KR100884978B1

KR100884978B1 - Reflective type mask, and method for fabricating thereof

Info

Publication number: KR100884978B1
Application number: KR1020070112587A
Authority: KR
Inventors: 박지용
Original assignee: 주식회사 동부하이텍
Priority date: 2007-11-06
Filing date: 2007-11-06
Publication date: 2009-02-23

Abstract

A reflective type mask and a method for fabricating the same are provided to confirm a dimension of a pattern on a wafer with the dimension of the absorbing layer pattern in an EUV(Extreme Ultra Violet) exposure process by maintaining the trapezoidal shape to prevent a shadow effect. A reflective type mask includes a substrate(21), a reflecting layer(22) formed in the substrate, and an absorbing layer pattern(25) formed on the reflecting layer. The EUV(Extreme Ultra Violet) light is reflected by the reflecting layer and is absorbed by the absorbing layer pattern. Each side wall of the absorbing layer pattern is formed with the step type. An incline angle between each side wall of the absorbing layer pattern and the reflective layer is equal to the incident angle or the reflective angle of the EUV light.

Description

Reflective mask and manufacturing method thereof

The present invention relates to a mask and a method of manufacturing the same, and more particularly to a reflective mask and a method of manufacturing the same.

In the conventional semiconductor manufacturing process, a pattern was formed using a transmissive mask. However, optical theory using the transmissive mask has led to the reality that it is difficult to form a fine pattern of 50 nm or less.

Accordingly, techniques such as immersion lithography or double exposure have been developed. These are techniques for reducing the line width of the pattern. However, because they also have limitations in reducing the line width, Extreme Ultra Violet Lithography (EUVL) has been researched and developed as a next-generation lithography technology.

EUVL is an exposure technique that realizes a fine line width of 50 nm or less in a photolithography process of a semiconductor manufacturing process, and utilizes an exposure wavelength in the EUV region.

Most materials in the EUV region have large light absorption properties. Therefore, an EUVL reflective mask is used for the exposure technique using EUV.

In general, a reflective mask for EUVL forms a pattern as an absorbing layer capable of absorbing EUV light on a reflecting layer having a high reflectance in the EUV region.

Accordingly, when dividing the semiconductor substrate into absorption regions absorbing EUV light and reflective regions reflecting EUV light, the region where the surface of the reflective layer is covered with the absorption layer pattern is the absorption region, except that the reflective layer surface is exposed. Area is the reflecting area.

1 and 2 are views showing examples of a conventional EUVL reflective mask pattern, Figure 1 is a cross-sectional view showing a pattern of the basic structure, Figure 2 is a cross-sectional view showing a pattern of the trapezoidal structure.

Referring to FIG. 1, a conventional EUVL reflective mask includes a semiconductor substrate 2, a reflective layer 3 formed on the substrate 2, and an absorption layer pattern 4 formed on the reflective layer 3. It is composed. Here, FIG. 1 is a sectional view, in which the actual absorbing layer pattern 4 forms a pattern line.

As the absorbing layer pattern 4 is formed, the semiconductor substrate 2 is divided into an absorbing region 5 absorbing EUV light 1 and a reflecting region 6 reflecting the EUV light 1.

In detail, an absorption layer pattern 4 is formed on the surface of the reflection layer 3 in the absorption region 5, and the reflection layer 6 is formed in the reflection region 6 without the absorption layer pattern 4 being formed in the reflection region 6. (3) The surface is exposed.

However, when the EUVL reflective mask of FIG. 1 is exposed to EUV light, the EUVL reflective mask of FIG. There was a problem that the dimensions of the pattern to be formed is different. That is, there is a problem that the width of the pattern actually formed on the wafer becomes larger than the width of the absorber layer pattern.

This problem is caused by the incident angle of EUV light, the layer thickness of the absorber layer pattern 4, and the like, as well as the shadow effect caused by the side of the absorber layer pattern 4 being perpendicular to the surface of the reflective layer 3. to be.

