JP2002057087A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner which can suppress a possibility of adhesion of foreign matters onto a mask after being inspected with respect to foreign matter and, even when lots of identical data continue, can suppress the possibility of foreign matters onto the mask. SOLUTION: The apparatus includes a mask table for carrying a mask 10 thereon at the time of exposure, a mask changer 12 for exchange of a plurality of masks, a projection optical system 13, a mask transfer section 14 for loading or unloading the mask 10 onto or from the mask table 11, a mask foreign-matter inspecting device 15 for detecting foreign matters on the mask 10, a mask library 16 for keeping masks accommodated in a mask case 17, a library arm 18, a mask cache 19 for leaving a plurality of masks to be used waiting, an illumination system 20 for exposure, a stage 21 for carrying a photosensitive substrate thereon 22, and the photosensitive substrate 22. A controller 30 detects a processing time of the projection optical system 13 when a first mask is used and controls the inspection device 15 to make the processing of a second mask by the device 15 wait on the basis of the detected processing time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for exposing a reticle or mask pattern to a substrate.

[0002]

2. Description of the Related Art In a photolithography process which is a part of a semiconductor manufacturing process or a liquid crystal display device manufacturing process, a reticle or a mask (hereinafter, referred to as a mask) is used for each process.
The circuit pattern is printed on the wafer, and the process proceeds to the next process. Usually, patterns used in the photolithography process are different from each other. Therefore, various masks are required in accordance with each process, and a desired mask is generally taken out when necessary and used in a photolithography process. For this reason, various masks are housed in an apparatus called a reticle library, taken out and used as needed.

In the photolithography process, exposure processing of various circuit patterns is performed in lot units. In the exposure processing of the circuit pattern, a pattern on the mask is transferred using a mask. Exposure of different types of circuit patterns requires a mask suitable for each lot. Therefore, at the beginning of the lot, it is necessary to prepare the mask so that it can be used. As one of the preparations, there is a foreign substance inspection for inspecting whether a foreign substance is attached to the mask. If foreign matter is contained in the mask, the entire lot will be defective depending on the transfer of the foreign matter to the substrate. Therefore, foreign matter inspection is one of important processes.

However, since this foreign substance inspection requires a long time for measurement, usually, during a certain exposure process, the foreign substance inspection of the mask of the next lot is performed. In other words, during the exposure processing of a certain lot, at the stage where the type of the next lot is recognized by the exposure apparatus, when the foreign matter inspection of the mask is possible, the mask foreign matter inspection of the next lot is performed in parallel with the exposure. Put the mask on standby. In this way, the inspection of foreign matter on the mask is performed in the background of the exposure processing of the previous lot, so that no time is lost when the lot is switched. Also, the same data as the previous lot may come to the next lot. In this case, since the same mask is used in the next lot, the foreign substance inspection is unnecessary. Therefore, when the same data continues, a method of omitting the foreign substance inspection is adopted.

[0005]

However, in such a conventional foreign matter inspection method, after the mask foreign matter inspection is performed, the apparatus is kept at the standby position for a long time. Normally, there is a low possibility that foreign matter will adhere to the inside of the case, but once the case comes out, there is access to the outside, so the possibility of foreign matter being attached increases. For this reason, there is a high possibility that the foreign matter adheres to the mask that has been out of the case and has been waiting at the standby position for a long time for the waiting time. Therefore, a method of re-inspecting the mask for foreign matter immediately before exposure is also known. However, this method significantly increases the lot switching time and also increases the useless device driving time. Further, in the conventional processing method, when many lots of the same data are connected, it is impossible to perform the foreign substance inspection of the mask for a long time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to suppress the possibility of foreign matter sticking to a mask after the mask foreign matter inspection, and to prevent foreign matter sticking to a mask even when lots of the same data continue. It is an object of the present invention to provide an exposure apparatus capable of suppressing the possibility of the exposure.

