KR20110008495A

KR20110008495A - Double patterning method for fine patterning

Info

Publication number: KR20110008495A
Application number: KR1020090065865A
Authority: KR
Inventors: 심연아
Original assignee: 주식회사 동부하이텍
Priority date: 2009-07-20
Filing date: 2009-07-20
Publication date: 2011-01-27

Abstract

PURPOSE: A double patterning method for fine patterning is provided to implement accurate pattern by minimizing damage to a photosensitive film. CONSTITUTION: A target layer(20) is formed on a semiconductor substrate. A first photoresist is spread on a semiconductor substrate to form a first photoresist pattern(31) through an exposure and development process. A freezing chemical is spread and a baking process and a photolithography process are performed. The second photosensitive film is spread to perform the exposure process. A second photosensitive pattern(32) is formed through the development process.

Description

Double patterning method for fine patterning

The present invention relates to a method of forming a fine pattern of a semiconductor device, and more particularly to a double patterning method for forming a pattern of fine pitch by a double patterning method.

Pattern refinement is essential in manufacturing highly integrated semiconductor devices. In order to integrate a large number of devices in a small area, the size of the individual devices should be made as small as possible. For this purpose, the pitch, which is the sum of the widths of the patterns to be formed and the spacing between the patterns, should be made small. do.

Recently, as the design rule of a semiconductor device is drastically reduced, there is a limit in forming a pattern having a fine pitch due to a resolution limitation in a photolithography process for forming a pattern required for semiconductor device implementation. have.

In the photolithography process, a photoresist is coated on the substrate, and an exposure process is applied to the photoresist using an exposure mask having a fine pattern defined using a light source having a wavelength of 365 nm, 248 nm, 193 nm, and 153 nm. Then, the development process is performed to form a fine photoresist pattern.

In such a photolithography process, the resolution R is determined according to the wavelength λ and the numerical aperture NA of the light source, such as R = k1 × λ / NA.

In the above equation, k1 means a process constant, which has a physical limit, and thus it is almost impossible to reduce the value by a conventional method, and a new photoresist material which is highly reactive to the short wavelength is developed with an exposure apparatus using the short wavelength. Since it is necessary, it is difficult to form a fine pattern having a line width of short wavelength or less.

Therefore, a double patterning method has been developed in which a fine pattern can be formed by overlapping a pattern considering the process capability of the exposure apparatus.

The double patterning method refers to a process technology that enables circuit pattern formation having a size corresponding to half of the original resolution by performing two exposures for forming one circuit pattern.

Several double patterning methods have been reported so far: the dual-trench process (litho-etch-litho-etch) and the dual-line process (litho-litho-etch).

Of these two methods, the dual-line process is the one that attracts more attention because the process is simpler. However, the dual-line process has a disadvantage in that damage occurs in the first photoresist pattern when the second photolithography process is performed.

In addition, in the double patterning method, it is known that the overlay property becomes more stringent because the position matching accuracy affects the critical dimension (CD).

In addition, since two processes using two masks must be performed to perform one process, the process is cumbersome, and the manufacturing cost may be increased and the yield may be lowered.

1A to 1B are cross-sectional views illustrating a conventional double patterning method.

As shown in FIG. 1A, the first photoresist layer is coated on the semiconductor substrate 10 on which the etched layer 20 is formed, and a predetermined portion of the first photoresist layer is exposed and developed to expose the first photoresist layer pattern 31. To form. In this case, the first photoresist layer pattern 31 may have a line width of an exposure limit level.

Then, as shown in FIG. 1B, a second photoresist film is coated on the etched layer 20 on which the first photoresist film pattern 31 is formed. Next, a predetermined portion of the second photoresist film is exposed and developed to form a second photoresist pattern 32 so that a pattern is formed between the first photoresist pattern 31.

Similarly, the line width of the second photoresist pattern 32 may also be at an exposure limit level. In this case, the photoresist patterns 31 and 32 having a fine pitch below the exposure limit may be formed.

However, when the second photolithography process is performed, damage occurs to the first photoresist pattern, which is performed first, and thus, the shape of the photoresist pattern is deformed, and the circuit pattern formed by the photoresist pattern is also poorly formed. have.

Accordingly, the present invention has been made to solve the above-described problems, and provides a double patterning method for forming a fine pattern that can implement a precise and accurate pattern by minimizing the damage of the first photosensitive film during the double patterning process There is a purpose.

