KR100966980B1 - Method for compensating semiconductor CD - Google Patents

Abstract

In the CD compensation method of the semiconductor device of the present invention, forming a photoresist pattern by applying a photoresist film on the semiconductor substrate, an exposure and development process using an EUV exposure mask, and measuring a CD of the photoresist pattern to form a CD uniformity map. And forming a compensation thin film pattern on the EUV exposure mask using the CD uniformity map.

EUV exposure mask, CD compensation

Description

CD compensation method of semiconductor device {Method for compensating semiconductor CD}

The present invention relates to a method for compensating a CD of a semiconductor device, and a method of compensating for a CD of a semiconductor device formed using EUV.

In the exposure technology of forming a pattern of a reticle on a wafer, the integration of patterns formed on the wafer is increased, and as the design rule of the semiconductor device is reduced, the line width of the semiconductor device is also reduced. The wavelength has also been reduced.

In the conventional exposure process, I-line, G-line, krF, and ArF are used as the exposure source, but due to the high integration of semiconductor devices, patterning is difficult, and thus, extreme ultraviolet radiation (EUV) having a shorter wavelength than the conventional exposure source is used. Has been proposed an exposure method.

In the conventional exposure method, a pattern is formed on a wafer using light transmitted through an exposure mask. The exposure process using extreme ultraviolet light uses high-energy light at a wavelength of 13.5 nm, so the conventional exposure method uses a wafer. You cannot form a pattern on it.

That is, since the exposure source has high energy in the short wavelength band, most of the light incident on the exposure mask and the lens from the exposure source is absorbed by the absorbing layer of the mask and disappears, and thus cannot reach the wafer and form a pattern. .

Therefore, in the exposure method using EUV, a reflection type system is required.

FIG. 1 shows an exposure process using a reflection type system, in which light incident from an exposure source (not shown) and reflected by the exposure mask 10 is reflected back through a reflection device 20 such as a reflection mirror, thereby providing a wafer. 30 is used to form a pattern on the wafer 30 using the same.

On the other hand, the mask image transferred to the wafer surface during the exposure process is affected by the size and shape of the pattern due to the effect such as optical proximity effect (OPE) generated as the spacing of neighboring patterns decreases due to the reduction of design rules. This affects the CD uniformity of the pattern formed on the wafer.

That is, when the patterns designed with the same dimensions are transferred onto the wafer through the same exposure mask, the degree of undesirably varying the dimensions of the patterns depending on the position at which the patterns are transferred in the exposure process is seriously increased.

The exposure mask using a method of transmitting and patterning light according to the prior art changes the illumination system used for exposure by introducing a diffraction grating or a filter on the back side of the photo mask in order to improve the uniformity of the pattern formed on the wafer. The CD uniformity of the pattern embodied on the wafer is controlled by using the transmittance of the exposure source transmitted through the mask.

However, since the EUV exposure mask uses a reflection process for reflecting and patterning a light source, the conventional method cannot be used, and thus, the compensation of the pattern CD is difficult to improve the pattern uniformity realized on the wafer. .

In the present invention, when the EUV exposure mask using the reflection method is applied, it is impossible to apply the CD compensation method applied to the exposure mask using the conventional transmission method. .

In the CD compensation method of the semiconductor device of the present invention, forming a photoresist pattern by applying a photoresist film on the semiconductor substrate, an exposure and development process using an EUV exposure mask, and measuring a CD of the photoresist pattern to form a CD uniformity map. And forming a compensation thin film pattern on the EUV exposure mask using the CD uniformity map.

The CD uniformity map may include a first patch defining a region where the CD of the photoresist pattern and a CD of the mask pattern on the EUV exposure mask are the same, and a second patch defining the region that is not the same. It is characterized by.

The compensation thin film pattern may be formed in a corresponding region on the EUV exposure mask by using the second patch of the CD uniformity map.

In this case, the second patch is characterized in that it comprises a plurality of areas consisting of areas where the CD difference between the CD of the EUV exposure mask pattern and the photosensitive film pattern is constant.

