JP2003249433A - Exposure system and exposure controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure system and an exposure control method capable of easily detecting a defective pattern due to defocusing without deteriorating high manufacturing efficiency. <P>SOLUTION: A reticle stage 13, an image projection system 14, an alignment system 15, and a wafer stage 16 are arranged in a thermostatic chamber 10 also having a lighting system 11. A focus value measuring mechanism 19 utilizes an automatic focusing mechanism 18 for measuring a focus value for each shot region, and stores the measurements in a memory 20. An arithmetic unit 21 compares focus values for specified shot regions with each other, out of the measured focus values, and differences between the focuses are compared with a predetermined value for evaluation. Then, shot regions in conformity with the evaluation by the arithmetic unit 21 are exposed one after the other while those not in conformity with the evaluation are left unexposed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor device manufacturing, and more particularly to an exposure apparatus and an exposure control method in a manufacturing line in which a pattern of an integrated circuit on a semiconductor substrate is repeatedly and sequentially exposed.

[0002]

2. Description of the Related Art Circuit patterns required for LSI manufacturing are sequentially exposed on a semiconductor substrate by a plurality of reticle patterns. For example, a reduction projection exposure apparatus (not shown) in which a predetermined reticle is set projects and exposes a repetitive pattern while sequentially shifting the projection target area on the semiconductor substrate. By such a step-and-repeat method, a predetermined number of integrated circuit chip areas are acquired in the semiconductor substrate.

One area of the integrated circuit chip area is overlaid by a plurality of pattern exposures, for example according to alignment marks present in the scribe line area. Such an exposure process is carried out regardless of the presence or absence of irremovable scratches or foreign matter existing on the back surface of the semiconductor substrate. The non-removable scratch existing on the back surface of the substrate is generated, for example, through the transport system. Due to the scratches and the foreign matter, a pattern defect due to the focus shift occurs.

FIG. 8 is a flow chart showing a process of detecting a pattern defect including a focus shift by a conventional exposure apparatus. First, as shown in process S81, a visual inspection is performed after pattern formation by development. As a result, it is determined whether the pattern is defective (process S82). If no pattern defect is detected, it goes directly to the subsequent process,
If a pattern defect is detected, a re-exposure process, that is, a resist peeling process to a rework process of resist re-application is performed (process S83).

After the re-exposure process, if it is judged that the defect is completely eliminated, the cause is clarified, and after the cause is analyzed, it may be sent to a subsequent process (process S8).
4). If the pattern defect reoccurs even after the re-exposure process, or if it is a suspicious judgment even if it is not a pattern defect, it is judged whether or not it is completely defective in the operation of the IC circuit (process S85). If it is determined to be completely defective, the process is directly transferred to the subsequent process (process S8).
7). That is, it is detected as a defect in a later operation test or the like. If it is unknown whether the pattern will be completely defective, the pattern portion is intentionally destroyed, or the resist is brushed to completely render the pattern defective (step S86).
Move to the subsequent process.

[0006]

Even if the appearance inspection is carried out in the above step S82, there is a possibility that it may not be surely detected, and a pattern defect may flow out to a subsequent process. In particular, it is difficult to detect a pattern defect in the contact hole forming process.

Further, regarding the reworked product that has undergone the processing S83, if the cause of the defect is an irremovable scratch or foreign matter on the back surface of the substrate, the defect will reoccur. Therefore, the re-exposure process (S83) itself is wasted. Whether or not the scratches or foreign matter on the back surface of the substrate can be removed cannot be determined after all through the resist peeling process. In addition, the number of foreign substances that can be removed is very small, and most of them are scratches and foreign substances that cannot be removed.

Further, it takes a considerable amount of time to judge whether or not the pattern defect in the process S85 is completely defective. As a result, there is a concern that product flow will be stagnant for a long time and production efficiency will decline. As a matter of course, also in the subsequent step S86, there is a problem in work efficiency such as brush coating of resist,
In the worst case, there is a possibility that the good chip area may be erroneously processed.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide an exposure apparatus and an exposure control method capable of maintaining high production efficiency and easily detecting a pattern defect due to a focus shift. To do.