[0007]

According to the present invention, in an exposure apparatus for exposing a pattern on a substrate by sequentially exchanging a mask (10), an exposure unit (for example, a projection optical system) for exposing the pattern on the substrate is provided. (13), an exposure preparation unit (foreign matter inspection device) (15) for preparing for the exposure prior to the exposure of the exposure unit (13), and an exposure unit (13) using a first mask. ), A processing time detecting device (30) for detecting the processing time, and the exposure preparation unit (1).
The above object is achieved by providing a standby device (30) that causes the processing of the second mask according to 5) to wait based on the processing time detected by the processing time detection device (30).

A control device (30) for interrupting exposure using the first mask when the processing time detected by the processing time detecting device (30) exceeds a predetermined time.
May be provided. The control device (3)
0) The first mask may be processed by the exposure preparation unit (15) when the exposure is interrupted.

The exposure preparation unit (15) may include a foreign matter detection device (15) for detecting foreign matter attached to the mask (10).
5) may have a storage device (mask cache) (19) for temporarily storing the mask after the foreign substance detection by the foreign substance inspection device (15) is completed. Further, the processing time detecting device (30) may detect the processing time based on the number of substrates processed using the first mask.

According to the present invention, there is provided an exposure apparatus for exposing a pattern on a substrate by sequentially replacing a mask (10).
An exposure unit (13) for exposing the pattern to the substrate;
An exposure preparation unit (foreign matter inspection device) (15) for preparing for the exposure prior to the exposure of the exposure unit (13);
A processing time detecting device (30) for detecting a processing time by the exposure unit (13) when the mask group is used; and a processing time detecting device for processing the second mask group by the exposure preparing unit (15). The above object is achieved by providing a standby device (30) for performing standby based on the processing time detected by (30). The exposure section (13) may include a mask holding device (16) for holding a plurality of the masks (10).

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an exposure apparatus according to an embodiment of the present invention. The exposure apparatus shown in FIG. 1 is applied to, for example, an exposure apparatus for exchanging a mask on which a pattern of a liquid crystal display element is formed and exposing the pattern on a substrate which is a square glass plate. For example, a step-and-repeat type projection type exposure apparatus (stepper) for sequentially transferring a mask pattern to a plurality of shot areas on a photosensitive substrate (exposure substrate) via a projection optical system, or a step-and-scan type Of the projection type scanning exposure apparatus (scanning stepper).

In FIG. 1, reference numeral 10 denotes a mask, 11 denotes a mask table on which a mask is mounted at the time of exposure, 12 denotes a mask changer capable of exchanging masks at a high speed when a plurality of masks are used, and 13 denotes a pattern on a substrate. A projection optical system that constitutes an exposure unit for exposing a mask, 14 is a mask transport unit that loads or unloads a mask on or from a mask table 11, 15 is a mask foreign matter inspection device that detects foreign matter on a mask, and 16 is a mask case 17 A mask library (mask holding device) for storing the masks obtained, 18 a library arm for loading or unloading the masks from the library, 19 a mask cache capable of holding a plurality of masks to be used, An exposure illumination system 20 irradiates the mask with exposure illumination light emitted from an exposure light source. Stage for placing a photosensitive substrate, 2
2 is a photosensitive substrate.

The mask table 11 holds the mask 10 and moves two-dimensionally in a plane perpendicular to the optical axis of the projection optical system 13. The illumination light for exposure that has passed through the mask 10 is incident on the projection optical system 13, and the projection optical system 13 reduces the image of the mask pattern to １ ／ or ４ and projects it on the photosensitive substrate 22. The projection optical system 13 is not limited to a reduction system, but may be an equal magnification system or an enlargement system. Photosensitive substrate 22
Is mounted on a stage 21, and the stage 21 is two-dimensionally moved by a driving device (not shown) in a plane perpendicular to the optical axis of the projection optical system 13. In addition, the mask foreign matter inspection device 15 performs an inspection on the mask 10 used at the time of exposure for foreign matter such as dust. And
The mask 10 having a good inspection result is the mask case 1
7 or the mask cache 19, and further loaded and stored in the mask library 16 or the mask cache 19 for each of a plurality of slots.

