KR100359769B1 - Halftone phase shift mask and method for fabricating the same - Google Patents

Abstract

The present invention is to provide a halftone phase shift mask and a method of manufacturing the halftone phase shift mask that can prevent the accumulation of charge by the guard ring without forming a separate conductive material layer, A halftone phase inversion mask, comprising: a mask pattern region, a guard ring pattern defined at an outer edge of the mask pattern region, a light shielding film formed at an outer side of the guard ring pattern, and a light shielding film and the mask across the guard ring pattern And a plurality of conductive layer patterns connecting the pattern region and a ground pin connected to the light blocking film.

Description

Halftone phase inversion mask and manufacturing method thereof {HALFTONE PHASE SHIFT MASK AND METHOD FOR FABRICATING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a mask, and in particular, to create an electron transfer path for electrons to escape to the ground pin, to prevent the accumulation of charge by the guard ring, the manufacturing cost and additional process of the mask A halftone phase inversion mask manufacturing method is unnecessary.

1A to 1H are cross-sectional views illustrating a method of manufacturing a halftone phase shift mask according to the prior art.

As shown in FIG. 1A, as the phase inversion layer 12 on the quartz substrate 11, a MoSiN layer is formed. Thereafter, a chromium layer is formed as the light shielding film 13 on the phase inversion layer 12, and the photoresist 14 is coated on the light shielding film 13.

As shown in FIG. 1B, the photoresist 14 is patterned by an exposure and development process, and as shown in FIG. 1C, the light-shielding film 13 at the center is subjected to an etching process using the patterned photoresist 14 as a mask. Remove it.

Thereafter, as shown in FIG. 1D, after the photoresist 14 is removed, the lower phase inversion layer 12 is selectively removed by an etching process using the light shielding film 13 as a mask, thereby allowing the quartz substrate 11 to be removed. Selectively expose

Subsequently, as shown in FIG. 1E, a photoresist 15 is applied to the entire surface including the exposed quartz substrate 11, and as shown in FIG. 1F, a conductive material layer (eg, on the photoresist 15) is applied. 16).

Thereafter, as shown in FIG. 1G, after the photoresist 15 is patterned using an electron beam, the conductive material layer 16 is removed, and as shown in FIG. 1H, the unnecessary light blocking film 13 is removed. . When the photoresist 15 is removed, the mask manufacturing process according to the prior art is completed.

In general, a blank mask used in the manufacture of a mask is a binary mask having chromium (Cr) on quartz.

However, unlike a binary mask using a chromium layer as a light shielding film, a halftone phase inversion mask using a MoSiN layer as a phase inversion mask requires two exposure processes.

That is, after etching the chromium and MoSiN layer using the pattern formed in the first exposure, the desired final pattern is obtained. At this time, the chromium layer remains on the MoSiN layer.

Here, any of the chromium layers present in the region used for wafer exposure must be removed, and those present in the other region must be present as they are. Therefore, there is a need to protect with photoresist for selective wet etching. To this end, the MoSiN layer is etched and then subjected to secondary exposure with an electron beam.

In this case, when the guard ring for protecting the device is installed in the mask, the part to be subjected to the second exposure and the part to which the chromium layer should remain are disconnected by the guard ring.

2 is a plan view of a halftone phase shift mask having a conventional guard ring pattern formed thereon.

As shown in FIG. 2, a mask pattern 21 is defined at a central portion, a guard ring pattern 22 is defined at an outer side thereof, and a light shielding film 13 is formed at an outer side of the guard ring pattern 22. It has a structure in which the ground pin 23 is formed outside the guard ring pattern 22 at a predetermined distance.

Here, the mask pattern 21 is made of MoSiN.

This will be described in detail with reference to FIGS. 3A to 3E.

For reference, FIGS. 3A to 3D are cross sections taken along the line AA ′ of FIG. 2, and FIG. 3E is a cross section taken along the line B-B ′.

First, as shown in FIG. 3A, a MoSiN layer is formed on the quartz substrate 11 as the phase inversion layer 12. Thereafter, a chromium layer is formed as the light shielding film 13 on the phase inversion layer 12, and the photoresist 14 is coated on the light shielding film 13.

As shown in FIG. 3B, the photoresist 14 is patterned to exist only at both peripheral portions of the mask by an exposure and development process, and as shown in FIG. 3C, an etching process using the patterned photoresist 14 as a mask is performed. The light shielding film 13 in the center is removed.

