KR100215897B1 - Method of forming overlay pattern used in measuring alignment - Google Patents

Abstract

The present invention relates to an overlay pattern for measuring alignment of semiconductor devices, and more particularly, to a method for forming an overlay pattern for measuring alignment, which is suitable for measuring alignment of three layers.

According to the present invention, there is provided a method of forming an overlay pattern for measuring alignment, forming a hollow outer box on a semiconductor substrate, forming an insulating film on the entire surface of the outer box, and forming an insulating film on the insulating film. Positioning a small inner box in the outer box forming region, applying a photoresist to the entire surface of the insulating film including the inner box, and selectively exposing and developing the photoresist to form an outrigger-shaped middle bar above the outer box forming region. Including the step to reduce the shot (shot) process on the wafer (wafer) has the effect of improving the yield of the wafer.

Description

How to form an overlay pattern for measuring alignment

The present invention relates to an overlay pattern for measuring alignment of semiconductor devices, and more particularly, to a method for forming an overlay pattern for measuring alignment, which is suitable for measuring alignment of three layers.

Generally, several masks are needed to make a semiconductor device. When a mask is formed on a wafer and then exposed using a stepper, it is necessary to check whether the underlying pattern is correctly aligned. Do.

An overlay pattern is formed to confirm such an overlay pattern. The overlay pattern is used for measuring overlays on the above-described area with a scribe lane or a test die area between the main chips on the wafer. A pattern is formed to measure the degree of alignment of the semiconductor device. In this measurement method, the box-in-box type is generally used to measure the overlay between two layers. The characteristic of the box-in-box type is that the inner box smaller than the hollow outer box and the outer box are placed in the outer box. The overlay between the two layers is measured.

Hereinafter, a method of forming an overlay pattern for measuring conventional alignment degree will be described with reference to the immersed drawings.

1A to 1F are cross-sectional views and plan views of a process of forming an overlay pattern for measuring conventional alignment.

First, as shown in FIG. 1A, a hollow outer box 2 is formed on a predetermined region of the semiconductor substrate 1. At this time, the outer box 2 uses a film in the preceding process. In this case, the outer box 2 is a first overlay measurement target for measuring the degree of alignment. In this standard design of the first outer box 2, the hollow hole is about 20 mu m, and one side of the first outer box 2 has a length of about 30 to 40 mu m.

As shown in FIG. 1B, after forming a first film 3 on the entire surface of the semiconductor substrate 1 including the first outer box 2, a first photoresist is formed on the first film 3. (4) is applied.

As shown in Fig. 1C, the first photoresist 4 is patterned to have a smaller area than the first outer box 2 in the exposure and development processes to form a first inner box 4a. At this time, the standard design of the first inner box 4a is formed such that one side of the first inner box 4a has a length of about 10 μm. The first inner box 4a is a second overlay measurement target. By forming the first outer box 2 and the first inner box 4a as described above, a box-in-box overlay pattern is used to measure the degree of alignment between the two layers. The forming process was completed. However, a first photoresist for forming a second outer box other than the first inner box 4a on another region of the semiconductor substrate 1 in order to measure the degree of alignment for layers other than the two layers as described above. The pattern 4b was formed.

As shown in FIG. 1D, the first film 3 under the first photoresist pattern 4b is formed as the second outer box 3a by an etching process using the first photoresist pattern 4b as a mask. . In other words, a third overlay measurement target was formed. At this time, the first film 3 under the first inner box 2 is an etching layer irrelevant to the overlay measurement target.

As shown in Fig. 1E, the first photoresist pattern 4b is removed. At this time, the first inner box 4a made of photoresist is also removed at the same time. Next, a second film 5 is formed on the entire surface including the first outer box 2, the second outer box 3a, and the semiconductor substrate 1. Subsequently, a second photoresist 6 is applied onto the second film 5.

As shown in FIG. 1F, the second photoresist 6 is patterned to a width smaller than that of the second outer box 3a by the exposure and development processes to form a second inner box 6a. That is, the fourth overlay measurement target is formed. As described above, in the method of forming an overlay pattern for measuring the degree of alignment, a box-in-box type alignment chart requiring four alignment charts in order to measure the alignment of three layers. Two measurement targets were formed to measure the degree of alignment of the preceding and subsequent steps.