In addition, the EUV exposure mask having the compensation thin film pattern may include a reflection layer formed on the mask substrate, an absorption layer pattern sequentially provided on the reflection layer, and the absorption layer pattern formed on the second patch and the reflection layer adjacent to the reflection layer. It characterized in that it comprises a pattern.

The compensation thin film pattern may include forming a compensation thin film and a photoresist film on the reflective layer including the absorption layer pattern, patterning the photoresist film by a direct writing method to form a photoresist pattern, and etching the photoresist pattern. And patterning the compensation thin film as a mask.

In this case, the compensation thin film is formed by a chemical vapor deposition (CVD) method or a sputtering method.

The compensation thin film is formed of an insulating film.

At this time, the insulating film is characterized in that it comprises an oxide film.

The method may further include a buffer layer pattern on the reflective layer.

In a CD compensation method of a semiconductor device according to another embodiment of the present invention, forming a photoresist pattern by applying a photoresist film on a semiconductor substrate, an exposure and development process using an EUV exposure mask, and measuring the CD of the photoresist pattern. Forming a CD uniformity map, forming a first compensation thin film pattern on the EUV exposure mask using the CD uniformity map, and repeating the steps n times (where n is a natural number of 2 or more). And further forming a compensation thin film pattern.

In this case, the CD uniformity map may include a first patch in which the CD of the photoresist pattern and the CD of the mask pattern on the EUV exposure mask define the same region and n patches that define the non-identical region. It is characterized by.

The compensation thin film pattern may be formed in a corresponding region on the EUV exposure mask using the n patches of the CD uniformity map.

The nth patch may be classified into regions in which the CD of the EUV exposure mask pattern and the CD error rate of the photoresist pattern are constant.

The EUV exposure mask on which the n th compensation thin film pattern is formed may be formed on the reflective layer provided on the mask substrate, the absorbing layer pattern sequentially provided on the reflective layer, the absorbing layer patterns corresponding to the n regions, and the adjacent reflective layer. And the first compensation thin film pattern to the n th compensation thin film pattern.

In this case, the first compensation thin film pattern to the n compensation thin film pattern may include forming a compensation thin film and a photoresist film on the reflective layer including the absorption layer pattern and patterning the photoresist film by a direct writing method to form a photoresist film pattern. And patterning the compensation thin film using the photoresist pattern as an etching mask.

The present invention has the advantage of compensating the CD of the semiconductor device while preventing the loss of the reflective layer by laminating a material capable of adjusting the reflectance on the EUV exposure mask pattern.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

2 is a cross-sectional view showing an EUV exposure mask according to the present invention.

As shown in FIG. 2, the EUV exposure mask may include a reflector 120 reflecting light formed on the mask substrate 110, a buffer layer pattern 130 sequentially formed thereon, and An absorber pattern 140 for absorbing light and a compensation thin film pattern 165 for compensating for the CD to be implemented in the wafer are provided.

In this case, the buffer layer pattern 130 and the absorber layer pattern 140 absorb light when patterned from an exposure process using an EUV exposure mask, and the reflective layer 20 reflects light to be patterned on a wafer in a desired shape. It acts as a mask pattern.

In addition, the reflective layer 120 is preferably formed of a multi-layered laminated structure including a material capable of optimally reflecting light.

In this case, the multilayer stack structure includes a structure in which two different layers are alternately stacked, and the two different layers include a silicon film and a molybdenum film.

In addition, a capping layer 150 may be further formed between the reflective layer 120 and the buffer layer pattern 130 of the EUV exposure mask according to the present invention.

In addition, the compensation thin film pattern 165 is a material different from that of the absorption layer pattern 140, and preferably an insulating film, and more preferably an oxide film.

At this time, the position where the compensation thin film pattern 165 is formed is determined by the following.

First, the incident light injected from the exposure source is irradiated to the EUV exposure mask to perform an exposure process.

At this time, the incident light irradiated with the absorbing layer pattern of the EUV exposure mask is absorbed, and the incident light irradiated with the reflecting layer is reflected and reaches the wafer on which the photosensitive film is applied, thereby being exposed.