[0010]

An exposure apparatus according to the present invention sequentially performs an exposure process according to a reticle pattern on a resist on a semiconductor substrate held on an exposure stage via a projection exposure system for each shot area. An exposure apparatus of a step-and-repeat type having a mechanism capable of performing the above-mentioned operation, characterized in that successive shot areas are actually exposed or unexposed in accordance with a focus condition associated with the exposure processing.

According to the above-described exposure apparatus of the present invention, the shot area which is not exposed is always defective in terms of circuit operation. This eliminates the need to determine a pattern defect that is difficult to detect, and also eliminates the need for determining whether or not the pattern is completely defective. It contributes to the improvement of production efficiency.

An exposure apparatus as a more preferred embodiment of the present invention sequentially performs exposure processing according to a reticle pattern on a resist on a semiconductor substrate held on an exposure stage via a projection exposure system for each shot area. A step-and-repeat type exposure apparatus having a mechanism capable of adjusting, an autofocus mechanism for automatically adjusting a focus at a predetermined point of the shot area, and a focus value for each shot area using the autofocus mechanism. And a focus value measuring mechanism that stores each as data, and a calculation unit that compares focus values corresponding to a predetermined shot area among the focus values and determines a focus difference. Sequential shot areas are actually exposed or unexposed according to the judgment result Characterized in that it.

According to the above-described exposure apparatus of the present invention, the arithmetic unit for determining the focus difference is provided. If the focus difference is larger than the allowable range, the backside of the board may be scratched.
It is recognized that there is a high possibility that foreign matter will adhere. If such a shot area is left unexposed, the shot area will be completely defective in terms of circuit operation. This eliminates the need to determine a pattern defect that is difficult to detect, and also eliminates the need for determining whether or not the pattern is completely defective. It contributes to the improvement of production efficiency.

According to the above-described exposure apparatus of the present invention, the shot area in the unexposed state is always defective in circuit operation. This eliminates the need to determine a pattern defect that is difficult to detect, and also eliminates the need for determining whether or not the pattern is completely defective. It contributes to the improvement of production efficiency.

In the exposure apparatus according to the present invention, the arithmetic unit is prepared with a preset value in advance and determines whether the focus difference is larger or smaller than the preset value. The setting value for the determination is arbitrary, and the determination according to the process, device, etc. is possible.

Further, the above-mentioned exposure apparatus according to the present invention is characterized by further comprising a storage section for storing position information of a shot area which is unexposed according to the determination result of the arithmetic section. Since the past unexposed position information before the current processing of the semiconductor substrate can be stored, it contributes to the investigation of the cause of the focus shift with respect to the specific portion of the substrate.

Further, in the above-described exposure apparatus according to the present invention, a storage unit that stores position information of a shot area that is unexposed according to the determination result of the arithmetic unit, and an unexposed shot for each processed semiconductor substrate. And a display mechanism for displaying position information of the area. By displaying the position information, the operator can easily recognize the position information that causes the focus shift.

Each of the above-described exposure apparatuses according to the present invention is characterized by having an alarm or a mechanism for stopping the subsequent exposure processing at the same time as the alarm depending on the determination result of the arithmetic unit. It is one of the recognition means for the operator. Further, there is a possibility that the cause is not on the back surface of the substrate but on the device side (exposure stage side) depending on the position information that causes defocus, and in that case it is better to stop the subsequent exposure processing.

Further, each of the above-described exposure apparatuses according to the present invention is characterized by further comprising an exposure optical system for transferring an identification mark to an unexposed shot area in accordance with the determination result of the arithmetic unit. To do. By arranging the identification mark, it can be easily confirmed in all subsequent steps. In addition, the exposure optical system is configured to form the identification mark in a size that can be visually recognized.

