JPS62189733A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To simplify an amendment of displacement of a mask by measuring a reflected light reflected from a semiconductor substrate through an optical discolored film between the substrate and the mask to detect the displacement of the mask, thereby eliminating a development. CONSTITUTION:When an i beam projected from a light source is emitted from X toward a direction X' and a reflected light is measured, the level of the reflected light is altered in a boundary of a pattern 7 formed in the previous step on a silicon substrate 1. The position where the level alteration crosses a slice level S is detected to measure the distance xa between points x1 and x2 and the distance xb between points x3 and x4. When it is designed that the center of an exposure portion 6 is superposed on the center of the pattern 7 already formed, the displacement DELTAx in x-axis direction can be calculated by xa-xb, and the displacement DELTAY in Y-axis direction can be similarly measured. When the displacements DELTAX, DELTAY of superposing photomasks are obtained, the displacement may be amended, and after the amendment, remaining shot is exposed on other positions 4a, 4b....

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and in particular to a method for manufacturing an exposure mask by measuring the reflected light from a semiconductor device of light transmitted through a photobleaching film. The present invention relates to a method for manufacturing a semiconductor device that allows easy alignment.

[Conventional technology]

As a method for mask alignment in conventional semiconductor device manufacturing methods, for example, the mask and semiconductor substrate are placed parallel to each other by a minute distance, and the enlarged image is viewed with a microscope while being
There are some that perform alignment in the axis, Y axis, and rotational direction. By this mask alignment, it is possible to prevent the relative positions of the pattern already formed on the semiconductor substrate and the pattern to be formed next from being misaligned, and it is possible to manufacture a semiconductor device with a predetermined pattern.

[Problem that the invention seeks to solve]

However, according to the mask alignment method in the conventional semiconductor device manufacturing method, certain factors (for example, deformation of the pattern on the semiconductor substrate, distortion of the mask or lens system, misalignment of the optical axis, A misalignment may occur between the pattern on the semiconductor substrate and the exposed pattern due to misalignment, etc., and this misalignment cannot be detected unless it is developed after exposure (this detection corrects the misalignment).

[Problem that the invention seeks to solve]

The present invention has been made in view of the above, and in order to detect misalignment before development and easily correct it, a photobleachable film provided between a semiconductor substrate and a mask is provided. The present invention provides a method for manufacturing a semiconductor device in which reflected light reflected from a semiconductor substrate is measured.

〔Example〕

The method for manufacturing a semiconductor device according to the present invention will be explained in detail below.

Figure 1 shows a reduction projection exposure system, for example, i-line (wavelength 3
65m+), a condensing lens 12 that condenses the projected light, and a photomask 13 having a predetermined exposure pattern and a correction pattern at a position shifted by a minute distance from this exposure pattern to correct the shift. , photomask 13
The wafer 15 has a reduction lens system 16 that reduces the pattern light transmitted through the wafer 15 to a predetermined magnification and forms an image on a predetermined position 4 of a wafer 15 placed on a stage 14.

FIG. 2(a) shows a wafer 15 placed on a stage 14, with a silicon substrate 1 having a pattern formed in the previous step and a positive photoresist 2 coated thereon.
and a photobleaching film 3 coated on this photoresist 2. When this photobleaching film 3 is irradiated with light, the i-line transmittance changes from about 2% to 85%, and C
EL-388 (SST Japanese version 1985/July issue 5
(see page 8) is appropriate.

Further, the photomask 13 has a pattern for performing shot exposure drawn at the center position 4 of the wafer 15 shown in FIG. It is depicted. This correction pattern has a rectangular exposed portion 6 within the unexposed portion 5, as shown in FIG. 2(C).

In the above configuration, after the wafer 15 is placed on the stage 14 and aligned, one shot exposure is performed at the center position 4. At this time, the photobleachable film 3 is irradiated through the exposed portion 6 of the correction pattern, and the light transmittance of the area corresponding to that portion increases. Here, the i-ray is irradiated in the direction from X to X'' and the reflected light is measured.

Figure 2 (Curve R below C1 indicates the level of reflected light;
The level of reflected light changes at the boundary of the pattern 7 formed on the silicon substrate 1 in the previous step. The position where this level change crosses the slide level S is detected, and the distance x1 between points x1 and x2 and the distance xb between points X and x4 are measured. If the design is made so that the center of the exposure area 6 and the center of the pattern 7 that has already been formed overlap, the amount of deviation in the X-axis direction ΔX
can be calculated using x and -Xb. In the same way, the amount of deviation ΔY in the Y-axis direction can also be measured.

Once the amounts of deviation ΔX and ΔY in the overlapping of the photomasks 13 are determined in this way, the deviation can be corrected.

After this correction, as shown in FIG.
The remaining shots are exposed at other positions 4a, 4b of 5.

In the above embodiments, the photobleachable film 3 is used as the first resist 2.
Although the coating is applied above, the present invention is not limited thereto (in FIG. 1, it may be applied to any position on the optical path connecting the photomask 13 and the wafer 15).

〔Effect of the invention〕

As explained above, according to the method of manufacturing a semiconductor device of the present invention, the reflected light transmitted through the photobleachable film provided between the semiconductor substrate and the mask and reflected from the semiconductor substrate is measured to determine the misalignment of the mask alignment. Since this is detected, the need for development can be eliminated and the correction can be easily performed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a reduction projection exposure system. Figure 2 (al~
(d+ is an explanatory diagram showing one embodiment of the present invention. Explanation of symbols 1--1--Half quadrilateral board 2----
---Photoresist 3--1.-Photobleachable film

Claims (1)

[Claims] A method for manufacturing a semiconductor device in which a photoresist on a semiconductor substrate is exposed to light based on a pattern drawn on a photomask, the photomask including a correction mask having an exposure portion of a predetermined shape. forming a photobleachable film that increases light transmittance upon exposure between the photomask and the photoresist; exposing the photobleachable film to light through the exposed portion of the photomask; The method is characterized in that the light transmitted through a portion of the fading film whose light transmittance is increased by exposure to light is first reflected by the semiconductor substrate on which a pattern is formed, and the misalignment of the mask alignment is detected by this reflected light. A method for manufacturing a semiconductor device.