JP2002359174A - Exposure process managing system, method therefor and program for managing exposure process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manage overlay accuracy in an exposure process for manufacturing a semiconductor while considering changes with time. SOLUTION: In an exposure process, a prescribed pattern is exposed on a piece of wafer using a first aligner and a second aligner. Deviation is generated on the pattern exposed on the piece of wafer. An exposure process managing apparatus includes an inspection data storing section 32 for storing date and time when exposure process is executed and deviation amount, and an accuracy fluctuation detecting section 22 for determining whether or not a dispersion value of the deviation amount of a wafer processed during a first period is equal to a dispersion value of the deviation amount of a wafer processed during a second period, and allowing a display section 40 to display the fluctuation in the deviation amount when the deviation amounts are not equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor manufacturing technique, and more particularly, to a technique for improving the pattern overlay accuracy in a plurality of exposure steps.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a production management system for optimizing production has been constructed by automating a semiconductor manufacturing apparatus itself and comprehensively managing information on manufacturing.

In the exposure process of such a semiconductor device, in recent years, various types of exposure methods have been used due to miniaturization and enlargement of a semiconductor chip. An optimal exposure method is adopted for each of a plurality of exposure steps, and different types of exposure apparatuses are used according to the steps. In such a case, there are the following problems.

[0004] Each lens of the exposure apparatus has a unique distortion called distortion. As a result, the positional accuracy of the transferred pattern is shifted from the position to be transferred due to design. When patterns are overlapped by the same exposure apparatus, there is no relative shift between the patterns to be overlapped and the patterns to be overlapped because they have the same distortion. When patterns are superimposed by different exposure apparatuses, since two different exposure apparatuses have their own distortions, relative distortion occurs due to the combination of the two apparatuses when the patterns are superimposed. This relative deviation of distortion is called distortion fluctuation.

Japanese Patent Application Laid-Open No. 2000-114132 addresses such a problem by automatically judging the overlay accuracy of an exposure pattern in consideration of distortion fluctuation to improve the production efficiency of a semiconductor device. A production support system is disclosed.

[0006] This production support system stores a lens distortion variation in a combination of all the exposure apparatuses among a plurality of exposure apparatuses arranged in a plurality of exposure steps, and stores an inspection standard in the exposure step. An inspection standard storage unit, a receiving unit that receives an actual measurement value of the overlay deviation measured by the overlay accuracy inspection device from the overlay accuracy inspection device, and reads and reads the lens distortion variation between the two exposure devices. A calculating unit that calculates the true overlay accuracy deviation amount based on the lens distortion fluctuation and the received actual overlay deviation amount measurement value, and the calculated true overlay accuracy deviation amount and inspection standard. And a determination unit for making a pass / fail determination based on

According to this system, the storage unit stores lens distortion fluctuations in all lens combinations, which are measured in advance by experiments. The calculation unit calculates a true overlay accuracy deviation amount based on the stored lens distortion fluctuation between the two exposure apparatuses and an actual measurement value of the overlay deviation amount by the overlay accuracy inspection device. The determination unit compares the calculated true overlay accuracy with the overlay accuracy standard of the exposure process to determine whether the overlay accuracy is within the overlay accuracy standard. Accordingly, even when the exposure pattern is processed using different exposure apparatuses, the deviation amount of the true overlay accuracy can be calculated in consideration of the error factors caused by the two lens distortions.

[0008]

However, in this system, only a fluctuation factor of the overlay accuracy measured in advance by an experiment, such as a lens distortion fluctuation, is considered. In this system, it is not possible to detect a deterioration in accuracy due to the apparatus such as deterioration of components constituting the exposure apparatus, and a change in accuracy due to a change in the shape of a base film formed in the overlapping step.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can analyze overlay accuracy in an exposure step of semiconductor manufacturing in consideration of a temporal variation, and can analyze a factor of the variation. An exposure process management system, an exposure process management method, and a program for managing an exposure process are provided.

[0010]

An exposure step management system according to a first aspect of the present invention is a system for managing an exposure step of a semiconductor wafer. In the exposure step, a predetermined pattern is exposed on one wafer using the first exposure apparatus and the second exposure apparatus. A shift occurs between the pattern exposed by the first exposure device and the pattern exposed by the second exposure device. In the exposure step, the deviation is managed so as to fall within a predetermined range. The exposure step management system includes a storage unit for storing the date and time when the exposure step was processed, a shift amount in the exposure step, and a plurality of shift amounts with respect to the wafer processed in the first period. To determine whether or not the variances of the shift amounts in each set are equal to each other in the two sets based on the set including And a detecting means connected to the determining means for detecting that the deviation amount in the exposure step has changed if the variances of the deviation amounts are not equal to each other, and a detection result of the detecting means connected to the detecting means. And an output unit for outputting

[0011] According to the first invention, the judging means comprises: a set including a plurality of shift amounts for the wafer processed in the first period; and a set for the wafer processed in the second period.
It is determined whether or not the variances of the shift amounts in the set including the plurality of shift amounts are equal to each other in the two sets. If the variances of the shift amounts are not equal to each other, the detecting means detects that the shift amount in the exposure process has changed. This allows
If the variance of the shift amount fluctuates due to a temporal factor, the output means outputs that the shift amount fluctuates. As a result, it is possible to provide an exposure step management system that can analyze the overlay accuracy in the exposure step of semiconductor manufacturing by using a statistical method and considering temporal variations.

According to a second aspect of the present invention, in the exposure step management system according to the first aspect, the determining means includes a variance value of a set including a plurality of shift amounts with respect to the wafer processed in the first period. And the ratio of the variance value of the set including the plurality of shift amounts to the wafers processed in the second period is equal to or greater than a predetermined value. Means for determining whether two sets are equal to each other.