In the exposure control method according to the present invention, the exposure process according to the reticle pattern is sequentially performed on each of the shot areas by autofocus on the resist on the semiconductor substrate held on the exposure stage via the projection exposure system. Regarding the exposure of the step-and-repeat method that can be performed, the focus value by the auto focus is measured for each shot area, and the focus value measurement step of storing each as data, and the focus value for the latest shot area by the focus value measurement step is the same as before. Comparing with the focus value of one or more adjacent shot areas, it is determined whether the focus difference is larger or smaller than a preset setting value, and As a result, if the focus difference is smaller than the set value, the latest shot area is Light treatment is achieved, the latest shot area if focus difference is greater than the set value, characterized in that the transition to remain unexposed next shot area.

According to the exposure control method of the present invention,
The degree of defocus can be detected by the calculation process. If the focus difference is larger than the set value, the latest shot area remains unexposed and moves to the next shot area. If the focus difference is large and it is judged to be abnormal, scratches on the back surface of the substrate,
There is a high possibility that foreign matter will adhere. If this shot region is left unexposed, it is possible to ensure that the circuit operation is completely defective. This eliminates the need to determine a pattern defect that is difficult to detect, and also eliminates the need for determining whether or not the pattern is completely defective. It contributes to the improvement of production efficiency.

In the exposure control method according to the present invention, the position information of the shot area which is not exposed according to the judgment result of the calculation step is stored and used for the next exposure processing or comprehensive evaluation of the semiconductor substrate. It is characterized by using.
Since the past unexposed position information before the current processing of the semiconductor substrate can be stored, it contributes to the investigation of the cause of the focus shift with respect to the specific portion of the substrate.

In the exposure control method according to the present invention, the position information of the unexposed shot area is stored according to the determination result of the calculation step and the unexposed shot area of each processed semiconductor substrate is stored. The feature is that it is displayed so that the position information can be confirmed. By displaying the position information, the operator can easily recognize the position information that causes the focus shift.

In each of the above-described exposure control methods according to the present invention, the position information of the shot area that is unexposed according to the result of the determination in the operation step is stored, and the result of the operation step determination or the past position information is stored. Depending on the above, the following exposure processing is stopped at the same time as the alarm. The alarm is useful as one of the recognition means for the operator. Further, there is a possibility that the cause is not on the back surface of the substrate but on the device side (exposure stage side) depending on the position information that causes defocus, and in that case it is better to stop the subsequent exposure processing.

Further, in each of the above-described exposure control methods according to the present invention, a visually recognizable identification mark is transferred to the unexposed shot area in accordance with the result of the determination in the calculation step. . By arranging the identification mark, confirmation is easy in all subsequent steps.

In a more preferable embodiment of the exposure control method according to the present invention, an exposure process corresponding to a reticle pattern is auto-focused for each shot on a resist on a semiconductor substrate held on an exposure stage via a projection exposure system. Regarding step-and-repeat exposure that can be sequentially performed for each area, a focus value measurement step of measuring the focus value by the autofocus for each shot area and storing each as data, and the latest shot by the focus value measurement step A calculation step in which the focus value for the area is compared with the focus values of one or more previous adjacent shot areas, and it is determined whether the focus difference is larger or smaller than a preset setting value; And a special exposure processing step that operates according to the determination result, If the focus difference is smaller than the set value as a result of the determination in the calculation step, the exposure processing is achieved in the latest shot area, and if the focus difference is larger than the set value, the latest shot area is identified by the special exposure processing step. Is transferred to the next shot area.

According to the exposure control method of the present invention,
If the identification mark is transferred when the focus shift exceeds the permissible range, it is easy to confirm in all subsequent steps, which contributes to further improvement in production efficiency.

