JPH05142748A - Phase shift mask and its production - Google Patents

Abstract

PURPOSE:To enable the simultaneous formation of light shielding layers for shielding exposing rays and phase shifters which are phase boundary regions and to enable the independent and exact control of the sizes of the phase shifters. CONSTITUTION:The micro-phase shifters 23a consisting of the same material as the material of the phase shifters 22 are provided in the light shielding regions in such a manner that the light transmitted through the micro-phase shifters 23a and a transparent substrate 21 and the light transmitted only through the transparent substrate 21 have a phase difference which acts in the direction negating each other by interference, by which the pseudo-light shielding layers 23 are formed. The micro-phase shifters constituting the pseudo- light shielding layers and the phase shifters which are the phase boundary regions are simultaneously formed by selectively etching away the phase shift films.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask used in a photolithography process, which is one of the manufacturing processes of semiconductor devices, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 24 is a plan view of a conventional phase shift mask 10A used for forming a contact hole using a positive resist, and FIG. 25 is a sectional view taken along line GG of the phase shift mask 10A. Is. FIG. 26 is a plan view of a conventional phase shift mask 10B used when forming a pillar using a positive resist.
In the following description, the phase shift mask 10 for forming a contact hole using a positive resist.
The configuration of A and the manufacturing method thereof will be described in detail, and the phase shift mask 10B will be denoted by the same or corresponding reference numerals in the drawings and description thereof will be omitted.

As shown in FIGS. 24 and 25, in this phase shift mask 10A, the phase shifter 2 is formed on the transparent substrate 1.
And the metal light shielding layer 3 is formed. The phase shifter 2 is provided with an opening H1 having a shape corresponding to the contact hole, while the metal light-shielding layer 3 is provided with an opening H2 which is slightly larger than the opening H1 so as to surround the opening H1. Are formed.

When the light from the exposure light source is incident on the phase shift mask 10A having the phase boundary region 2a as described above, the phase of the light passing through the phase boundary region 2a changes to the aperture H1.
Is shifted by about 180 ° with respect to that of the light passing through the area corresponding to (hereinafter referred to as "reference transmission area"). As a result, the change in light intensity at the edge of the reference transmission area becomes sharp,
The contact hole (opening H1) can be transferred with high accuracy.

[0005]

By the way, the phase shift mask 10A is manufactured without using the self-alignment method as described below. That is, after the phase shift film is deposited on the transparent substrate 1, the phase shift film is patterned by a conventionally well-known electron beam lithography process to form the phase shifter 2. Then, after depositing a metal film of chromium or the like on the transparent substrate 1 and the phase shifter 2, the metal film is patterned by an electron beam lithography process to form the metal light shielding layer 3.

As described above, in manufacturing the phase shift mask 10A, the electron beam lithography process is performed twice. Therefore, when performing the second electron beam exposure, highly precise alignment with the pattern formed in the first electron beam lithography process, that is, the phase shifter 2 is required. Therefore, there is a problem that the degree of freedom in the manufacturing process is small.

Therefore, as a means for solving such a problem, a phase shift mask is self-aligned (= self-aligned).
The technology of manufacturing by the method) has been conventionally proposed. FIG. 27 is a sectional view of a phase shift mask manufactured by the self-alignment method described below.

First, a metal film, a phase shift film and a positive resist film for electron beam are deposited on the transparent substrate 1. Then, the positive resist film is patterned by an electron beam lithography process to form a resist layer. Then, using the resist layer as a mask, the metal film and the phase shift film are selectively removed by plasma dry etching to form the phase shifter 2 having the opening H1 and the metal layer. Further, after removing the resist layer, the metal layer is under-etched by wet etching using the phase shifter 2 as a mask to form a metal light-shielding layer 3 having an opening H2. Thus, the phase shifter 2
An overhanging portion that functions as the phase boundary region 2a is formed at.

As described above, when the self-alignment method is used, the phase shift mask can be manufactured by one electron beam lithography step, so that the above-mentioned problem is solved, but another problem occurs. Occurs. That is, since the metal light shielding layer 3 is formed by patterning the metal layer by wet etching, the width of the opening H2 of the metal light shielding layer 3 cannot be accurately controlled, and as a result, the size of the phase boundary region 2a is increased. Becomes uneven. Further, in general, it is desirable to control the size of the phase shifter independently, but according to this method, only the same size can be manufactured.

The present invention has been made to solve the above-mentioned problems, and it is possible to simultaneously form a light-shielding layer that shields exposure light rays and a phase shifter that is a phase boundary region, and the size of the phase shifter is independent. It is an object of the present invention to provide a phase shift mask and a manufacturing method thereof that can be accurately controlled.

