JPS62121675A - Method for applying resist - Google Patents

Abstract

PURPOSE:To form a thin film without irregularity, in applying a resist to the layer to be etched on a large substrate, by diluting a resist solution to adjust the same to desired visconsity before performing spin coating at a relatively low rotational speed. CONSTITUTION:A resist solution contains a photosensitive material made of naphthoquinone diazide and is diluted so that desired viscosity is 1-4 centistokes on a dynamic viscosity basis. A photomask blank 10 obtained by preliminarily laminating a light blocking layer made of Cr as a layer to be etched by a sputtering method is placed on a spin coater 11 and sucked thereto under vacuum. Next, the diluted resist solution is dripped on the Cr-film from a nozzle 13 and a motor 14 is driven to rotate the photomask blank 10 at a rate of rotation of 1,000rpm or less. By this method, a resist film with a thickness of below 1,000Angstrom can be formed to the substrate with a main dimension of 8 inch or more without detaching from a vacuum chuck 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a layer to be etched, such as a light-shielding film in the case of a mask blank or a transparent conductive film in the case of a display panel such as a liquid crystal panel. Apply resist on top
In particular, the present invention relates to a method for applying a resist onto a layer to be etched on a large substrate.

[Conventional technology]

Conventionally, a photo mask made of a large soda lime glass measuring 8 inches x 10 inches x 0.09 inches was used.Regime 1 to the film were deposited on a light-shielding layer (layer to be etched) made of a Cr film provided on a mask blank substrate. The second method of forming
There was an O-ru coating method using a roll coater as shown in the figure.

In other words, while moving the photomask blank 2 with the light-shielding layer placed on the conveyor belt 1 in the direction shown by the arrow in the figure, the film A is placed between the coating roll 3 and the conveyor belt 1. ]・Light-shielding FP of mask blank 2
1, a resist film 4 adhering to the side surface of the coating roll 3 is applied. In addition, coding roll 3
The thickness of the resist film attached to the side surface of the doctor bar is 5.
Set by. Moreover, 6 is a stand for setting the interval between the conveyor belt 1 and the coating [1-ru 3].

[Problem that the invention seeks to solve]

However, in the conventional resist coating method using the roll coating method, a resist with a kinematic viscosity of 30 to 120 centistokes was applied, resulting in a very thick resist film of 10,000 to 20,000 Å or more. There was a drawback that the film thickness varied by more than 1000 Å. Due to this drawback, patterns for large photomasks and large display panels such as liquid crystal panels, which have been required in recent years, have not been able to be manufactured with high precision. In other words, if the film thickness varies by more than 1000 Å, the pattern width will not be constant or will cause waviness, while if the film thickness is more than 10000 Å, it will not be possible to fabricate a pattern with a pattern width of less than 10 μm. Ta.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention is characterized in that a resist diluted to a desired viscosity is applied on a layer to be etched of a substrate having a main dimension of 8 inches or more. Drop the liquid and rotate the resist film with a thickness of less than 1000 rpm at 11,000 rpm.
It is formed by the spin code method below. In an embodiment of the present invention, the resist solution contains a photosensitive material containing naphthoquinone diazide as a constituent, and has a desired viscosity of 1 to 41? It's about being a nji stokes.

In addition, the main dimension of the present invention means the long side when the main surface of the board is rectangular (including square), the diameter when it is circular, and the long axis when it is within the range. It is something to do. In addition, when the layer to be etched is, for example, a photomask blank, the layer to be etched may be a light-shielding layer on the substrate, such as Cr,
It includes metals such as No, Ta, and W, and their oxides, nitrides, carbides, and silicides, and also includes not only one layer but also multiple layers. In the case of display panels and solar cells, the term refers to transparent conductive films, and in the case of semiconductor substrates such as silicon wafers, the term refers to the substrate itself. That is, the layer to be etched includes a layer to be etched using a resist film.

〔Example〕

An embodiment of the resist coating method of the present invention will be described in detail with reference to FIG. Note that FIG. 1 is a schematic diagram showing a spin coater.

First, a light-shielding layer made of Cr (thickness: approximately 700 mm
A photomask blank 10 is manufactured by laminating the photomask blanks 10 by sputtering. Next, as shown in FIG. 1, the photomask blank 10 is placed on the vacuum chuck 12 of the spin coater 11 with the C film facing upward, and vacuum suction is performed.