In the exposure control method according to the present invention, the position information of the shot area to which the identification mark is transferred is stored according to the judgment result of the calculation step, and the judgment result of the calculation step or the past position is stored. It is characterized in that an alarm or the subsequent exposure processing is stopped at the same time as the alarm depending on the information. The alarm is useful as one of the recognition means for the operator. Further, there is a possibility that the cause is not on the back surface of the substrate but on the device side (exposure stage side) depending on the position information that causes defocus, and in that case it is better to stop the subsequent exposure processing.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing a main configuration of an exposure apparatus according to a first embodiment of the present invention. The figure shows a step-and-repeat type exposure apparatus, a so-called stepper. An illumination system 11 is provided side by side in the constant temperature chamber 10, and a reticle stage 13 for holding and positioning the reticle 12, a projection optical system 14, and an alignment system 1 are provided.
5. A wafer stage 16 that holds the semiconductor substrate Waf is provided. With such a configuration, the semiconductor substrate W
An exposure process according to the reticle pattern can be sequentially performed for each shot area on the resist applied on af. The display unit 17 is installed in a place where an operator can operate, and can perform various input / output operations such as recipes and monitors.

The autofocus mechanism 18 automatically adjusts the focus at a predetermined point in the shot area. The focus value measurement mechanism 19 uses this autofocus mechanism 18 to measure the focus value for each shot area,
Each is stored as data in the memory unit (20). Also,
The calculation unit 21 compares the focus values corresponding to a predetermined shot area among the focus values, and determines the focus difference.

For example, the focus value Z for the shot area A at the current processing stage is compared with the focus value Zn for the shot area An adjacent to the shot area A (n is one or more; n = 1, 2, ...), Derive the focus difference. It is necessary to consider the first shot area with respect to the substrate or the shot area with very little data in the adjacent shot area. In that case, the focus value Zn of the shot area An corresponding to the adjacency relationship of the previously processed substrate (may be the master substrate) may be read and compared.

A set value is prepared in advance in the calculation unit 21, and this set value is compared with the focus difference. That is, the above-described determination is made by the calculation unit 21 for the sequential shot areas, and the exposure process or the unexposed state is actually performed according to the determination result.

According to the exposure apparatus of the above embodiment, the arithmetic unit 21 for determining the focus difference is provided. It is recognized that an abnormality such as a focus difference exceeding an allowable range (set value) is likely to be a scratch or foreign matter attached to the back surface of the substrate. If such a shot area is left unexposed, the circuit operation will always be completely defective. This allows
It is not necessary to determine a pattern defect that is difficult to detect, and it is possible to send the pattern to a subsequent process without any need for determining whether or not the pattern is completely defective. Therefore, the re-exposure process which has been a problem in the past is almost eliminated, which contributes to the improvement of production efficiency.

FIG. 2 is a flow chart showing an exposure control method for the exposure apparatus shown in the first embodiment. Description will be made with reference to FIG. First, the semiconductor substrate Waf is moved by the exposure stage, and the latest shot area A to be subjected to the exposure processing enters the processing environment (processing S1). next,
The focus value measuring mechanism 19 is the autofocus mechanism 18
The focus value Z relating to the shot area A is measured by using (step S2). The focus value Z is stored in the memory section (2
0) and is sent to the calculation unit 20. Further, the focus value Zn (n = 1,2, ...) Of the data before the shot area A from the memory section (20), here, the shot area An (n = 1,2, ...) Adjacent to the shot area A is used.
...) is read and sent to the calculation unit 21 (process S3).

The computing unit 21 compares the focus value Z and the focus value Zn, respectively, and compares the focus value Z with the focus difference (| Z-Zn
|) Is derived. Then, it is determined whether or not the focus value Z is appropriate by comparing with a preset setting value (step S4). If the focus difference is smaller than the set value as a result of the determination by the calculation unit 21, normal exposure processing is achieved in the latest shot area A (step S5). If the focus difference is larger than the set value, the latest shot area A is obtained. The area A is left unexposed (process S6), and the process moves to the next shot area.

According to the above exposure control method, the degree of defocus is inspected in the calculation step of step S4. That is, it is possible to accurately detect a focus shift due to a scratch on the back surface of the substrate, adhesion of foreign matter, or the like. Further, the setting value for the determination is arbitrary, and the determination can be made according to the process, the device, etc.

