JP2002351056A - Method for producing photomask blank, photomask blank and method for producing photomask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a photomask blank capable of producing a photomask having high accuracy of position, to provide such a photomask blank and to provide a method for producing such a photomask having high accuracy of position. SOLUTION: In the method for producing a photomask blank, an electrically conductive light shielding film is formed on the surface of one side of a glass substrate through a step for forming a light shielding material into a film while fixing the material on one side of the glass substrate by first substrate support parts and a step for forming a light shielding material into a film while fixing the material on the one side by second substrate support parts which do not overlap the first substrate support parts. In the method for producing a photomask, a photosensitive resin is disposed on the resulting photomask blank comprising the glass substrate and the electrically conductive light shielding film formed on the whole surface of one side of the substrate and exposure with an electron beam exposure system, development and etching are carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a photomask blank, which is a material before patterning, necessary for manufacturing a photomask used for IC and other fine pattern exposure, a photomask blank, and a photomask. The present invention relates to a technique relating to a method for manufacturing a mask.

[0002]

2. Description of the Related Art A conventional photomask blank manufacturing method uses a holder 21 as shown in FIG.
In the holder 21, an opening 24 having a shape similar to that of the glass substrate 12 is provided in the frame 22, but since the glass substrate cannot be fixed only by the opening, the substrate supporting portions 23 are provided at the four corners.

In order to manufacture such a photomask blank, the glass substrate 12 is inserted into the opening 24 and put into a film forming apparatus, and the conductive light-shielding material is removed by a physical film forming method. 12 has a conductive light shielding film 1 on one side.
3 was formed to produce the photomask blank 11. As a result of the manufacturing, the completed photomask blank 11 had the conductive light-shielding film 13 formed thereon except for four corners on one side.

Further, a photosensitive resin layer is provided on the surface of the completed photomask blank. Then, the photosensitive resin at the irradiated portion is exposed by pattern exposure using an electron beam irradiation device.

Next, by exposing only the photosensitive resin layer other than the exposed portions, only the portions other than the pattern exposed portions are exposed. Then, the conductive light-shielding film other than the pattern-exposed portion is removed by etching the conductive light-shielding film on the photomask blank exposing only the portion other than the pattern-exposed portion.

Finally, by removing the photosensitive resin, a photomask in which a conductive light-shielding film remains only in a portion exposed to a pattern has been manufactured.

[0007]

The conventional photomask blank 11 has four corners on which no conductive light shielding film 13 is formed, as shown in the figure. The glass substrate 12 is directly exposed in a portion where such a conductive light shielding film is not formed.

In some cases, electric charges are generated on the surface of the glass substrate 12 due to electron beam irradiation or other causes. However, since the conductivity of the surface of the glass substrate 12 is low, the generated charges cannot move and may stay forever.

[0009] Such accumulated charges on the surface of the glass substrate 12 cause an attractive or repulsive force to act on the electrons irradiated at the time of electron beam exposure, so that the irradiation position of the electron beam shifts. Particularly, electron beam irradiation at a high accelerating voltage is greatly affected by electric charges. However, electron beam irradiation at a high accelerating voltage has been frequently used to improve positional accuracy, and thus has a serious problem.

Under such circumstances, a method of manufacturing a photomask blank capable of manufacturing a photomask having such high positional accuracy, and a method of manufacturing such a photomask blank,
In addition, there has been a demand for a method of manufacturing a photomask having such high positional accuracy.

[0011]

According to the present invention, in order to solve the above-mentioned problems, according to the first aspect of the present invention, a light-shielding material is formed while being fixed to one surface of a glass substrate by a first substrate supporting portion. A photomask blank for forming a conductive light-shielding film on one surface by a process and a step of forming a light-shielding material in a state where the light-shielding material is fixed on the one surface by a second substrate support that does not overlap with the first substrate support. Is provided.

According to a second aspect of the present invention, there is provided a method of manufacturing a photomask blank according to the first aspect, wherein the first substrate supporting portion and the second substrate supporting portion have complementary patterns. It is.