[0013] According to the second invention, the judging means determines the variance value of the set including the shift amount processed in the first period and the variance value of the set including the shift amount processed in the second period. If the ratio is equal to or larger than a predetermined value, it is determined that the variance values of the shift amounts in each set are not equal to each other in the two sets. When the dispersion tendency of the shift amount in the second period changes compared to the first period, it is detected that the shift amount has changed.

An exposure step management system according to a third invention is a system for managing an exposure step of a semiconductor wafer. The exposure step management system is a storage unit for storing a shift amount in the exposure step, and a calculating unit connected to the storage unit, for calculating a variance of a shift amount in a set including a plurality of shift amounts for the wafer, A stop accuracy storing means for storing a plurality of data indicating a shift amount of the stop of the wafer in the first exposure apparatus and the second exposure apparatus measured using the test wafer, and a stop accuracy storage means; And a standard deviation calculating means for calculating a standard deviation of the data, and an analysis for analyzing a factor of a shift in the exposure process based on the variance and the standard deviation, the analysis means being connected to the calculating means and the standard deviation calculating means. Means.

According to the third aspect, the calculating means calculates the variance of the shift amount in the set including the plurality of shift amounts with respect to the wafer. The standard deviation calculating means calculates a standard deviation of a plurality of data indicating a shift amount of the stop of the wafer in the first exposure apparatus and the second exposure apparatus, which is measured using the test wafer. The analysis means analyzes the cause of the shift in the exposure process based on the variance and the standard deviation.
Thus, the standard deviation is converted into a value that can be compared with the variance, and the distribution of the deviation amount of the device factor can be analyzed based on the converted value and the variance. As a result, it is possible to provide an exposure step management system capable of analyzing a cause of a change in overlay accuracy in an exposure step of semiconductor manufacturing.

In the exposure step management system according to a fourth aspect, in addition to the configuration of the third aspect, the calculating means includes means for calculating a variance value of a shift amount in a set including a plurality of shift amounts. . The analysis means includes a means for analyzing a ratio of a shift caused by the device based on a ratio between the variance value and a value based on the standard deviation.

According to the fourth aspect, it is possible to analyze the ratio of the deviation caused by the apparatus based on the ratio between the variance value and the value based on the standard deviation. Accordingly, the administrator can specify the ratio of the factor due to the exposure apparatus to other factors, such as a factor due to a process such as a change in the shape of the formed base film.

According to a fifth aspect of the present invention, in addition to any one of the first to fourth aspects of the present invention, the exposure step management system is connected to the storage means, and based on the shift amount in the exposure step stored in the storage means. To divide the wafer into multiple regions,
An instruction unit for instructing positioning correction at the time of exposure is further included.

According to the fifth aspect of the present invention, the wafer surface is divided into a plurality of regions and corrected, so that even if there is a non-linear deformation due to superposition, a residual error (a shift amount of a plurality of positions in the wafer) is reduced. (A difference from a displacement due to linear deformation calculated from the displacement measured by the inspection device).

According to a sixth aspect of the present invention, in addition to the configuration of the first to fourth aspects of the present invention, the exposure step management system is connected to the storage means and based on the difference in the shift amount in the exposure step stored in the storage means. In addition, the first exposure apparatus and the second exposure apparatus are combined to further include an instruction unit for instructing the position correction at the time of exposure.

According to the sixth aspect of the invention, it is possible to manage by combining exposure apparatuses in which the difference between the shift amounts is smaller than a predetermined value (the characteristics of the lenses of the exposure apparatuses are similar and the shift amounts are close to each other).

An exposure step management method according to a seventh invention is a method for managing an exposure step of a semiconductor wafer. The exposure step management method includes a storage step of storing a date and time when the exposure step was processed, a shift amount in the exposure step, a set including a plurality of shift amounts with respect to the wafer processed in the first period, and a second step. A determination step of determining whether or not the variance of the shift amount in each set is equal to each other in the two sets based on a set including a plurality of shift amounts for the wafers processed in the period; If they are not equal to each other, the method includes a detecting step of detecting a change in the shift amount in the exposure step and an output step of outputting a result detected in the detecting step.

According to the seventh aspect, the judging step includes the step of determining a set including a plurality of shift amounts for the wafer processed in the first period and the plurality of shift amounts for the wafer processed in the second period. The variance of the deviation amount in the set containing
It is determined whether the two sets are equal to each other. The detecting step detects that the shift amount in the exposure process has changed if the variances of the shift amounts are not equal to each other. As a result, when the variance of the shift amount fluctuates due to a temporal factor, the fact that the shift amount fluctuates in the output step is output. As a result, it is possible to provide an exposure step management method that can analyze the overlay accuracy in the exposure step of semiconductor manufacturing by using a statistical method and considering temporal variations.

An exposure step management method according to an eighth aspect of the present invention, in addition to the configuration of the seventh aspect, further comprises the step of: determining a variance value of a set including a plurality of shift amounts with respect to the wafer processed in the first period. And for the wafer processed during the second period,
It is determined whether or not the variances of the shift amounts in each set are equal to each other in the two sets based on whether or not the ratio of the variance value of the set including the plurality of shift amounts to a predetermined value or more. Including steps.

According to the eighth aspect, the determining step includes determining a variance value of the set including the shift amount processed in the first period and a variance value of the set including the shift amount processed in the second period. If the ratio is equal to or larger than a predetermined value, it is determined that the variance values of the shift amounts in each set are not equal to each other in the two sets. When the dispersion tendency of the shift amount in the second period changes compared to the first period, it is detected that the shift amount has changed.

An exposure step management method according to a ninth aspect is a method for managing an exposure step of a semiconductor wafer. The exposure step management method includes a storage step of storing a shift amount in the exposure step, a calculation step of calculating a variance of a shift amount in a set including a plurality of shift amounts with respect to the wafer, and a measurement step using the test wafer. First exposure apparatus and second exposure apparatus
In the exposure apparatus, a stop accuracy storing step of storing a plurality of data representing a shift amount of the stop of the wafer, a standard deviation calculating step of calculating a standard deviation of the data stored in the stop accuracy storing step, An analyzing step of analyzing a factor of the deviation in the exposure process based on the deviation.

