KR20110001141A

KR20110001141A - Method for correcting optical proximity effect

Info

Publication number: KR20110001141A
Application number: KR1020090058544A
Authority: KR
Inventors: 김중찬; 유균
Original assignee: 주식회사 하이닉스반도체
Priority date: 2009-06-29
Filing date: 2009-06-29
Publication date: 2011-01-06

Abstract

PURPOSE: An optical proximity effect correction method is provided to improve the reliability of a correction by setting coordinates for extracting the critical dimension data of a wafer pattern based on each region of a mask. CONSTITUTION: The layout of a target pattern is set, and a wafer pattern is formed(110). The number and the coordinates of critical dimension data with respect to the target pattern are set based on each region of a mask(120). The critical dimension data of the wafer pattern is extracted(130). The extracted critical dimension data is classified based on data types(140). A recipe for correcting mask transmittance is generated(170).

Description

Method for correcting optical proximity effect

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of correcting an optical proximity effect appearing in an exposure process.

In general, photolithography technology is a basic technology leading to high integration of semiconductor devices, and forms a pattern on a wafer, which is a semiconductor substrate, using light. That is, by irradiating light of exposure equipment such as ultraviolet rays, electron beams, or X-rays to a position where a pattern such as an insulating film or a conductive film should be formed on a semiconductor substrate, a photoresist whose solubility is changed is coated and a photoresist is used by using a photomask. After exposing a predetermined portion of to light, a photoresist pattern is formed by removing a portion having a high solubility with respect to a developer. A portion exposed by the photoresist pattern is removed by an etching process to form a desired semiconductor device pattern.

At present, an electron beam apparatus is used as an exposure apparatus of a photo mask for forming a photoresist pattern, and the electron beam is incident on the photoresist to cause scattering on the resist and the lower substrate. These scattered electrons affect the pattern, which affects the fidelity and the critical dimension (CD) of the pattern. As such, the electron beam exposure method is a method of exposing actual pattern data directly to a photo mask, not a method of exposing using a reticle as a medium like a stepper. The area to be exposed is divided into small pixels, and the area containing data is filled with an electron beam suitable for the pixel size. However, as the degree of integration of semiconductor devices increases, the effect of improving both depth of focus and resolution decreases in irregularly disposed patterns commonly found in logic devices such as microprocessors.

In order to overcome this problem, when a pattern having a numerical value close to a resolution limit is formed, a so-called optical proximity effect occurs, in which a design pattern and a pattern actually formed on a semiconductor substrate are separated from each other. Due to the difference between the design and the actual pattern, the performance of the device is significantly degraded compared to the design. Accordingly, by performing optical proximity effect correction (OPC) on the distortion of the pattern occurring at the resolution limit in the photolithography process, it is possible to faithfully complete the fine pattern of the photo mask on the wafer as designed.

In order to secure the characteristics of the semiconductor device and high yield, it is very important to improve the CD uniformity of the pattern formed on the wafer. To this end, a method of improving the CD uniformity in the field by adjusting the light transmittance of the corresponding portion of the photomask by using the CD data extracted from the wafer pattern is used. Based on the measured CD data and the measurement position information acquired from the wafer, the laser beam is used to correct the transmittance of a specific region of the mask, and the approximate correction is performed by sorting the data in an area of a predetermined transmittance adjustment unit. However, in such a conventional mask transmittance correction method, various layouts present in all fields in the mask are not considered but are collectively corrected, so that accurate correction is not made and application thereof is limited. For example, in the case of the core region and the peripheral circuit region, the transmittance adjustment is performed using the closest cell data. Therefore, only the cell region in the mask needs to be corrected, but the transmittance correction is also performed in the core region and the peripheral circuit region. do. Alternatively, there is a disadvantage in that a separate transmittance adjustment is desired only for a specific region such as a peripheral circuit region.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method for correcting optical proximity effects capable of correcting transmittance for each region of a mask in consideration of various layouts in a mask.

In order to achieve the above technical problem, the optical proximity effect correction method according to the present invention includes designing a layout of a target pattern and forming a pattern on a wafer, and setting the number and coordinates of the pattern CD data to be measured, Setting by region, extracting CD data of a wafer pattern, classifying the extracted pattern CD data according to data type, determining presence or absence of correction according to the data type, and generating boundary coordinates for each region And generating a recipe for mask transmittance correction, correcting a transmittance of the mask according to the generated recipe, and performing wafer exposure and verification using the corrected mask.

In the step of setting the number and coordinates of the pattern CD data to be measured, the number and coordinates of each region may be set by dividing it into a cell region, a core region, and a peripheral circuit region of the wafer.

Extracting the CD data of the wafer pattern may be performed by pattern matching with a database using a metrology tool.

In the step of generating a recipe for correcting the mask transmittance, a recipe may be generated for each area of the mask.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below.

