JPS60234318A - Photographic processing method - Google Patents

Abstract

PURPOSE:To prevent clogging of dicing blade by exposing at a time the wafer part other than the chip pattern before or after the exposure of chip pattern and thereby eliminating photo resist of this region. CONSTITUTION:A wafer 1 where a metal film is formed as a lower film on the entire part and a positive photo resist film is formed thereon is placed on a movable stage 18 of a stepper 10 by a rotatable transfer arm 15 after it is moved to a temporary positioning table 14 from a cartridge 12 of a loader 13. A chip pattern 1b is arranged and exposed on the surface of wafer 1. At a sub- exposure 11, the wafer 1 is placed on a fixed stage 24 and a prepositioned mask 25 is deposited on the wafer 1. The wafer 1 is irradiated with the light only at the periphery 1a other than the chip pattern 1b and is accommodated within the cartridge 16. Thereby a positive photo resist is eliminated by development, the lower film at the region other than the chip pattern can be eliminated in the etching process and thereby clogging of dicing blade can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a photographic processing technique, and particularly to a technique effective for use in photographic processing in the manufacture of semiconductors.

[Background technology]

In the IJ Sogelafye process, which is one of the manufacturing processes for semiconductor devices, a photoresist film is formed on the surface of a semiconductor wafer, and this photoresist film is made into a butter by exposing it to light in a desired pattern and developing it. In step t2, the kneading is further used as a mask for the lower layer film to perform pattern etching of the lower layer film. For this reason, when exposing a chip pattern on a wafer in this photolithography process, a stepper (step-and-repeat camera) is used to reduce the chip pattern on the reticle and place it one by one on the wafer in U rows. There are possible ways. In this case, as shown in FIG.
In case a, it is conceivable to prevent the stepper from actively exposing the chip pattern 1b, thereby eliminating wasteful stepper operation and improving throughput.

However, in this method, the 7-layer photoresist remains in the unexposed area around the wafer, and the lower layer film in this area is not etched even when the lower layer film is etched in a later step. Therefore, the lower layer film is left as it is, and in the dicing process for dividing the wafer into individual chips, this lower layer film is simultaneously diced, causing the dicing blade to become clogged with debris and dust, resulting in the dicing function not working properly. The present inventors have clarified that a problem arises when the

Also, as mentioned above, there is a metal film around the wafer.

Aged oxide film 1 For example, if the A, 8 film remains, thermal stress based on the difference in thermal expansion coefficient between AA and the wafer (silicon) will occur when the wafer undergoes temperature changes, causing the wafer to curve and become flat. There is also the problem that sexuality is inhibited. Furthermore,
If the AA film that is not etched during etching of the film occupies a relatively large area, the amount of information for detecting the etching end point using spectroscopy etc. will be small, making it difficult to detect the etching end point with high precision. It has been revealed by the inventor that there is a problem.

[Object of the Invention] The object of the present invention is to eliminate the remaining A2 film at the periphery of the wafer without reducing the throughput of chip pattern exposure, thereby preventing clogging of the dicing blade and detecting wafer curvature and etching end point. An object of the present invention is to provide a semiconductor manufacturing method that can prevent a decrease in accuracy.

The above and other objects and novel features of the present invention are as follows:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, by using a method in which parts of the wafer other than the chip pattern are exposed all at once before and after the exposure of the 5-chip pattern, and the 7-photoresist in this part is removed, it is possible, for example, to remove the metal film as the underlying film by etching. This is intended to prevent clogging of the dicing blade, as well as to prevent wafer curvature and improve etching end point detection accuracy.

〔Example〕

First, an example of an apparatus for carrying out the method of the present invention will be explained with reference to FIG. As shown in the figure, this apparatus is equipped with a stepper 10 for reducing exposure of chip patterns one by one on a semiconductor wafer, and a sub-exposure section 11 for subsequently exposing the periphery of the wafer other than the chip patterns at once. . On the front side of the stepper 10, there is a loader section 13 in which a cartridge 12 containing a wafer 1 is installed, and a temporary positioning table 14 capable of roughly positioning the wafer 1 using an orifice 7. Furthermore, it has a rotary transfer arm 15 for transferring the wafer 1 on the positioning table 14 to the stepper 10 or the sub-exposure section 11. Further, on the rear side of the sub-exposure section 11, there is an unloader section 1 in which the wafer is stored after exposure is completed.
7.

The unloader section 17 and the loader section 13 are provided with an unshader (not shown), which allows the wafer to be moved from the cartridge 12 to the temporary positioning table 14 and from the sub-exposure section 1 to the cartridge 16.

The stepper 10 places the wafer 1 and moves it to X, Y.
It has a movable stage 18 that can move in two directions, and further in the θ direction, and an optical system 20 that reduces and projects a reticle 19 on which a chip pattern is formed. This optical system 20 includes a light source 21.degree. condenser lens 22. Reduction imaging lens 23. Furthermore, a shutter (not shown) or the like is provided to reduce the size of the pattern on the reticle 19 and perform image projection exposure onto the wafer 1.

In conjunction with the operation of the movable stage 1B, a plurality of chip patterns 1b are arrayed and exposed in a grid pattern on the wafer 1 (see FIG. 1).

