KR101179518B1 - Mask for euv exposure process and method for fabricating the same - Google Patents

Abstract

An EUV exposure process mask includes a silicon substrate having a window; A buffer layer formed on the silicon substrate; An absorption layer formed on the buffer layer; And an additional absorbing layer formed on the entire surface of the stacked pattern formed of the buffer layer and the absorbing layer, wherein the buffer layer and the absorbing layer have a portion disposed in a window of the silicon substrate in a pattern form.

Description

EV exposure mask and manufacturing method thereof {MASK FOR EUV EXPOSURE PROCESS AND METHOD FOR FABRICATING THE SAME}

1 is a cross-sectional view for explaining a mask for EUV exposure process according to an embodiment of the present invention.

2A to 2G are cross-sectional views of processes for describing a method for manufacturing a mask for EUV exposure processes according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100,200: silicon substrate 102,202: first oxide film for buffer

104,204 tungsten nitride film for buffer 106,206 buffer layer

108,208 Absorbing layer film 108a, 208a Absorbing layer

110,210: second oxide film 112,212: silicon nitride film

114,214: third oxide film 116,216: additional absorption layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure mask for semiconductor manufacturing, and more particularly, to an EUV exposure process that improves a shadow effect during an EUV (Extream Ultra-Violet) exposure process and prevents pattern deformation due to defects in a reflective layer. A mask and a method of manufacturing the same.

In manufacturing a semiconductor device, various patterns including contact holes are formed through a photolithography process. The photolithography process includes a process of forming a resist pattern on an object to be etched and a process of etching an etched layer using the resist pattern as a mask, and the process of forming the resist pattern is itself on an etched layer. A resist is applied, a step of selectively exposing the resist using a specific exposure mask, and a developing step of removing portions of the resist that are exposed or not exposed with a predetermined chemical solution.

On the other hand, the critical dimension of the pattern that can be implemented by such a photolithography process is largely dependent on which wavelength of light source is used in the exposure process. This is because the critical dimension of the actual pattern is determined by the width of the resist pattern that can be realized through the exposure process.

For example, in the past, an exposure process using a G-line (λ = 436 nm) or I-line (λ = 365 nm) light source has been performed. In recent years, KrF (shorter wavelength) than KrF ( An exposure technique using λ = 248 nm) as a light source has been developed, and an exposure process using ArF (λ = 193 nm) having a wavelength shorter than that of KrF has been developed.

Further, an EUV (Extream Ultra-Violet) exposure process using a laser beam having a wavelength of 13.4 nm as a light source has been developed.

Here, unlike the KrF and ArF exposure processes using transmission optics, the EUV exposure process uses reflective optics, and thus the structure of the mask used in the process is also different.

In other words, the KrF and ArF exposure process masks using transmission optics have an opaque chromium pattern formed on a transparent quartz substrate, whereas the EUV exposure process masks using reflection optics have a reflective layer formed on a silicon substrate. And an absorbing layer is selectively formed on the reflective layer.

Briefly describing the EUV exposure process, the light irradiated from the laser light source becomes an EUV beam having a wavelength of 13.4 nm through the EUV beam generator, and the EUV beam reaches the mask through a condenser lens and several lenses. The EUV beam reflected from the mask is transferred to the wafer via a reduction lens.

The lenses are mirror-type lenses coated with a reflective film, and a mask is formed with a reflective layer on a silicon substrate, a capping layer is formed on the reflective layer, and a buffer layer and radiation that act as a buffer for stress on the capping layer. The absorbing layer absorbing the EUV beam is laminated in the form of a pattern.

Here, the reflective layer has a structure in which a silicon film of about 4 nm and a molybdenum film of about 3 nm are formed in a pair, and about 40 pairs are stacked, and the overall thickness is approximately 280 nm. In addition, the capping layer is formed of a silicon film, the buffer layer is formed of a silicon oxide film, the absorption layer is formed of a metal film such as gold, copper, aluminum, germanium, titanium, tantalum silicon, etc., and the thickness thereof is about 100 nm. .

In such a mask for EUV exposure process, light incident on the absorbing layer is blocked from being irradiated to the wafer by the absorbing layer, while light incident on the reflecting layer is reflected from the reflecting layer and irradiated onto the wafer.