The above-described mask foreign matter inspection device 15, mask library 16, mask case 17, library arm 18
The mask cache 19 and the mask cache 19 as a whole constitute an exposure preparation unit that prepares for exposure prior to exposure of the projection optical system 13 that is an exposure unit.
A foreign object detection device that detects foreign objects attached to the mask is configured. Further, the mask cache 19 constitutes a storage device for temporarily storing a mask on which foreign matter detection by the mask foreign matter inspection device 15 has been completed.

The mask in the mask case 17 stored in the mask library 16 is stored parallel to the XY plane in FIG. For this reason, a library arm 18 for taking out a desired mask 10 from the mask case 17 and returning it to the mask case 17 is provided so as to be movable in the Y and Z directions. Further, in the present embodiment, a guide (not shown) for moving the library arm 18 in the Z direction is configured to be movable in the X direction, so that each case in the mask library 16 and the mask foreign matter inspection device 15 can be moved. The transfer of the mask 10 is enabled. The library arm 18 enters the case mounted on the mask library 16 and
Only the mask 10 designated in advance is taken out in the Y direction, and is moved to the uppermost position in the Z direction as it is.
The mask 10 is transported to the transfer position. The library arm 18 is provided with a vacuum suction hole, and holds and releases the mask 10 by turning on and off a vacuum pump (not shown).

The mask transport section 14 is movable in the X and Z directions, and transports the mask 10 from a delivery position to a mask cache 19 (storage device). Mask transport unit 14
The load arm 14a and the unload arm 14b are movable in the Y and Z directions. The load arm 14a and the unload arm 14b are individually movable in the Y direction between the mask library 16 and the mask table 11, and are integrally moved in the Z direction. The load arm 14a and the unload arm 14b are provided with vacuum suction holes for holding the mask 10 similarly to the library arm 18, so that the vacuum is turned on and off.
Thereby, the mask 10 can be held and released by suction.

The control device 30 controls the entire exposure apparatus, receives the inspection result of the mask foreign matter inspection device 15 and the alignment output of the alignment system, and adjusts the imaging characteristics inside the projection optical system 13. It outputs a control signal for controlling the mechanism. The control device 30 is configured by a microcomputer or the like, has a storage device 31,
As will be described later, a processing time detecting device for detecting a processing time by the projection optical system 13 (exposure unit) when the first mask is used, and a processing time detection for processing the second mask by the mask foreign matter inspection device 15. Control is performed to function as a standby device that causes a standby based on the processing time detected by the device. In particular, the control device 30 controls the exposure using the first mask to be interrupted when the detected processing time exceeds the predetermined time. When the exposure is interrupted, the control device 30 controls the first mask. It is processed by the mask foreign matter inspection device 15. In the detection of the processing time, the processing time is detected based on the number of substrates processed using the first mask.

The storage device 31 includes a ROM, a RAM, and an electrically rewritable nonvolatile memory, such as an EEPROM (el
ectrically erasable programmable ROM) and stores a program of the control device 30, control data for static exposure in the case of scanning exposure or stepper type, and data for calculating "expected exposure processing end time" and "expected mask preparation time". I do.

Hereinafter, the operation of the exposure apparatus configured as described above will be described. The mask to be used is stored in the mask library 16 in a dedicated case. First, when the use of the mask is required, the mask contained in the mask case 17 is taken out by the library arm 18. Thereafter, the mask foreign matter inspection device 15 checks whether foreign matter is attached to the mask. Here, if foreign matter has adhered, the judgment is left to the operator or an alternative mask is automatically used. If the mask can be used for exposure, the mask is transferred to the transfer arms 14a and 14b, and a barcode checker (not shown) checks whether the mask to be used is correct, and then places the mask on the mask table 11. When a plurality of masks are used, this process is performed for the number of masks. At this time, the mask placed on the mask table 11 is placed on the mask changer 12 until it is used for exposure. Of the series of processes, the one that takes the longest time is the inspection of foreign substances on the mask.
Therefore, the foreign substance inspection is performed at the timing as shown in FIG. 3. For convenience of explanation, first, the conventional foreign substance inspection of the mask will be described.