[0011]

According to a first aspect of the present invention, a transparent substrate having a reference transmission region and a phase shifter provided on the transparent substrate in a phase boundary region adjacent to the reference transmission region are provided. A phase shift mask having a pseudo light-shielding layer formed by scattering a plurality of minute phase shifters made of the same material as the phase shifter on the transparent substrate in a light-shielding region adjacent to the phase boundary region,
In order to achieve the above object, in the light-shielding region, there is a phase difference in which light passing through the minute phase shifter and the transparent substrate and light passing through only the transparent substrate act in a direction in which they cancel each other due to interference. Thus, the minute phase shifter is provided.

According to a second aspect of the present invention, in the phase shift mask according to the first aspect, part of the pseudo light shielding layer is replaced with a metal light shielding layer provided on the transparent substrate.

According to a third aspect of the present invention, a transparent substrate having a reference transmission region, a phase shifter provided on the transparent substrate in a phase boundary region adjacent to the reference transmission region, and a phase boundary region provided in the phase boundary region. In the adjacent shaded area,
A method for manufacturing a phase shift mask comprising a plurality of minute phase shifters made of the same material as the phase shifter and a pseudo light-shielding layer scattered on the transparent substrate, in order to achieve the above object, A step of forming a phase shift film and a resist film on a transparent substrate in this order, and a step of selectively removing the resist film to form a resist layer having a pattern corresponding to the phase shifter and the minute phase shifter And a step of simultaneously forming the phase shifter and the minute phase shifter by selectively removing the phase shift film using the resist layer as a mask.

According to a fourth aspect of the present invention, a transparent substrate having a reference transmission region, a phase shifter provided on the transparent substrate in a phase boundary region adjacent to the reference transmission region, and adjacent to the phase boundary region. A method of manufacturing a phase shift mask comprising a pseudo light-shielding layer and a metal light-shielding layer formed by scattering a plurality of minute phase shifters made of the same material as the phase shifter on the transparent substrate in a light-shielding region, In order to achieve the object, after forming a metal film on the transparent substrate, a step of selectively removing the metal film by etching to form the metal light-shielding layer, and on the metal light-shielding layer and the transparent substrate A step of forming a phase shift film and a resist film in this order, and a pattern corresponding to the phase shifter and the minute phase shifter by selectively removing the resist film. Forming a resist layer by selectively removing the phase shift film using the resist layer as a mask, and a step of simultaneously forming said phase shifter and said micro phase shifter.

[0015]

In the first to fourth aspects of the present invention, the light passing through the minute phase shifter and the transparent substrate and the light passing through only the transparent substrate act in the directions canceling each other due to interference in the light-shielding region. By providing the minute phase shifter so as to have a phase difference, a pseudo light shielding layer is formed. Therefore, the intensity of the transmitted light of the pseudo light shielding layer becomes zero, and the pseudo light shielding layer functions as a light shielding layer.

The minute phase shifter and the phase shifter, which is the phase boundary region, which constitute the pseudo light-shielding layer are made of the same material, and are simultaneously formed by selectively removing the phase shift film by etching. Moreover, the size of the phase shifter can be independently and accurately controlled.

[0017]

1 is a plan view showing a first embodiment of a phase shift mask according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. The phase shift mask 20A is a phase shift mask used when forming a contact hole using a positive resist. This phase shift mask 20
In A, the phase shifter 22 functioning as a phase boundary region is formed on the transparent substrate 21. This phase shifter 22
Has an opening H1 corresponding to the contact hole, and the region surrounded by the phase shifter 22 corresponds to the contact hole, that is, the reference transmission region 21.
It is a. In this way, the phase boundary region is provided adjacent to the reference transmission region 21a of the transparent substrate 21.

Further, the phase boundary region (phase shifter 2
A light shielding region is formed adjacent to 2). That is,
A pseudo light shielding layer 23 is provided on the transparent substrate 21 so as to surround the phase shifter 22. The pseudo light-shielding layer 23 is configured by arranging square micro-phase shifters 23a having a size smaller than the resolution characteristic of the light projecting device for transferring the contact holes using the phase shift mask 20A in a check pattern. ing. For convenience of description below, the minute phase shifter 2 in the pseudo light-shielding layer 23 is used.
An area where 3a is not formed is a "fine transmission area" 23b
Called.

When light is incident on the pseudo light shielding layer 23,
A phase difference of about 180 ° occurs between the light transmitted through the minute phase shifter 23a and the transparent substrate 21 and the light transmitted through the minute transmission region 23b. Therefore, two lights having a phase difference of 180 ° cancel each other due to interference, and the pseudo light-shielding layer 23 functions as if it were a light-shielding layer.