However, in the case of the mask for the conventional EUV exposure process described above, it is difficult to form a pure reflection-free layer between the silicon film and the molybdenum film when forming a reflective layer having a structure in which the silicon film and the molybdenum film are laminated. As a result, defects in the reflective layer cause pattern deformation on the wafer.

In addition, since the reflective layer is formed in a trench type, light is incident on the mask due to EUV characteristics, and a shadow effect is generated in which the size of the pattern is changed according to the direction of the pattern. In addition, the oblique incident light is scattered at the side of the absorbing layer, thereby reducing image contrast.

Accordingly, the present invention provides a mask for an EUV exposure process and a method of manufacturing the same, which can prevent a shadow effect in an EUV (Extream Ultra-Violet) exposure process.

In addition, the present invention provides a mask for the EUV exposure process and a method of manufacturing the same that can prevent the pattern deformation due to defects in the reflective layer during the EUV exposure process.

In one embodiment, a mask for an Extreme Ultra-Violet (EUV) exposure process includes a silicon substrate having a window; A buffer layer formed on the silicon substrate; And an absorbing layer formed on the buffer layer, wherein the buffer layer and the absorbing layer are provided in a pattern form at portions disposed in a window of the silicon substrate.

Here, the buffer layer is formed of a laminated film of an oxide film and a tungsten nitride film on the silicon substrate, and a single film of a tungsten nitride film on the window of the silicon substrate.

The absorbing layer is formed of any one of a tungsten film, a chromium film, a germanium film, a tantalum nitride film, and a tantalum boron nitride film.

Further comprising an additional absorber (additional absorber) formed on the entire surface of the laminated pattern consisting of the buffer layer and the absorber layer.

In another embodiment, a method of manufacturing an EUV exposure mask includes depositing a buffer first oxide film, a tungsten nitride film and an absorbing layer film in sequence on a front surface of a silicon substrate having a window forming region; Etching the absorbing layer film and the tungsten nitride film to form a stacked pattern of a buffer layer and an absorbing layer; Sequentially depositing a second oxide film, a silicon nitride film, and a third oxide film on the entire surface of the silicon substrate including the stacked pattern of the buffer layer and the absorbing layer; Etching a portion of the third oxide film and the silicon nitride film deposited on the rear surface of the silicon substrate to expose the second oxide film portion of the window forming region; Using the etched silicon nitride film as an etching mask to etch the exposed second oxide film portion and the silicon substrate below to form a window and to remove the third oxide film; And removing portions of the silicon nitride layer, the second oxide layer, and the first oxide layer in the window region.

Here, the buffer layer is formed of a laminated film of a first oxide film and a tungsten nitride film on the silicon substrate, and a single film of a tungsten nitride film on the window of the silicon substrate.

The absorption layer film is formed of any one of a tungsten film, a chromium film, a germanium film, a tantalum nitride film, and a tantalum boron nitride film.

The third oxide film is removed together with the etching of the second oxide film.

And removing an additional absorber layer on an entire surface of the stacked pattern including the buffer layer and the absorber layer after removing the silicon nitride layer, the second oxide layer, and the portion of the first oxide layer in the window region. .

(Example)

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

This invention manufactures the transmissive mask which applied the scattering CPM (Cell Projection Mask) on a silicon substrate. In addition, an additional absorber layer is formed on the entire surface of the laminated pattern including the buffer layer and the absorber layer of the mask.

In this way, it is not necessary to form a reflective layer having a structure in which a silicon film and a molybdenum film are laminated, and thus, pattern deformation can be prevented on the wafer due to defects in the reflective layer.

In addition, in contrast to light incident upon the application of the conventional reflective mask, since the light is incident vertically, the transmissive mask may improve a shadow effect generated by the oblique incident light. It is possible to prevent the deterioration of the imaging contrast.

In addition, the present invention has the advantage that by forming an additional absorption layer on the entire surface of the laminated pattern consisting of the buffer layer and the absorbing layer, it is possible to suppress the scattering of light generated on the sidewall of the laminated pattern, which is advantageous in terms of defects. .

1 is a cross-sectional view illustrating a mask for an EUV exposure process according to an exemplary embodiment of the present invention.