The present invention proposes a method for correcting transmittance of a photomask, in which a correction region can be set for each mask region in consideration of various layouts existing in the mask.

1 is a flowchart illustrating an optical proximity effect correction method according to an exemplary embodiment of the present invention, and FIGS. 2 and 3 are photographs showing a region for correcting transmittance in a mask. 4 is a photograph showing blocking of a portion of a mask where a transmittance correction is not desired.

First, a layout of a target pattern to be transferred onto a wafer is designed, and the designed layout is transferred onto an actual wafer to form a wafer pattern (step 110). In this case, in some cases, a layout of a test pattern having a specific shape may be used instead of the layout of the target pattern. This process may be performed by a method of forming a resist pattern by firstly OPC the layout of a target pattern, manufacturing a mask, applying a photoresist on a wafer, and exposing the photoresist. Accordingly, the wafer pattern may be a resist pattern, and in some cases, may be a film formed by etching with a photoresist pattern.

After the pattern is formed on the wafer, CD data of the wafer pattern is extracted to measure the uniformity, and the transmittance of the photomask is corrected to improve the CD uniformity. To this end, first, the number and coordinates of the data for the wafer pattern required for the transmittance correction of the mask are set (step 120). The CD of the pattern formed on the wafer is measured to extract data necessary for the correction of the transmittance of the mask. At this time, the number of data to be measured and the coordinates of the measurement points are set. Normally, 40,000 to 50,000 points are set per field of the wafer, but can be adjusted according to the mask transmittance correction device. In addition, the data measurement area is set in consideration of various layouts in the mask. For example, in the case of the cell region, the core region, and the peripheral circuit region, since the layout of the patterns arranged in each is different from each other, the size of the CD data measurement region can be set as shown in FIG. 3 in consideration of the layout of each region. In addition, as shown in FIG. 4, in the case of an area where correction is not desired, some areas 220 and 230 which do not need correction may be blocked, and only the remaining area 210 may be set as an area for correction.

If the number and coordinates of the CD data to be measured are set, the CD data of the wafer pattern is extracted (step 130). CD data extraction of the wafer pattern is achieved by matching the database with the pattern. The database stores data of a good pattern image set as a reference or data of a target pattern layout, for example, as data for comparison in the measurement process. CD measurement data required for transmittance correction is obtained by matching the measured data of the wafer pattern with the layout data of the target pattern stored in the database. In addition, data about a cell region, a core region, a peripheral circuit region, or a specific region may be extracted and extracted.

After extracting the CD data for the wafer pattern, the extracted CD data is classified according to the data type (step 140), and the presence or absence of transmittance correction according to the data type is determined (step 150). If the transmittance correction is determined according to the data type, boundary coordinates for each region are generated (step 160). The boundary coordinates of a region requiring transmittance correction are generated by considering various layouts of each region for a cell region, a core region, a peripheral circuit region, or a specific region.

If the coordinates for each region are set, a recipe for mask transmittance correction is generated, and the transmittance correction of the mask is performed according to the generated recipe (steps 170 and 180). After the transmittance of the mask is corrected, wafer exposure and verification are performed using the corrected mask (step 190).

According to the optical proximity effect correction method according to the present invention described above, when setting coordinates to extract CD data of a wafer pattern, various types of layouts present in the mask by setting the cell area, the core area, the peripheral circuit area, or the specific area. Considering this, the transmittance can be corrected to improve the reliability of the correction. In addition, individual correction is possible according to each area, and the correction can be excluded in the case of an area where the correction is not desired. In addition, there is an advantage that precision correction for each position of the acquired field CD data is possible.

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 technical spirit of the present invention. Do.

1 is a flowchart illustrating an optical proximity effect correction method according to the present invention.

2 and 3 are photographs showing a region for correcting transmittance in a mask.

4 is a photograph showing blocking of a portion of a mask where a transmittance correction is not desired.

Claims

Designing a layout of the target pattern and forming a pattern on the wafer;

Setting the number and coordinates of the pattern CD data to be measured, and setting each area of the mask;

Extracting CD data of the wafer pattern;

Classifying the extracted pattern CD data according to a data type;

Determining presence or absence of correction according to the data type and generating boundary coordinates for each region;

Generating a recipe for mask transmittance correction;

Correcting transmittance of the mask according to the generated recipe; And

And performing wafer exposure and verification using the corrected mask.

The method of claim 1,

In the step of setting the number and coordinates of the pattern CD data to be measured:

And dividing the cell region, the core region, and the peripheral circuit region of the wafer to set the number and coordinates according to each region.

The method of claim 1,

Extracting the CD data of the wafer pattern,

A method for correcting optical proximity effects, which is performed by pattern matching with a database using a metrology tool.

The method of claim 1,

In the step of generating a recipe for the mask transmittance correction,

And generating a recipe for each area of the mask.