FIG. 3 is a plan view of a phase shift mask 20B used when forming a pillar using a positive resist, and FIG. 4 is a sectional view taken along line BB of FIG. As in the above case, the phase shift mask 20B is denoted by the same or corresponding reference numeral in the drawings, and the description thereof is omitted.

Next, a method of manufacturing the phase shift mask 20A will be described with reference to FIGS. First,
As shown in FIG. 5, the phase shift film 24 is formed on the transparent substrate 21.
F and a positive resist film 25F for electron beam are deposited in this order. Subsequently, the resist film 25F is selectively etched and removed by the electron beam lithography method to form the resist layer 25 (FIG. 6). Then, the phase shift film 24F is selectively removed by dry etching using the resist layer 25 as a mask to simultaneously form the phase shifter 22 and the minute phase shifter 23a as shown in FIG. Finally, by removing the resist layer 25, the phase shift mask 20A shown in FIGS. 1 and 2 is formed.

As described above, according to the first embodiment, the phase shifter 22 is formed by one electron beam lithography process.
Since the micro phase shifter 23a and the micro phase shifter 23a are formed at the same time, the alignment error between the phase boundary region (phase shifter 22) and the pseudo light shielding layer 23 is eliminated, and the degree of freedom in the manufacturing process is increased. Moreover, the manufacturing process is simplified and the manufacturing throughput can be shortened. Further, the size of the phase shifter 22 is not affected by the size of the pseudo light shielding layer 23,
Its size can be controlled independently.

8 to 11 are views showing a second embodiment of the phase shift mask according to the present invention. FIG. 8 is a plan view of a phase shift mask 30A used when forming a contact hole using a positive resist, and FIG. 9 is a sectional view taken along line CC of FIG. This phase shift mask 30
The point that A is largely different from that of the first embodiment is that a part of the pseudo light shielding layer is replaced with the metal light shielding layer 34.
That is, as shown in FIGS. 8 and 9, the phase boundary region 3
The metal light-shielding layer 34 is formed on the transparent substrate 31 so as to surround the pseudo light-shielding layer 33 provided around the transparent substrate 31. The phase shift mask 30B used when forming a pillar using a positive resist is also the same as described above, as shown in FIGS.

Next, a method of manufacturing the phase shift mask 30A will be described with reference to FIG. First, as shown in FIG. 12, a metal film 34F of chromium or the like and a positive resist film 35F for electron beam are formed on the transparent substrate 31.
Deposit. Then, after irradiating a predetermined position on the resist film 35F with an electron beam, the exposed portion is removed to form a resist layer 35 (FIG. 13). Subsequently, the metal film 34F is selectively removed by dry etching using the resist layer 35 as a mask to remove the metal light-shielding layer 34.
Are formed (FIG. 14). Then, as shown in FIG.
The resist layer 35 is removed.

Next, as shown in FIG. 16, after the phase shift film 32F is entirely coated on the transparent substrate 31 and the metal light shielding layer 34, a positive resist film 36F for electron beam is deposited on the phase shift film 32F ( (Fig. 17). Then, the resist film 36F is patterned by electron beam lithography to form a resist layer 36 (FIG. 18). Following that, as shown in FIG.
Using the as a mask, the phase shift film 34F is selectively removed by a dry etching method to form a minute phase shifter 33a. Although not shown in the figure, a phase shifter functioning as a phase boundary region is also formed at the same time.

Finally, the resist layer 36 is removed to complete the manufacture of the phase shift mask 30A shown in FIG.

As described above, according to the second embodiment,
The irradiation amount of the electron beam for forming the minute phase shifter 33a forming the pseudo light shielding layer can be significantly reduced, and the irradiation time of the electron beam can be shortened.

Further, in this second embodiment, FIG. 8 and FIG.
As shown in FIG. 4, the minute phase shifter 33a is designed so that a part thereof overlaps with the metal light shielding layer 34, and therefore has the following advantages. That is, in the phase shift mask 30A having the configuration according to the second example, it is necessary to manufacture each of them so that no gap is created between the pseudo light shielding layer 33 and the metal light shielding layer 34. That is, as shown in FIGS. 20 and 21, it is necessary to form the minute phase shifter 33a while accurately aligning it with the metal light shielding layer 34.

On the other hand, in the second embodiment, since the part of the minute phase shifter 33a overlaps the metal light shielding layer 34, the minute phase shifter 33a and the metal light shielding layer 3 are formed.
2 even if an alignment error with 4 occurs.
2 and FIG. 23, it is possible to prevent the generation of a gap between the metal light shielding layer 34 and the minute phase shifter 33a. Therefore, the degree of freedom in the manufacturing process can be made relatively large.