According to the ninth aspect, the calculation step calculates a variance of the shift amount in the set including the plurality of shift amounts with respect to the wafer. In the standard deviation calculating step, the standard deviation of a plurality of data representing the shift amount of the stop of the wafer between the first exposure apparatus and the second exposure apparatus, which is measured using the test wafer, is calculated. The analysis step analyzes a factor of a shift in the exposure process based on the variance and the standard deviation. Thereby, the standard deviation is converted into a value that can be compared with the variance, and the distribution of the deviation amount of the apparatus can be analyzed based on the converted value and the variance. As a result, it is possible to provide an exposure step management method capable of analyzing a cause of a change in overlay accuracy in an exposure step of semiconductor manufacturing.

An exposure step management method according to a tenth aspect of the present invention
In addition to the configuration of the ninth aspect, the calculation step includes a step of calculating a variance value of a shift amount in a set including a plurality of shift amounts. The analyzing step includes a step of analyzing a ratio of a shift caused by the device based on a ratio between the variance value and a value based on the standard deviation.

According to the tenth aspect, it is possible to analyze the ratio of the deviation caused by the apparatus based on the ratio between the variance value and the value based on the standard deviation. Accordingly, the administrator can specify the ratio of the factor due to the exposure apparatus to other factors, such as a factor due to a process such as a change in the shape of the formed base film.

An exposure step managing method according to an eleventh aspect of the present invention comprises:
In addition to the configuration of any one of the seventh to tenth aspects, the wafer is divided into a plurality of regions based on the shift amount in the exposure step stored in the storage step, and a positioning correction at the time of exposure is instructed. An instruction step is further included.

According to the eleventh aspect of the present invention, there is provided an exposure step management method capable of reducing a residual error even when a non-linear deformation due to superposition exists by dividing a wafer surface into a plurality of regions and performing correction. Can be provided.

An exposure step management method according to a twelfth aspect of the present invention
In addition to the configuration of any one of the seventh to tenth aspects, the first exposure apparatus and the second exposure apparatus are combined based on the difference in the shift amount in the exposure step stored in the storage step, The method further includes an instruction step of instructing positioning correction at the time of exposure.

According to the twelfth aspect, it is possible to manage by combining exposure apparatuses in which the difference in the shift amount is smaller than a predetermined value (the characteristics of the lenses of the exposure apparatus are similar and the shift amounts are close to each other). An exposure step management method can be provided.

A program according to a thirteenth aspect is a program for managing an exposure process of a semiconductor wafer.
The program causes the computer to store a date and time at which the exposure step was processed, a storage procedure for storing a shift amount in the exposure step, a set including a plurality of shift amounts for the wafer processed during the first period, and a second set. A determination procedure for determining whether or not the variance of the shift amount in each set is equal to each other in the two sets based on a set including a plurality of shift amounts for the wafers processed in the period; If they are not equal to each other, a detection procedure for detecting a change in the shift amount in the exposure step and an output procedure for outputting a detection result by the detection procedure are executed.

According to the thirteenth aspect, the determination procedure is the first procedure.
For the wafers processed during the period, the set including the plurality of shift amounts, and for the wafers processed during the second period, the dispersion of the shift amount in the set including the plurality of shift amounts,
It is determined whether the two sets are equal to each other. In the detection procedure, if the variances of the shift amounts are not equal to each other, it is detected that the shift amount in the exposure process has changed. As a result, if the variance of the shift amount fluctuates due to a factor over time,
The fact that the deviation amount has changed in the output procedure is output. As a result, it is possible to provide a program for managing the exposure process, which can analyze the overlay accuracy in the exposure process of the semiconductor manufacturing by using the statistical method and considering the change over time.

According to a fourteenth aspect of the present invention, there is provided a program according to the thirteenth aspect.
In addition to the configuration of the invention according to the first aspect, the determination procedure includes a variance value of a set including a plurality of shift amounts for the wafer processed in the first period, and a plurality of shift amounts for the wafer processed in the second period. Is determined based on whether or not the ratio of the variance to the set including is equal to or greater than a predetermined value, to determine whether or not the variance of the deviation amount in each set is equal to each other in the two sets.

According to the fourteenth aspect, the determination procedure is the first procedure.
The variance of the set including the shift amount processed during the period
If the ratio of the variance value of the set including the shift amount processed during the period is equal to or greater than a predetermined value, it is determined that the variance values of the shift amounts in each set are not equal to each other in the two sets. When the dispersion tendency of the shift amount in the second period changes compared to the first period, it is detected that the shift amount has changed.

A program according to a fifteenth aspect is a program for managing a semiconductor wafer exposure step.
The program is a computer, a storage procedure for storing the shift amount in the exposure step, a calculation procedure for calculating the variance of the shift amount in a set including a plurality of shift amounts for the wafer, and a measurement procedure using the test wafer. A stop accuracy storing procedure for storing a plurality of data representing a shift amount of the stop of the wafer in the first exposure apparatus and the second exposure apparatus;
A standard deviation calculation procedure for calculating a standard deviation of data and an analysis procedure for analyzing a factor of a shift in an exposure process based on the variance and the standard deviation are executed.

According to the fifteenth aspect, in the calculation procedure, a variance of a shift amount in a set including a plurality of shift amounts with respect to the wafer is calculated. In the standard deviation calculation procedure, the standard deviation of a plurality of data indicating the shift amount of the stop of the wafer in the first exposure apparatus and the second exposure apparatus, which is measured using the test wafer, is calculated. The analysis procedure analyzes the cause of the shift in the exposure process based on the variance and the standard deviation. Thereby, the standard deviation is converted into a value that can be compared with the variance, and the distribution of the deviation amount of the apparatus can be analyzed based on the converted value and the variance. As a result, it is possible to analyze the cause of the variation in the overlay accuracy in the exposure process of semiconductor manufacturing,
A program for managing the exposure process can be provided.

