JPH0697066A - Photomask for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE:To remove photoresist from the peripheral portion of a wafer for preventing photoresist from peeling-off and turning into suspended dust which may contaminate the wafer or equipment when fixing or conveying the wafer within equipment for giving a treatment to the wafer for semiconductor device. CONSTITUTION:A chip pattern 11 for semiconductor device is arranged for a portion corresponding to a central portion 3 of a wafer 1 of a light exposure photomask 10 of a photoresist film applied to the wafer 1, and a mark pattern 12 for mask matching is formed by pushing in the array. Also, a portion corresponding to a peripheral portion 4 of the wafer 1 is formed to an unpattern portion with a clear ground or a black ground, the photoresist film exposed to light by the photomask 10 is certainly removed from the peripheral portion 4 of the wafer 1 during development, and a possibility of peeling-off off of the resin of the photoresist as a result of the contact of a presser jig 30 to the peripheral portion 4 when fixing the wafer 1 within a treatment equipment can be completely eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask for patterning a photoresist used when processing a wafer on which a semiconductor device is to be formed.

[0002]

2. Description of the Related Art In order to manufacture a semiconductor device such as an integrated circuit or an individual element, it is well known to perform a process such as ion implantation of impurities and etching of various films on a wafer for use in a predetermined pattern. Before that, be sure to apply a photoresist film on the surface of the wafer first, and then perform a photo process of exposing and developing it using a photomask that specifies the pattern for processing, and as a mask film for processing It is necessary to form a photoresist film in a specified pattern.

In this photoresist film, a large number of chip patterns are arranged side by side in order to form a plurality of semiconductor devices on a wafer, and a mark pattern for a so-called alignment mark is included for mask alignment of the wafer during exposure. 2A is a typical example of such a pattern arrangement. As is customary, a substantially circular wafer 1 is provided with a so-called orientation flat 2 which is a notch for distinguishing the vertical and horizontal directions, and the photoresist film on the surface thereof has a continuous two-dimensional array of rectangular chip patterns 11. A plurality of them, in the example shown, two peripheral portions of the wafer 1 are formed into a pattern in which the mark patterns 12 are replaced. In the figure, the chip pattern 11 shown with hatching and a very simple shape has a complicated internal pattern, and the mark pattern 12 is a T-shaped or M-shaped alignment mark.

The photoresist film on the wafer 1 is shown in FIG.
In order to pattern as shown in the figure, a photomask having exactly the same pattern as that in the figure is used to expose it at the same size, or a so-called reticle which is a photomask having an enlarged chip or mark pattern is used. The reticle may be switched while performing sequential exposure, and reduction exposure may be performed, and then the photoresist film may be developed by performing a simple heat treatment as usual and then immersing it in a dedicated developer. Both positive and negative types of photomasks and reticles are appropriately used depending on the case.

[0005]

However, a wafer 1 having a photoresist film patterned as shown in FIG. 2 (a) is used.
Then, there is a problem that a part of the photoresist film is peeled off to become floating dust when it is fixed in the processing facility or is transported to and from the facility, which easily contaminates the wafer surface and the inside of the processing facility. As shown in the enlarged view of FIG. 2 (b), the wafer 1 is fixed on the processing table in the equipment by the holding jig 30 at the peripheral portion thereof, but the photoresist film at the position where the sharp claw 32 of the jig hits Relatively soft resin is easy to peel off. Even during the transportation of the wafer 1, the photoresist film is likely to be peeled off due to the friction when the corners of the peripheral edge of the wafer 1 come into contact with the transportation jig.

The floating dust of the peeled photoresist film becomes a defect when it adheres to the wafer surface, which reduces the manufacturing yield, or adheres and accumulates on the inner wall of the processing equipment to reduce the vacuum degree. There is a problem such as getting lost in the part and lowering the acceleration voltage. The cause of such a problem is that the peripheral edge of the wafer 1 is provided with a photoresist film. Conventionally, after the photoresist film is applied by spin coating, it is always removed from the peripheral edge by so-called edge rinse, and further back rinsed by back rinse. Although it is also removed from the side, it is still difficult to remove the photoresist film from the peripheral portion of the wafer 1.

This is because it is originally difficult to limit the removal range of the photoresist film due to the principle that the edge rinse is performed by pouring a solvent such as acetone onto the peripheral portion of the wafer 1, and in addition, the spin-coated photoresist is used. Is more likely to be thicker on the peripheral portion than on the central portion of the wafer 1, so that the photoresist film is washed away from the adjacent area where it is needed while the photoresist film is completely removed from the peripheral portion.
An object of the present invention is to solve such a problem and to reliably remove the photoresist film from the peripheral portion of the wafer to prevent the trouble caused by the dust of the resin.