In the above embodiments, the shape of the minute phase shifter forming the pseudo light shielding layer is square, but the shape is not limited to this, and the minute phase shifter is constituted by, for example, a rectangle or a thin line. You may.

[0031]

As described above, in the first to fourth aspects of the present invention, the light passing through the minute phase shifter and the transparent substrate interferes with the light passing through only the transparent substrate in the light shielding region. Thus, the pseudo light-shielding layer is formed by providing the minute phase shifter so as to have a phase difference that acts in a direction of canceling each other.
Therefore, the minute phase shifter and the phase shifter, which is the phase boundary region, forming the pseudo light-shielding layer can be formed of the same material, and can be simultaneously formed by selectively removing the phase shift film by etching. .. Moreover, the phase shifter can be controlled independently of the minute shifter.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a phase shift mask according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a plan view of a phase shift mask used when forming a pillar using a positive resist.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 6 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 7 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 8 is a plan view showing a second embodiment of the phase shift mask according to the present invention.

9 is a sectional view taken along line CC of FIG.

FIG. 10 is a plan view of a phase shift mask used when forming a pillar using a positive resist.

11 is a cross-sectional view taken along the line DD of FIG.

12 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 13 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 14 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 15 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

16 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 17 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 18 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 19 is a cross-sectional view showing the method of manufacturing the phase shift mask of FIG.

FIG. 20 is a plan view showing a modified example of the phase shift mask according to the second embodiment.

21 is a cross-sectional view taken along the line EE of FIG.

FIG. 22 is still another modification of the phase shift mask according to the second embodiment.

23 is a cross-sectional view taken along the line FF of FIG.

FIG. 24 is a plan view of a phase shift mask used when forming a contact hole using a positive resist.

FIG. 25 is a sectional view taken along line GG of the phase shift mask.

FIG. 26 is a plan view of a phase shift mask used when forming a pillar using a positive resist.

FIG. 27 is a cross-sectional view of a phase shift mask manufactured by a self-alignment method.

[Explanation of symbols]

 21, 31 Transparent substrate 22, 32 Phase shifter 23, 33 Pseudo light shielding layer 23a, 33a Micro phase shifter 34 Metal light shielding layer

Claims (4)

[Claims] 1. A transparent substrate having a reference transmission region, a phase shifter provided on the transparent substrate in a phase boundary region adjacent to the reference transmission region, and a light shielding region adjacent to the phase boundary region in the phase boundary region. A phase shift mask comprising a pseudo light-shielding layer in which a plurality of minute phase shifters made of the same material as a phase shifter are scattered on the transparent substrate, wherein the minute phase shifter and the transparent substrate are provided in the light-shielding region. The phase shift mask, wherein the minute phase shifter is provided such that light passing through the transparent substrate and light transmitting only the transparent substrate have a phase difference that acts in a direction in which they cancel each other due to interference. 2. The phase shift mask according to claim 1, wherein a part of the pseudo light shielding layer is replaced with a metal light shielding layer provided on the transparent substrate. 3. A transparent substrate having a reference transmission region, a phase boundary region adjacent to the reference transmission region, a phase shifter provided on the transparent substrate, and a light shielding region adjacent to the phase boundary region, A method of manufacturing a phase shift mask, comprising: a plurality of minute phase shifters made of the same material as a phase shifter; and a pseudo light-shielding layer dispersed on the transparent substrate, wherein a phase shift film and a resist are provided on the transparent substrate. Forming a film in this order, forming a resist layer having a pattern corresponding to the phase shifter and the minute phase shifter by selectively removing the resist film, and using the resist layer as a mask A step of simultaneously forming the phase shifter and the minute phase shifter by selectively removing the phase shift film. Manufacturing method. 4. A transparent substrate having a reference transmission region, a phase shifter provided on the transparent substrate in a phase boundary region adjacent to the reference transmission region, and a phase shifter in a light shielding region adjacent to the phase boundary region. Is a method for manufacturing a phase shift mask including a pseudo light-shielding layer and a metal light-shielding layer in which a plurality of minute phase shifters made of the same substance are scattered on the transparent substrate, wherein a metal film is formed on the transparent substrate. After the formation, a step of selectively removing the metal film by etching to form the metal light-shielding layer; and a step of forming a phase shift film and a resist film on the metal light-shielding layer and the transparent substrate in this order. A step of selectively removing the resist film to form a resist layer having a pattern corresponding to the phase shifter and the minute phase shifter; By selectively removing the phase shift film as disk, a method of manufacturing a phase shift mask and a step of simultaneously forming said phase shifter and said micro phase shifter.