FIG. 2 is a diagram showing a conventional mask preparation processing timing. The upper part of the broken line in FIG. 2 shows the processing timing of the upstream apparatus, and the lower part of the broken line of FIG. 2 shows the processing timing of the exposure apparatus. The horizontal axis represents the elapsed time and indicates the order in which the exposure processing is performed. As shown in FIG.
As described above, the first lot (Lot-1) is subjected to a foreign substance inspection, a bar code check, and the like for the mask in the mask library 16 and loaded on the mask table 11, and then the exposure processing is started. Normally, a processing instruction for the next lot is sent from the upstream apparatus during exposure. At this time, the exposure apparatus performs time-consuming inspection of the mask foreign matter in parallel with the exposure processing of the previous lot. Although exposure has been performed,
The use of the device portion not used for exposure enables foreign substance inspection by parallel processing.

First, a used mask is taken out of the mask library 16 and a foreign substance is inspected using the mask foreign substance inspection device 15. After the inspection is completed, the lot is switched fastest by keeping the mask on standby in the transport unit closest to the mask table 11. However, when exposing a liquid crystal display element, it is usual to use a plurality of masks. In this case, the mask transport unit 14 cannot have all the masks for which the foreign substance inspection has been completed. Therefore, the mask that has been inspected is returned to the mask library 1
6 or store it in a standby area called a mask cache 19 near the mask table 11.

Normally, the inspection of foreign matter on a mask is completed earlier than the exposure processing, and therefore, as shown in FIG. On the other hand, when the mask is stored in the mask case 17, the foreign matter is less likely to adhere, but after the mask is removed from the mask case 17, the foreign matter may adhere. Therefore, the longer the waiting time of the mask after the inspection is completed, the higher the possibility that foreign matter adheres to the mask. Further, if the inspection of foreign substances on the mask is performed again, the switching time of the lot is affected accordingly, and the productivity is reduced. Next, an embodiment of the present invention for solving the above-mentioned problems will be described.

FIG. 3 is a diagram showing the mask preparation processing timing of the present embodiment. The upper part of the broken line in FIG. 3 shows the processing timing of the upstream apparatus, and the lower part of the broken line of FIG. 3 shows the processing timing of the exposure apparatus. ing. The horizontal axis represents the elapsed time and indicates the order in which the exposure processing is performed. As shown in FIG. 3, the mask preparation for the first lot (lot-1) is performed at the beginning of the lot. Here, “mask preparation” refers to a process of inspecting a used mask for foreign substances and moving the mask to a standby position. The timing of the start of the mask preparation for the second lot (lot-2) becomes a problem. Conventionally, as described above with reference to FIG. 2, preparations are made immediately upon notification of the type of lot to be used to the exposure apparatus. But,
At this timing, the standby time becomes longer.

Therefore, in the present embodiment, it is determined when to start the preparation of the mask, and preparation of the mask is performed after the time comes. In order to make this determination, it is necessary to know “expected exposure processing end time” and “expected mask preparation time”. To know the “expected exposure processing end time”, the number of remaining substrates, the exposure time, the number of shots, the alignment time for one substrate, and the like are required. Among them, values other than the number of remaining substrates are predetermined values and can be managed for each lot. However, the number of remaining substrates cannot be known until a notification of “the last substrate” is received from an upstream device. However, since the number of substrates in one lot is usually fixed, the number of remaining substrates can be obtained for the following reasons. That is, when moving between production lines by an AGV (Auto Guided Vehicle) or the like, the substrate is put in a cassette and moved. This cassette uses almost one kind in one line. Further, the substrate of one cassette is usually a unit of one lot. Therefore, in a normal production line, the number of substrates stored in a cassette is the number of substrates in one lot. Therefore, if the current number of substrates is counted during the exposure processing, the remaining number of substrates can be predicted.

