JP3690164B2 - Photomask blanks and photomasks - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photomask blank and a photomask for manufacturing a photomask for exposure transfer used in a photolithography process in a semiconductor manufacturing process.
[0002]
[Prior art]
Conventional blanks for photomasks are generally used by forming a chromium or chromium oxide film on a glass substrate by sputtering or vapor deposition. In this film forming process, from the viewpoint of reducing defects in the photomask blanks, a method is used in which a glass substrate is disposed above an evaporation source such as a target and a film is formed from below the glass substrate.
[0003]
FIG. 3 is a plan view of the film formation substrate holder 30 including the holder frame 31 and the substrate support portion 32, and FIG. 4 is a plan view of a photomask blank 40 manufactured using the film formation substrate holder 30. Since that supports the glass substrate at a substrate support portion 32 when deposition substrate holder 30 to produce a photomask blank 40 by using the deposition substrate holder 30, substrate support 32 (typically four corners ) the deposition is inhibited, non-film portion 42 is generated in the four corners of the blank for a photomask 4 0. The non-film forming unit 42 is determined by the shape of the substrate supporting portion 32 of the deposition substrate holder 30, is formed on the four corners of ordinary glass substrate, but a small part, in a manner of forming the glass substrate downward, this It is impossible to eliminate the non-film forming part 42.
[0004]
When a resist is formed on the photomask blank 40 having the non-film forming portion 42 and a pattern is drawn by an electron beam lithography machine, charges are accumulated on the photomask blank by electron beam irradiation (referred to as charge-up). This causes a problem that the drawing pattern of the photomask produced is distorted.
However, in a drawing machine having an accelerating voltage of 10 to 20 kV, which is widely introduced at present, charge accumulation is suppressed to an extent that there is no problem by grounding the film forming portion of the photomask blank.
[0005]
On the other hand, an electron beam drawing machine having a high acceleration voltage of 50 kV, which is superior in terms of resolution and drawing accuracy, is superior to an electron beam drawing machine having an acceleration voltage of 10 to 20 kV, which has been mainstream until now. It has begun to be introduced.
[0006]
However, when the acceleration voltage increases, the electron beam scatters backward, and charges accumulate on the non-film-formation part on the photomask blank with high insulating properties, causing charge-up and near the corner of the photomask. Only the problem that the position accuracy is greatly deteriorated has occurred.
[0007]
[Problems to be solved by the invention]
The present invention has been devised in view of the above-mentioned problems. Photomask blanks and patterns that do not charge up charges on resist-coated blanks when electron beam writing is performed using an electron beam writing machine with a high acceleration voltage. An object is to provide a photomask with excellent positional accuracy.
[0008]
[Means for Solving the Problems]
In order to solve the above problems in the present invention, in the first claim 1, for a photomask having a HiNaru film unit to the four corners of the film forming portion and the transparent substrate made of chromium or chromium oxide film on a transparent substrate In the blank, the photomask blank is characterized in that a conductive thin film is additionally formed on the non-film forming portion of the photomask blank.
[0009]
According to a second aspect of the present invention, in the photomask blank according to the first aspect, the conductive thin film is a transparent conductive thin film.
[0010]
Furthermore, in claim 3, the photomask blank according to claim 1 or 2 is used to perform a series of patterning processes such as electron beam drawing and development by an electron beam drawing machine. This is a photomask.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a plan view of an additional film formation substrate holder 10 having an additional film formation window 12 for producing the photomask blanks 20 of the present invention, and FIG. 2 is produced using the additional film formation substrate holder 10. 3 is a plan view showing an embodiment of the photomask blank 20 according to the present invention, FIG. 3 is a plan view of a film formation substrate holder 30 for producing a conventional photomask blank 40, and FIG. 4 is a film formation. The top view which shows one Example of the blanks 40 for the conventional photomasks produced using the substrate holder 30 for an operation is shown, respectively.
[0012]
A method for manufacturing the blank for photomask and the photomask of the present invention will be described.