In general, in the case of using a positive type photosensitive film having good sensitivity to light, for example, a process of forming a photosensitive film pattern, incident light absorbed by an absorbing layer pattern of an EUV exposure mask is formed on a wafer. Since the light is not reached to the photoresist pattern, it does not affect the photoresist pattern, and the light reflected from the reflective layers between the EUV exposure mask absorbing layer patterns and reaching the wafer is removed by removing the photoresist film at the portion where the light reaches according to the positive photoresist characteristic. Will form.

Thus, a photosensitive film pattern formed on the wafer in the shape of the absorbing layer pattern of the EUV exposure mask is formed.

However, although the CD of the photoresist pattern formed on the wafer by the photolithography process using the EUV exposure mask should be the same as the CD of the mask patterns formed on the EUV exposure mask, the mask pattern formed on the EUV exposure mask is caused by various factors. It will have a different value than the CD.

That is, when transferring onto a wafer using an exposure mask having mask patterns having the same dimensions, patterns having the same dimensions as the mask pattern should be formed, but the dimensions of the mask pattern and the wafer are formed according to the exposure area. The dimensions of the photosensitive film pattern are different.

Here, the CD of the mask pattern formed on the EUV exposure mask and the CD of the photoresist pattern formed on the wafer are the same region (hereinafter referred to as a 'reference area'), and the CD of the mask pattern formed on the EUV exposure mask and the photoresist film formed on the wafer. A region where the CD of the pattern is not formed identically (hereinafter referred to as an 'error region') is set.

That is, the reference area will be an area having the same CD value as the CD of the desired target in the entire exposure area, that is, the CD of the mask pattern formed on the exposure mask, and the error area is the CD of the desired target in the entire exposure area. It may be a region where the CD is smaller or larger than the CD of the desired target, i.e., not satisfied.

The compensation thin film pattern is deposited in the above-described error region to adjust the reflectance of the incident light incident from the exposure source and adjust the energy of the light reaching the actual wafer so that the CD of the photoresist pattern formed on the actual wafer is the same as the CD of the mask pattern. It plays a role.

In this case, in order to more accurately define the reference region and the error region, it is preferable to create a CD uniformity map. This is defined as a patch where the difference between the mask pattern CD and the photoresist pattern CD on the wafer is defined as a patch. The photoresist pattern CD on the wafer is controlled by forming a compensation thin film pattern to adjust the reflectivity.

In more detail, the reference region may be defined as the first patch, and the error region may be defined as the second patch or n patches (where n is a natural number of 2 or more).

The n patches are preferably classified according to the difference in the error rate between the mask pattern CD and the photosensitive film pattern CD.

A first compensation thin film pattern having a first reflectance may be formed in the second patch, and an n th compensation thin film pattern having different reflectances may be formed in the n patches.

3A to 3D are schematic views showing a method of forming an EUV exposure mask according to the present invention.

As shown in FIG. 3A, after the reflective layer 120 reflecting light is formed on the transparent substrate 110, the buffer layer pattern 130 and the absorbing layer pattern 140 absorbing light are formed thereon. The compensation thin film 160 is formed on the entire surface, and the photosensitive film 170 is coated on the compensation thin film 160.

In this case, the compensation thin film 160 may be formed by a chemical vapor deposition (CVD) method or a sputtering method or coated with a coating material.

3B, the photoresist pattern 175 is formed on the photoresist 170 coated on the compensation thin film 160 by a direct write method using a laser or an electron beam.

In this case, the region where the photoresist pattern 175 is formed includes an error region obtained from the above-described CD uniformity map, that is, a second patch, and is later formed to form a compensation thin film pattern.

3C, the compensation thin film material is removed by exposing the absorption layer pattern 140 and the buffer layer pattern 30 on which the photoresist pattern 175 is not formed, using the photoresist pattern 175 as an etch mask. The thin film pattern 165 is formed.

In this case, the region from which the compensation thin film 160 is removed includes a reference region, that is, a first patch, obtained from the CD uniformity map described above.

That is, the region where the compensation thin film pattern 165 is formed is on the absorption layer pattern 140 of the EUV exposure mask corresponding to the second patch or n patches and the reflective layer adjacent thereto.