A program according to a sixteenth aspect of the present invention is the program according to the fifteenth aspect.
In addition to the configuration of the present invention, the calculation step includes a step of calculating a variance value of a shift amount in a set including a plurality of shift amounts.
The analysis procedure includes a procedure of analyzing a ratio of a shift caused by the device based on a ratio between the variance value and a value based on the standard deviation.

According to the sixteenth aspect, based on the ratio between the variance value and the value based on the standard deviation, it is possible to analyze the ratio of the deviation caused by the device. Accordingly, the administrator can specify the ratio of the factor due to the exposure apparatus to other factors, such as a factor due to a process such as a change in the shape of the formed base film.

A program according to a seventeenth aspect of the present invention provides a program according to the thirteenth aspect.
In addition to the configurations of the sixteenth aspect, the computer further includes an instruction to divide the wafer into a plurality of regions based on the shift amount in the exposure step stored in the storage procedure and to instruct positioning correction during exposure. Execute the procedure.

According to the seventeenth aspect, by correcting the wafer surface by dividing the wafer surface into a plurality of regions, even if there is a non-linear deformation due to superposition, a residual error can be reduced, and the exposure process is managed. Can provide a program for

A program according to an eighteenth aspect of the present invention is the program according to the thirteenth aspect.
In addition to the configuration of the sixteenth aspect, the computer further includes a combination of the first exposure apparatus and the second exposure apparatus based on the difference in the shift amount in the exposure step stored in the storage procedure. An instruction procedure for instructing position correction at the time is executed.

According to the eighteenth aspect, it is possible to manage by combining exposure apparatuses in which the difference in the shift amount is smaller than a predetermined value (the characteristics of the lenses of the exposure apparatus are similar and the shift amounts are close to each other). A program for managing the exposure process can be provided.

[0046]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are the same. Therefore, detailed description thereof will not be repeated.

Referring to FIG. 1, an exposure process control apparatus 10 according to the present embodiment includes a control unit 20 for controlling the exposure process control apparatus 10, a data storage unit 30 for storing various data, And a communication unit 60 that communicates with the plurality of exposure devices 70 and the inspection devices 80.

The control section 20 includes an accuracy fluctuation detecting section 22 and a fluctuation factor estimating section 24. The data storage unit 30 includes an inspection data storage unit 32 that stores the inspection data after the exposure processing.
And a maintenance data storage unit 34 for storing the shift amount of the drive stage of the exposure apparatus 70 measured using the test wafer.
And a processing result data storage unit 36 that stores the processing result of the exposure process.

The precision fluctuation detecting section 22 searches the processing result data storage section 36 for a corresponding product type and process based on the exposure apparatus specified by the user and the two periods of the fluctuation detection target. The accuracy variation detecting unit 22 searches the inspection data storage unit 32 for the corresponding inspection data based on the searched product type and process. The accuracy variation detection unit 22
The variance value of the shift amount included in the two periods is calculated. The accuracy variation detecting unit 22 performs an equal variance test on the variance of the shift amounts included in the two calculated periods.

The equal variance test will be described. The equal variance test is performed on two populations each containing multiple data.
This is a statistical method for determining whether the variances of the respective groups are equal to each other. The variance of each group is V
Assuming that 1, V2, the number of samples is n1, n2. When the dispersions are equal to each other, the dispersion ratio F = (V1 / V2)
Determines whether or not the variances of the respective groups are equal to each other by utilizing the F distribution with the degrees of freedom (n1-1, n2-1).

The fluctuation factor estimating unit 24 is a processing result data storage unit 36 based on the exposure apparatus designated by the user.
Search for the corresponding product type and process. Variation factor estimation unit 2
4 retrieves the corresponding test data from the test data storage unit 32 based on the retrieved product type and process. The variation factor estimating unit 24 calculates a first variance value of the shift amount. The variation factor estimating unit 24 searches the maintenance data storage unit 34 for the maintenance data of the corresponding exposure apparatus, based on the exposure apparatus specified by the user. The fluctuation factor estimating unit 24 calculates the standard deviation of the searched maintenance data. The variation factor estimating unit 24 converts the calculated standard deviation into a second variance value that can be compared with the first variance value. Variation factor estimator 24
Calculates the ratio of the factors of the shift caused by the exposure apparatus based on the ratio between the first variance value and the second variance value. In this way, the fluctuation factor estimating unit 24 can separate the fluctuation caused by the exposure apparatus from the other fluctuations (for example, fluctuations caused by a process such as a change in the shape of the formed base film). The basis for this separation is based on the additive nature of the variance and the central limit theorem in statistical methods.

Referring to FIG. 2, the test data stored in test data storage unit 32 will be described. As shown in FIG. 2, the inspection data includes measurement result data of overlay accuracy, inspection standard, and inspection date and time for each inspection target lot name, inspection target product name, and inspection target process name. The measurement result data of the overlay accuracy includes, for example, an X-direction offset component, a scaling component, and a wafer rotation component, a Y-direction offset component, a scaling component, and a wafer rotation component. FIG. 3 shows the meaning of each component.

The calculation of the linear component shown in FIG. 3 will be described. The linear component is calculated by decomposing the amount of overlay deviation into a linear component. X at multiple locations on the wafer
The deviation amount in the Y direction is measured. A linear component is calculated based on this deviation amount and the following equation. At this time,
The least squares method is used for the following equation:

Dx = A + Bx−Cy, dy = D + Ey + Fx where x and y are coordinates of a measurement position of the overlay accuracy in the wafer surface. dx and dy are overlay displacement amounts at coordinates X and Y in the wafer. A is an offset component in the x direction. B is a scaling component in the x direction. C is a wafer rotation component in the x direction. D
Is an offset component in the y direction. E is a scaling component in the y direction. F is a wafer rotation component in the y direction. The rotation shown in FIG. 3 is (F + C) /
2 is calculated. The orthogonality is calculated by (FC).