Some of the incident EUV light 7 is normally reflected while the other 8 is not reflected but is absorbed in the absorbing layer pattern 4 causing a shadow effect.

Reducing the shadow effect in the conventional EUVL is a problem that must be solved in order to commercialize the EUVL technology. Of course, in addition to the shadow effect, it is also important to solve defects caused by mask deposition or to select a suitable material as a mask.

On the other hand, in the prior art to improve the pattern with a trapezoidal structure as shown in Figure 2 to eliminate the shadow effect.

Referring to FIG. 2, a conventional trapezoidal EUVL reflective mask also includes a semiconductor substrate 11, a reflective layer 12 formed on the substrate 11, and an absorbing layer pattern formed on the reflective layer 12 ( 15). 2 is a cross sectional view where the actual absorbent layer pattern 15 forms a pattern line.

As the absorption layer pattern 15 is formed, the semiconductor substrate 11 is divided into an absorption region 13 that absorbs the EUV light 10, and a reflection region 14 that reflects the EUV light 10.

However, the EUVL reflective mask of FIG. 2 has a trapezoidal structure so that the shadow effect does not occur, that is, the EUV light reflected from the reflective layer 12 is prevented from being absorbed by the absorbing layer pattern 15 and all are reflected. Has

However, it is technically and economically difficult to deposit EUVL reflective masks of the trapezoidal structure described above. That is, the present technology has a lot of difficulties in depositing obliquely without a step on the side of the trapezoidal absorbent layer pattern 15.

Accordingly, in the prior art, in order to introduce a trapezoidal reflective mask into the actual device fabrication process, the absorber layer pattern may need to be modified into a form favorable for deposition.

An object of the present invention has been made in view of the above points, when the EUVL reflective mask is exposed to EUV light, the reflection to ensure that exactly the dimensions of the pattern actually formed on the wafer corresponding to the respective dimensions of the absorbing layer pattern It is to provide a type mask and a manufacturing method thereof.

It is still another object of the present invention to provide a reflective mask and a method of manufacturing the same, which are more advantageous in forming an absorbing layer pattern having a trapezoidal structure while forming a mask pattern so that no shadow effect occurs.

A feature of the reflective mask according to the present invention for achieving the above object is a substrate, a reflective layer formed on the substrate to reflect Extreme Ultra Violet (EUV) light, and absorbs the EUV light on the reflective layer; , And each side wall is configured to include an absorbing layer pattern formed in a stepped shape.

Preferably, at each sidewall of the absorber layer pattern, the inclination angle with the reflective layer formed by the connecting line of the stair edges is equal to the incident angle or the reflection angle of the EUV light.

A feature of the reflective mask manufacturing method according to the present invention for achieving the above object is the step of forming a reflective layer for reflecting extreme ultra violet (EUV) light on a substrate, and absorbing the EUV light on the reflective layer Forming an absorbing layer and forming an absorbing layer pattern having stepped sidewalls by patterning the absorbing layer stepwise.

According to the present invention, in the EUVL reflective mask, the absorption layer pattern may be formed in a step shape, thereby maintaining the pattern shape of the trapezoidal structure.

In addition, the present invention is advantageous in terms of technology, economics, and time since the deposition for forming the entire mask pattern is easy while exhibiting the beneficial effect of the trapezoidal structure. That is, since the trapezoidal shape which does not generate a shadow effect at the time of exposure with EUV light is maintained as it is, when exposing with EUV light, the dimension of the pattern actually formed on a wafer corresponds exactly to each dimension of the absorption layer pattern.

In the present invention, when manufacturing the mask pattern in the trapezoidal form, it is easy to adjust the angle of the trapezoidal structure. As a result, the factor of occurrence of errors in the process can be significantly reduced.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a reflective mask according to the present invention and a method of manufacturing the same.

3 is a cross-sectional view showing an EUVL reflective mask pattern according to the present invention.

