JPH11121589A - Method and device for carrier, and projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for carrier, and a projection aligner that can be used in photolithographic process for manufacturing a semiconductor device, a liquid crystal display, or the like, and is capable of confirming the existence of a substrate, when the substrate is carried without the use of a vacuum suction system. SOLUTION: A device has an exposure part 6 for transferring a pattern formed at a reticle 4 onto a wafer 2, reticle and wafer carrier parts 12 and 14 for carrying the reticle 4 or the wafer 2 to the exposure part 6, a chamber 1 for covering the exposure part 6 with a vacuum state, and reticle and wafer image-pickup parts 28 and 30 for taking each image of the reticle and wafer carrier parts 12 and 14 for carrying, and detects the the presence or absence of the reticle 4 and water 2 in the reticle and wafer carrier parts 12 and 14, based on image information which is image picked up at the reticle and wafer image-pickup parts 28 and 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer method and apparatus used in a photolithography process for manufacturing a semiconductor device or a liquid crystal display device, and an exposure apparatus.

[0002]

2. Description of the Related Art In a photolithography process in a manufacturing process of a semiconductor device, a liquid crystal display device, or the like, a circuit pattern formed on a reticle or a mask (hereinafter, referred to as a reticle) is formed by a semiconductor wafer or a glass plate (hereinafter, referred to as a reticle) via an optical system. A wafer is used as an example for explanation.) An exposure apparatus for exposing the wafer is used. There are various types of exposure apparatuses.For example, in the case of manufacturing a semiconductor device, a wafer is step-and-repeat type via a projection optical system having an image field capable of containing the entire reticle circuit pattern. There are a projection exposure apparatus that performs exposure, and a so-called step-and-scan projection exposure apparatus that performs one-dimensional scanning of a wafer while scanning a reticle one-dimensionally.

In these exposure apparatuses, reticle or wafer as a substrate is mainly transferred by vacuum suction. For example, when transporting a reticle, the reticle transport system takes out the reticle from the reticle library that stores the reticle, places it on the transport arm, transports it while holding it by vacuum suction, and transports it on the reticle stage of the exposure apparatus. Place on reticle holder. The transfer of the wafer is performed by the same operation.

In the above-described transfer operation, it is determined whether the reticle (or wafer) is mounted on the transfer arm in a predetermined state or the reticle (or wafer) is held on the transfer arm during transfer. The degree of vacuum in vacuum suction is measured to determine whether or not a predetermined degree of vacuum exists.

[0005]

However, in a next-generation exposure apparatus such as an exposure apparatus using a charged particle beam or an X-ray exposure apparatus, the entire exposure apparatus including a transport system has a vacuum space. Therefore, the vacuum holding method cannot be used for a substrate holding unit that moves while holding a substrate by a transfer system such as a wafer or a reticle. For this reason, there is a problem in that it is not possible to confirm the holding of the reticle (or wafer) and the existence of the reticle (or wafer) in the middle of transport, which have been performed by using vacuum suction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer method and apparatus capable of confirming the presence of a substrate in a substrate transfer without using a vacuum suction method, and an exposure apparatus.

[0007]

Means for Solving the Problems When described with reference to FIGS. 1 to 3 showing an embodiment of the present invention, the above objects are as follows.
The substrate (2, 4) is placed on the substrate stage (18, 20), and the substrate (2, 4) is placed on the substrate stage (18, 2).
0) In the transfer device to be carried out from above, the substrate (2, 4)
Holding portions (24, 26) for holding the substrate stage (18, 2) by moving the holding portions (24, 26).
0) on the transport unit (12, 1) for placing the substrate (2, 4) on it.
4) and an imaging unit (2) for imaging the holding units (24, 26).
(8, 30) and a detection unit (46 to 50) for detecting whether or not the substrate (2, 4) exists on the holding unit (24, 26) using the output of the imaging unit (28, 30). This is achieved by a transport device characterized by comprising:

In the transfer apparatus of the present invention, the substrate (2,
4) is characterized by being transported in a vacuum space. Further, the imaging unit (28, 30) is characterized in that the imaging unit tracks and images the holding unit (24, 26). Further, the imaging unit (2
8, 30) is the substrate (2, 2) in the substrate storage (8, 10).
4) can also be imaged.

The above object is also achieved by an exposure main body (6) for transferring a pattern onto a photosensitive substrate (2) and a transport for transporting at least the mask (4) or the photosensitive substrate (2) to the exposure main body (6). A chamber (1) for covering an exposure main body (6) in a vacuum state in the exposure apparatus having the parts (12, 14).
And cameras (28, 3) for imaging the transport units (12, 14).
0) and a detection unit (46 to 50) for detecting the presence or absence of the substrate (2, 4) in the transport unit (12, 14) using the output of the camera (28, 30). Is achieved by the following exposure apparatus.