Thereafter, as shown in FIG. 3D, after the photoresist 14 is removed, the lower phase inversion layer 12 is selectively removed by an etching process using the light shielding film 13 as a mask, thereby allowing the quartz substrate 11 to be removed. Selectively expose For reference, FIG. 3D is a cross-sectional view taken along line BB ′ of FIG. 2.

Through this process, a halftone phase inversion mask is manufactured, and when the process of FIG. 3d is completed, the guard ring patterns 22 are defined on both sides of the mask area in the center portion as shown in FIG. 3e. For reference, FIG. -C 'is the cross section along the line.

The mask having such a structure causes a charge up phenomenon in the second exposure through the following process.

That is, when the electron beam used for exposure reaches a resist, it is conducted along the chromium layer which is the light shielding film 13. When the light blocking film 13 and the phase inversion layer 12 are etched to reach the guard ring pattern 22 having only the quartz substrate 11, electrons are collected.

Thereafter, as the exposure proceeds, more and more electrons accumulate and generate a strong electric field. As the electric field becomes stronger, the trajectory of the electron beam is changed, and the position of the pattern is changed, thereby making it impossible to manufacture a correct mask.

However, the conventional halftone phase shift mask has the following problems.

First, in order to reduce the charge accumulation phenomenon, a conductive layer must be formed separately. That is, since the conductive material layer must be formed on the entire surface of the mask for the second exposure, the process takes about 1 hour and the cost increases accordingly.

Second, foreign matters are generated in the process of applying the conductive material layer. That is, the productivity of the mask is reduced due to the foreign matter generated during the exposure to the atmosphere and the formation of the conductive material layer.

Third, the properties of the conductive material layer are changed. In other words, the lifetime of the conductive material layer is short, so that it is easy to change and difficult to manage, and if the conductive material is formed again, the process takes a long time due to several operations.

The present invention has been made to solve the above problems of the prior art, to provide a halftone phase shift mask that can prevent the accumulation of charge by the guard ring without forming a separate conductive material layer. There is this.

1A to 1H are cross-sectional views illustrating a method of manufacturing a halftone phase shift mask according to the related art.

2 is a plan view of a halftone phase shift mask according to the prior art;

3A to 3D are cross-sectional views taken along line AA ′ of FIG. 2.

3E is a cross-sectional view taken along the line BB ′ of FIG. 2.

4 is a plan view of a halftone phase shift mask according to the present invention;

5A through 5D are cross-sectional views taken along line AA ′ of FIG. 4.

FIG. 5E is a cross-sectional view taken along the line BB ′ of FIG. 4.

5F is a cross-sectional view taken along the line CC 'of FIG. 4.

Explanation of symbols for main parts of the drawings

11,51: quartz substrate 12,52: phase inversion layer

13,53 shading film 14,54 photoresist

16: conductive material layer 12, 42: guard ring pattern

123,45: ground pin 44: conductive layer pattern

The halftone phase shift mask according to the present invention for achieving the above object comprises a mask pattern region, a guard ring pattern defined at an outer edge of the mask pattern region, and an outer edge of the guard ring pattern. The light blocking film is formed, a plurality of conductive layer patterns crossing the guard ring pattern and connecting the light blocking film and the mask pattern region, and a ground pin connected to the light blocking film.

The method for manufacturing a halftone phase shift mask according to the present invention corresponds to a mask pattern region using a process of forming a phase shift layer on a quartz substrate, a process of forming a light shielding film on the phase shift layer, and an electron beam exposure and development process. Removing the light shielding film, forming a phase inversion layer using the light shielding film as a mask, applying a photoresist on the entire surface, patterning the photoresist by electron beam exposure and development, and patterning the photoresist And selectively removing the light shielding film with a mask.

First, the halftone phase inversion mask of the present invention is characterized by preventing a phenomenon in which electrons accumulate due to exposure by electrically connecting portions where the mask pattern region and the light shielding film are disconnected from each other by a guard ring.

Hereinafter, a halftone phase inversion mask of the present invention will be described with reference to the accompanying drawings.

4 is a plan view of the phase shift mask of the present invention.

As shown in FIG. 4, the mask pattern region 41 in the center portion, the guard ring pattern 42 defined along the outer surface of the mask pattern region 41, and the outer surface of the guard ring pattern 42 are formed. A plurality of conductive layer patterns 44 crossing the light blocking film 53, the guard ring pattern 42, and connecting the mask pattern region 41 and the light blocking film 53, and a ground connected to the light blocking film 53. It is configured to include a pin 45.