Referring to FIG. 4, security data stored in security data storage unit 34 will be described. As shown in FIG. 4, the maintenance data includes, for each exposure apparatus (unit), measurement data of a stage driving device, which is measured regularly or irregularly using a test wafer, measurement date and time, and manual input maintenance. And data. The measurement result data of the stage driving device includes the number of measurements, for example, the amount of displacement in the X direction and the amount of displacement in the Y direction. The deviation in each direction includes an average value and a standard deviation.

Referring to FIG. 5, processing result data storage unit 3
The processing result data stored in No. 6 will be described. FIG.
As shown in (1), the processing result data includes, for each exposure apparatus (unit), an exposure target lot name, an exposure target product name, an exposure target process name, an exposure condition, and a processing date and time.

The management function in the exposure step according to the present embodiment is implemented by a CPU (Central Proc
This is realized by executing a predetermined program by an essing unit.

FIG. 6 shows an external view of a computer system which is an example of the exposure step management apparatus 10. Referring to FIG. 6, this computer system has an FD (Flexible Disk).
Drive 106 and CD-ROM (Compact Disc-Rea
d Only Memory) Computer 1 with drive device 108
02, a monitor 104, a keyboard 110, and a mouse 112.

FIG. 7 is a block diagram showing the configuration of the computer system. As shown in FIG. 7, the computer 102 includes the above-described FD driving device 106 and a CD.
-In addition to the ROM drive device 108, it includes a CPU (Central Processing Unit) 120, a memory 122, a fixed disk 124, and a communication interface 126 for communicating with other computers, which are connected to each other by a bus. The FD 116 is mounted on the FD driving device 106.
A CD-ROM 118 is mounted on the CD-ROM drive 108. These FD116 and CD-ROM1
18 stores a predetermined program corresponding to the software.

As described above, the exposure step management apparatus 10 having the function of managing the exposure step is realized by computer hardware and software executed by the CPU 120. Generally, such software is stored and distributed as a program on a recording medium such as the FD 116 or the CD-ROM 118, and the FD driving device 10
6 or read from the recording medium by the CD-ROM drive device 108 or the like and temporarily stored in the fixed disk 124. Further, the data is read from the fixed disk 124 to the memory 122 and executed by the CPU 120.

The hardware itself of these computers is general. The computer includes a control circuit including a CPU, a storage circuit, an input circuit, an output circuit, and an OS.
(Operating System) and an environment for executing programs. The program of the present invention is a program for realizing a function of managing the exposure process in such a computer. Therefore, the most essential part of the present invention is a program recorded on a recording medium such as an FD, a CD-ROM, a memory card, and a fixed disk.

Since the operation of the computer shown in FIGS. 6 and 7 is well known, detailed description thereof will not be repeated here. The control unit 20 shown in FIG.
120, the data storage unit 30 stores in the fixed disk 124,
The display unit 40 corresponds to the monitor 104, the input unit 50 corresponds to the keyboard 110 and the mouse 112, and the communication unit 60 corresponds to the communication interface 126.

Referring to FIG. 8, the program executed by the exposure step managing apparatus according to the present embodiment has the following control structure for the accuracy fluctuation detection processing.

Step (hereinafter, step is abbreviated as S)
At 100, CPU 120 detects, using keyboard 110 and mouse 112, the exposure apparatus (unit) to be detected and the fluctuation detection period, which are input by the user of the exposure process management apparatus. In S110, CPU 120 searches for the type and process processed using the exposure apparatus to be detected, based on the processing result data (FIG. 5) stored in processing result data storage unit 36.

At S120, CPU 120 reads the measurement result (for example, offset) of the overlay accuracy for the retrieved product type and process based on the inspection data (FIG. 2) stored in inspection data storage unit 32. put out. At this time, in the exposure device 70, the exposure process may be performed in a state where the offset component has been corrected. In this case, the following processing is performed using a value obtained by subtracting the correction amount at the time of exposure processing from the offset amount of the inspection data (FIG. 2) stored in the inspection data storage unit 32.

In S 130, CPU 120 calculates a variance value for the read overlay accuracy measurement result (offset). At S140, CPU 120 calculates a variance ratio in the two periods based on the calculated variance value. In S150, CPU 120 performs an equal variance test. CPU 120 determines whether or not the calculated dispersion ratio is larger than a predetermined value. If the dispersion ratio is larger than a predetermined value (Y in S150)
ES), the process proceeds to S160. If not (NO in S150), the process proceeds to S170.

At S160, CPU 120 determines that there is a significant difference in the fluctuation of the deviation. At S170, CPU 1
No. 20 judges that there is no significant difference in the fluctuation of the deviation. S18
At 0, CPU 120 outputs the result to monitor 104. At this time, the variance value in each period, and the presence / absence of a significant difference in the variance ratio and the shift in the deviation in each period are displayed for each exposure apparatus (unit), product type, and process.

Referring to FIG. 9, the program executed by the exposure step managing apparatus according to the present embodiment has the following control structure for the variation factor estimating process.

In S 200, CPU 120 uses keyboard 110 and mouse 112, and the exposure apparatus (unit) to be measured is inputted by the user of this exposure step management apparatus.
Is detected. In S210, CPU 120 stores the processing result data stored in processing result data storage unit 36 (FIG. 5).
, The type and process processed using the exposure apparatus to be estimated are searched.

In S 220, CPU 120 determines the measurement result (for example, offset amount) of the overlay accuracy for the retrieved product type and process based on the inspection data (FIG. 2) stored in inspection data storage unit 32. Read. S23
At 0, CPU 120 calculates a first variance value for the read overlay accuracy measurement result (offset amount). In S240, CPU 120 reads the maintenance data (FIG. 4) of the exposure apparatus to be estimated, which is stored in maintenance data storage unit 34.