As described above, when it is determined that there is a defect such as a scratch or a foreign substance depending on the degree of defocus, the shot area is in an unexposed state. Since no pattern is formed, the circuit operation is completely defective. Therefore,
It is not necessary to determine a pattern defect that is difficult to detect, and it is not necessary to determine whether the pattern is completely defective. In other words, the production efficiency is improved and the reliability of the subsequent process is significantly improved.

Next, with respect to the above-mentioned embodiment, the configuration of a more preferable second embodiment will be described. In the exposure apparatus of FIG. 1, position information of an unexposed shot area may be further stored according to the determination result of the calculation unit 21. In this case, a predetermined storage area is provided in the memory unit (20) to store the position information. Such position information of the unexposed shot area can also be displayed on the display unit 17. In addition to the effects obtained in the first embodiment, there is an advantage that a processing history can be recorded. This contributes to investigating the cause such as when the focus shift occurs in a specific portion of the substrate.

FIG. 3 is a flow chart showing an exposure control method for the exposure apparatus shown in the second embodiment. Compared to FIG. 2, the process S6, that is, the process S7 of storing the position information of the unexposed shot area after issuing the unexposed command is added. Although not shown, of course, the position information of the unexposed shot area can be displayed on the display unit 17 if there is a display command. The other processing flow is the same as that in FIG. 2, and therefore the same reference numerals are given and the description thereof is omitted.

According to the exposure control method of the present invention,
In addition to the effect similar to that of the first embodiment, it can be used for the next exposure processing or comprehensive evaluation of the semiconductor substrate.
That is, the past unexposed position information prior to the current processing of the semiconductor substrate can also be stored, which contributes to the investigation of the cause such as defocusing with respect to a specific portion of the substrate.

For example, the case where a plurality of semiconductor substrates to be processed always have a specific unexposed position can be detected. In that case, there is a possibility that the cause is not on the back surface of the substrate but on the device side (exposure stage side). In addition, there may be a case where the specific part in the transport system is abnormal, and early detection can be expected. In any case, it is effective for accurate maintenance and reliability recovery in a shorter time.

FIG. 4 is a schematic view showing a main configuration of an exposure apparatus according to the third embodiment of the present invention. The difference from the configuration of the first or second embodiment (shown in FIG. 1) is that
This is the point where the alarm and process interruption mechanism 31 is provided. Depending on the determination result of the calculation unit 21, an alarm or the subsequent exposure process is stopped at the same time as the alarm. Since other configurations are the same as those in FIG. 1, the same reference numerals are given and description thereof is omitted.

The exposure apparatus according to the above-described embodiment is useful as one of means for making the operator recognize more clearly, in addition to the effect similar to that of the second embodiment. As described above, when the plurality of semiconductor substrates to be processed always have a specific unexposed position, the alarm improves the recognition level. Further, depending on the position information of the focus shift as described above, there is a possibility that the cause is not on the back surface of the substrate but on the apparatus side (exposure stage side), and in that case, means for stopping the subsequent exposure processing is taken. The alarm can also be used to detect an abnormally large focus shift and other troubles.

FIG. 5 is a flow chart showing an exposure control method for the exposure apparatus shown in the third embodiment. Compared to FIG. 3, after the focus abnormality is detected in the calculation step of the process S4, it is determined whether or not the positions of the corresponding shot areas similarly exist in the plurality of processed substrates, the process of S8, the alarm, and the following. The process S9 of stopping the exposure process of is added.
Since the other processing flow is the same as that in FIG. 3, the same reference numerals are given and description thereof is omitted.

That is, if it is detected in step S8 that the shot area to be unexposed is always the same position on a plurality of substrates, step S9 is carried out, and the operator confirms and the exposure process is automatically performed to investigate the cause. Will be discontinued.
The detection in step S8 also depends on the setting of the number of substrates. If the result in step S8 is negative, the process proceeds to step S6 and the device processing is continued.
For example, it is conceivable that a warning is issued if the unexposed shot areas match on two consecutive substrates, but the apparatus processing continues, and the exposure processing is stopped if the unexposed shot areas match on the next substrate.