Here, the conductive layer pattern 44 serves to transfer electrons generated when the electron beam is exposed to the ground pin 45, and the conductive layer pattern 44 is formed separately from the light shielding film 53 or of the light shielding film 53. It is possible to use a part as the conductive layer pattern 44.

The shape of the conductive layer pattern 44 includes forming a polygon.

This will be described in more detail with reference to FIGS. 5A to 5F as follows.

5A through 5F are cross-sectional views illustrating a method of manufacturing a halftone phase inversion mask according to the present invention. FIGS. 5A through 5D are taken along line AA ′ of FIG. 4, and FIG. 5E is BB of FIG. 4. 5 is a cross section taken along the line C-C in FIG. 4.

As shown in FIG. 5A, a MoSiN layer is formed as a phase inversion layer 52 on the quartz substrate 51, and a chromium (Cr) layer is formed as a light shielding film 53 on the phase inversion layer 52. Form.

Thereafter, after the photoresist 54 is applied onto the light shielding film 53, as shown in FIG. 5B, the photoresist 54 is patterned by developing after the electron beam exposure.

Subsequently, as illustrated in FIG. 5C, the light blocking film 53 is selectively removed by an etching process using the patterned photoresist 54 as a mask.

In general, the light shielding film 53 may have portions corresponding to the mask pattern region 41 and the guard ring pattern 42, and the present invention removes all of the light shielding film 53 corresponding to the guard ring pattern 42. Not partially.

Thereafter, as shown in FIG. 5D, after removing the photoresist 54, the quartz substrate 51 is removed by removing the lower phase inversion layer 52 using the light shielding film 53 as a mask. Selective exposure completes the halftone phase inversion mask manufacturing process according to the present invention.

When the mask is manufactured through the above process, the cross section taken along the line B-B 'of FIG. 4 is shown in FIG. 5E, and the cross section taken along the line C-C ′ of FIG. 4 is shown in FIG. 5F.

In the present invention as described above, the conductive layer pattern 44 should be small enough so that the electrons can pass freely and small enough not to be exposed to the wafer during exposure.

Accordingly, the length and width of the conductive layer pattern 44 are adjusted to satisfy the above two conditions.

That is, the length should be narrow because it is a region through which light is transmitted at the time of exposure. However, the length must be such that the mask pattern region inside the light shielding film can be isolated.

The value that satisfies this condition is about several micrometers, and the width is to allow electrons to pass through and light to pass through. If the width is too small, electrons may pass through and break, and if too large, a pattern may remain on the wafer.

In this case, when the electrons pass through and are disconnected, a method of forming a plurality of conductive layer patterns may be solved. However, the case where the patterns remain on the wafer depends on the light source used. For example, in the case of a 5 × stepper using 365 nm as a light source, the width of the conductive layer pattern is maintained at about 1 μm, when 245 nm is used as the light source, about 0.35 μm, and when 193 nm is used as the light source. If it is kept below 0.25 占 퐉, no pattern is formed on the wafer.

As a result, when the length of the conductive layer pattern is maintained at about several μm and the width is formed at about 0.25 μm, all of the aforementioned conditions can be satisfied.

As described above, the halftone phase inversion mask of the present invention has the following effects.

The manufacturing period can be shortened by eliminating the charge-up phenomenon caused by the electrons generated during the exposure by the electron beam, and by simplifying the mask manufacturing process.

In addition, mask manufacturing equipment is possible without the investment of new equipment.

Claims (5)

In the halftone phase inversion mask, The mask pattern area, A guard ring pattern defined at an outer surface of the mask pattern region; A light shielding film formed on an outer surface of the guard ring pattern; A plurality of conductive layer patterns having a polyhedral structure crossing the guard ring pattern and connecting the light blocking film and the mask pattern region; And a ground pin connected to the light shielding film. delete The halftone phase shift mask of claim 1, wherein the conductive layer pattern is made of the same material as the light blocking film. The halftone phase shift mask of claim 1, wherein a length of the conductive layer pattern is maintained at a size that can isolate the mask pattern region, and a width thereof is maintained at 0.5 to 1 μm. Forming a phase inversion layer on the quartz substrate; Forming a light shielding film on the phase inversion layer; Removing the light shielding film corresponding to the mask pattern region using an electron beam exposure and development process; Forming a phase inversion layer using the light shielding film as a mask; Applying a photoresist to the entire surface; Patterning the photoresist by electron beam exposure and development; And removing the light shielding film selectively using the patterned photoresist as a mask to electrically connect the mask pattern region to the light shielding film.