Referring to FIG. 3, the EUVL reflective mask according to the present invention includes a semiconductor substrate 21, a reflective layer 22 formed on the substrate 21, and an absorption layer pattern 25 formed on the reflective layer 22. It consists of 3 is a cross sectional view where the actual absorbing layer pattern 25 forms a pattern line.

The reflective layer 22 formed on the substrate reflects incident EUV light.

As the absorption layer pattern 25 is formed, the semiconductor substrate 21 is divided into an absorption region 23 that absorbs the EUV light 20 and a reflection region 24 that reflects the EUV light 20.

In detail, in the absorption region 23, an absorption layer pattern 25 is formed on the surface of the reflective layer 22, and in the reflection region 24, the absorption layer pattern 25 is not formed, but in the reflection region 24, the reflection layer is formed. (22) The surface is exposed.

The absorption layer pattern 25 formed in the absorption region 23 absorbs EUV light.

In particular, in the EUVL reflective mask according to the present invention, the absorption layer pattern 25 is stepped so that a shadow effect does not occur, that is, the EUV light reflected from the reflection layer 22 is prevented from being absorbed by the absorption layer pattern 25 and all are reflected. It is formed into a mold. That is, sidewalls of the absorbers 26 constituting the absorber layer pattern 25 are formed in a calculation form.

The absorber layer pattern 25 maintains the trapezoidal shape by the connecting lines 27 and 28 of the step edges. And, as an example, the inclination angle with the reflective layer 22 formed by the connection lines 27 and 28 is equal to the incident angle or the reflection angle of the EUV light 20.

In order to form the reflective mask having the above structure, first, the reflective layer 22 for reflecting EUV light is formed on the semiconductor substrate 21.

Subsequently, an absorbing layer (not shown) that absorbs EUV light is formed on the reflective layer 22.

Subsequently, an absorbing layer pattern 25 having a stepped sidewall according to the present invention is formed. As an example, an absorbing layer (not shown) formed on the reflective layer 22 is patterned in steps to form an absorbing layer pattern 25 having stepped sidewalls.

Accordingly, when the edges of the stairway walls of the absorber pattern 25 are connected, the connecting line is inclined with respect to the reflective layer 22.

In addition, the step patterning may be to pattern a plurality of times in each step unit. In addition, the absorber layer pattern 25 may be formed of a material including a metal material, and may be formed of a material including a different metal material for each layer forming the stairs, and neighboring layers may be formed of a material including different metal materials. It may be formed.

For example, the first step layer formed directly on the reflective layer 22 is formed of tantalum nitride (TaN), the second step layer is formed of titanium nitride (TiN), and the third step layer is titanium titanium. It can form in (Ta).

While the preferred embodiments of the present invention have been described so far, those skilled in the art may implement the present invention in a modified form without departing from the essential characteristics of the present invention.

Therefore, the embodiments of the present invention described herein are to be considered in descriptive sense only and not for purposes of limitation. Should be interpreted as being included in.

3 is a cross-sectional view showing an EUVL reflective mask pattern in accordance with the present invention.

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

20: EUV light 21: semiconductor substrate

22: reflective layer 23: absorption region

24 reflection area 25 absorbing layer pattern

25a: absorbent layer

Claims

Board;

A reflective layer formed on the substrate to reflect Extreme Ultra Violet (EUV) light;

A reflective mask, comprising: an absorption layer pattern absorbing the EUV light on the reflection layer, wherein each sidewall is formed in a step shape.

According to claim 1, At each side wall of the absorber layer pattern,

And the inclination angle with the reflective layer formed by the connecting lines of the stair edges is the same as the incident angle or the reflected angle of the EUV light.

Forming a reflective layer reflecting Extreme Ultra Violet (EUV) light on the substrate;

Forming an absorbing layer on the reflective layer to absorb the EUV light;

And patterning the absorbing layer stepwise to form an absorbing layer pattern having stepped sidewalls.