[0008]

According to the present invention, such an object is to provide a chip pattern and a wafer at a portion corresponding to a central portion of a wafer on which a semiconductor device of a photomask for patterning a photoresist film is to be formed side by side. A mark pattern for mask alignment with is provided, and the portion corresponding to the peripheral edge of the wafer is always placed as a non-patterned portion.
This is accomplished by allowing the photoresist film applied to the wafer surface to be automatically removed from the periphery during the photo process. Note that the above-mentioned non-patterned area of the photomask usually needs to be a portion corresponding to the peripheral portion of the wafer having a width of at least 2 mm. Further, the present invention can be applied in principle to the reticle-type photomask described above, but is most suitable for a photomask in which a chip pattern is formed in a size for equal-magnification exposure on a wafer.

The present invention can of course be applied to both positive and negative photomasks, and the above-mentioned non-patterned portion is transparent in the positive type and opaque or black in the negative type. . When patterning a photoresist film using the photomask of the present invention, a reference wafer having the same mark pattern as the photomask at the same position is prepared in advance, and the exposure apparatus is loaded with the reference wafer. After fixing the photomask with its mark pattern by using, the mask alignment of each work wafer to this photomask is advantageous in accurately controlling the width of the peripheral portion of the wafer from which the photoresist film should be removed. This also facilitates mask alignment work. It is sufficient to prepare only one reference wafer for all photomasks used for manufacturing a specific semiconductor device.

[0010]

According to the present invention as described in the above paragraph, in addition to arranging a large number of semiconductor device chip patterns to be formed in the wafer in a portion corresponding to the central portion of the wafer of the photomask, the wafer is arranged in this arrangement. Also, the mask alignment mark pattern of No. 1 is arranged so as to be interrupted, and accordingly, all the portions corresponding to the peripheral portion of the wafer of the photomask are made non-patterned, so that the photomask is exposed during the photoprocess. The photoresist film is completely and automatically removed from the peripheral portion of the wafer when it is developed and developed.

[0011]

Embodiments of the present invention will be described below with reference to FIG. FIG. 1 (a) is a top view of the photomask of the present invention, and FIG.
1 (b) is a top view of a wafer having a photoresist film patterned thereby, FIG. 1 (c) is a top view of a reference wafer used when fixing a photomask to an exposure apparatus, and FIG. 1 (d) is shown in FIG. FIG. 3 is an enlarged top view of essential parts showing a state in which the wafer of b) is fixed on a processing table of processing equipment by a holding jig in comparison with FIG. 2 (b). In the examples described below, the photomask is for equal-magnification exposure and for a positive photoresist film.

The photomask 10 shown in FIG. 1 (a) is for exposing a photoresist film applied to the wafer 1 shown by thin lines in the figure, and is used for each photoprocess step in a wafer process for manufacturing a semiconductor device. The chip patterns 11 and the like having different contents are used. Photo mask
When the wafer 1 has a diameter of 100 mm, for example, a size of about 125 mm square, a square of several mm square within the range corresponding to the central portion 3 of the wafer 1, and a square chip pattern for each semiconductor device in the illustrated example. A large number of 11 are arranged in a two-dimensional array, and two mark patterns are inserted in the array by interrupting this array.
The 12 are placed as far apart from each other as possible. Further, the annular portion of the photomask 10 corresponding to the peripheral portion 4 of the wafer 1 is always a non-patterned portion in the present invention, which is a transparent ground in this embodiment. It is usually necessary to set the width of the non-patterned portion or the peripheral portion 4 to at least 2 mm or more.

In the photomask 10 for the first photo process, usually for etching the process oxide film covering the wafer 1, the mark pattern 12 is used as the above-mentioned T-shaped or M-shaped alignment mark on the wafer surface. In this embodiment, a uniform black background pattern is used so that the oxide film is marked, and the photomask 10 for the subsequent photo process uses a photoresist film to protect the first marking as much as possible, although the mask pattern 10 may be slightly different. It is good to say

The photoresist film on the wafer 1 is exposed and developed by the photomask 10 to obtain the state shown in FIG. 1B. At this time, the photomask 1 is attached to the exposure apparatus as shown in FIG. It is advantageous to prepare and place the reference wafer 20 of The reference wafer 20 is exactly the same as the work wafer 1 and, for example, an oxide film having a film thickness of about 0.5 μm is attached to the reference wafer 20 and, preferably, a photomask using the photomask for the first photoprocess described above is used. A mark pattern formed from an oxide film by subjecting it to etching
The reference wafer 20 preferably comprises at least 12 as shown. In this case, an oxide film is formed not only on the mark pattern 12 but also on the chip pattern 11, but of course there is no problem.

To expose the photoresist film on the working wafer 1 by the photomask 10 shown in FIG.
In the state where the reference wafer 20 of (c) is loaded in the exposure apparatus, the photomask 10 is fixed to the exposure apparatus according to the mark pattern 12 thereof, and thereafter, the working wafers 1 are sequentially loaded in the exposure apparatus and exposed. However, in the subsequent steps except the first photo process, the wafer 1 and the photo mask 10 are mask-aligned so that the mark patterns 12 of the photo mask 10 match with each other, and then exposed. As described above, the photomask 10 is formed by using the reference wafer 20.
Is attached to the exposure apparatus, the mask alignment work can be facilitated, and the width of the peripheral portion 4 of the wafer 1 from which the photoresist film is removed can be controlled very accurately.