At S250, CPU 120 converts the standard deviation included in the read maintenance data into a second variance that can be compared with the first variance. At this time, the standard deviation is set to σ. A second variance value is calculated by [(σ × σ) / n] based on the standard deviation σ and the number of measurements n for which the standard deviation σ has been calculated. As a result, the value becomes a value that can be compared with the first dispersion value for each product type and process.

At S260, CPU 120 classifies the variation factors into device-induced variation and process-induced variation based on the first variance and the second variance. S270
The CPU 120 outputs the result to the monitor 104. At this time, a variance value for all variations, a variance value due to device variations, and a variance value due to process variations are displayed for each exposure apparatus (unit), product type, and process.

The operation of the exposure step managing apparatus based on the above structure and flowchart will be described.

[Accuracy Fluctuation Detection Operation] The user of the exposure process control apparatus inputs an exposure apparatus (unit) to be detected and a fluctuation detection period (S100). Processing result data storage unit 3
Based on the processing result data (FIG. 5) stored in No. 6, a type and a process processed by using the exposure apparatus to be detected are searched (S110). About the searched varieties and processes,
Test data stored in test data storage unit 32 (FIG. 2)
Is read out (S12).
0). A variance value for the read measurement result (offset amount) is calculated (S130). At this time, S100
A variance value is calculated for each of the two detection periods input at. Based on the calculated two variance values, a ratio (variance ratio) of the variance values in the two periods is calculated (S140). If the dispersion ratio is larger than a predetermined value (for example, 1.8) (YE at S150)
S), it is determined that there is a significant difference (S160).

As described above, as a result of the accuracy fluctuation detecting operation,
The accuracy fluctuation detection result shown in FIG. 11 is displayed on the monitor 104. As shown in FIG. 10, the accuracy fluctuation detection result includes data representing the exposure apparatus (unit), type, process, period 1, period 2, variance ratio, and significant difference.

[Variation Factor Estimation Operation] The user of the exposure process control apparatus inputs an exposure apparatus (unit) to be measured (S
200). Based on the actual processing data (FIG. 5) stored in the actual processing data storage unit 36, the type and process processed using the exposure apparatus to be estimated are searched (S21).
0). For the retrieved product type and process, the measurement result (offset amount) of the inspection data (FIG. 2) stored in the inspection data storage unit 32 is read (S220). A first dispersion value for the read measurement result (offset amount) is calculated (S230). The maintenance data of the exposure apparatus whose fluctuation factor is estimated is read from the security data storage unit 34 (S240). The standard deviation included in the read maintenance data is converted into a second variance value that can be compared with the first variance value (S250). Based on the first variance value and the second variance value, variation factors are classified into device-induced variation and process variation-induced variation (S260).

The result estimated by the variation factor estimating operation is displayed on the monitor 104 as shown in FIG. 11 (S270). As shown in FIG. 11, the estimation result includes data indicating the machine type, product type, process, total variation, device variation, and process variation. Thereby, the user can grasp the fluctuation amount due to the device fluctuation and the fluctuation amount due to the process among the fluctuations of the deviation amount, and can take an immediate action for the fluctuation of the deviation amount.

As described above, the exposure step management apparatus according to the present embodiment can grasp the variation of the amount of shift over time based on the amount of shift measured in a plurality of exposure apparatuses in the exposure step. it can. Further, the fluctuation of the measured shift amount can be estimated separately from the fluctuation due to the apparatus and the fluctuation due to the process. as a result,
In an exposure process of a semiconductor device, it is possible to provide an exposure process management system that can analyze overlay accuracy in an exposure process and analyze a factor of the variation in consideration of a change in a temporal shift amount.

<First Modification> The first modification of the above-described embodiment will be described.
A modified example will be described. This modification is different from the control unit 20
Further includes a correction instruction unit 26.

The correction instructing unit 26 includes an inspection data storage unit 32
Is searched for the shift amount specified by the user. The correction instructing unit 26 divides the wafer surface into a plurality of parts to perform the positioning correction at the time of exposure to the exposure apparatus 70 based on the retrieved deviation amount.

The correction instructing unit 26 decomposes the shift amounts at a plurality of positions in the wafer measured by the inspection device 80 into linear components shown in FIG. Make corrections. At this time, as shown in FIG. 12, the wafer surface is divided into two regions 1000 and 1010, and the shift amounts of a plurality of measurement points in each region are measured. A linear component is calculated from the measured shift amount. Using the calculated linear component, the shift amount of a plurality of measurement points in each area is calculated for each area. As a result, even when there is a non-linear deformation in the shift amount, the residual error (the difference between the shift amount at a plurality of locations in the wafer and the shift amount measured by the inspection device 80) is compared with the correction that does not divide the wafer surface. Difference) is reduced.

<Second Modification> The second modification of the above embodiment
A modified example will be described. This modification is different from the control unit 20
Further includes a correction section setting unit 28.

The correction section setting section 28 searches the inspection data storage section 32 for a shift amount designated by the user.
The correction division setting unit 28 sets a set of two or more types and processes different from each other, in which the difference between the shift amounts is smaller than a predetermined value, in one correction group. The correction section setting unit 28 outputs an instruction to perform positioning correction at the time of exposure for the exposure apparatus in the group unit.

