the time of transfer,
By shifting the scanning direction of the photomask or the transferred object with respect to the exposure light by a predetermined angle, the angle deviation of the photomask pattern with respect to the reference pattern (design pattern) is corrected (orthogonality correction). This angle shift is, for example, an angle formed with respect to a reference line of a straight line connecting certain reference points of the design coordinate data, and a reference line of a straight line connecting the corresponding reference points of the design coordinate data. This is the amount of deviation from the angle made with respect to the straight line, and the correction is a correction that minimizes this amount of deviation.

In addition, the deviation of the entire pattern from the reference pattern is corrected by adjusting the magnification of the transfer optical system (magnification correction).

With such a correction, even if a photomask evaluated as being out of the allowable range by the method according to the above-mentioned proposal is used, transfer with an accuracy within the allowable range is finally performed. May occur. That is, the evaluation method according to the above proposal is an evaluation based on only a direct comparison between the pattern actually formed on the photomask and the design pattern without considering the correction by the exposure apparatus. In this case, a photomask that can transfer images within an allowable range may be evaluated as a defective product.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned background, and determines the quality of a transfer pattern formed on a photomask used when performing exposure using an exposure apparatus equipped with a transfer pattern correction function. It is an object of the present invention to provide a method and an apparatus for evaluating a photomask pattern that can be appropriately evaluated, and a pattern transfer method using the method for evaluating a photomask pattern.

[0015]

In order to solve the above-mentioned problems, a method for evaluating a photomask pattern according to the present invention is described as follows. (Structure 1) A photomask used for an exposure apparatus equipped with a transfer pattern correction function is formed on a photomask. In a method for evaluating a transfer pattern, the quality of a transfer pattern formed on a light-transmitting substrate based on design coordinate data indicating each position of the pattern is evaluated. A coordinate value measurement step of measuring coordinate values at two or more positions in the formed pattern to obtain measured coordinate data; and comparing the measured coordinate data obtained in the coordinate value measurement step with the design coordinate data. The coordinate data is subjected to the same correction as the correction by the transfer pattern correction function provided in the exposure apparatus, and the actually measured coordinate data after the correction and the design A mutual position determining step of superposing and aligning the coordinate systems of the two data so that the overall deviation from the target data is statistically minimized; and a step of determining both positions at the position determined by the mutual position determining step. And a shift amount evaluation step of evaluating whether the shift amount of the data is within an allowable range. As an aspect of the first aspect, (Structure 2) Evaluation of the photomask pattern of the first aspect In the method, the two data mutual position determination step is performed so that the sum of the squares of the shift amounts between the points of the actually measured coordinate data and the design coordinate data that correspond to each other is minimized. Has an operation of performing one or both of a rotational movement and a parallel movement about an arbitrary point in one coordinate system.

Further, the photomask pattern evaluation apparatus according to the present invention comprises: (Structure 3) A transfer pattern formed on a photomask used in an exposure apparatus equipped with a transfer pattern correction function, wherein each position of the pattern is determined. In a photomask pattern evaluation apparatus that evaluates the quality of a transfer pattern formed on a light-transmitting substrate based on the indicated design coordinate data, a coordinate value of two or more positions in the pattern formed on the photomask is calculated. Coordinate value measuring means for measuring and measuring measured coordinate data, and comparing the measured coordinate data obtained by the coordinate value measuring means with the design coordinate data, and correcting the measured coordinate data with the transfer pattern correction provided in the exposure apparatus. A correction equivalent to the correction by the function is performed, and the overall deviation between the measured coordinate data after the correction and the design coordinate data is statistically considered. Means for determining the mutual position of the two data so that the coordinate systems of the two data are overlapped so as to be small, and whether or not the amount of deviation between the two data at the position determined by the mutual position determining means is within an allowable range. And a shift amount estimating means for evaluating whether or not the two data mutual position determining means are arranged in the photomask pattern evaluation apparatus according to the third aspect. In order to minimize the sum of the squares of the deviation amounts between the points of the actually measured coordinate data and the design coordinate data that correspond to each other, one or both of the two data points are centered on an arbitrary point in one coordinate system. And a means for performing either one or both of the rotational movement and the parallel movement described above.