According to the exposure control method of the above embodiment, in addition to the same effect as the second embodiment, it contributes to clear recognition to the operator, early detection of abnormalities, and prevention of yield reduction. Further, there is a possibility that the correlation of the maintenance points can be grasped by the position information of the focus shift, and a more reliable monitoring function for each exposure apparatus and its processing can be obtained.

FIG. 6 is a schematic view showing a main configuration of an exposure apparatus according to the fourth embodiment of the present invention. The difference from the configuration of the first or second embodiment (shown in FIG. 1) is that
This is the point where the identification mark transfer mechanism 41 is provided. Depending on the determination result of the calculation unit 21, for the unexposed shot area,
The identification mark 42 is transferred. The identification mark 42 preferably has a size that can be visually confirmed (visible).

The identification mark transfer mechanism 41 transfers the identification mark to a predetermined shot area not through the projection optical system 14 but through a dedicated exposure optical system by controlling the movement of the wafer stage 16, for example. Alternatively, various mechanisms are conceivable, such as installing a dedicated identification mark mask in place of a normal reticle by controlling the movement of the reticle stage 13 and transferring the identification mark to a predetermined shot area via the projection optical system 14. Since other configurations are the same as those in FIG. 1, the same reference numerals are given and description thereof is omitted.

In the exposure apparatus of FIG. 6, the position information of the shot area to which the identification mark is transferred may be stored according to the determination result of the arithmetic unit 21, as in the second embodiment. In this case, a predetermined storage area is provided in the memory unit (20) to store the position information. Such position information of the identification mark shot area is displayed on the display unit 17
It can also be displayed in. Since the processing history can be left, it contributes to the investigation of the cause such as the case where the defocus occurs in the specific portion of the substrate.

According to the exposure apparatus of the above embodiment, the same effect as that of the second embodiment can be obtained. That is, the calculation unit 21 detects an abnormality in the focus difference, and the identification mark is transferred to the shot area where there is a high possibility of scratches, foreign matter adhesion, etc. on the back surface of the substrate. If the identification mark is in a patterned state, the circuit operation is always completely defective. As a result, it becomes unnecessary to determine a pattern defect that is difficult to detect, and it is possible to send the process to a subsequent process without requiring any work for determining whether the pattern is completely defective. Moreover, since the area of the abnormal shot can be visually recognized by the identification mark even when the process goes to the subsequent step, the marking operation can be facilitated or omitted.
Of course, the re-exposure process which has been a problem in the past is almost eliminated, which contributes to the improvement of production efficiency.

FIG. 7 is a flow chart showing an exposure control method for the exposure apparatus shown in the fourth embodiment. It corresponds to FIG. 3, and in comparison with FIG. 3, an identification mark transfer process of process S11 is provided instead of the process S6, and a position storage process of the identification mark shot area of process S12 is provided instead of the process 7. Although not shown, of course, the position information of the identification mark shot area can be displayed on the display unit 17 if there is a display command. The other processing flow is the same as that in FIG. 2, and therefore, the same reference numerals are given and the description thereof is omitted.

According to the exposure control method of the present invention,
It is similar to the effect of the above-described fourth embodiment, and can be used for the next exposure processing of the semiconductor substrate or comprehensive evaluation. That is, the position information of the past identification mark shot area before the current processing of the semiconductor substrate can also be stored. This contributes to the investigation of the cause of defocus in a specific portion of the substrate. Further, since it can be easily confirmed by a person who handles it in a later process, it can be expected that the cause investigation work will be advanced.

