KR100811404B1 - Phase Shift Mask for Performing Exposure Process using Extreme Ultra-Violet Light Source and Method for Manufacturing the its - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask for an Extreme Ultra-Violet (hereinafter referred to as “EUV”) exposure process and a method of manufacturing the same. More specifically, in order to prevent damage to the reflective layer, A high resolution fine pattern is formed by forming a reflective layer on a quartz substrate including a trench etched to a thickness sufficient to cause a phase difference, or ii) a buffer layer pattern formed to a thickness sufficient to cause a phase difference. The present invention relates to a phase inversion mask for an EUV exposure process and a method of manufacturing the same.

Description

Phase Shift Mask for Performing Exposure Process using Extreme Ultra-Violet Light Source and Method for Manufacturing the its}

1A and 1B are cross-sectional views showing the structure of a phase inversion mask according to the prior art.

2A to 2C are cross-sectional views illustrating a phase inversion mask according to a first embodiment of the present invention.

3A to 3C are cross-sectional views illustrating a phase shift mask according to a second embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

1, 21, 31: quartz substrate 3, 3-1, 3-2: reflective layer pattern

5, 27: absorber layer pattern 7, 39: buffer layer

23, 33: photoresist pattern 25: trench

27, 37: reflective layer having phase inversion region

39-1: buffer layer pattern h: trench thickness formed on the substrate

h ', h ″': step difference between phase inversion region and non-phase inversion region of reflective layer

h ″: Buffer layer thickness formed on the substrate

The present invention relates to a phase shift mask for an Extreme Ultra-Violet (hereinafter referred to as "EUV") exposure process and a method of manufacturing the same.

In the process of manufacturing a semiconductor device, various patterns including contact holes are formed through a photolithography process. The photolithography process is a process of forming a photoresist pattern on the etched layer, a process of etching the lower etched layer using the photoresist pattern as an etch mask, and after completion of the etching process, It includes a process of removing. In addition, the process of forming the photoresist pattern is a process of applying a photoresist material on the layer to be etched, selectively exposing the photoresist using a specific exposure mask and exposed or unexposed using a predetermined chemical solution And a developing process for removing the photoresist material in the region.

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

The width of the photoresist pattern that can be realized through the exposure process is determined by the following Rayleigh's equation.

R = K (λ / NA)

Where R is the critical dimension, or resolution, of the photoresist pattern, λ is the wavelength of light, NA is the aperture of the lens, and K is a process-related constant that varies with process capability, but is approximately 0.4 to 0.5 in mass production. to be.

For example, when performing an exposure process using a conventional G-line (λ = 436 nm) or I-line (λ = 365 nm) light source, if the aperture of the lens of the exposure equipment is about 0.6, A pattern having a resolution of about 0.5 μm is implemented. In this case, the pattern having a resolution of 0.5 μm means that the critical dimension of the pattern width that can be realized by the photolithography process is about 0.5 μm, and thus, the highly integrated fine pattern at the present time when the effective channel length of the semiconductor device is reduced to within 0.30 μm is obtained. It is very difficult to get.

As an improvement to this, an exposure process using a shorter wavelength than the light sources, for example, a deep ultra violet (DUV) light source such as KrF (λ = 248 nm) or ArF (λ = 193 nm) has been developed. An EUV exposure process using a 13.5 nm wavelength light source has been developed. In this case, in the EUV exposure process, a phase inversion mask using reflective optical for increasing the contrast of an image formed on the photosensitive agent is used instead of a KrF or ArF light-transmitting mask having high absorption.

A structure of a phase inversion mask for an EUV exposure process according to the prior art will be briefly described with reference to FIGS. 1A and 1B.

A conventional phase inversion mask for an EUV exposure process is formed by an etching process on a specific portion of a quartz substrate 1 as shown in FIG. 1A and includes a phase inversion region capable of inverting the phase of the projected light by 180 degrees. The multilayer reflective layer pattern 3 and the absorber layer pattern 5 are provided. Alternatively, as illustrated in FIG. 1B, the first and second reflective layer patterns 3-1 and 3-2 and the buffer layer pattern 7 of the multilayer including the phase inversion region by the etching process on the quartz substrate 1 are formed. The laminated pattern and the absorber layer pattern 5 are provided.

When the exposure process is performed using the phase shift mask for the EUV exposure process, light incident on the absorbing layer is blocked from being irradiated onto the wafer, while light incident on the reflective layer is reflected and irradiated onto the wafer. The resolution is improved by generating a destructive interference effect due to the phase difference between the reflected light and the absorbed light.

However, the phase inversion mask for EUV exposure process according to the prior art as described above has the following problems.

