JPS5963728A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To perform positioning of high accuracy by using the first exposure mask and the second exposure mask which has a projected part extending from the reduced main part and the main part of an alignment mark for the former mask over the alignment mark. CONSTITUTION:The alignment mark 4 for the second exposure mask 7 is projected out of the algnment mark 5 for the first exposure mask 6 at the parts 10, and is small except them. The mark 4 is made to coincide, by the mark 5 for the mask 6, with a target mark formed on a semiconductor substrate. In other words, the center 8 of the mark 5 is made to agree with the center 9 of the mark 4. When the dimensional difference between the target mark on the semiconductor substrate and the projected parts 10 are determined with high accuracy, the masks can be superposed with high accuracy by the projected parts 10. Besides, the using order of the first and second masks can be exchanged to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a semiconductor device that requires multiple photo-etching operations, and more specifically, to a method of manufacturing a semiconductor device that requires complex and highly accurate alignment of an exposure mask. The present invention relates to a manufacturing method using an exposure mask having alignment marks used in

Conventional Structures and Problems In general, in the manufacturing technology of semiconductor devices, for example, in the case of bipolar transistors, photolithography is used in each of the above steps to perform base diffusion, emitter diffusion, contact hole formation, electrode wiring, etc. Each time the work is performed, it is necessary to align the position with the semiconductor substrate using a different exposure mask for each process.

A conventional method for aligning multiple types of exposure masks for each process will be explained using FIGS. 1 and 2. First, when a photolithography process is performed using a first exposure mask, a first rectangular hole 2 with a small diameter is formed in an insulating film 1 on the surface of a semiconductor substrate, as shown in FIG. Next, photolithography is performed using the first hole 2 as a reference and aligning it with the alignment mark 3 of the second exposure mask. At this time, in the case of Fig. 1, a positive photoresist is applied to leave the insulating film outside the alignment mark 3, but the alignment mark 3 must be made larger than the first hole 2. I can't see it and can't match it. In the case of FIG. 2, a negative photoresist is used to leave the insulating film outside the first hole 2, and the second exposure alignment mark 3 must be made smaller than the first hole 2. I can't make eye contact between the marks.

As described above, the size of the alignment marks on conventional exposure masks is determined by the type of photoresist used, so the second exposure mask cannot be used before the first exposure mask. In order to eliminate this drawback, conventionally, multiple alignment marks are provided on the same exposure mask.
These alignment marks were different in size from the alignment marks of the next exposure mask, one alignment mark was larger than the alignment mark of the first mask, and the other alignment mark was smaller than the alignment mark of the first mask. things have been used. However, this method requires a plurality of alignment marks, which increases the area for alignment marks.

OBJECT OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and is capable of minimizing alignment marks and highly accurate mask alignment when the second exposure mask is used before the first exposure mask. It is an object of the present invention to provide a method for manufacturing a semiconductor device that makes it possible to perform the following steps.

Structure of the Invention The present invention provides an alignment mark on a second exposure mask that is proportionally reduced in proportion to the alignment mark on the first exposure mask, and a main part in which the alignment mark on the first exposure mask is proportionally reduced. The present invention provides a method for manufacturing a semiconductor device, characterized in that an exposure mask having a protruding portion extending beyond the alignment mark of the first exposure mask from the main portion is used. According to this configuration, when the first and second exposure masks are overlapped, the alignment marks of the other pair form the inner and outer edges of the reduced main part and the protruding part, so the alignment order of the rain exposure masks can be changed. It is also possible to use them interchangeably.

DESCRIPTION OF THE EMBODIMENTS FIG. 3 shows the alignment mark of the exposure mask according to the embodiment of the present invention, in which alignment mark 4 of the second exposure mask is superimposed on alignment mark 6 of the first exposure mask. be. That is, the alignment mark 4 of the second exposure mask is proportionally reduced with respect to the alignment mark 6 of the first exposure mask.
a and a protruding portion 4b.

4 and 6 are diagrams showing the overlapping of exposure masks according to an embodiment of the present invention. In FIG. 4, 6 is a first exposure mask, and 7 is a second exposure mask. . Fifth
The figure is the same as each exposure mask used in FIG. 4, but the overlapping order is reversed.

First, FIG. 4(a) shows the alignment mark portion of the first exposure mask 6, and the semiconductor layer corresponding to the alignment mark 6 is shown.

The alignment marks or target marks on the body substrate are formed by photolithography. The mask alignment operation is performed by etching the alignment mark 4 of the second exposure mask 7 onto a predetermined semiconductor substrate using the alignment mark 6 attached to the first exposure mask 6, as shown in FIG. Align the mask to the target mark. This and 1 first exposure mask 60 alignment mark 6
The center point 8 of the alignment mark 4 of the second exposure mask 70 and the center point 9 of the alignment mark 4 of the second exposure mask 70 are the same point. ing. This protruding part 1
0 is achieved by precisely determining the dimension of the difference from the target mark on the semiconductor substrate, and by this protruding portion 1Q,
It becomes possible to superimpose the target mark with high precision.

On the other hand, FIG. 5(a) is the same mask as the second exposure mask shown in FIG. 4(b)K, and using this mask, a target mark having the same shape as this alignment mark 4 is photographed on a semiconductor substrate. Formed by etching. Then, in FIG. 5(b),
Superposition is performed using the same mask as the first exposure mask 6 shown in FIG. 4 (2L).

At this time, as in FIG. 4, the center points 9 and 8 of each mask alignment mark are the same point. In FIG. 5(b), the protruding portion of the alignment mark is 11, and this protruding portion 11 makes it possible to overlap the target mark on the semiconductor substrate with high precision.

In this example, the type of photoresist used for overlaying does not matter at all.

Effects of the Invention As described above, the present invention makes it possible to reverse the overlapping order of the first exposure mask and the second exposure mask, and to perform overlapping with high precision, thereby achieving excellent practical effects. It is something that you have.

[Brief explanation of the drawing]

1 and 2 are plan views in which a conventional exposure mask and a target mark are superimposed, and FIG. 3 is a plan view of a conventional exposure mask and a target mark, and FIG. A plan view of the alignment marks of the second exposure mask superimposed on each other, and FIGS. 4(a) and 6(b) and FIGS. 6(a) and 6(b) are planar process drawings that are not intended to explain the present invention in detail. . 4.6... Exposure mask alignment mark, 4a.
...Proportional reduction main part, 4b...Protrusion part, 6...First exposure mask, 7...Second
Exposure mask, 8, 9... Center point of the alignment mark, 10, 11... Protruding portion of the alignment mark. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] With respect to the alignment mark attached to the first exposure mask, a main part that is proportionally reduced in proportion to the alignment mark of the first exposure mask, and a part that exceeds the alignment mark of the first exposure mask from this main part. 1. A method for manufacturing a semiconductor device, characterized in that mask alignment is performed using a second exposure mask configured to have a protrusion.