The above object is also achieved by moving a holding portion (24, 26) for holding a substrate (2, 4) to move the substrate (2, 4).
In the transport method for transporting the image, the holding unit (24, 26) is imaged, and the substrate (2, 4) is placed on the holding unit (24, 26) based on the captured image information of the holding unit (24, 26). This is achieved by a transport method characterized in that it is checked whether it exists. Further, based on the image information, an imaging unit (28, 30) for calculating a moving direction and a moving amount of the substrate (2, 4) on the holding unit (24, 26) and imaging the holding unit (24, 26). Tracking the movement of the substrate (2, 4).

According to the present invention, the substrate holding section (24, 26) is provided by the camera monitoring system of the imaging section (28, 30).
The presence of the board (2, 4) on the board holding section (24, 26) is confirmed by image recognition and the board holding section (24, 26).
Since the transfer tracking of 26) is performed, it is possible to easily confirm the presence of the substrate (2, 4) in the substrate transfer method without using the vacuum suction method.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A transport method and apparatus and an exposure apparatus according to an embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of a transport apparatus and an exposure apparatus according to the present embodiment will be described with reference to FIG.

In FIG. 1, the entire exposure apparatus including a transfer apparatus is installed in a vacuum space in a chamber 1. An exposure main body 6 for transferring a circuit pattern formed on a reticle (or mask) 4 onto a wafer 2 is provided in the chamber 1. The exposure main unit 6 includes, for example, the charged particle beam 1.
6 is provided. Further, a reticle stage 18 on which the reticle 4 is mounted and movable two-dimensionally in the exposure main body 6 and a wafer stage 20 on which the wafer 2 as a photosensitive substrate is mounted and movable two-dimensionally are provided. I have. Further, the reticle stage 18 and the wafer stage 20
The charged particle beam 16 from the radiation source 17 passes through the reticle 4, enters the optical system 22, and exits the optical system 22. Irradiation is performed on the wafer 2 on the wafer 20. In the present embodiment, the pattern image of the reticle 4 is transferred to the wafer 2, but it is also possible to directly draw a pattern stored in advance on the wafer 2 without passing through the reticle 4.

A reticle storage unit 8 having a reticle library storing a plurality of reticles 4 and a wafer storage unit 10 having a wafer cassette for storing a plurality of wafers 2 are provided in the chamber 1. I have. The reticle storage unit 8 and the wafer storage unit 10 and the exposure main unit 6 are installed on different base units.

A reticle transport system 12 for transporting the reticle 4 and a wafer transport system 14 for transporting the wafer 2 are arranged between the reticle storage unit 8 and the wafer storage unit 10 and the exposure main unit 6. . As described above, in the present embodiment, since the wafer 2 and the reticle 4 are transported in a vacuum space, vacuum suction cannot be used to hold the substrate during the transport. Therefore, the reticle transport system 12 in the present embodiment has a reticle holding unit 24 that holds the reticle 4 by electrostatic attraction, and the reticle holding unit 24 takes out a desired reticle 4 from the reticle library in the reticle storage unit 8. , And can be transported to the reticle stage 18 of the exposure main body 6. Further, the wafer transfer system 14 has a wafer holding unit 26 that holds the wafer 2 by electrostatic suction, and the wafer holding unit 26 takes out a desired wafer 2 from a wafer cassette in the wafer storage unit 10 and holds the wafer 2 by suction. The wafer can be transferred to the wafer stage 20 of the exposure main body 6.

FIG. 2 shows a schematic structure of the wafer holder 26.
Shown in FIG. 2A shows a plane of the wafer holding unit 26,
FIG. 2B is a cross-sectional view taken along line AA of FIG.
As shown in FIG. 2, a Y-shaped electrostatic attraction part 38 is provided at the tip of the arm 36, and the surface of the electrostatic attraction part 38 is electrically charged to (+) (−) to attract and fix the wafer 2. I do. The configuration of the reticle holding unit 24 is the same. Further, holding of the reticle 4 and the wafer 2 in the vacuum space
The configuration is not necessarily limited to electrostatic attraction, and may be configured to mechanically grip a substrate edge, for example. In any case, it is preferable to minimize the area of the wafer 2 or the reticle 4 that contacts the substrate surface.