In the conventional method for forming the overlay pattern for measuring the degree of alignment, a target corresponding to all the layers for measuring the overlay must be formed, thereby increasing the area where these overlay measurement targets are formed. That is, because of the above reasons, an additional area other than the area occupied by the actual main chip is required, and as a result, the size of the shot (exposure) implemented on the wafer increases, ultimately yield of the wafer. This deterioration problem occurred.

The present invention has been made in order to solve the problems of the conventional method for forming the overlay pattern for measuring the degree of alignment as described above, the overlay pattern for measuring the degree of alignment of the overlay measurement target from the box-in-box type to three layers An object of the present invention is to provide an overlay pattern forming method for measuring the degree of alignment.

1A to 1F are cross-sectional views and plan views of an overlay pattern forming process for measuring a conventional alignment

2A to 2E are cross-sectional views and plan views of an overlay pattern forming process for measuring alignment of the present invention;

Explanation of symbols for main parts of the drawings

10 semiconductor substrate 11: outer box

12: first act 13a: inner box

14 second photoresist 15 outrigger type middle bar

According to the present invention, there is provided a method of forming an overlay pattern for measuring alignment, forming a hollow outer box on a semiconductor substrate, forming an insulating film on the entire surface including the outer box, and having an inner smaller than the outer box on the insulating film. Positioning a box in an outer box forming region, applying a photoresist to the entire surface of the insulating film including the inner box, and selectively exposing and developing the photoresist to form an outrigger-shaped middle bar above the outer box forming region. It includes.

Such a method of forming an overlay pattern for measuring alignment of the present invention will be described with reference to the submerged drawings.

2A to 2E are cross-sectional views and plan views of an overlay pattern forming process for measuring alignment of the present invention.

First, as shown in FIG. 2A, a hollow outer box 11 is formed on a predetermined region of the semiconductor substrate 10. At this time, the outer box 11 is used by selectively patterning the film (photolithography process + etching process) in the previous step. In this case, the outer box 11 is a first overlay measurement target for measuring the degree of alignment.

As shown in FIG. 2B, a first film 12 is formed on the entire surface of the semiconductor substrate 10 including the outer box 11, and then a first photoresist 13 is formed on the first film 12. ) Is applied.

As shown in FIG. 2C, an inner box 13a is formed by patterning the first photoresist 13 to have an area smaller than that of the outer box 11 by an exposure and development process. At this time, such an inner box 13a is a second overlay measurement target. The formation process of the box-in-box overlay pattern for measuring the degree of alignment between the two layers was completed by the process of forming the outer box 11 and the inner box 13a as described above. . At this time, unlike the conventional process, the process of forming the first photoresist pattern for forming the outer box for the other area of the semiconductor substrate 10 for measuring the alignment degree for the other layers other than the two layers was not performed.

As shown in Fig. 2D, two photoresists 14 are formed on the first film 12 including the inner box 13a.

As shown in FIG. 2E, the second photoresist 14 on the upper layer of the outer box 11 forming region is partially removed in the form of an outrigger type middle bar 15 by the exposure and development processes. 3 Form an overlay measurement target. At this time, the outrigger type middle bar 15 is formed to be narrower than the width of the outer box 11 of the lower. In addition, in order to suppress an error in the overlay measurement between the outrigger type middle bar 15 and the outer box 11, the outer surface of the outrigger type middle bar 15 and the outer side of the outer box 11 have a distance of about 3 μm. Keep your car. Due to the present invention, in order to measure the alignment of three layers, the overlay measurement target should be formed as an overlay measurement target in the form of two box-in-boxes, but in the present invention, one box-bar-box (Box- The overlay pattern target in the form of a bar-box can measure the alignment of three layers.

In the method for forming the overlay pattern for measuring the degree of alignment according to the present invention, two box-in-box type overlay measurement targets are required to measure the overlay pattern between three layers to be aligned, but in the present invention, one box-bar Box-Bar-Box type overlay pattern targets can measure the alignment of three layers, forming these overlay measurement targets in one shot. The yield is improved.

Claims (2)

Forming a hollow outer box on the semiconductor substrate; Forming an insulating film on the entire surface including the outer box; Positioning an inner box in the outer box forming region on the insulating film, the inner box being smaller than the outer box; Applying a photoresist to the entire surface of the insulating film including the inner box; Selectively exposing and developing the photoresist to form an outrigger-shaped middle bar over the outer box formation region. The method of claim 1, wherein the outer surface of the middle bar of the outrigger shape is formed at a distance difference of 3 μm from the outer surface of the outer box.