Further, the pattern transfer method according to the present invention is characterized in that: (Structure 5) a pattern transfer method for transferring a pattern formed on a photomask using an exposure apparatus having a transfer pattern correction function, The photomask pattern evaluation method according to any one of claims 1 to 2, wherein the mutual position determination step is performed using a photomask which is evaluated as being within an allowable range between the two data, and the exposure apparatus is used as the exposure apparatus. Or a method provided with a function of performing a correction equivalent to the correction performed in the mutual position determination step in the photomask pattern evaluation method described in (2) or (3).

[0018]

According to the above configuration 1, the measured coordinate data obtained in the coordinate value measuring step is compared with the design coordinate data, and the measured coordinate data is corrected to the same level as the correction by the transfer pattern correcting function provided in the exposure apparatus. In order that the overall deviation between the actually measured coordinate data after the correction and the design coordinate data is statistically minimized, the mutual position of both data is determined by superimposing and aligning the coordinate systems of both data, By evaluating whether the shift amount of both data at the position determined in this way is within the allowable range, firstly, the overall shift in pattern arrangement is statistically seen. However, as in the conventional case in which a reference point is determined in advance and the difference is mechanically matched to determine the shift, the shift amount of the reference position is added to the shift amount of each data, and the apparent shift amount is smaller than the true shift amount. big Is less likely to occur, and the actual measurement data is corrected in advance by the correction function of the transfer pattern provided in the exposure apparatus, and then superimposed on the coordinate system of the design data. If the correction is performed, the possibility that a photomask capable of transferring within an allowable range is evaluated as a defective product can be eliminated, and the quality of the photomask pattern can be evaluated very accurately. Moreover, since the amount of data to be handled can be reduced, the processing is relatively easy.

According to the configuration 2, since relatively simple statistical processing is used, accurate evaluation can be quickly performed by simple processing.

Further, according to the constitutions 3 and 4, it is possible to obtain an apparatus which can execute the method of the constitutions 1 and 2.

According to the fifth aspect, the pattern transfer with a precision higher than a predetermined value is always performed while eliminating the risk of discarding a photomask which is originally a good product as a defective product and preventing the photomask from being wasted. It becomes possible.

[0022]

FIG. 1 is a diagram showing a configuration of a photomask pattern evaluation apparatus according to one embodiment of the present invention, and FIG. 2 is a summary of a procedure of a photomask pattern evaluation method according to one embodiment of the present invention. FIG. 3 is a diagram schematically showing a state in which the measured coordinate data and the design coordinate data after performing only the orthogonality correction are superimposed, and FIG. 4 is an actual measurement after performing both the orthogonality correction and the magnification correction. FIG. 5 is a diagram schematically illustrating a state in which coordinate data and design coordinate data are overlapped, and FIG. 5 is a diagram schematically illustrating a state in which measured coordinate data and design coordinate data are overlapped by a conventional method as a comparative example. Hereinafter, a method for evaluating a photomask pattern, an apparatus therefor, and a pattern transfer method according to one embodiment will be described with reference to these drawings. In the following description, first, a photomask to be evaluated will be described, then a configuration of a photomask pattern evaluation apparatus of one embodiment will be described, and then a photomask pattern evaluation method of one embodiment will be described. Next, a comparison result between the photomask pattern evaluation method of one example and the method of the comparative example will be described, and thereafter, the pattern transfer method of one example will be described.

The photomask to be evaluated was obtained as follows.

First, a chromium light-shielding film having a thickness of 980 Å is formed on the surface (main surface) of a low-expansion glass substrate of 400 mm × 400 mm × 5 mm by a sputtering method, and a resist (AZ-1350: a product of Hoechst) is formed thereon. Name) is applied to 10,000 angstrom.

Next, the resist thus formed is subjected to laser writing according to the design coordinate data. Here, for the sake of simplicity, in this embodiment, the design coordinate data is a total of 28 rows of 4 columns in the X direction and 7 columns in the Y direction.
A pattern representing a pattern having three reference points was used. In this case, the distance between each of these reference points in the X and Y directions was 50000.00 μm.