On the other hand, the "expected mask preparation time" can be obtained by knowing the number of masks to be used, the position of the mask case 17 to be used, the standby position after the mask inspection, and the transport time.
More specifically, a device fixed value as shown in FIG. 4 and a value that varies from lot to lot are prepared as data necessary for the exposure processing.

FIG. 4 is a diagram showing an example of data for calculating a mask preparation start time, which is an example of data of a device fixed value and a lot-to-lot variation value of "expected exposure processing end time" and "expected mask preparation time". For example, assume that the data in FIG. 4 is given. The “expected exposure processing end time” can be firstly known from the exposure time, the number of shots, the shot position, the stage drive speed, and the number of substrate positioning marks. Next, when the “number of masks to be used” and the “mask replacement time” are considered, the time per one substrate can be determined. Furthermore, the approximate remaining exposure processing time can be calculated from “the number of substrates in one lot”. However, a very small number of substrates may flow in a test in the middle of the production line. At that time, the number of substrates in one lot is input in advance to the data for each lot, and it may be determined whether or not this value is different from the fixed value “the number of substrates in one lot”.

The "expected mask preparation time" can be roughly calculated based on the mask foreign matter inspection time, the mask transport time, the mask waiting time after inspection, the number of masks used, and the used mask position. However, since these values are approximate values, it is necessary to end the inspection with a margin. For this purpose, a “post-inspection mask standby time” is provided. From these values, the mask preparation start timing is calculated so that the waiting time after the end of the inspection is optimized. As a result, the possibility of foreign matter adhering after the inspection is significantly reduced.

The above can be applied to a scanning type exposure apparatus using a large mask. In this case, only a small number of masks are used, and the calculation of the inspection start time can be performed in the same way. The processing described above is performed when lots of different data continue. However, lots of the same data may continue without interruption.

FIG. 5 is a diagram showing a conventional mask foreign matter inspection timing based on the same data. As shown in FIG.
When lots of the same data continue without interruption, after the mask foreign matter inspection is performed in the first lot, the foreign matter inspection is not usually performed again because the same mask is used. This shortens the lot switching time. However, depending on the form of the production line, many lots of the same data may continue. In this case, the foreign matter inspection of the mask cannot be performed as long as the lot continues. There is no problem if the time is short, but it cannot be said that the possibility of foreign matter adhesion is zero when the time is long. Further, when a foreign substance is attached, the damage is not limited to one lot, but extends to a plurality of lots.

Therefore, in this embodiment, when a lot of the same data continues, even if the same mask as that used for exposure is used after a certain period of time, even if the same mask is used again, It is considered that a foreign substance inspection is performed to eliminate defects of the photosensitive substrate due to foreign substance adhesion.

FIG. 6 is a diagram showing the timing of mask foreign matter inspection according to the present embodiment. In FIG. 6, it is assumed that lots A to D are lots using the same data. Since the data is the same, the mask used is the same. In this case, the foreign substance inspection of the mask of the recipe A which is the head is performed,
After that, since the same mask is used, the foreign substance inspection is omitted. However, if the time exceeds a certain allowable time, foreign matter inspection is performed even if the same mask is to be used. In this case, as shown in FIG. The permissible time of the foreign substance inspection is determined in advance. In addition, the elapsed time to be compared with the above-described foreign substance inspection allowable time may be determined by observing the time when the lot is switched from the time when the foreign substance inspection was last performed. In FIG. 6, since the allowable time has been exceeded in the course of the recipe C, the foreign substance inspection is performed in the recipe D. Here, the allowable time of the foreign substance inspection is not limited to the time, and various parameters related to the time can be used. For example, the number of lots, the number of substrates to be processed, the number of mask movements, and the like can be given.