After the photoresist film on the wafer 1 has been exposed by the photomask 10 and developed as described above, the chip pattern 11 is formed on the central portion 3 of the wafer 1 as shown in FIG. 1 (b). A photoresist film of the mark pattern 12 is formed, and the photoresist film of the peripheral portion 4 is positive in this example and is exposed during exposure, so that it is completely removed during development. In the photoprocess using the photomask 10 of the present invention, the photoresist film is surely removed from the peripheral edge portion 4 of the wafer 1 in this manner. Therefore, it is desirable to perform back rinse after the spin coating. There is no need to perform edge rinse, and therefore troubles associated therewith can be prevented.

When loading or fixing the wafer 1 shown in FIG. 1 (b) on a processing table which is a target of ion implantation equipment, for example,
Suppressor of restraining jig 30 as shown in the enlarged view of the main part of FIG. 1 (d)
31 is brought into contact with the peripheral edge portion 4 of the wafer 1 to suppress it, but in the wafer 1 in which the photoresist film is exposed and developed using the photomask 10 of the present invention, the photoresist film is surely removed from the peripheral edge portion 4 and the resin There is no risk of peeling. Holding jig
Even when the wafer 1 is processed in a facility in which 30 is provided with a claw 32 and an annular suppressor that suppresses the entire circumference of the peripheral edge portion 4 as shown in FIG. 2B, the generation of floating dust due to resin peeling is very small. It is also recognized that the present invention can significantly reduce stripping of the photoresist film during automatic transfer of the wafer 1 in the facility.

Although the photoresist film applied to the wafer 1 is a positive type in the embodiment described above, in the case of a negative type, it corresponds to the peripheral portion 4 of the wafer 1 of the photomask 10 of FIG. 1 (a). The annular portion to be formed may be opaque, for example, a black background so that it can be easily seen. Further, in the embodiment, the photomask 10 is used for equal-magnification exposure, but the present invention is also applicable when it is for reduction exposure or a reticle. As described above, the present invention is not limited to the above-described embodiments and can be implemented in various modes.

[0019]

As described above, in the photomask of the present invention, the chip pattern of the semiconductor device is arranged in the portion corresponding to the central portion of the wafer in which the semiconductor device is to be formed, and the mark pattern for mask alignment is interrupted in the arrangement. By removing the photoresist film applied to the wafer surface from the peripheral portion of the wafer during the photo process, by forming the portion corresponding to the peripheral portion of the wafer on the transparent or black non-patterned portion. As a result, the problem of contaminating the wafer surface and the inside of the processing equipment is almost eliminated when the wafer is fixed in the processing equipment or is transferred to and from the equipment, and the photoresist film peels off and becomes floating dust. In particular, it is possible to prevent the occurrence of defects in the integrated circuit device and improve the manufacturing yield.

[Brief description of drawings]

FIG. 1 shows an embodiment of a photomask according to the present invention and a wafer. FIG. 1A is a top view of the photomask, FIG.
(b) is a top view of the wafer with the photoresist film patterned by it, (c) is a top view of the reference wafer used when fixing the photomask to the exposure apparatus, and (d) is the same figure ( FIG. 6 is an enlarged top view of the relevant part showing the state in which the wafer of b) is fixed on the processing table of the processing equipment by a holding jig.

FIG. 2 is for explaining a conventional photomask and its problems,
FIG. 1A is a top view of a wafer having a photoresist film patterned by a conventional photomask, and FIG. 1B is an enlarged top view of essential parts showing a state where the wafer is fixed by a holding jig.

[Explanation of symbols]

 1 wafer 3 central part of wafer 4 peripheral part of wafer 10 photomask 11 photomask chip pattern 12 photomask mark pattern 20 photomask reference wafer for attachment

Claims (3)

[Claims] 1. A photomask for patterning a photoresist used when processing a wafer on which a semiconductor device is to be formed, the semiconductor device being provided on a portion corresponding to a central portion of the wafer on which the semiconductor devices are to be formed side by side. A mark pattern for mask alignment between the chip pattern for wafer and the wafer is provided, and the portion corresponding to the peripheral edge of the wafer is formed and placed in the non-patterned portion, and the photoresist film coated on the wafer surface is used during the photo process. A photomask for manufacturing a semiconductor device, wherein the photomask is removed from the peripheral portion of the photomask. 2. The photomask according to claim 1, wherein
A photomask for manufacturing a semiconductor device, wherein each chip pattern in the photomask is formed in a size for equal-magnification exposure on a wafer. 3. The photomask according to claim 1, wherein
A photomask for manufacturing a semiconductor device, wherein a photomask portion corresponding to a peripheral portion having a width of at least 2 mm of a wafer is formed in a non-patterned portion.