KR100831675B1 - A photo mask for establishing a best focus and method of establishing best focus using the same - Google Patents

Abstract

Disclosed are a photomask and a method for setting the best focus, by which the best focus can be set for each area of a field without having to perform several CD measurements. The disclosed photo mask includes a quartz substrate and a plurality of inspection pattern portions disposed in a matrix form on the quartz substrate, wherein the inspection pattern portions are formed of first to fourth heavy inspection patterns in the form of stripes. The first heavy inspection pattern is composed of a plurality of first small patterns and a second small pattern having alternately 100% transmittance arranged side by side, the second heavy inspection pattern having a single small transmission having a transmittance of 6% The third heavy inspection pattern is composed of a plurality of third small patterns spaced at a distance having a 100% transmittance, and the fourth heavy inspection pattern has a 100% transmittance and is arranged alternately side by side. It consists of a plurality of fourth small patterns and fifth small patterns, each of the small patterns having a predetermined phase grating.

Photo Mask, Best Focus, Grating

Description

A photo mask for establishing a best focus and method of establishing best focus using the same}

1 is a plan view showing a photo mask for setting the best focus for explaining an embodiment of the present invention.

FIG. 2 is an enlarged plan view of the inspection pattern part of FIG. 1. FIG.

3A to 3D are graphs showing CD changes according to a focus offset when a photoresist pattern is formed with individual heavy inspection patterns constituting the inspection pattern portion.

The present invention relates to a mask and an inspection method using the same, and more particularly, to a mask for inspecting a best focus change of a semiconductor device and a method of inspecting a change of a best focus using the same.

In order to cope with high integration and miniaturization in semiconductor integrated circuits, miniaturization of patterns is rapidly progressing. In particular, photolithography has become a basic technique for forming patterns. The photolithography process is a technique of transferring a pattern on a mask to a photoresist coated on a wafer surface by an exposure apparatus as is well known.

The exposure apparatus includes a light source, an aperture, a lens, and a support on which the wafer is to be mounted, and a mask is interposed between the light source and the lens to transfer the pattern shape of the mask to the wafer (photoresist film on the wafer). do. At this time, the line width of the photoresist pattern is determined by the wavelength of the exposure source, the numerical aperture of the aperture, and the focal length. Since the wavelength of the exposure source and the aperture number of the aperture are factors already determined during the exposure process, it is important to form a fine pattern by adjusting the focal length.

Currently, the best focus is determined by measuring the CD (critical dimension) of the photoresist pattern formed through an arbitrary exposure process. More specifically, CDs of five or more photoresist patterns formed in one field are measured to set the best focus at each point of the field.

However, in the conventional method of setting the best focus, since CDs need to be measured several times for each focus offset in each area, the best focus measurement takes a long time and multiple CD measurements can cause errors in the CD measuring apparatus. .

Accordingly, it is an object of the present invention to provide a photomask and a method for setting the best focus by which the best focus can be set for each area of a field without having to perform several CD measurements.

In order to achieve the above object of the present invention, the present invention includes a quartz substrate, and a plurality of inspection pattern portions disposed in a matrix form on the quartz substrate, wherein the inspection pattern portions are first to fourth heavy inspection patterns in the form of stripes. The first heavy inspection pattern is composed of a plurality of first small pattern and the second small pattern having a 100% transmittance alternately arranged side by side, the second heavy inspection pattern of 6% The third heavy inspection pattern is composed of a single small pattern having a transmittance, and the third heavy inspection pattern is composed of a plurality of third small patterns spaced at a predetermined distance having a 100% transmittance, and the fourth heavy inspection pattern has a 100% transmission. And a plurality of fourth small patterns and fifth small patterns alternately arranged side by side, each of the small patterns having a predetermined phase grating.

The first small pattern, the pattern constituting the second medium pattern, the third small pattern, and the fourth small pattern have a g phase of g, the second small pattern has a grating of 3 p / 2, and a fifth small pattern. It is preferable to have a grating of (pi) / 2 phase.

The grating of each of the small patterns preferably has a width of 0.2 μm, a height and a spacing of 0.06 μm.

According to another aspect of the present invention, a method of setting a best focus includes performing exposure under a selected focus offset by using a mask arranged in a matrix form and including a plurality of inspection pattern portions formed of patterns having different best focuses. Measuring the CD distribution of the photoresist pattern formed by the exposure process, and setting the best focus for each field by the CD distribution of the photoresist pattern.

<Example>

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only the embodiments are to make the disclosure of the present invention complete, the scope of the invention to those skilled in the art It is provided to fully understand the present invention, the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

1 illustrates a photomask for setting a best focus according to the present invention.

Referring to FIG. 1, a plurality of test pattern parts 150 are formed on a quartz substrate 100. A plurality of test pattern parts 150 are arranged in a matrix form on the quartz substrate 100, and the test pattern parts 150 are formed of first to fourth medium test patterns 110, 120, 130, and 140.

