KR20050064596A - Method of measuring overlay by using vernier of organic film - Google Patents

Abstract

The present invention relates to a method for measuring the degree of overlap using an organic film vernier, a first step of coating an organic film on top of the parent vernier having an etch slope; a second step of depositing a photoresist on the organic film ; Etching the organic layer through the photoresist exposure, and vertically etching the organic layer in a form including the inclination of the parent vernier; A fourth step of forming the ruler vernier on an upper portion of the parent vernier layer exposed through an etching process; And a fifth step of measuring a degree of overlap between the parent vernier and the vernier by sensing a signal peak.

Description

Method of measuring overlay by using vernier of organic film}

The present invention relates to a method for measuring the degree of overlap using an organic layer, and in particular, when a slope is formed during etching of a lower pattern, the degree of overlap between the lower pattern and the upper pattern is measured after covering the slope using the organic layer. It is about a method.

In general, in the process of manufacturing a semiconductor device, the deposition process and the etching process are repeated to form a single device by overlapping a plurality of deposition films. Here, in order to deposit the upper pattern on the lower pattern, an alignment process between the lower pattern and the upper pattern is performed. In particular, a mother vernier of the lower pattern and the child vernier of the upper pattern are performed through a lithography process. This is done by measuring the degree of overlap between child verniers.

According to the conventional method of measuring the degree of overlap, as shown in FIG. 1A, a photoresist (PR) 2 is deposited on the semiconductor device substrate 1, and a desired pattern is formed on the PR through an exposure process.

Thereafter, an etch process forms a lower parent vernier 1 'and removes the remaining PR (FIG. 1b).

Then, a ruler (3) is formed on the etched parent vernier (1 ') (FIG. 1C).

The degree of overlap between the parent vernier (1 ') and the child vernier (3) is measured. In general, as shown in FIG. 2D, the peak value of the signal is sensed to determine the degree of deviation between the parent vernier (1') and the child vernier (3). Measured (FIG. 1D).

However, according to this conventional technique, due to the etching characteristics, a slope is generated in the etching cross section of the parent vernier (1 '), and when such an inclination occurs, the inclined portion as shown in FIG. Because noise is generated in the signal for, the accurate superimposition cannot be measured.

In particular, the parent vernier (1 ') is generally formed of a metal oxide film such as oxide, nitride, Al, and the like, and since the metal oxide material has a high reflectance, noise due to diffuse reflection is additionally generated during the overlap measurement. There is a problem that cannot be accurate in the measurement results.

As a result, accurate alignment cannot be performed, and in some cases, a short column fail occurs, resulting in a decrease in the reliability or yield of the process of the entire semiconductor device.

Focusing on the problems of the prior art, the present invention eliminates the inclination of the parent vernier by stacking the organic film on the top of the parent vernier at right angles, thereby eliminating not only the noise signal generated from the metal oxide but also the noise signal caused by the inclination. The purpose.

In order to achieve this object, the present invention is a method for measuring the degree of overlap between the parent vernier and the child vernier made of a metal oxide, the method comprising: a first step of coating an organic film on top of the parent vernier having an etching slope; Depositing a photoresist on the organic layer; Etching the organic layer through the photoresist exposure, and vertically etching the organic layer in a form including the inclination of the parent vernier; A fourth step of forming the ruler vernier on an upper portion of the parent vernier layer exposed through an etching process; And a fifth step of measuring a degree of overlap between the parent vernier and the vernier by detecting a signal peak.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

First, since the process of forming the basic structure of the parent vernier is the same as the conventional method, a detailed process will be omitted, and refer to FIGS. 1A and 1B.

As described above, in a state in which the structure of the parent vernier 10 is already formed, the organic film 20 is coated on the parent vernier 10 (FIG. 3A). Here, since the deposited organic film has almost no light reflectance, the noise problem due to reflection can be solved. According to a preferred embodiment of the present invention, the organic film is not limited to any particular kind and may be any one as long as there is little light reflectance. In addition, the thickness of coding the organic film 20 may be reduced to 300 to 1000 mW.

Then, the PR 30 is coated on the organic film 20, and the organic film is etched by exposing the PR (FIG. 3B).

After the etching process, as illustrated in FIG. 3C, the organic layer 20 is vertically formed on the inclined etching portion of the parent vernier 10. Therefore, the noise problem due to the slope can be solved.

Thereafter, a ruler 40 is formed on the parent vernier 10 (FIG. 3D), and the degree of overlap is measured.

According to the above-described configuration, the noise problem generated in the metal oxides on the left and right sides of the parent vernier can be solved through the organic layer, and in particular, the noise problem due to the etching slope of the parent vernier can be solved, so that the lithography overlap is measured. In this case, the effects of errors that may occur can be eliminated, thereby reducing the possibility of a short with a sub pattern in a subsequent photo process, thereby improving device characteristics and process yield.

1A to 1D illustrate a method of measuring overlapping according to a conventional scheme.

Figure 2 shows a problem according to the conventional scheme.

3A to 3D are diagrams illustrating a method of measuring overlapping degree according to the present invention.

Claims (2)

In the method for measuring the degree of overlap between the parent and child vernier consisting of metal oxides, A first step of coating an organic layer on top of the parent vernier having an etching slope; Depositing a photoresist on the organic layer; Etching the organic layer through the photoresist exposure, and vertically etching the organic layer in a form including the inclination of the parent vernier; A fourth step of forming the ruler vernier on an upper portion of the parent vernier layer exposed through an etching process; And A fifth step of measuring a degree of overlap between the parent vernier and the vernier by detecting a signal peak Method comprising a. The method of claim 1, In the second step, the thickness of the coating of the organic film is characterized in that 300 to 1000 mm.