The correction section setting unit 28 reads out the shift amount (for example, the offset amount in the X and Y directions) stored for each exposure apparatus, product type, and process from the inspection data storage unit 32. In the exposure process, when the offset component is corrected, the following process is performed using a value obtained by subtracting the correction amount at the time of the exposure process from the offset amount read from the inspection data storage unit 32. Correction section setting unit 28
Calculates the average value of the read deviation amounts (offset amounts in the X and Y directions). The correction section setting unit 28 creates the correlation diagram shown in FIG. Referring to FIG. 13, each point in the correlation diagram where the horizontal axis is the offset amount in the X direction and the vertical axis is the offset amount in the Y direction is the deviation amount for each product type and process. The correction section setting unit 28 calculates the distance between the points, and combines types and processes smaller than a predetermined value. In this way, the correction section setting unit 28 sets the positioning correction groups 1100, 1110, and 1120 for the exposure apparatus 70.
The correction section setting unit 28, according to the set group,
Instruct correction. In addition, the correction division determination unit 28 may have a function of calculating a distance between each point and combining a type and a process smaller than a predetermined value, as well as a function of allowing a user to set a group.

In this way, the most suitable type and process can be
The correction can be set as one group.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a control block diagram of an exposure step management apparatus according to the present embodiment.

FIG. 2 is a diagram showing test data stored in a test data storage unit.

FIG. 3 is a diagram showing a form of a shift at the time of superimposing wafers.

FIG. 4 is a diagram showing security data stored in a security data storage unit.

FIG. 5 is a diagram showing processing result data stored in a processing result data storage unit.

FIG. 6 is an external view of a computer for realizing the exposure step management device shown in FIG.

FIG. 7 is a control block diagram of the computer shown in FIG.

FIG. 8 is a diagram illustrating a flowchart of an accuracy variation detection process executed by the exposure process management apparatus.

FIG. 9 is a view showing a flowchart of a variation factor estimating process executed by the exposure process managing apparatus.

FIG. 10 is a diagram illustrating a display example (1) of the display unit 40.

FIG. 11 is a diagram illustrating a display example (2) of the display unit 40.

FIG. 12 is a diagram showing an example of area division of a wafer.

FIG. 13 is a diagram illustrating a distribution of a shift amount.

[Explanation of symbols]

10 Exposure process management device, 20 control unit, 30 data storage unit, 40 display unit, 50 input unit, 60 communication unit,
70 exposure apparatus, 80 inspection apparatus, 100 server, 1
02 computer, 104 monitor, 106 FD drive, 108 CD-ROM drive, 110 keyboard, 112 mouse, 116 FD, 118 CD-
ROM, 120 CPU, 122 memory, 124 fixed disk, 126 communication interface.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Keiji Takeuchi, 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Yutaka Akami 2-3-2, Marunouchi, Chiyoda-ku, Tokyo Inside Mitsui Electric Co., Ltd. (72) Inventor Taira Nakagawa 12-56, Wakaba-cho, Tadotsu-cho, Nakatado-gun, Kagawa Prefecture Inside Shikoku Keisoku Kogyo Co., Ltd. Rishi Electric Co., Ltd. F term (reference) 5F046 DA13 FC03 FC10

Claims (18)