As illustrated in FIG. 2, the first to fourth heavy inspection patterns 110, 120, 130, and 140 have a stripe shape spaced apart from each other.

In more detail, the first heavy inspection pattern 110 includes a plurality of first small patterns 111 and second small patterns 112 that are alternately arranged side by side. The first and second small patterns 111 and 112 have 100% transmittance, the first small pattern 111 has a g phase of π phase, and the second small pattern 112 has 3π / 2. Has a grating on the top. In this case, the grating has a width of 0.2㎛, height and spacing of 0.06㎛.

The second heavy inspection pattern 120 is composed of a single small pattern of 6% transmissive material, and the second heavy inspection pattern 120 has a g phase of?. The grating is designed to have a width of 0.2 μm, a height and a spacing of 0.06 μm.

The third heavy inspection pattern 130 is composed of a plurality of third small patterns 131 spaced apart from each other by a predetermined distance. The third small pattern 131 has 100% transmittance and has a g phase grating. In this case as well, the grating is designed to have a width of 0.2 μm, a height and a spacing of 0.06 μm.

The fourth heavy inspection pattern 140 includes a plurality of fourth small patterns 141 and a fifth small pattern 142 that are alternately arranged side by side. The fourth and fifth small patterns 141 and 142 have 100% transmittance, the fourth small pattern 141 has a g phase of π phase, and the fifth small pattern 112 has a π / 2. Has a grating on the top. In this case, the grating has a width of 0.2 μm, a height and a spacing of 0.06 μm.

3A to 3D are graphs showing CD changes according to a focus offset when a photoresist pattern is formed using the individual heavy inspection patterns 110 to 140.

3A to 3D, when the photoresist pattern is formed by the first heavy inspection pattern 110, the best focus according to the optimal pattern CD is 0.0 μm, and the second heavy inspection pattern 120 is In this case, the best focus was 0.025 μm, the best focus was 0.05 μm in the third heavy inspection pattern 130, and the best focus was 0.075 μm in the fourth heavy inspection pattern 140.

Based on this, by performing exposure under the selected focus offset with the photo mask of FIG. 1 and collectively measuring the CD of each pattern, it is possible to predict the CD distribution for each area of the field, thereby causing an image plane deviation. deviation at a glance.

In addition, since the difference in focus offset caused by the heavy inspection patterns 110 to 140 is 0.025 μm, respectively, as shown in FIGS. 3A to 3D, the CD formed by the heavy inspection pattern is measured and compared with the difference. You can also predict how far out of focus is in the field, so you can set the best best focus.

As described in detail above, the exposure is performed by a photomask in which a plurality of inspection pattern groups having different transmittances and grating distributions are formed, thereby deviating the best focus and image plane according to the photoresist pattern CD distribution obtained by the exposure process. You can check at a glance.

As a result, the best focus of the entire field can be confirmed, so that accurate best focus setting can be easily performed, and a plurality of pattern CD measurements can be prevented in a specific field area.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. .

Claims (4)

Quartz substrates; And an inspection pattern part disposed in plural in a matrix form on the quartz substrate, The inspection pattern portion may include first to fourth heavy inspection patterns in a stripe shape, and the first heavy inspection pattern may include a plurality of first small patterns and second small patterns having 100% transmittance alternately arranged side by side. Consists of patterns, The second heavy inspection pattern is composed of a single small pattern having a transmittance of 6%, The third heavy inspection pattern is composed of a plurality of third small patterns spaced at a distance having a 100% transmittance, The fourth heavy inspection pattern has a 100% transmittance and is composed of a plurality of fourth small patterns and fifth small patterns alternately arranged side by side, Each of the small patterns has a phase grating. The method of claim 1, The first small pattern, the pattern constituting the second medium pattern, the third small pattern, and the fourth small pattern have a g phase of g, the second small pattern has a grating of 3 p / 2, and a fifth small pattern. A mask, characterized in that it has a grating of? / 2 phase. The method of claim 2, And the grating of each of the small patterns has a width of 0.2 [mu] m, a height and a spacing of 0.06 [mu] m. A quartz substrate and a plurality of inspection pattern portions disposed in a matrix form on the quartz substrate, the inspection pattern portion is composed of the first to fourth heavy inspection patterns of the stripe shape, the first heavy inspection pattern alternately A plurality of first small patterns having a 100% transmittance arranged side by side and a second small pattern, wherein the second heavy inspection pattern is composed of a single small pattern having a transmittance of 6%, and the third The heavy inspection pattern is composed of a plurality of third small patterns spaced at a predetermined distance with a 100% transmittance, and the fourth heavy inspection pattern has a plurality of fourth small patterns and a third having a 100% transmittance and alternately arranged side by side. 5 small patterns, each of the small patterns performing exposure under a selected focus offset using a mask having a predetermined phase grating; Measuring a CD distribution of the photoresist pattern formed by the exposure process; And And setting the best focus for each field by the CD distribution of the photoresist pattern.

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