First, a transparent substrate is set on a film formation substrate holder 30 having a substrate holder frame 31 and a substrate support portion 32, and a chromium or chromium oxide film is formed on the transparent substrate from below by sputtering or vapor deposition. A conventional photomask blank 40 having 41 and a non-film forming portion 42 is produced.
[0013]
Next, a transparent conductive thin film is additionally formed by sputtering or vapor deposition on the non-film forming portion 42 of the conventional photomask blank 40 using the additional film forming substrate holder 10 having the additional film forming window 12. The blank 20 for photomasks of this invention which has the additional film-forming part 22 is produced.
Here, as a material of the transparent conductive thin film, a metal such as Ta (tantalum) and a metal oxide such as In ₂ O ₃ (indium oxide) can be used.
[0014]
Next, a photoresist is applied on the photomask blanks 20, a photosensitive layer is formed, electron beam writing is performed using an electron beam writing machine with a high acceleration voltage, and patterning processing such as development is performed to perform the process of the present invention. A photomask is manufactured.
Here, it is possible to prevent charge-up during electron beam writing, in particular, charge-up at corner portions, and as a result, a photomask with greatly improved pattern position accuracy can be obtained.
In addition, since the shape of the corner portion of the photomask blank of the present invention can be recognized even after the additional film formation, the film type of the blank can be easily identified.
[0015]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
First, a transparent substrate made of synthetic quartz is set on a film formation substrate holder 30 having a substrate support portion 32, and a film formation portion 41 made of a two-layer film of chromium and chromium oxide is formed on the transparent substrate by sputtering, A conventional photomask blank 40 having a non-film forming portion 42 was produced.
[0016]
Next, the conventional photomask blank 40 is set in an additional film formation holder 10 having an additional film formation window 12, and Ta is formed from below using a sputtering apparatus to have an additional film formation unit 22. The blank 20 for photomasks of this invention was produced.
[0017]
Next, an electron beam resist is applied on the photomask blank 20 of the present invention to form a photosensitive layer, and electron beam writing is performed using an electron beam drawing machine (HL-800M, manufactured by Hitachi, Ltd.) having a high acceleration voltage. Then, patterning treatment such as development was performed to produce a photomask of the present invention.
[0018]
【The invention's effect】
By using the photomask blank of the present invention, it is possible to reliably prevent charge-up on the resist-coated photomask blank when performing electron beam writing using an electron beam drawing machine having a high acceleration voltage.
As a result, a highly accurate photomask having excellent pattern position accuracy can be obtained.
[Brief description of the drawings]
FIG. 1 is a plan view of an additional film formation substrate holder 10 for producing photomask blanks of the present invention.
FIG. 2 is a plan view showing one embodiment of the photomask blanks 20 of the present invention manufactured using the additional film formation substrate holder 10;
FIG. 3 is a plan view of a film formation substrate holder 30 for producing a conventional photomask blank 40.
FIG. 4 is a plan view showing an example of a conventional photomask blank 40 manufactured using a film formation substrate holder 30. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Additional film formation substrate holder 11 ... Holder frame 12 ... Additional film formation window 20 ... Photomask blanks 21 ... Film formation part 22 ... Additional film formation part 30 ... Film formation substrate holder 31 …… Substrate holder frame 32 …… Substrate support portion 40 …… Photomask blanks 41 …… Deposition unit 42 …… Non-deposition unit

Claims (3)

In blanks for photomask having a HiNaru film unit to the four corners of the film forming portion and the transparent substrate made of chromium or chromium oxide film on a transparent substrate, a conductive thin film on the non-deposition portion of blanks for the photomask Blanks for photomasks characterized by additional film formation.   The photomask blank according to claim 1, wherein the conductive thin film is a transparent conductive thin film.   A photomask obtained by performing a series of patterning processes such as electron beam drawing and development by an electron beam drawing machine using the photomask blank according to claim 1.

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