According to a third aspect of the present invention, there is provided a photomask blank in which a conductive light-shielding film is provided on the entire surface of one surface of a glass substrate.

According to a fourth aspect of the present invention, a photosensitive resin is placed on a glass substrate and a photomask blank in which a conductive light-shielding film is provided on the entire surface of one side of the glass substrate. An object of the present invention is to provide a method for manufacturing a photomask characterized by etching.

By using the method for manufacturing a photomask blank according to the first aspect, a method for manufacturing a photomask blank capable of manufacturing a photomask capable of accurately drawing upon irradiation with an electron beam becomes possible.

By using the method for manufacturing a photomask blank according to the second aspect, in addition to the effects described in the first aspect, it is possible to manufacture a photomask capable of forming a pattern with high accuracy without waste of material. This enables a method for manufacturing a photomask blank.

By using the photomask blank of the third aspect, it is possible to provide a photomask blank capable of manufacturing a photomask capable of accurately drawing upon irradiation with an electron beam.

By using the method for manufacturing a photomask according to the fourth aspect, it is possible to manufacture a photomask having an accurate pattern.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method of manufacturing a photomask blank according to the present invention, first, a first conductive light-shielding film 14 is manufactured using a holder 23 as shown in FIG. In the holder 21, an opening 24 having a shape similar to that of the glass substrate 12 is provided in the frame 22, but since the glass substrate cannot be fixed only by the opening, the substrate supporting portions 23 are provided at the four corners.

In this case, the glass substrate 12 is inserted into the opening 24 and put into a film forming apparatus, and the conductive light-shielding material is removed by a physical film forming method, in this embodiment, sputtering. A glass substrate 16 having a first conductive light-shielding film 14 formed on one surface of such a glass substrate 12 has been manufactured.

Next, the second conductive light-shielding film 14 was manufactured using the holder 25 as shown in FIG. In the holder 25, an opening 29 having a shape similar to that of the glass substrate 12 is provided in the frame 26. However, the glass substrate cannot be fixed only by the opening, and therefore, the substrate supporting portions 27 are provided at positions other than the four corners.

Since the area is too large for the actual support, the actual contact is supported by the projections 28. In this case, the glass substrate 16 on which the first conductive light-shielding film 14 is formed is inserted into the opening 29 and the film is placed in a film forming apparatus, and the conductive light-shielding material is skipped by a physical film forming method. A second conductive light-shielding film 15 is formed on one surface of a glass substrate 12 as shown in FIG.

As a result, the completed photomask blank 11 has the second conductive light-shielding film 15 at four corners on one side, and the first conductive light-shielding film 14 except for the four corners. Thus, the conductive light-shielding film 13 was provided on the entire surface.

Next, a method of manufacturing a photomask using such a photomask blank will be described below.

The photomask blank has a conductive light shielding film 32 formed on a glass substrate 31 as shown in FIG. Further, as shown in FIG. 6, a photosensitive resin layer 33 is provided on the conductive light shielding film 32 on the surface of the photomask blank. Then, the photosensitive resin layer 33 is divided into an exposed photosensitive resin layer 34 and an unexposed photosensitive resin layer 35 as shown in FIG. 7 by pattern exposure using an electron beam irradiation device.

Next, as shown in FIG. 8, exposure is performed to remove only the unexposed photosensitive resin layer 35, thereby exposing the conductive light-shielding film 32 where there is no exposed photosensitive resin layer 34. Then, as shown in FIG. 9, the portion of the conductive light-shielding film 32 where there is no exposed photosensitive resin layer 34 is removed by etching, and the conductive light-shielding film 32 is removed in a pattern.

Finally, as shown in FIG. 10, by removing the exposed photosensitive resin layer 34, a photomask in which the conductive light-shielding film 32 remains only in the pattern-exposed portion is manufactured.