In addition, although not shown in the fourth embodiment, of course, the exposure apparatus shown in the third embodiment (see FIG. 4).
The warning and processing interruption mechanism 31) and the exposure control method (FIG. 5). That is, the identification mark transfer process is performed while leaving the abnormal focus shot area unexposed. Furthermore, it is determined whether or not the positions of the corresponding shot areas similarly exist in the plurality of processed substrates (see processing S8 in FIG. 5). According to this determination, the alarm and the subsequent exposure processing are stopped (see processing S9 in FIG. 5). This contributes to the clear recognition to the operator and the person handling in the subsequent process, early detection of abnormalities, and prevention of yield reduction. As described above, when the plurality of semiconductor substrates to be processed always have the identification mark shot area at a specific position, the degree of recognition is improved by the alarm.

According to each of the above embodiments and the exposure control method, it is noted that scratches and foreign matters on the back surface of the substrate are almost unremovable, and the shot area is not exposed to an unacceptable defocus. , Patterning the identification mark. This makes it possible to completely detect a shot area that is likely to cause a pattern defect, and eliminate a shot area that is ambiguous as to whether or not the pattern will be defective. Also,
Maintenance for improving the yield can be performed more accurately from the shot area position of the unexposed or identification mark. As a result, the exposure process can be continued unless there is a concern that the yield will decrease due to the outflow of a large number of defects.

[0055]

As described above, according to the present invention,
The shot area to which the focus condition conforms is subjected to normal exposure processing, and the shot area to which the focus condition does not conform is left unexposed, or the identification mark is transferred. As a result, the shot area to which the focus condition does not meet always becomes completely defective in circuit operation. Confirming and grasping the shot area position of the unexposed or identification mark contributes to yield improvement measures (early identification of inspection and maintenance points) and early recovery of reliability. As a result, the exposure process can be continued unless there is a concern that the yield will decrease due to the outflow of a large number of defective products. As a result, it is possible to provide an exposure apparatus and an exposure control method capable of maintaining high production efficiency and easily detecting a pattern defect due to a focus shift.

[Brief description of drawings]

FIG. 1 is a schematic view showing a main configuration of an exposure apparatus according to a first embodiment or a second embodiment of the present invention.

FIG. 2 is a flowchart showing an exposure control method for the exposure apparatus shown in the first embodiment.

FIG. 3 is a flowchart showing an exposure control method for the exposure apparatus shown in the second embodiment.

FIG. 4 is a schematic view showing a main configuration of an exposure apparatus according to a third embodiment of the present invention.

FIG. 5 is a flowchart showing an exposure control method for the exposure apparatus shown in the third embodiment.

FIG. 6 is a schematic view showing a main configuration of an exposure apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a flowchart showing an exposure control method for the exposure apparatus shown in the fourth embodiment.

FIG. 8 is a flowchart showing a process of detecting a pattern defect including a focus shift by a conventional exposure apparatus.

[Explanation of symbols]

10 ... Constant temperature chamber 11 ... Illumination system 12 ... Reticle 13 ... Reticle stage 14 ... Projection optical system 15 ... Alignment system 16 ... Wafer stage 17 ... Display unit 18 ... Auto focus mechanism 19 ... Focus value measurement mechanism 20 ... Memory unit (CPU / Memory 21 ... Computation unit 31 ... Warning and processing interruption mechanism 41 ... Identification mark transfer mechanism 42 ... Identification marks S1 to S9, S11, S12, S81 to S87 ... Processing step Waf ... Substrate

Claims (15)