Next, the resist is developed and baked to form a resist pattern. Further, using the resist pattern as a mask, the chromium film is etched with a predetermined etchant to form a chrome light-shielding pattern. Thereafter, the remaining resist film is peeled off, and a washing and drying process is performed to obtain a photomask.

Apparatus for evaluating photomask pattern according to one embodiment
In location Figure 1, reference numeral 1 denotes a photomask, reference numeral 2 denotes a coordinate value measured device, reference numeral 100 is a computer.

The photomask 1 has the above 28 reference points 1
This is a photomask on which a chrome light-shielding pattern having a is formed.

The coordinate value measuring device 2 includes an XY stage 2a for placing the photomask 1 and moving in the XY directions, and simultaneously measuring the XY coordinates by accurately calculating the amount of movement.
It comprises a position detection optical system 2b for optically detecting a reference point 1a on the surface of the photomask 1, and a coordinate value measurement / control function of the computer 100. That is, the coordinate value measuring device 2 is configured such that the XY stage 2a and the position detection optical system 2b are controlled by the coordinate value measurement / control function 2c of the computer 100 and the reference point 1a of the light-shielding pattern formed on the photomask 1. , The coordinate value is measured, and the measured value is taken into the computer 100 as the actually measured coordinate data.

The computer 100 fetches design coordinate data in addition to the fetched actually measured coordinate data, and performs a coordinate conversion process including a fixed statistical process, a correction process equivalent to a correction process provided by a correction function provided in the exposure apparatus, and the like. And a function 3 for performing arithmetic processing and determining the mutual position of the coordinate systems of both data so that the difference between the two data is statistically minimized. At the same time, a function 4 is provided for obtaining the shift amount of each point (reference point) of both data in the mutual positional relationship thus determined, and evaluating whether or not these shift amounts are within a predetermined allowable range. Is what it is.

Evaluation Method of Photomask Pattern in One Embodiment
The outline of the procedure of the photomask pattern evaluation method according to the first embodiment is as shown in FIG. 2, and this procedure is executed by using the above-described photomask pattern evaluation apparatus. Hereinafter, the procedures (a) to (e) will be described in detail.

(A) Coordinate value actual measurement step The coordinate value of each reference point of the photomask 1 is actually measured by using the coordinate value actual measurement device 2 and the measured coordinate data (Pxij, Pxij
yij) (where i = 1 to 4, j = 1 to 7).

(B) Step of Importing Design Coordinate Data In the computer 100, a reference point (Xi
j, Yij) (where i = 1 to 4, j = 1 to 7). This step may be performed before the coordinate value measurement step.

(C) Step of Overlapping Coordinate System of Both Data Both data are superimposed by matching the origin of the coordinate system of both data taken in steps a and b.

(D) Step of Determining Mutual Positions of Both Coordinate Systems The actually measured coordinate data is determined so that the overall deviation between the measured coordinate data obtained in the coordinate value measuring step and the design coordinate data is statistically minimized. An orthogonality correction and a magnification correction equivalent to the correction by a correction function provided in an exposure apparatus for transferring a pattern using a photomask are performed to determine the mutual position of both data.

For this reason, first, for each of the design coordinate data and the actually measured coordinate data, the average value of the slopes of the line segments connecting the reference points adjacent in the X direction and the Y direction is determined. Is determined as the orthogonality correction coefficient a. That is, first, the rotation is performed such that the average value of the inclination of the line segment in the X direction becomes equal in both data. Next, the X component is converted so that the average value of the gradient of the line segment in the Y direction is equal for both data. The X component to be converted at this time depends on the Y component, the degree of dependence on Y is the orthogonality correction value a, and a is determined from the condition that the average value of the gradient of the line segment in the Y direction is equal in both data. Can be. Specifically, it is obtained as follows.

Assuming that the inclination of the measured data (Pxij, Pyij) with respect to the X axis is Ipx, and the inclination of the design coordinate data (Xij, Yij) with respect to the X axis is Irx, these are X
It can be regarded as the average value of the slope of the line segment connecting the reference points adjacent in the direction, and can be expressed by the following equation.

[0038]

(Equation 1) A rotation angle θ is determined so that Ipx and Irx in the above equations (1) and (2) become equal.