As the glass substrate in the present invention, various glass substrates such as soda lime glass and quartz glass that transmit light used for exposure can be used, and the type is not limited. Further, the conductive light-shielding film only needs to be one that does not allow exposure light to pass through and has at least conductivity that does not cause a problem of stagnation of charges.

Therefore, not only chromium and chromium oxide, but also various metals and metal oxides are used. Further, the light-shielding material does not need to have conductivity or light-shielding property itself, and may be a material having conductive light-shielding property in a film-formed state.

Furthermore, the film forming method according to the present invention may be a physical vapor deposition method (PVD), a chemical vapor deposition method, or the like, if it relates to a film forming method in which a glass substrate needs to be fixed by a substrate support. It does not matter what kind such as the phase film forming method (CVD). Also, various methods such as vacuum deposition and sputtering can be used for PVD.

Further, in sputtering, not only simple sputtering but also various sputtering such as ion assist, various gas assists, and plasma assist can be used. However, it is common to use sputtering in terms of film forming accuracy, manufacturing cost, and the like.

Further, the substrate is supported by a holder, a tray,
Although there are various support methods such as direct support, various methods requiring a substrate support portion are used. Note that the substrate support is generally of a holder support type that can be used only by changing the holder even if the size of the substrate changes.

If the first support substrate and the second support substrate do not overlap each other, even if there is a part that is not included in either the first support substrate or the second support substrate. good. However, the conductive light-shielding film in a portion not included in both of them is thicker than the conductive light-shielding film in the other portion.

Therefore, it takes time to etch the conductive light-shielding film in that portion, the material cost increases, and the amount of side etching increases, which causes a decrease in pattern accuracy. Therefore, it is preferable to minimize the portions not included in both.

In addition, the first and second support substrate portions can be easily realized by a complementary pattern in which there is no overlap or a portion not included in either of them.
The boundary between the first support substrate and the second support substrate may be anywhere in principle.

However, it is preferable not to cover an area used for patterning with an actual photomask as much as possible. This is because it is not easy to make the thickness of the conductive light-shielding film in the boundary region the same as the other portions.

In this embodiment, the first support substrate is provided at the four corners, and the second support substrate is provided at a position other than the four corners. May be used, but it must be in a form capable of supporting a glass substrate.

It is not necessary that all portions of the support substrate are necessary for supporting the glass substrate. Like the second support substrate of the present embodiment, the projections are useful for the actual support. Only the part may be used, and the other part may have a structure that merely performs the shielding function.

Further, in the present embodiment, the photosensitive resin is a resin which actually reacts to an electron beam and should be referred to as an electron beam resin. In the present invention, the term "photosensitive resin" is used. Similarly, in the case of drawing an electron beam, the term “exposure” is used in accordance with a custom, but it is natural that the electron is regarded as light, and the other terms are expressed in accordance with it.

Therefore, as long as the photosensitive resin of the present invention has electron beam sensitivity, it does not matter whether it is sensitive to light, ultraviolet rays, heat or the like.

Although the photosensitive resin exposed to an electron beam and exposed to light and patterned by development has been described, a photosensitive resin in which the exposed part is dissolved by development and the unexposed part is patterned may be used. good. However, in the case of a photosensitive resin in which an exposed portion is dissolved by development and a non-exposed portion is patterned, the drawing portion is often large and is not generally practical.

Further, in many cases, the development of the exposed portion is performed after various processes such as a fixing process are performed in order to surely perform patterning.

The etching process is also performed with various etching solutions,
Although it is possible to use etching conditions such as temperature and concentration, generally, due to various requirements such as a small side etch, a good etching shape, and a high etching rate,
Various types are selected according to the material of the conductive light-shielding film. Dry etching using plasma is also performed.

[0044]

[Example] Square (15.2 cm on a side, 6.35 m in thickness)
m) The quartz glass substrate is fixed to the film forming place in the sputtering apparatus using the holder shown in FIG. 3, a target made of Cr is set, sputtering is performed, and the surface of the glass substrate other than the first substrate supporting portion is set. A chromium film having a thickness of 100 nm was formed.