As described above, in the exposure apparatus of the present embodiment, the mask table 11 on which the mask 10 is mounted at the time of exposure, the mask changer 12 for exchanging a plurality of masks, the projection optical system 13, and the mask 10 Mask transport unit 14 for loading or unloading, mask foreign matter inspection device 15 for detecting foreign matter on mask 10, mask case 1
Library 1 for storing the masks housed in 7
6, a library arm 18, a mask cache 19 for waiting a plurality of masks to be used, an illumination system 20 for exposure,
The control device 30 includes a stage 21 on which a photosensitive substrate is mounted, and a photosensitive substrate 22. The control device 30 detects the processing time of the projection optical system 13 when the first mask is used, and controls the mask foreign matter inspection device 15 to detect the processing time of the second mask. Since the processing is controlled so as to be on standby based on the detected processing time, it is possible to reduce the possibility of foreign matter adhering to the mask used for exposure, and also reduce the time for lot switching. As a result, the productivity of the photosensitive substrate can be increased.

Although the above embodiment is an application example in which the pattern is exposed on the substrate by sequentially changing the mask, the exposure apparatus may be of any type, for example, 5 to 15 nm (soft). The present invention can also be applied to a step-and-scan type scanning projection exposure apparatus that uses EUV (Extreme UltraViolet) light having an oscillation spectrum in the X-ray region as exposure illumination light.

[0034]

According to the present invention, it is possible to suppress the possibility of foreign matter adhering to the mask after mask foreign matter inspection, and to suppress the possibility of foreign matter adhering to the mask even when lots of the same data continue. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an example of an exposure apparatus according to the present invention.

FIG. 2 is a diagram showing a conventional mask preparation processing timing.

FIG. 3 is a diagram showing a mask preparation processing timing according to the embodiment.

FIG. 4 is a diagram showing an example of data for calculating a mask preparation start time.

FIG. 5 is a diagram showing a conventional mask foreign matter inspection timing based on the same data.

FIG. 6 is a diagram showing mask foreign matter inspection timing according to the present embodiment.

[Explanation of symbols]

Reference Signs List 10 mask, 11 mask table, 12 mask changer, 13 projection optical system, 14 mask transport unit, 1
5: Mask foreign matter inspection device, 16: Mask library (mask holding device), 17: Mask case, 18: Library arm, 19: Mask cache, 20: Illumination system for exposure, 21: Stage, 22: Photosensitive substrate, 30 ... Control device, 31 ... Storage device

Claims (8)

[Claims] 1. An exposure apparatus for exposing a pattern on a substrate by sequentially exchanging masks, comprising: an exposure section for exposing the pattern on the substrate; and an exposure preparation for preparing for the exposure prior to the exposure of the exposure section. A processing time detecting device for detecting a processing time by the exposure unit when the first mask is used; and a processing time detected by the processing time detecting device for processing the second mask by the exposure preparing unit. An exposure apparatus, comprising: a standby device that causes standby based on the condition. 2. A control device for interrupting exposure using the first mask when a processing time detected by the processing time detecting device exceeds a predetermined time. Exposure apparatus according to the above. 3. The exposure apparatus according to claim 2, wherein the control device causes the first mask to be processed by the exposure preparation unit when the exposure is interrupted. 4. The exposure apparatus according to claim 1, wherein the exposure preparation unit includes a foreign matter detection device that detects foreign matter attached to the mask. 5. The exposure apparatus according to claim 4, wherein the exposure preparation unit includes a storage device for temporarily storing the mask on which foreign matter detection by the foreign matter inspection device has been completed. 6. The processing time detecting device according to claim 1, wherein the processing time detecting device detects the processing time based on the number of the substrates processed using the first mask. Exposure apparatus according to Item. 7. An exposure apparatus for exposing a pattern on a substrate by sequentially exchanging masks, comprising: an exposure section for exposing the pattern on the substrate; and an exposure preparation for preparing for the exposure prior to the exposure of the exposure section. A processing time detecting device that detects a processing time of the exposure unit when the first mask group is used, and a processing that the processing time detecting device detects the processing of the second mask group by the exposure preparing unit. An exposure apparatus, comprising: a standby device that waits based on time. 8. The exposure apparatus according to claim 7, wherein the exposure unit includes a reticle holding device that holds a plurality of the masks.