[Claims] 1. A system for managing an exposure process of a semiconductor wafer, wherein a predetermined pattern is formed on one wafer by using a first exposure device and a second exposure device in the exposure process. A shift occurs between the pattern exposed and exposed by the first exposure apparatus and the pattern exposed by the second exposure apparatus, and the shift amount is predetermined in the exposure step. A storage unit for storing a date and time when the exposure step is processed, and a shift amount in the exposure step; and a system connected to the storage unit, and configured to perform processing during a first period. Based on a set including a plurality of shift amounts for the processed wafers and a set including a plurality of shift amounts for the wafers processed in the second period, the variance of the shift amounts in each of the sets is calculated by the aforementioned 2 Determining means for determining whether or not the two sets are equal to each other; and connected to the determining means, for detecting that the shift amount in the exposure step has changed if the variances of the shift amounts are not equal to each other. An exposure step management system, comprising: a detection unit; and an output unit connected to the detection unit and configured to output a detection result by the detection unit. 2. The method according to claim 1, wherein the determining unit includes a variance value of a set including a plurality of shift amounts with respect to the wafer processed in the first period and a plurality of shift amounts with respect to the wafer processed in the second period. Means for determining whether or not the variance value of the deviation amount in each of the sets is equal to each other in the two sets depending on whether or not the ratio of the set to the variance value is equal to or greater than a predetermined value. The exposure process management system according to claim 1, comprising: 3. A system for managing an exposure process of a semiconductor wafer, wherein a predetermined pattern is formed on one wafer by using a first exposure device and a second exposure device in the exposure process. A shift based on a plurality of factors occurs between the pattern exposed and exposed by the first exposure apparatus and the pattern exposed by the second exposure apparatus. Is controlled so as to fall within a predetermined range, the system includes: a storage unit for storing a shift amount in the exposure step; and a set connected to the storage unit and including a plurality of shift amounts with respect to the wafer. Calculating means for calculating the variance of the shift amount in the first exposure apparatus and the second exposure apparatus, which are measured using a test wafer. Stopping accuracy storing means for storing a plurality of data representing the amount; connected to the stopping accuracy storing means, a standard deviation calculating means for calculating a standard deviation of the data; the calculating means and the standard deviation calculating An exposure step management system, comprising: analysis means connected to the means for analyzing a factor of a shift in the exposure step based on the variance and the standard deviation. 4. The calculation means includes means for calculating a variance value of a shift amount in a set including a plurality of shift amounts, and the analysis means includes a ratio between the variance value and a value based on the standard deviation. 4. The exposure step management system according to claim 3, further comprising: means for analyzing a ratio of a shift caused by the apparatus based on the information. 5. The exposure step management system is connected to the storage unit, and divides the wafer into a plurality of regions based on a shift amount in the exposure step stored in the storage unit, and performs positioning during exposure. 5. The exposure step management system according to claim 1, further comprising an instruction unit for instructing correction. 6. The exposure process management system is connected to the storage device, and the first exposure device and the second exposure device are based on a difference in a shift amount in an exposure process stored in the storage device. 5. The exposure step management system according to claim 1, further comprising an instruction unit for instructing positioning correction at the time of exposure in combination with the above. 7. A method for managing an exposure step of a semiconductor wafer, wherein a predetermined pattern is formed on one wafer by using a first exposure apparatus and a second exposure apparatus in the exposure step. A shift occurs between the pattern exposed and exposed by the first exposure apparatus and the pattern exposed by the second exposure apparatus, and the shift amount is predetermined in the exposure step. The exposure step management method includes: storing a date and time when the exposure step is processed, a storage step of storing a shift amount in the exposure step, and a plurality of wafers processed during the first period. Based on the set including the shift amount and the set including the plurality of shift amounts for the wafers processed in the second period, the dispersion of the shift amounts in each of the sets is equal to each other in the two sets. A determination step of determining whether or not the variance of the shift amounts is not equal to each other; a detection step of detecting that the shift amount in the exposure process has changed; and outputting a result detected in the detection step. An exposure step management method including an output step. 8. The determining step includes a variance value of a set including a plurality of shift amounts for a wafer processed in a first period, and a plurality of shift amounts for a wafer processed in a second period. A step of determining whether or not the ratio of the variance of the set to the variance of the set is equal to or greater than a predetermined value, the variance of the amount of deviation in each of the sets is equal to each other in the two sets An exposure process management method according to claim 7. 9. A method for managing an exposure process of a semiconductor wafer, wherein a predetermined pattern is formed on one wafer by using a first exposure device and a second exposure device in the exposure process. A shift based on a plurality of factors occurs between the pattern exposed and exposed by the first exposure apparatus and the pattern exposed by the second exposure apparatus. The exposure step management method includes: a storage step of storing a shift amount in the exposure step; and calculating a variance of a shift amount in a set including a plurality of shift amounts with respect to the wafer. And calculating a plurality of data indicating the shift amount of the stop of the wafer in the first exposure apparatus and the second exposure apparatus measured using the test wafer. Stopping accuracy storing step, a standard deviation calculating step of calculating a standard deviation of the data stored in the stopping accuracy storing step, based on the variance and the standard deviation, a factor of a shift in the exposure process. And an analyzing step of analyzing. 10. The calculating step includes a step of calculating a variance value of a shift amount in a set including a plurality of shift amounts, and the analyzing step is based on a ratio between the variance value and a value based on the standard deviation. The method according to claim 9, further comprising: analyzing a ratio of a shift caused by the apparatus. 11. An exposure step managing method comprising: an instruction step of dividing the wafer into a plurality of regions based on a shift amount in the exposure step stored in the storage step, and instructing positioning correction at the time of exposure. The exposure step management method according to claim 7, further comprising: 12. The exposure step management method according to claim 1, wherein the first exposure apparatus and the second exposure apparatus are combined based on a difference in a shift amount in the exposure step stored in the storage step. The exposure step management method according to claim 7, further comprising an instruction step of instructing a positioning correction at the time. 13. A program for managing an exposure step of a semiconductor wafer, wherein a first
A predetermined pattern is exposed on one wafer by using the exposure apparatus and the second exposure apparatus, and the pattern exposed by the first exposure apparatus and the pattern exposed by the second exposure apparatus. Gap between the pattern and
In the exposure step, the shift amount is managed so as to fall within a predetermined range, and the program stores, in a computer, a date and time when the exposure step is processed, and a storage procedure for storing the shift amount in the exposure step, Based on a set including a plurality of shift amounts for the wafers processed in the first period and a set including a plurality of shift amounts for the wafers processed in the second period, the shift amount in each of the sets is determined. A determination procedure for determining whether or not the variances are equal to each other in the two sets; a detection procedure for detecting that the shift amount in the exposure step has changed if the shift amounts of the shift amounts are not equal to each other; A program for executing an output procedure for outputting a detection result by the procedure. 14. The determination procedure includes a variance value of a set including a plurality of shift amounts for a wafer processed in a first period, and a plurality of shift amounts for a wafer processed in a second period. A step of determining whether or not the ratio of the variance of the sets to the variance of the sets is equal to or greater than a predetermined value, the variance of the amount of deviation in each of the sets is equal to each other in the two sets, The program according to claim 13. 15. A program for managing an exposure step of a semiconductor wafer, wherein the first step is performed in the exposure step.
A predetermined pattern is exposed on one wafer by using the exposure apparatus and the second exposure apparatus, and the pattern exposed by the first exposure apparatus and the pattern exposed by the second exposure apparatus. And a deviation based on a plurality of factors, which are managed in the exposure step so that the deviation amount falls within a predetermined range. A storage procedure for storing an amount, a calculation procedure for calculating a variance of a shift amount in a set including a plurality of shift amounts with respect to the wafer, and the first exposure apparatus and the second exposure apparatus measured using a test wafer. A stop accuracy storing procedure for storing a plurality of data representing a shift amount of the stop of the wafer in the exposure apparatus; a standard deviation calculating procedure for calculating a standard deviation of the data; Dispersing said based on the standard deviation, to perform the analysis procedure for analyzing the cause of deviation in the exposure step,
program. 16. The calculation step includes a step of calculating a variance value of a shift amount in a set including a plurality of shift amounts, and the analysis step is based on a ratio between the variance value and a value based on the standard deviation. The program according to claim 15, further comprising a step of analyzing a ratio of a shift caused by the device. 17. The program further instructs the computer to divide the wafer into a plurality of areas based on a shift amount in an exposure step stored in the storage procedure and to perform positioning correction during exposure. The program according to any one of claims 13 to 16, which causes an instruction procedure to be executed. 18. The computer program, further comprising: combining the first exposure apparatus with the second exposure apparatus based on a difference in a shift amount in an exposure step stored in the storage procedure. The program according to any one of claims 13 to 16, which causes an instruction procedure for instructing positioning correction at the time of exposure to be executed.