Returning to FIG. 1, a reticle image pickup unit 2 having a camera device for picking up an image of a reticle holding unit 24 is provided in a chamber 1 of the transfer apparatus and the exposure apparatus according to the present embodiment.
8 and a wafer imaging unit 30 having a camera device for imaging the wafer holding unit 26. Reticle imaging unit 2
The reticle stage 8 moves from the stage of taking out the reticle 4 from the reticle storage unit 8 including the imaging of the reticle 4 in the reticle storage unit 24 following the movement of the reticle holding unit 24 in the reticle transport system 12, The reticle holder 24 is arranged so that the reticle 4 can be imaged in all stages up to the stage where the reticle 4 is placed. The camera device of the reticle imaging unit 28 has a direction turning function, and is installed on, for example, the wall of the chamber 1 so that the reticle holding unit 24 can be monitored over the entire transport path as indicated by an arrow 32 in FIG. Have been.

On the other hand, the wafer imaging unit 30 follows the movement of the wafer holding unit 26 in the wafer transport system 14 and includes the wafer storage unit 1 including the imaging of the wafer 2 in the wafer storage unit 10.
From the stage of taking out the wafer 2 from 0, the wafer stage 2
The wafer holding unit 26 is arranged so that the image of the wafer holding unit 26 can be imaged up to the stage of mounting the wafer 2 on the wafer 0. The camera device of the wafer imaging unit 30 has a direction turning function, and for example, monitors the chamber 1 so that the wafer holding unit 26 can be monitored over the entire transfer path as indicated by an arrow 34 in FIG.
It is installed on the wall.

When the reticle 4 or the wafer 2 is transported by the reticle imaging section 28 and the wafer imaging section 30 as described above, the reticle 4 is placed on the reticle holding section 24.
Can be confirmed whether or not the wafer 2 exists on the wafer holding unit 26. Furthermore, since these camera devices are tracked during transport, the reticle 4
It is also possible to monitor whether or not the wafer 2 has fallen off from the holding sections 24 and 26. This function is particularly useful when the substrate is transported while being tilted or set up in the vertical direction.

Next, the reticle image pickup unit 28 and the wafer image pickup unit 3 for explaining the transfer method according to the present embodiment.
The outline of the configuration of each of the camera devices 0 and the detection unit that detects the presence of the reticle 4 or the wafer 2 from the output of the camera device will be described with reference to FIG. FIG. 3 illustrates the camera device and the detection unit of the wafer imaging unit 30 for confirming the presence of the wafer 2 as an example, but the same applies to the case of the reticle imaging unit 28.

As shown in FIG. 3, a CCD area sensor 40 is used in the input section of the camera device. An image signal as image information output from the CCD area sensor 40 is converted from an analog signal to a digital signal in an A / D converter 42. At this time, an output image signal is taken into the A / D converter 42 from the CCD area sensor 40 based on a desired sample hold time and the like set by the CCD and the A / D timing circuit 44. The image signal converted into the digital signal is then sent to the detection unit (46, 48, 5).
0). The image signal is first input to the edge enhancement circuit 46 of the detection unit, and the outer peripheral portion of the imaged wafer 2 is enhanced. In the edge enhancement processing, digital image data is subjected to, for example, filtering for image sharpening using a Laplacian (secondary differential) filter, high-frequency enhancement filtering using Fourier transform, and the like. In FIG. 3, the edge enhancement processing is realized by hardware. However, the edge processing may be performed by software. The image data subjected to the edge enhancement processing is stored in the memory 48.

Next, the outer periphery of the wafer is recognized by predetermined processing software in the processing unit (CPU) 50, and the wafer position on the wafer holding unit 26 is confirmed. The presence of the wafer 2 is confirmed based on the wafer position information, and the wafer position information is output to the direction turning drive circuit 52, so that the camera device is turned and the wafer 2 is turned.
Can be tracked on the wafer holding unit 26 on which the wafer is placed.

The outline of the procedure for recognizing the outer periphery of the wafer by the CPU 50 will be described first. First, a circular portion of the wafer 2 is searched. The image of the wafer 2 picked up by the camera device that turns following the movement of the wafer holding unit 26 changes from a circular shape to an elliptical shape in the outer peripheral portion of the wafer 2 with the turning of the camera device. Since the image data is stored in advance, the captured image data is multiplied by a predetermined magnification to compare sizes, or feature points such as a curvature and a circular shape are extracted to determine whether or not the image is a wafer. In particular, in the case of a wafer, an orientation flat portion (OF portion) and a notch (notch portion) used for pre-alignment or the like may be detected. Thus, the wafer 2
, The outer periphery of the wafer is recognized by detecting a part of the circular portion, the OF or the notch. In this case, the notch can obtain an image signal having a larger feature amount than that of the OF section, so that the outer periphery of the wafer can be recognized with high accuracy.