In the double patterning method for forming a fine pattern of the present invention for realizing the above object, a first photosensitive film is coated on an upper surface of a semiconductor substrate on which an etched layer is formed, and an exposure and development process is performed to form a first photosensitive film pattern. A first step of doing; A second step of applying a freezing chemical and performing a baking process and a developing process; A third step of applying a second photosensitive film and performing an exposure process; And a fourth step of forming the second photosensitive film pattern by performing the developing process.

In addition, the second step is characterized by using a freezing chemical in which an alcohol group (OH) or a carboxyl group (COOH) is present.

In addition, the second step is characterized in that the baking process proceeds under the process conditions of the baking temperature of 120 ~ 140 ℃ and baking time of 60 ~ 120 seconds.

The double patterning method for forming a fine pattern according to the present invention has the effect of minimizing the damage of the first photoresist film during the double patterning process to implement an accurate and accurate pattern.

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the preferred embodiment of the present invention will be described in detail to be easily carried out by those skilled in the art.

However, the configuration and operation of the present invention shown in the drawings and described by it are described as at least one embodiment, by which the technical spirit and core construction and operation of the present invention described above are not limited.

That is, the present invention may be variously modified and have various embodiments, and it should be understood that the present invention includes all the transforms, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

2A to 2G are cross-sectional views illustrating a double patterning method for forming a fine pattern according to an embodiment of the present invention.

Double patterning method for forming a fine pattern according to an embodiment of the present invention comprises a first step to a fourth step.

As shown in FIG. 2A, in the first step, the first photoresist film is coated on the semiconductor substrate 10 on which the etched layer 20 is formed, and the exposure and development processes are performed to form the first photoresist film pattern 31. ) To form.

As shown in FIGS. 2B to 2C, the second step is to apply a freezing chemical 400 to a baking process and a developing process.

Here, the freezing chemical 400 is preferably an alcohol group (OH) or a carboxyl group (COOH). In addition, the baking process is preferably proceeded to the process conditions of the baking temperature of 120 ~ 140 ℃ and baking time of 60 ~ 120 seconds.

Therefore, a cross-linkage reaction occurs between the first photoresist pattern 31 and the freezing chemical 400 during the baking process, which is formed as a thin layer on the surface of the first photoresist pattern 31. After the development, the development process removes all the portions that do not have cross linkage.

That is, as shown in Schemes 1 to 2 below, H is released when heat is applied to a freezing chemical containing an alcohol group (OH) or a carboxyl group (COOH), and the remaining O is crosslinked with the existing photoresist film. Will be achieved.

Scheme 1

Scheme 2

As shown in FIG. 2D to FIG. 2E, the third step is to apply a second photosensitive film and to perform an exposure process.

As shown in FIGS. 2F to 2G, the fourth step is a double patterning process for forming a fine pattern according to an embodiment of the present invention by forming a second photoresist pattern 31 by performing a development process. Complete the method.

In the double patterning method for forming a fine pattern according to an embodiment of the present invention as described above, the second photolithography process is performed to prevent damage of the photoresist pattern formed in the first photolithography during the double patterning process. Is to use freezing chemical before.

At this time, as a freezing chemical, the photosensitive film of other types except the photosensitive film originally used may be used. Such freezing chemicals act to solidify the resist pattern formed in the first photolithography process so as not to be dissolved in the photoresist solvent applied in the second photolithography process.

Therefore, according to the double patterning method for forming a fine pattern according to an embodiment of the present invention, not only the uniformity of the CD is improved but also the process margin is widened in the second photolithography process. .

It is apparent to those skilled in the art that the present invention is not limited to the above-described embodiments and can be practiced in various ways within the scope not departing from the technical gist of the present invention. It is.

1A to 1B are cross-sectional views illustrating a conventional double patterning method;

2A to 2F are cross-sectional views illustrating a double patterning method for forming a fine pattern according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10 semiconductor substrate 20 etching target layer

31: first photosensitive film pattern 32: second photosensitive film pattern

400: Freezing Chemical

Claims

A first step of forming a first photoresist pattern by applying a first photoresist layer on the semiconductor substrate on which an etched layer is formed, and performing an exposure and development process; A second step of applying a freezing chemical and performing a baking process and a developing process; A third step of applying a second photosensitive film and performing an exposure process; And a fourth step of forming a second photoresist pattern by performing a developing process.

The double patterning method of claim 1, wherein the second step uses a freezing chemical having an alcohol group (OH) or a carboxyl group (COOH).

The method of claim 1, wherein the second step is a double patterning method for forming a fine pattern, characterized in that for performing a baking process at a baking condition of 120 ~ 140 ℃ and a baking time of 60 ~ 120 seconds.