The sub-exposure section 11 includes a fixed stage 24 for roughly positioning the wafer 1 using an orientation flat, a mask 25 for projecting a mask pattern onto the surface of the wafer 1 on the fixed stage 24, a lamp 26, and a condenser lens 27. The illumination system 28 exposes the pattern of the mask 25 onto the wafer 1. Like the reticle 19, the mask 25 has a structure in which a metal film such as Cr is patterned on a transparent substrate. The pattern of the mask 25 in this example is as shown in FIG.
A portion of the wafer 1 that is to be exposed to the chip pattern 1b is covered with a mask 25aL, and only the peripheral portion 1a of the wafer 1 other than the chip pattern 1b can be irradiated with light, that is, exposed.

Next, an example of the method of the present invention using the apparatus configured as described above will be explained.

A wafer 1 to be processed has a metal film formed on the entire surface as a lower layer film, and a positive type 7 photoresist film is formed thereon. The wafer 1 is transferred from the cartridge 12 of the loader section 13 onto the temporary positioning table 14, and after being temporarily positioned using the orientation flat, the rotary transfer arm 15
is placed on the movable stage 18 of the stepper 10. The X and Y movements of this stage 18 and the optical system 2
A plurality of chip patterns 1b are arranged and exposed in a square pattern on the surface of the wafer 1 by the cooperation of the projection action of 0. In this case, the chip patterns are exposed so that each has a perfect shape, and therefore, the periphery of the wafer, which has a chipped shape due to the arcuate sides, is not exposed. After this exposure is completed, the wafer 1 is transferred by rotation. It is transferred to the sub-exposure section 11 by the arm 15.

In the sub-exposure section 11, the wafer 1 is placed on a fixed stage 24, and approximately positioned using its orientation flat. Then, the mask 25 is positioned in advance with respect to the fixed position.
is placed on the wafer 1, and the wafer 1 is exposed to light using the illumination system 28. As a result, only the peripheral portion 1a of the wafer 1 other than the chip pattern 1b is irradiated with light at once.The wafer 1 on which the sub-exposure has been completed is stored in the cartridge 16 of the unloader section 17. Note that during this sub-exposure, the chip pattern of the next wafer 1 is exposed in the stepper 10 to improve processing efficiency.

The wafer 1 that has been exposed as described above is then subjected to a photoresist development process, but this is because the photoresist other than the chip pattern 1b of the wafer 1 has been exposed by sub-exposure.

In this development process, the photoresist in the core portion is removed and the underlying metal film is exposed. Therefore, in the next etching step, usually dry etching, all of the AA film in this area will be etched away.

As a result, the blade does not become clogged in the subsequent dicing process, and the wave does not become curved due to thermal stress after etching. On the other hand, since a relatively large area (periphery) of the metal film is etched even during dry etching, the etching end point can be detected with high precision.

〔effect〕

(1) Since the areas other than the nap pattern are exposed all at once before and after the exposure of the chip pattern, the positive photoresist is removed by development, and the underlying film in areas other than the chip pattern is removed during the etching process. can.

(2) According to (1) above, there is no need to cut the lower layer film at the periphery of the wafer during chinobutding, and even when a metal film is used as the lower layer film, clogging of the dicing blade does not occur.

(3) According to (1) above, thermal stress is not generated between silicon and a lower layer film such as a metal film in the periphery of the wafer, and wafer bending can be prevented.

(4) Since the lower layer film around the wafer is dry-etched, the etching area can be increased and the accuracy of detecting the end point of etching can be improved.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, a sub-exposure section may be provided in front of the stepper, and the peripheral portion may be exposed all at once before exposing the chip pattern. Further, a part of the optical system of the stepper may be changed so that the peripheral portion can be exposed at once at substantially the same time as the exposure by the stepper.

[Application field]

In the above explanation, the invention made by the present inventor is mainly applied to the field of application which is the background of the invention, which is an exposure technique using a stepper in units of one chip. However, the present invention is not limited to this. The present invention can be similarly applied to an exposure method using a stepper that exposes several chips at the same time.

[Brief explanation of drawings]

FIG. 1 is a wafer plan view for explaining the chip pattern and peripheral area on the wafer. FIG. 2 is a perspective view of the overall configuration of an apparatus for carrying out the method of the present invention, and FIG. 3 is a plan view of a mask. DESCRIPTION OF SYMBOLS 1... Wafer, 1a... Peripheral part, 1b... Chip pattern, 10... Stepper, 11... Sub-exposure part, 13... Loader part, 14... Temporary positioning table, 15 ... Rotating transfer arm, 17... Unloader section,
19... Reticle, 20... Optical system, 25... Mask, 28... Illumination system. Figure 1) /4 Figure 3 S

Claims (1)

[Claims] 1. Selective exposure of a chip pattern on a wafer. 1. A photographic processing method characterized in that when performing a lithography process, light is irradiated all at once to areas other than the exposed area of the chip pattern before and after exposing the chip pattern. 2. Form a positive photoresin film on the wafer. 2. The photographic processing method according to claim 1, wherein the chip pattern exposure and light irradiation are performed on the photoresist film at the same time.