Next, a commercially available resist consisting of a photosensitive material (solute) consisting of naphthoquinonediazide and a phenol novolak resin and a cellosolve acetate solvent as the main solvent (for example, A Z 1350) further diluted with cellosolve acetate (kinematic viscosity = 2.
4 centistokes) was dropped from the nozzle 13 onto the Cr1ll. Next, the motor 14 was driven to rotate the photomask blank 10 vacuum-adsorbed on the vacuum chuck 12 at a rotational speed of 75 rpm for 60 seconds to form a resist film on the Cr film. Note that the resist scattered during this rotation does not scatter outward from the cup 15.

The resist thus formed had a film thickness of 460 mm.
There were 0 people, and the standard deviation was 50 people.

Next, the photomask blank with the resist film is removed from the vacuum chuck 12, placed in a competition oven, and prebaked at 90° C. for 30 minutes. Next, take out a photomask blank with a resist film from the Competitive A-bun, expose a 2ttm pattern through the right photomask, and use an AZ exclusive developer to expose the photomask blank with a resist film for about 6 ttm.
Development was performed for 0 seconds, and the exposed Cr film was etched with a mixed solution of ceric ammonium nitrate and perchloric acid.

When the width of the pattern formed by this etching was measured, it was found to be a pattern of 2 μm±0.1 μm. That is, it was possible to obtain a sharp pattern with a constant pattern width and no undulations, which could not be obtained by conventional methods, and also to obtain a finer pattern.

According to this example, since a highly accurate pattern can be obtained and the resist solution has a low viscosity, the rotation speed of the vacuum chuck during spin-to-coating is set to a low rotation speed of 750 rllllll. As a result, even large substrates will not fall off the vacuum chuck, making it safe.

As described above, the present invention is not limited to the above embodiments, and may be as described below.

First, in the above example, the spin code was performed at a rotation speed of 750rl)Ill, but if the rotation speed is 11000rD or less,
Substrates with major dimensions of 8 inches or more will not come off the vacuum chuck. Next, in the above example, the kinematic viscosity of the resist solution containing the photosensitive material made of naphthoquinonediazide and phenol novolac resin was applied at 2°4 centistokes, but it is preferably in the range of 1 to 4 centistokes]-1 centistokes. . That is, if it is less than 1 centistoke, the amount of Wi medium in the resist solution becomes too large and a resist film cannot be easily formed, and if it exceeds 4 centistokes,
When using a large board and the rotation speed is 1000 rpm or less,
The thickness of the resist film may be 10,000 or more. Furthermore, a resist solution containing a photosensitive material containing naphthoquinone diazide as a component may be used as a resist solution containing a photosensitive material containing naphthoquinone diazide and a cresol phenol resin. Similarly to the resist liquid 1 containing a photosensitive material composed of 1-=1-nondiazide and a 7-enol novolak resin, the kinematic viscosity is preferably 1-4 centistokes. Further, in the present invention, other resist liquids may be used. That is, the resist solution is rotated at a rotation speed of 11,000 rpm.
The dilution may be adjusted so that a resist film having a thickness of less than 10,000 layers can be formed and variations can be prevented. In the above example, the resist film thickness was 4,600 people, but it was 1,000 people (if it was less than 1 person, the resist film thickness was 1,000A).
There is no variation in a, and if the film thickness is approximately 6000 Å or less, the variation will be about 50 standard deviations, making it possible to form a pattern with higher precision.

Furthermore, the present invention can be applied not only to the formation of resist films for producing photomasks, but also to the formation of resist films for producing display panels and solar cells.

(Effects of the Invention) As described above, according to the present invention, a resist film can be formed on a large substrate with little variation and with a thin film thickness, and thereby a highly accurate pattern can be formed. It is also possible to prevent the substrate from coming off the vacuum chuck during rotation.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a spin coater used in an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a roll coater used in a conventional method.

Claims (3)

[Claims] (1) Drop a resist solution diluted to a desired viscosity onto the layer to be etched of a substrate whose main dimensions are 8 inches or more,
A resist film with a thickness of less than 10,000 Å is rotated at a rotation speed of 1,000 r.
1. A resist coating method, characterized in that the resist is formed by spin coating at pm or less. (2) The resist coating method according to claim (1), wherein the resist solution contains a photosensitive material containing naphthoquinonediazide as a constituent element. (3) The resist coating method according to claim (2), wherein the desired viscosity of the resist solution is 1 to 4 centistokes in kinematic viscosity.