In other words, the EUV exposure process phase inversion mask is a step of forming a reflective layer pattern having a phase inversion region and a non-phase inversion region by depositing a plurality of reflective layers on a quartz substrate, and then performing an etching process on the reflective layer. In this case, various problems may occur such that the sidewalls of the reflective layer pattern are damaged during the etching process. As a result, the reflectance decreases during the subsequent exposure process, thereby degrading the image forming ability for the photoresist film.

Accordingly, the present inventors have completed the present invention by developing a phase inversion mask and a method of manufacturing the same, which can overcome the above-mentioned conventional problems without developing expensive equipment.

The present invention has been made to solve the problems occurring in the conventional process of manufacturing a phase inversion mask for the EUV exposure process, a trench or buffer layer on the quartz substrate instead of performing an etching process for the reflective layer when manufacturing a phase inversion mask for EUV. An object of the present invention is to provide a phase reversal mask for forming a pattern and forming a reflective layer pattern having a phase inversion region thereon and a method of manufacturing the same.

Phase inversion mask for EUV exposure process according to a first embodiment of the present invention for achieving the above object,

A quartz substrate comprising trenches etched to a depth sufficient to cause a phase difference of 180 degrees; And

It is formed on the entire surface of the substrate including the trench, characterized in that it comprises a reflective layer formed by alternately stacking a structure of a stack of several Mo film and Si film, or a Mo film and a Be film.

In this case, the phase shift mask may further include a buffer layer on the entire surface of the substrate before forming the reflective layer.

In order to achieve the above object, in the present invention,

Forming a photoresist pattern on the quartz substrate for exposure and development processes;

Forming a trench having a predetermined depth on the substrate by performing an etching process using the photoresist pattern as an etching mask;

Removing the photoresist pattern; And

A method of manufacturing a phase shift mask comprising depositing a reflective layer formed by alternately stacking a stacked structure of several Mo films and a Si film or a stacked structure of a Mo film and a Be film on an entire surface of a substrate including the trench.

In this case, the depth of the trench should satisfy the formula of φ = h × 2π / λ when the wavelength of the exposure light source is λ and the phase difference to be made is φ. That is, when the exposure light source is the EUV wavelength, the trench depth must be an odd multiple of lambda / 2 to make a phase difference of 180 degrees.

In addition, the phase inversion mask for EUV exposure process according to a second embodiment of the present invention,

Quartz substrates;

A buffer layer pattern formed on the entire surface of the substrate to a thickness sufficient to cause a phase difference of 180 degrees;

It is formed on the entire area of the substrate including the buffer layer pattern, it characterized in that it comprises a reflective layer formed by alternately stacking a laminated structure of several Mo film and Si film or a Mo film and Be film.

In order to achieve the above object, in the present invention,

Forming a buffer layer over the quartz substrate;

Forming a photoresist pattern on the buffer layer by exposure and development processes;

Forming a buffer layer pattern by performing an etching process on the buffer layer using the photoresist pattern as an etching mask;

Removing the photoresist pattern; And

Forming a reflective layer formed by alternately stacking a stacked structure of several Mo films and Si films or a stacked structure of Mo films and Be films on the entire surface including the buffer layer pattern and the substrate exposed through the etching process. Provided is a method of making a mask.

In this case, the thickness of the buffer layer should satisfy the formula of φ = h × 2Π / λ if the wavelength of the exposure light source is λ and the phase difference to be made is φ. That is, when the exposure light source is the EUV wavelength, the thickness of the buffer layer should be an odd multiple of lambda / 2 to make a phase difference of 180 degrees.

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

First, FIGS. 2A to 2C are cross-sectional views illustrating a method of manufacturing a phase shift mask for an EUV exposure process according to a first embodiment of the present invention.

As shown in FIG. 2A, a photoresist film (not shown) is formed on the entire surface of the quartz substrate 21, and a photoresist pattern 23 is formed by performing exposure and development processes.

An etching process using the photoresist pattern 23 of FIG. 2A as an etching mask is performed to form the trench 25 having a predetermined depth h on the quartz substrate 21 as shown in FIG. 2B.

At this time, the depth of the trench should satisfy the equation φ = h x 2π / λ if the wavelength of the exposure light source is λ and the phase difference to be made is φ. That is, when the exposure light source is the EUV wavelength, the trench depth must be an odd multiple of lambda / 2 to make a phase difference of 180 degrees. For example, the trench is formed to a depth h of 67 to 473 kPa.

Subsequently, the photosensitive film pattern 23 is removed, and then a reflective layer 27 formed by alternately stacking a stacked structure of several Mo films and Si films or a stacked structure of Mo films and Be films is formed on the entire surface of the resultant product.

In this case, a step h ′ having a thickness equal to the trench depth is formed between the phase inversion region and the nonphase inversion region formed in the reflective layer.

The method further includes forming a buffer layer (not shown) on the substrate before forming the multilayer reflective layer 27 or forming an absorbing layer (not shown) pattern thereon after the reflective layer 23 is formed. can do.