Now, the actually measured coordinate data (Pxij, Pyij)
Is rotated around the point (cx, cy) by θ obtained above, the measured coordinate data (Pxij, Pyij) becomes
Move as shown in equation (3).

[0040]

(Equation 2) In Equation (3), the center of rotation may be set to the center of gravity of the actually measured coordinate data (Pxij, Pyij) for convenience.

Measured coordinate data (P'xij, P ') after rotation
yij) is subjected to the orthogonality correction operation conversion represented by the following equation (4).

[0042]

(Equation 3) The rotated actual measured coordinate data (P'xij, P'yij)
Assuming that the inclination with respect to the Y axis after the conversion of the orthogonality correction operation of the equation (4) is Ip and the inclination of the design coordinate data (Xij, Yij) with respect to the Y axis is Ir, Ip and Ir are expressed by the following (5) ,
It is expressed by equation (6).

[0043]

(Equation 4) Assuming that Ip and Ir in the above equations (5) and (6) are equal, a determined at that time is expressed by the following equation (7).

[0044]

(Equation 5) Using the rotation angle θ thus obtained and the orthogonality correction value a, the actually measured coordinate data (Pxij, Pyij) is rotated and orthogonalized.

FIG. 3 is a diagram schematically showing measured coordinate data and design coordinate data whose mutual positions have been determined at the stage of performing the orthogonality correction. In FIG. 3, each point indicated by a circle is a coordinate value (Xi) of the reference point of the design coordinate data.
j, Yij), and each point indicated by an x mark is a coordinate value (P′xij, P ′) of the reference point after the coordinate transformation of the actually measured coordinate data.
yij). Also, in FIG. 3, the scale representing the shift amount is set to 5 of the scale representing the distance between adjacent reference points.
It is shown enlarged to 0000 times.

Next, a magnification correction including a magnification change and a parallel movement is performed on the actually measured coordinate data on which the orthogonality correction has been performed so that the deviation from the design coordinate data is minimized. Specifically, this is performed as follows.

That is, certain measured coordinate data (Pxij,
Pyij) for design coordinate data (Xij, Yij)

(Equation 6) It is assumed that when the magnification is changed and the parallel movement (ax, ay) is performed, the distance becomes closest. This operation is represented by the following equation (8).

[0048]

(Equation 7) The condition where the two approaches the most is the D expressed by the following equation (9).
Takes the minimum value.

[0049]

(Equation 8) Therefore, the following simultaneous equations (10) to (13) are solved such that the value obtained by partially differentiating D in the above equation (9) with each parameter becomes 0. The magnification change and the translation are determined so as to satisfy these equations.

[0050]

(Equation 9) In the above equation, the X component and the Y component can be solved independently, and since they are symmetric, only the X component is solved. When the above equations (10) and (11) are rewritten into the following equations (14) and (15) and modified, kx is obtained by the following equation (16).

[0051]

(Equation 10) Thus, ax can be obtained by the following equation (17).

[0052]

[Equation 11] Similarly, the Y component can be obtained.

Using the magnification change and the parallel movement thus obtained, the magnification correction can be executed by changing the magnification of the actually measured coordinate data (Pxij, Pyij) and then performing the parallel movement.

FIG. 4 is a diagram schematically showing actually measured coordinate data and design coordinate data whose mutual positions are determined at the stage of performing the magnification correction after performing the orthogonality correction. The display in FIG. 4 is the same as that in FIG.

(E) Deviation Amount Evaluation Step The coordinate values (P'xij, P'yij) of the reference point after the coordinate transformation of the design coordinate data (Xij, Yij) and the actually measured coordinate data.
Is determined, and whether or not the deviation is within an allowable range is evaluated to determine whether the photomask 1 is good or defective.

[0056] Comparison Figure 5 and the method of Comparative Example and the method of an embodiment is a diagram showing a state of repeating the design coordinate data and the measured coordinate data in a conventional manner serving Comparative Example schematically. FIG.
In the example shown in (1), (X11, Y11), which is one of the reference points of the design coordinate data, and the corresponding reference points (Px11, Py11) of the actually measured coordinate data coincide with each other and are overlapped.