Further, a chromium film of 100 nm was formed on the surface of the glass substrate other than the second substrate supporting portion, except that only the holder was replaced with that shown in FIG. 4 under the same conditions.

As a result, almost 100
A chromium film having a thickness of nm could be formed, and such a photomask blank was obtained.

Next, on this photomask blank,
Electron beam photosensitive resin (ZEP700 manufactured by Zeon Corporation)
0) with a 500 nm thick spin coater,
A photosensitive resin was formed on the entire surface of the photomask blank by a drying process.

Further, it is set in an electron beam exposure apparatus,
Drawing was performed at an acceleration voltage of 50 kV. Then, after fixing with a fixing solution, the unexposed portion of the electron beam photosensitive resin was removed with a developing solution to form a pattern.

Such a photomask blank was etched and patterned on Cr. Finally, after removing the unexposed portions of the electron beam photosensitive resin with a removing liquid, a patterned photomass was obtained by a drying step.

In such a photomask, the writing position accuracy was 0.025 μm as the maximum deviation amount. In the conventional photomask, the writing position accuracy is set to 0.
Since it was 122 μm, it can be said that the drawing position accuracy was considerably improved.

[0051]

As described above, according to the present invention,
This enables accurate drawing at the time of electron beam irradiation, thereby increasing the possibility that a more accurate semiconductor device can be obtained, and may also facilitate drawing.

Accordingly, it becomes possible to lower the drawing price, improve the yield, and work even with a low level of skill in the drawing technique. Many photomass manufacturing methods are possible, such as the possibility of manufacturing a photomask that has been difficult to draw conventionally.

[Brief description of the drawings]

FIG. 1 is a front view of a photomask blank according to an embodiment of the present invention.

FIG. 2 is a front view of the photomask blank of FIG. 1 in the process of being manufactured.

FIG. 3 is a front view of a holder used for manufacturing the photomask blank of FIG.

FIG. 4 is a front view of another holder different from FIG. 3 used for manufacturing the photomask blank of FIG. 1;

FIG. 5 is a conceptual sectional view of a photomask blank according to an example of the present invention.

6 is a conceptual cross-sectional view of a method for manufacturing a photomask using the photomask blank of FIG.

7 is a conceptual cross-sectional view of a method for manufacturing a photomask using the photomask blank of FIG.

8 is a conceptual sectional view of a method for manufacturing a photomask using the photomask blank of FIG.

9 is a conceptual cross-sectional view of a method for manufacturing a photomask using the photomask blank of FIG.

10 is a conceptual cross-sectional view of a method for manufacturing a photomask using the photomask blank of FIG.

FIG. 11 is a front view of a conventional photomask blank to be compared with the present invention.

12 is a front view of a holder used for manufacturing the photomask blank of FIG.

[Explanation of symbols]

 11 Photomask blank 12 Glass substrate 13 Conductive light-shielding film 21 Holder 22 Frame 23 Substrate support 24 Opening 31 Glass substrate 32 Conductive light-shielding film 33 ...... photosensitive resin layer 34 exposed photosensitive resin layer 35 unexposed photosensitive resin layer

Claims (4)

[Claims] A step of forming a light-shielding material while fixing the glass substrate to one surface of the glass substrate by a first substrate support; and fixing the film to the one surface of the glass substrate by a second substrate support that does not overlap the first substrate support. A method for producing a photomask blank in which a conductive light-shielding film is formed on one surface by a step of forming a light-shielding material in a state of being formed. 2. The method according to claim 1, wherein the first substrate support and the second substrate support have complementary patterns. 3. A photomask blank comprising a glass substrate and a conductive light-shielding film provided on one entire surface of the glass substrate. 4. A photosensitive resin is placed on a glass substrate and a photomask blank provided with a conductive light-shielding film on the entire surface of one surface thereof, and is exposed, developed, and etched by an electron beam exposure apparatus. Manufacturing method of a photomask.