JPH01255221A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the effect for suppressing the occurrence of defects on chips so that the effect is equal to or higher than the effect in a double-diffusion method only by one alignment, by projecting light by using an exposure mask on a semiconductor wafer on which a resist film is applied, moving. the relative positions of the exposure mask and the semiconductor wafer by integer times of a chip size, and projecting the light. CONSTITUTION:A resist film is applied on a semiconductor wafer 2. Thereater light is projected on the semiconductor wafer 2 by using one exposure mask 1. Thus, a first exposure step is performed. Then, the relative positions of the exposure mask 1 and the semiconductor wafer 2 are moved by the integer times of a chip size, and the light is projected. Thus, a second exposure step is performed. For example, the negative resist film is applied on the semiconductor wafer 2. Then, the exposure mask 1 and the semiconductor wafer 2 are accurately aligned; the first exposure step is performed. Then, the exposure mask 1 which is used in the first exposure step is shifted by one-chip size on the semiconductor chip 2. Under this state, the second exposure step is performed. Thereafter, the resist which is not exposed to the light is dissolved with solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a pattern on a semiconductor wafer.

[Conventional technology]

Conventionally, the method for forming patterns on semiconductor wafers is as follows:
Photo-etching involves exposing a resist film coated on a semiconductor wafer surface to light through an exposure mask (hereinafter referred to as a mask) with a pattern formed on glass, and selectively dissolving either the exposed or non-exposed areas with a solvent. law is used.

However, if there is an abnormality in the mask pattern, this abnormality will also be transferred onto the semiconductor wafer surface, resulting in a defective chip.These pattern defects are not an abnormality in the mask itself, but are caused by the mask. The main cause of pattern defects is attached dirt, and other causes include scratches on the mask surface due to contact between the mask and the semiconductor wafer, and cracks generated in the glass substrate of the mask.

Since these pattern abnormalities cause the production of defective chips, the occurrence of such defective chips is usually suppressed by a means called a double exposure method. In this method, a first resist film is first applied onto a semiconductor wafer and exposed using a first mask, and then a second resist film is applied and exposure using the second mask is performed again. At this time, the first mask and the second mask may have the same pattern or may have different patterns, but it is necessary that the first mask and the second mask are not necessarily the same. The reason for this is that if the same mask is used, the defective positions of the mask will overlap in the first exposure process and the second exposure process, so that the defects will not be reduced. If the two masks are different, the defective positions of the patterns will also be different, so if this double exposure method is used, chip defects will almost never occur.

[Problem to be solved by the invention]

As described above, although the above-mentioned double exposure method is recognized to be highly effective, it is only used in some processes, and the reason for this is that the number of exposure steps is doubled. In order to perform exposure, alignment is required, but this alignment is performed for each wafer, which increases the number of exposure steps. This increases costs.

In view of the above-mentioned circumstances, an object of the present invention is to provide a method for manufacturing a semiconductor device that can obtain an effect of suppressing the occurrence of chip failures that is equal to or greater than that of the double diffusion method only by a -degree of alignment.

[Means to solve the problem]

According to the present invention, a method for manufacturing a semiconductor device includes a step of applying a resist film to a semiconductor wafer, a first exposure step of irradiating light onto the semiconductor wafer using one exposure mask, and a step of applying light to the semiconductor wafer using the exposure mask. and a second exposure step in which the relative positions of the semiconductor wafers are moved by an integral multiple of the chip size and irradiated with light.

〔Example〕

FIG. 1 and FIG. 2 do not show one embodiment of the present invention, but are diagrams of a semiconductor wafer exposure process. According to this embodiment, the first
As shown in the figure, after aligning the exposure mask 1 and the semiconductor wafer 2 accurately, the exposure process of the cylinder 1 is performed. FIG. 1 shows the positions of the wafer 2 and the mask 1 during this first exposure process. Each grid drawn on the mask represents one chip.

FIG. 2 shows a state in which the second exposure process is performed with the exposure mask 1 used in the first exposure process being shifted by one chip size on the semiconductor chip 2. The method of shifting at this time may be to move the exposure mask 1 or to move the wafer 2, and any method may be used as long as the first exposure process and the second exposure process can be performed while accurately overlapping each other. For example, when moving wafer 2, first align the moving direction of the stage (not shown) on which wafer 2 is placed with the repeating direction of mask 1, and then Perform alignment exposure of
Then, the stage may be shifted to the left by the chip size and a second exposure may be performed.

In actual work, after a negative type resist film is applied to the wafer 2, the first exposure and the second exposure are performed using the method described above. Thereafter, the resist in the areas that will not be exposed to light is dissolved using a solvent. At this time, even if there is dirt, scratches, or other contamination on the mask, one mask pattern will have the same shape for each chip, but the other mask pattern will have a different shape. Therefore, even if a position that should be exposed in the first exposure step remains unexposed due to dirt such as dust, it will be exposed in the second exposure step, so the pattern on the exposed area will not be affected by dust etc. The perfect shape is exposed.

FIG. 3 is a diagram showing a semiconductor wafer exposure process using a mirror projection exposure machine showing another embodiment of the present invention.

This embodiment has no process limitations from the previous embodiments, except that the semiconductor wafer 2 and the exposure mask 1 are not in close contact with each other but are separated from each other. In the case of this embodiment as well, by matching the moving direction of the wafer stage and the repeating direction of the mask 1 before performing the first exposure step, the second exposure step can be performed accurately without alignment. becomes possible.

〔Effect of the invention〕

As explained in detail above, according to the present invention, in forming a pattern on a semiconductor wafer, by performing two exposure steps shifted by one chip size, it is possible to reduce the defective rate and improve reliability. . In this exposure step, alignment only needs to be done once at the beginning, so it is possible to obtain a semiconductor device that is inexpensive and highly reliable. In addition, as a side effect, if an automatic alignment target is inserted into the mask, if the method of shifting is devised during alignment, the target will not be transferred to the wafer, so alignment can be done multiple times using the same pattern. Therefore, there is an advantage that the area of the target portion can be reduced.

Although the above example uses a contact print and mirror projection exposure machine, it is clear that the present invention can also be implemented in a stepper or ion beam exposure process. Further, the same effect can be obtained not only by shifting by one chip but also by shifting by an integral multiple of the chip length, or by performing the exposure process not only twice but several times.

[Brief explanation of the drawing]

1 and 2 are diagrams of a semiconductor wafer exposure process showing one embodiment of the present invention, and FIG. 3 is a diagram of a semiconductor wafer exposure process using a mirror projection exposure machine showing another embodiment of the present invention. . 1... Exposure mask, 2... Semiconductor wafer, 3...
Optical system, 4... light source.

Claims (1)

[Claims] a step of applying a resist film to a semiconductor wafer; a first exposure step of irradiating light onto the semiconductor wafer using one exposure mask; and adjusting the mutual position of the exposure mask and the semiconductor wafer by an integral multiple of the chip size. a second exposure step of irradiating light while moving the semiconductor device.