In order to compare the case of the method according to the above-described embodiment with the case of the method of the comparative example, the variation in the deviation amount of each point obtained by both methods is three times the standard deviation (3σ).
The results obtained in the form were as follows.

One embodiment of the present invention Stage where only orthogonality correction is performed (see FIG. 3) X component: 3σ = 0.55 μm Y component: 3σ = 0.43 μm Stage where orthogonality correction and magnification correction are performed (see FIG. 3) X component: 3σ = 0.35 μm Y component: 3σ = 0.33 μm Comparative example (see FIG. 5) X component: 3σ = 0.72 μm Y component: 3σ = 0.43 μm As is apparent from the results, It can be seen that the variation in the shift amount is smaller than that in the comparative example at the stage where only the orthogonality correction is performed, and the variation is smaller when the magnification correction is further performed. Therefore, when the orthogonality correction and the magnification correction are not taken into account as in the comparative example, the pattern transfer within the allowable range can be finally performed by the correction function of the exposure device, and the non-defective product may be obtained. Until then, it was not included in the allowable range and was evaluated as a defective product, but in one embodiment, it was possible to correctly evaluate this as a non-defective product.

Pattern Transfer Method of One Embodiment Next, using a photomask evaluated as non-defective by the method of evaluating a photomask pattern according to the above-described embodiment,
Exposure device with transfer pattern correction function (manufactured by Canon Inc.)
An example in which pattern transfer is performed on a transfer target (photomask blank with resist) by MPA-2000) will be described.

In this exposure apparatus, light from a light source passes through a slit and reaches a transfer target via a photomask, whereby pattern transfer is performed. At this time, the orthogonality correction described above is performed by shifting the scanning direction of the photomask and the transfer target with respect to the scanning direction of the slit by a predetermined angle, and the magnification correction is performed by adjusting the magnification of the optical system. .

The transfer pattern performed using such an exposure apparatus had an accuracy within a predetermined allowable range and was very close to the design coordinate data.

In the above-described embodiment, the rotation and the translation in the step of determining the mutual position of the two coordinate systems are performed around an arbitrary point (cx, cy). The adjustment may be performed centering on the center of gravity of one of the coordinate systems.

Further, in one embodiment, in the calculation of the orthogonality correction, the average value of the inclination of the line connecting the adjacent reference points in the X direction and the Y direction is used, but the present invention is not limited to this. A line segment may be drawn by the least squares method using the reference point of, and the slope or the like of the line segment may be used.

Further, in the above-described embodiment, as a specific method for statistically minimizing the overall deviation between the actually measured coordinate data and the design coordinate data, the coordinate values obtained by converting the actually measured coordinate data into coordinates ( X and Y of a set of corresponding points of P'xij, P'yij) and design coordinate data (Xij, Yij)
The condition for minimizing the sum D of the sum of the squares of the coordinate differences was determined. For example, the condition may be determined such that the standard deviation of the difference between the corresponding points of both data is minimized. Also,
Other statistical methods may be used.

In one embodiment, the coordinates of the reference point on the light-shielding pattern of the photomask are used as the design coordinate data and the actually measured coordinate data. Good. In addition, although the accuracy increases as the number of points used increases, it can be implemented in principle if there are two or more points.

Further, in the above-described embodiment, an example in which a photomask pattern patterned by laser writing is evaluated has been described. However, the present invention is not limited to this, and the present invention is not limited to this. Of course, the evaluation of the mask pattern can also be performed. In this case, the coordinates of the reference point of the reticle may be measured in advance, and the measurement data of the reticle may be used as design coordinate data.

[0067]

As described above in detail, the method and apparatus for evaluating a photomask pattern according to the present invention and the pattern transfer method use the exposure mask data to determine the deviation of the measured coordinate data from the design coordinate data. A correction equivalent to the correction by the transfer pattern correction function provided in the apparatus is performed, and the actually measured coordinate data after the correction is compared with the design coordinate data. By deciding the mutual position of the two data and then checking the individual deviations, more appropriate evaluation can be performed compared to the conventional evaluation method evaluated without considering the correction by the exposure apparatus. Also, by performing pattern transfer using a photomask evaluated as good by this evaluation method, the originally good photomask is discarded as a defective product. While preventing wasting photomask to remove it, it is possible to always perform a pattern transfer of a predetermined or higher accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a photomask pattern evaluation apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram showing a summary of a procedure of a method for evaluating a photomask pattern according to one embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating a state in which measured coordinate data and design coordinate data whose mutual positions are determined at a stage where only orthogonality correction of one embodiment is performed are superimposed.