3A to 3C are cross-sectional views illustrating a method of manufacturing a phase shift mask for an EUV exposure process according to a second exemplary embodiment of the present invention.

First, as shown in FIG. 3A, a buffer layer 39 having a thickness h ″ is formed on the entire surface of the quartz substrate 31 to form a phase difference, and then a photoresist film (not shown) is formed thereon. The photoresist pattern 33 is formed by performing exposure and development processes on the photoresist.

In this case, the thickness of the buffer layer 39 should satisfy the equation φ = h x 2π / λ if the wavelength of the exposure light source is λ and the phase difference to be made is φ. That is, when the exposure light source is the EUV wavelength, the thickness of the buffer layer should be an odd multiple of λ / 2 to make a phase difference of 180 degrees. For example, the buffer layer has a thickness h ″ of 67 to 473 mm 3.

Subsequently, an etching process is performed on the buffer layer 39 until the quartz substrate 31 is exposed using the photoresist pattern 33 of FIG. 3A as an etch mask, thereby forming a buffer layer pattern 39-39 as shown in FIG. 3B. To form 1).

As shown in FIG. 3B, a stacked structure of several Mo films and Si films, or a Mo film and Be film, as shown in FIG. 3C, is disposed on the entire surface including the quartz substrate 31 and the buffer layer pattern 39-1 exposed as shown in FIG. The reflective layer 37 formed by alternately stacking the stacked structure is formed.

At this time, a step h ′ ″ having a thickness equal to the buffer layer thickness h ″ is formed between the phase inversion region and the nonphase inversion region formed in the reflective layer.

Using the method of the present invention as described above, it is possible to manufacture not only the phase inversion mask for EUV, but also the phase inversion mask for DUV.

As described above, the invention according to the first and second embodiments of the present invention can form a reflective layer including a phase inversion region and a non-phase inversion region without performing an etching process on the reflective layer, thereby preventing damage to the reflective layer. This can improve the reflectance drop. Thus, the reflectance is increased in the subsequent exposure process to improve the image forming ability for the photoresist film.

As described above, the present invention does not perform an etching process during fabrication of a phase inversion mask, and by laminating a reflective layer on a quartz substrate having a trench or a quartz substrate having a buffer layer pattern, the phase inversion region and the nonphase inversion without damage. Since the reflective layer including the region can be formed to reduce the reflectance, the image forming ability to be irradiated to the photosensitive film used as the mask during the subsequent etching process can be improved.

Claims (9)

A quartz substrate comprising trenches etched to a depth that can cause a phase difference of 180 degrees; And A phase inversion mask for an EUV exposure process, formed on an entire surface of a substrate including the trench, and including a reflective layer formed by alternately stacking a plurality of Mo and Si films or a stacked structure of Mo and Be films. . The method of claim 1, The phase shift mask may further include a buffer layer under the reflective layer. The method of claim 1, And the trench has an odd depth of λ / 2 (where λ is a wavelength of an EUV exposure light source) to produce a phase difference of 180 degrees. Forming a photoresist pattern on the quartz substrate for exposure and development processes; Forming a trench having a predetermined depth on the substrate by performing an etching process using the photoresist pattern as an etching mask; Removing the photoresist pattern; And And depositing a reflective layer formed by alternately stacking a stacked structure of several Mo films and Si films or a stacked structure of Mo films and Be films on the entire surface of the substrate including the trench. Method of preparation. The method of claim 4, wherein The reflective layer has a step difference between the phase inversion region and the non-phase inversion region is an odd multiple of λ / 2 (where λ is the wavelength of the EUV exposure light source). Quartz substrates; A buffer layer pattern formed on the entire surface of the substrate to a thickness sufficient to cause a phase difference of 180 degrees; It is formed on the front surface of the substrate including the buffer layer pattern, the phase inversion for the EUV exposure process, characterized in that it comprises a reflective layer formed by alternately stacking a stacked structure of several Mo film and Si film or a Mo film and Be film Mask. The method of claim 6, And the buffer layer pattern has an odd thickness of? / 2 (where? Is a wavelength of an EUV exposure light source) to make a phase difference of 180 degrees. Forming a buffer layer over the quartz substrate; Forming a photoresist pattern on the buffer layer by exposure and development processes; Forming a buffer layer pattern by performing an etching process on the buffer layer using the photoresist pattern as an etching mask; Removing the photoresist pattern; And Forming a reflective layer formed by alternately stacking a stacked structure of several Mo films and Si films or a stacked structure of Mo films and Be films on the entire surface including the buffer layer pattern and the substrate exposed through the etching process. The manufacturing method of the phase inversion mask for EUV exposure processes made into. The method of claim 8, The reflective layer has a step difference between the phase inversion region and the non-phase inversion region is an odd multiple of λ / 2 (where λ is the wavelength of the EUV exposure light source).

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