As shown, the mask for EUV exposure process of the present invention, the silicon substrate 100 having a window (W), the buffer layer 106 formed on the silicon substrate 100 and the buffer layer 106 formed on The absorber layer 108a is provided, and the buffer layer 106 and the absorber layer 108a are provided in a pattern form at portions disposed in the window W of the silicon substrate 100.

In this case, the buffer layer 106 is formed of a laminated film of an oxide film 102 and a tungsten nitride film 104 on the silicon substrate 100, and of the tungsten nitride film 104 on the window W of the silicon substrate 100. It consists of a single layer.

In addition, the absorber layer 108a may be formed of any one of a tungsten film, a chromium film, a germanium film, a tantalum nitride film, and a tantalum boron nitride film, and may be formed on the entire surface of the stacked pattern including the buffer layer 106 and the absorber layer 108a. An additional absorber layer 116 is further formed.

Here, the present invention can prevent a pattern defect caused by a defect in the reflective layer by forming a mask without forming a reflective layer formed of a laminated film of a silicon film and a molybdenum film in a conventional mask.

In addition, the present invention by forming a transmissive mask instead of the conventional reflective mask, it is possible to improve the shadow effect caused by the oblique incident light, it is possible to prevent the degradation of the image contrast due to the scattering of the oblique incident light. .

In addition, the present invention can suppress the scattering phenomenon in the sidewall of the laminated pattern by forming the additional absorption layer 116 on the entire surface of the laminated pattern composed of the buffer layer 106 and the absorbent layer 108a, and also considerably in terms of defects. It is advantageous.

Hereinafter, a method of manufacturing a mask for an EUV exposure process according to an exemplary embodiment of the present invention will be described with reference to FIGS. 2A to 2G.

Referring to FIG. 2A, the buffer first oxide film 202, the tungsten nitride film 204, and the absorption layer film 208 are formed on the front surface of the mask silicon substrate 200 having the window forming region Wa. ) In order.

The absorption layer film 208 is formed of any one of a tungsten (W) film, a chromium (Cr) film, a germanium (Ge) film, a tantalum nitride (TaN) film, and a tantalum boron nitride (TaBN) film. Is formed of a tungsten (W) film.

Referring to FIG. 2B, the absorbing layer film and the tungsten nitride film 204 are patterned to form a stacked pattern of the buffer layer 206 and the absorbing layer 208a.

In this case, the buffer layer 206 is formed of a laminated film of the first oxide film 202 and the tungsten nitride film 204, and the first oxide film 202 is not patterned on the remaining silicon substrate 200 where the stack pattern is not formed. ) Exists only.

Referring to FIG. 2C, the second oxide film 210, the silicon nitride film 212, and the third oxide film 214 are formed on the entire surface of the silicon substrate 200 including the stacked patterns of the buffer layer 206 and the absorbing layer 208a. In order to deposit.

The second oxide film 210 may be formed to completely surround the substrate 200 including the stacked pattern while filling the space between the stacked patterns of the buffer layer 206 and the absorbing layer 208a.

Here, the second oxide film 210, the silicon nitride film 212, and the third oxide film 214 are formed for the back surface patterning process of the silicon substrate 200 to be subsequently performed.

Referring to FIG. 2D, portions of the third oxide film 214 and the silicon nitride film 212 deposited on the rear surface of the silicon substrate 200 are etched and formed on the window forming region Wa of the substrate 200. A portion of the corresponding second oxide film 210 is exposed.

Referring to FIG. 2E, the exposed portion of the second oxide film 210 and the silicon substrate 200 below are etched using the etched silicon nitride film 212 as an etch mask to form a window W.

In this case, during the etching process for forming the window W, the third oxide film is removed together, and the resultant of the substrate 200 including the window W is surrounded by the silicon nitride film 212.

Referring to FIG. 2F, portions of the silicon nitride film, the second oxide film, and the first oxide film 202 existing in the window W are completely removed from the substrate 200 on which the window W is formed.

Here, the laminated layer of the buffer tungsten nitride film 204 and the absorber layer 208a is formed in a pattern in the window W, and the buffer layer 206 and the absorber layer (on the silicon substrate 200 except for the window region W) are formed. A laminated film of 208a is formed.

Referring to FIG. 2G, the silicon substrate 200 including the lamination layer including the buffer layer 206 and the absorption layer 208a and the buffer tungsten nitride layer 204 and the absorption layer 208a formed in a pattern on the window W are formed. An additional absorber layer 216 is formed on the entire surface of the laminated pattern.