FIG. 4 is a diagram schematically showing a state in which measured coordinate data and design coordinate data whose mutual positions are determined at the stage of performing orthogonality correction and magnification correction of one embodiment are overlaid.

FIG. 5 is a diagram schematically showing a state in which actually measured coordinate data and design coordinate data are overlapped by a conventional method as a comparative example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photo mask, 2 ... Coordinate value measuring device, 3 ... Function of mutual position determination of design coordinate data and measured coordinate data, 4 ... Evaluation function of shift amount, 100 ... Computer.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 1/08 H01L 21/027

Claims (5)

(57) [Claims] 1. A transfer pattern formed on a photomask used in an exposure apparatus equipped with a transfer pattern correction function, the transfer pattern being formed on a translucent substrate based on design coordinate data indicating each position of the pattern. A method for evaluating the quality of a transfer pattern, the method comprising: measuring coordinate values of two or more positions in a pattern formed on the photomask to obtain measured coordinate data; The measured coordinate data obtained in the value actual measurement step is compared with the design coordinate data, and the measured coordinate data is subjected to a correction equivalent to the correction by the transfer pattern correction function provided in the exposure apparatus. Both data for which the coordinate systems of both data are superimposed and aligned so that the overall deviation between the data and the design coordinate data are statistically minimized A mutual position determining step, and a shift amount evaluating step of evaluating whether a shift amount between the two data at the position determined by the mutual position determining step is within an allowable range. Evaluation methods. 2. The method for evaluating a photomask pattern according to claim 1, wherein the mutual data position determination step is performed by calculating a square of a shift amount of each point of the actually measured coordinate data and the design coordinate data that correspond to each other. In order to minimize the sum, any one or both of the two data may include an operation of performing one or both of a rotational movement and a parallel movement about an arbitrary point in one coordinate system. Method of evaluating a photomask pattern. 3. A transfer pattern formed on a photomask used in an exposure apparatus equipped with a transfer pattern correction function, the transfer pattern being formed on a light-transmitting substrate based on design coordinate data indicating each position of the pattern. A photomask pattern evaluation apparatus for evaluating the quality of the transfer pattern, a coordinate value measuring means for measuring coordinate values of two or more positions in a pattern formed on the photomask to obtain measured coordinate data; The measured coordinate data obtained by the value measuring means is compared with the design coordinate data, and the measured coordinate data is subjected to a correction equivalent to the correction by the transfer pattern correction function provided in the exposure apparatus. Both data for which the coordinate systems of both data are superimposed and aligned so that the overall deviation between the data and the design coordinate data are statistically minimized Mutual position determining means, and a shift amount evaluating means for evaluating whether the shift amount between the two data at the position determined by the mutual position determining means is within an allowable range. Evaluation device. 4. The apparatus for evaluating a photomask pattern according to claim 3, wherein said mutual data position determining means calculates a square of a shift amount of each point of the measured coordinate data and the design coordinate data which correspond to each other. A means shall be provided for performing one or both of rotational and / or translational movement of one or both of the two data around an arbitrary point in one coordinate system so that the sum is minimized. A photomask pattern evaluation apparatus characterized by the following. 5. A pattern transfer method for transferring a pattern formed on a photomask using an exposure apparatus having a transfer pattern correction function, wherein the photomask according to claim 1 is used as the photomask. 3. A photomask which has been evaluated by the mutual position determination step in the pattern evaluation method as having a deviation amount between the two data within an allowable range, and is used as the exposure apparatus in the photomask pattern evaluation method according to claim 1 or 2. A pattern transfer method characterized by using a device provided with a function of performing a correction equivalent to the correction performed in the position determining step.