Next, an outline of a procedure of tracking the wafer 2 by the direction turning drive circuit 52 will be described. When the CPU 50 recognizes the outer periphery of the wafer, the direction turning drive circuit 52 determines a change in the edge position as the movement of the wafer 2 by focusing on the position of the recognized circular or elliptical edge of the recognized wafer 2. Then, the moving direction is calculated from the direction of the change. The moving speed is calculated from a change in the wafer detection position at each sampling interval of image capture. Although these calculations focus on the movement of the edge portion of the wafer 2, the movement direction and speed may be specified from a change in the movement amount of the center of the wafer.

As described above, according to the present embodiment, the camera monitoring system of the imaging unit images the substrate holding unit, confirms the presence of the substrate on the substrate holding unit by image recognition, and tracks the transfer of the substrate holding unit. Therefore, it is possible to easily confirm the presence of a substrate even in a substrate transfer method that does not use a vacuum suction method.
Therefore, even when the substrate is transported with the substrate tilted or set up vertically, the substrate can be transported while always checking the holding state of the substrate over the entire transport path. Even if it becomes unstable, it is possible to prevent the substrate from falling off from the holding unit by performing a predetermined process such as stopping the transport system.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above embodiment, reticle transport system 12 and wafer transport system 14 transport reticle 4 and wafer 2 from reticle storage unit 8 and wafer storage unit 10, respectively, to reticle stage 18 and wafer stage 20 of exposure main unit 6. As described above, the present invention can of course be applied to the case where the reticle 4 and the wafer 2 are transferred from the reticle stage 18 and the wafer stage 20 to the reticle storage unit 8 and the wafer storage unit 10, respectively.

[0027]

As described above, according to the present invention, it is possible to realize a transfer apparatus and an exposure apparatus capable of confirming the presence of a substrate in the transfer of a substrate without using the vacuum suction method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a transport device and an exposure device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a wafer holding unit according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a schematic configuration of a camera device and a detection unit according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 chamber 2 wafer 4 reticle 6 exposure main unit 8 reticle storage unit 10 wafer storage unit 12 reticle transfer system 14 wafer transfer system 16 charged particle beam 17 ray source 18 reticle stage 20 wafer stage 22 optical system 24 reticle holding unit 26 wafer holding unit 28 Reticle imaging unit 30 Wafer imaging unit 32, 34 Arrow 36 Arm 38 Electrostatic attraction unit 40 CCD area sensor 42 A / D converter 44 CCD, A / D timing circuit 46 Edge enhancement circuit 48 Memory 50 Processing unit 52 Direction turning drive circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02N 13/00 H01L 21/30 502J 514D

Claims (10)

[Claims] A substrate mounted on a substrate stage;
In a transfer device that unloads a substrate from a substrate stage, the transfer device includes a holding unit that holds the substrate, and moves the holding unit to place the substrate on the substrate stage. And a detecting unit that detects whether the substrate is present on the holding unit by using an output of the imaging unit. 2. The transfer device according to claim 1, wherein the substrate is transferred in a vacuum space. 3. The transfer device according to claim 1, wherein the holding unit electrostatically attracts the substrate. 4. The transfer device according to claim 1, wherein said substrate is a photosensitive substrate. 5. The transfer device according to claim 1, wherein the substrate is a mask on which a pattern is formed. 6. The transfer device according to claim 1, wherein the imaging unit tracks and images the holding unit. 7. The transfer device according to claim 1, further comprising a storage unit for storing at least one substrate, wherein the imaging unit images the substrate in the storage unit. Transfer device. 8. An exposure apparatus comprising: an exposure main unit for transferring a pattern onto a photosensitive substrate; and a transport unit for transporting at least the mask or the photosensitive substrate to the exposure main unit. An exposure apparatus comprising: a chamber to be covered; a camera that images the transport unit; and a detection unit that detects the presence or absence of the substrate in the transport unit by using an output of the camera. 9. A transfer method for transferring a substrate by moving a holding unit for holding a substrate, wherein the substrate is imaged on the holding unit based on image information of the imaged image of the holding unit. A transport method characterized in that it is checked whether or not a sheet exists. 10. The transfer method according to claim 9, wherein a moving direction and a moving amount of the substrate on the holding unit are calculated based on the image information, and an imaging unit for imaging the holding unit is provided on the substrate. A transport method characterized by tracking movement.