In this case, the compensation thin film pattern 165 formed in the EUV exposure mask area corresponding to the n patches may be further formed by repeating the above-described steps to further improve the CD uniformity of the semiconductor device.

3D, the photoresist pattern 275 is removed to expose the compensation thin film pattern 165 on the EUV exposure mask.

 As described above, even when the exposure mask using the reflection method such as the EUV exposure mask is applied, the compensation thin film pattern 165 is formed in the error area to maintain the overall reflectance of the exposure mask to be uniformly formed on the wafer. The uniformity of the pattern CD can be improved.

1 shows an exposure process employing a reflective system.

2 is a cross-sectional view showing an EUV exposure mask according to the present invention.

3A to 3D are schematic views showing a method of forming an EUV exposure mask according to the present invention.

Claims (16)

Applying a photoresist film on the semiconductor substrate; Forming a photoresist pattern in an exposure and development process using an EUV exposure mask; Measuring a CD of the photoresist pattern to construct a CD uniformity map; And Forming a compensation thin film pattern on the EUV exposure mask using the CD uniformity map. The method of claim 1, The CD uniformity map may include a first patch defining a region where CD of the photoresist pattern and a CD of a mask pattern on an EUV exposure mask are the same, and a second patch defining a region that is not the same. CD compensation method of a semiconductor device. 3. The method of claim 2, The compensation thin film pattern is formed in the corresponding region on the EUV exposure mask by using the second patch of the CD uniformity map. 3. The method of claim 2, And the second patch includes a plurality of regions including regions in which the CD of the EUV exposure mask pattern and the CD of the photoresist pattern are constant. 3. The method of claim 2, The EUV exposure mask on which the compensation thin film pattern is formed A reflective layer provided on the mask substrate; An absorbing layer pattern sequentially provided on the reflective layer; And And a compensation thin film pattern formed on an absorbing layer pattern and a reflection layer adjacent thereto in the second patch. The method of claim 5, The compensation thin film pattern is Forming a compensation thin film and a photoresist film on the reflective layer including the absorption layer pattern; Patterning the photoresist film by a direct writing method to form a photoresist pattern; And And patterning the compensation thin film using the photoresist pattern as an etching mask. The method of claim 6, The compensation thin film is a CD compensation method of a semiconductor device, characterized in that formed by chemical vapor deposition (CVD) or sputtering (sputtering) method. The method of claim 6, And the compensation thin film is formed of an insulating film. The method of claim 6, And the compensation thin film comprises an oxide film. The method of claim 5, And a buffer layer pattern on the reflective layer. Applying a photoresist film on the semiconductor substrate; Forming a photoresist pattern in an exposure and development process using an EUV exposure mask; Measuring a CD of the photoresist pattern to construct a CD uniformity map; Forming a first compensation thin film pattern on the EUV exposure mask using the CD uniformity map; And Repeating the steps n times to form an n-th compensation thin film pattern, wherein n is a natural number of 2 or more. The method of claim 11, The CD uniformity map may include a first patch that defines a region where the CD of the photoresist pattern and a CD of the mask pattern on an EUV exposure mask are the same and n patches that define a region that is not the same. CD compensation method of a semiconductor device. The method of claim 12, The compensation thin film pattern is formed in the corresponding region on the EUV exposure mask using the n patches of the CD uniformity map, CD compensation method of a semiconductor device. The method of claim 12, The n-th patch is a CD compensation method of the semiconductor device, characterized in that the CD error rate of the CD and the photosensitive film pattern of the EUV exposure mask pattern is classified into areas. The method of claim 12, The EUV exposure mask on which the nth compensation thin film pattern is formed A reflective layer provided on the mask substrate; An absorbing layer pattern sequentially provided on the reflective layer; And And a first compensation thin film pattern and an n-th compensation thin film pattern formed on the absorbing layer patterns corresponding to the n regions and the reflective layer adjacent thereto. The method of claim 15, The first compensation thin film pattern to n compensation thin film pattern Forming a compensation thin film and a photoresist film on the reflective layer including the absorption layer pattern; Patterning the photoresist film by a direct writing method to form a photoresist pattern; And And patterning the compensation thin film using the photoresist pattern as an etching mask.

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