[Claims] 1. A step-and-repeat system having a mechanism capable of sequentially performing an exposure process corresponding to a reticle pattern on a resist on a semiconductor substrate held on an exposure stage via a projection exposure system for each shot area. An exposure apparatus, wherein sequential shot areas are actually exposed or not exposed depending on a focus condition associated with the exposure processing. 2. A step-and-repeat system having a mechanism capable of sequentially performing an exposure process according to a reticle pattern on a resist on a semiconductor substrate held on an exposure stage through a projection exposure system for each shot area. An exposure apparatus, in which an autofocus mechanism that automatically adjusts a focus at a predetermined point in the shot area, and a focus value measurement that measures a focus value for each shot area using the autofocus mechanism and stores each as data A mechanism and a calculation unit that compares focus values corresponding to a predetermined shot area among the focus values to determine a focus difference, and includes a sequential shot area according to the determination result of the calculation unit. An exposure apparatus that is actually exposed or unexposed. 3. The exposure apparatus according to claim 2, wherein the arithmetic unit prepares a preset value in advance and determines whether the focus difference is larger or smaller than the preset value. 4. The exposure apparatus according to claim 2, further comprising a storage unit that stores position information of a shot area that is unexposed according to the determination result of the arithmetic unit. 5. A storage unit that stores position information of a shot region that is unexposed according to the determination result of the arithmetic unit, and a display mechanism that displays position information of an unexposed shot region for each processed semiconductor substrate. The exposure apparatus according to claim 2 or 3, further comprising: 6. The exposure apparatus according to claim 2, further comprising an alarm or a mechanism for stopping the subsequent exposure processing at the same time as the alarm according to the determination result of the arithmetic unit. 7. The exposure optical system according to claim 2, further comprising an exposure optical system that transfers an identification mark to an unexposed shot area according to a determination result of the arithmetic unit. Exposure equipment. 8. The exposure apparatus according to claim 7, wherein the exposure optical system is configured to form the identification mark in a visible size. 9. A step-and-repeat type exposure capable of sequentially performing an exposure process according to a reticle pattern on a resist on a semiconductor substrate held on an exposure stage through a projection exposure system by autofocus for each shot area. With respect to the focus value measurement step of measuring the focus value by the autofocus for each shot area, and storing each as data, the focus value for the latest shot area by the focus value measurement step is one or more of the previous adjacent focus values. And a calculation step of comparing the focus value of the shot area and determining whether the focus difference is larger or smaller than a preset setting value, the result of the judgment of the calculation step is that the focus difference is the set value. If it is smaller, the latest shot area has been subjected to the exposure process, An exposure control method, wherein if the dreg difference is larger than a set value, the latest shot area is moved to the next shot area without being exposed. 10. The position information of an unexposed shot area is stored according to the determination result of the calculation step, and is used for the next exposure processing of the semiconductor substrate or the comprehensive evaluation. The exposure control method described. 11. Position information of a shot region that is not exposed according to the result of the determination in the calculation step is displayed and displayed so that the position information of the unexposed shot region of each processed semiconductor substrate can be confirmed. The exposure control method according to claim 9, wherein 12. The position information of a shot area which is not exposed in accordance with the result of the determination of the calculation step is stored, and the subsequent exposure is performed at the same time as an alarm or an alarm depending on the result of the calculation step or past position information. 10. The exposure control method according to claim 9, wherein the processing is stopped. 13. An exposure mark according to claim 9, wherein a visually recognizable identification mark is transferred to an unexposed shot area according to a result of the calculation step. Control method. 14. A step-and-repeat type exposure capable of sequentially performing an exposure process according to a reticle pattern on a resist on a semiconductor substrate held on an exposure stage through a projection exposure system by autofocus for each shot area. With respect to the focus value measurement step of measuring the focus value by the autofocus for each shot area, and storing each as data, the focus value for the latest shot area by the focus value measurement step is one or more of the previous adjacent focus values. A calculation step that is compared with the focus value of the shot area, and that the focus difference is larger or smaller than a preset value, and a special exposure processing step that operates according to the determination result of the calculation step, As a result of the judgment in the calculation step, the focus difference is smaller than the set value. If the focus difference is larger than a set value, the latest shot area is subjected to the exposure processing, and if the focus difference is larger than a set value, the identification mark is transferred to the next shot area by the special exposure processing step. And an exposure control method. 15. The position information of the shot area to which the identification mark is transferred is stored according to the determination result of the calculation step, and an alarm or an alarm is issued simultaneously with the alarm according to the determination result of the calculation step or past position information. 15. The exposure control method according to claim 14, wherein the exposure process of step 1 is stopped.