Here, the present invention forms a transmissive mask including a buffer layer 206 and an absorbing layer 208a formed on the silicon substrate 200 without forming a reflective layer, thereby preventing pattern defects caused by defects in the reflective layer. have.

In addition, the present invention by forming a transmissive mask in which the light is incident vertically, it is possible to improve the shadow effect caused by the oblique incident light, it is possible to prevent the degradation of the image contrast due to the scattering of the oblique incident light. .

In addition, the present invention can suppress the scattering phenomenon in the sidewall of the laminated pattern by forming the additional absorption layer 116 on the entire surface of the laminated pattern composed of the buffer layer 106 and the absorbent layer 108a, and also considerably in terms of defects. It is advantageous.

As mentioned above, although the present invention has been illustrated and described with reference to specific embodiments, the present invention is not limited thereto, and the scope of the following claims is not limited to the scope of the present invention. It can be easily understood by those skilled in the art that can be modified and modified.

As described above, the present invention can prevent a pattern defect caused by a defect in the reflective layer by forming a transmissive mask that does not require the reflective layer.

In addition, the present invention can improve the shadow effect due to the obliquely incident light by forming a transmissive mask in which light is incident vertically, it is possible to prevent the degradation of the image contrast due to the scattering of the obliquely incident light.

In addition, the present invention has the advantage that the scattering phenomenon in the sidewall of the laminated pattern can be suppressed by forming an additional absorption layer on the entire surface of the laminated pattern composed of the buffer layer and the absorbent layer, and is also advantageous in terms of defects.

Claims (9)

A silicon substrate having a window; A buffer layer formed on the silicon substrate; An absorption layer formed on the buffer layer; and And an additional absorption layer formed on the entire surface of the stacked pattern including the buffer layer and the absorption layer. The buffer layer and the absorption layer is a mask for EUV (Extream Ultra-Violet) exposure process characterized in that the portion disposed in the window of the silicon substrate in the form of a pattern. Claim 2 has been abandoned due to the setting registration fee. The method of claim 1, The buffer layer is a mask for the EUV exposure process, characterized in that consisting of a laminated film of an oxide film and a tungsten nitride film on the silicon substrate, a single film of a tungsten nitride film on the window of the silicon substrate. Claim 3 has been abandoned due to the setting registration fee. The method of claim 1, The absorbing layer is a mask for EUV exposure process, characterized in that made of any one of a tungsten film, chromium film, germanium film, tantalum nitride film and tantalum boron nitride film. delete Depositing a buffer first oxide film, a tungsten nitride film, and an absorbing layer film in order on the front surface of the silicon substrate having the window forming region; Etching the absorbing layer film and the tungsten nitride film to form a stacked pattern of a buffer layer and an absorbing layer; Sequentially depositing a second oxide film, a silicon nitride film, and a third oxide film on the entire surface of the silicon substrate including the stacked pattern of the buffer layer and the absorbing layer; Etching a portion of the third oxide film and the silicon nitride film deposited on the rear surface of the silicon substrate to expose the second oxide film portion of the window forming region; Using the etched silicon nitride film as an etching mask to etch the exposed second oxide film portion and the silicon substrate below to form a window and to remove the third oxide film; Removing portions of the silicon nitride layer, the second oxide layer, and the first oxide layer in the window region; And And forming an additional absorber on the entire surface of the stacking pattern formed of the buffer layer and the absorber layer. Claim 6 has been abandoned due to the setting registration fee. 6. The method of claim 5, And the buffer layer is formed of a laminated film of a first oxide film and a tungsten nitride film on the silicon substrate, and is formed of a single film of a tungsten nitride film on a window of the silicon substrate without the absorbing layer. Claim 7 was abandoned upon payment of a set-up fee. 6. The method of claim 5, The absorbing layer film is a mask manufacturing method for the EUV exposure process, characterized in that formed of any one of a tungsten film, chromium film, germanium film, tantalum nitride film and tantalum boron nitride film. Claim 8 was abandoned when the registration fee was paid. 6. The method of claim 5, The third oxide film is removed during the etching of the second oxide film manufacturing method of the EUV exposure mask, characterized in that. delete

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