JPH0394872A - Method for coating resist - Google Patents

Abstract

PURPOSE:To decrease the difference in the film thickness of a resist between the central part and peripheral part of a substate by supplying the resist liquid to be applied onto the rotating substrate while continuously changing the concn. thereof in the method for coating resist by using a spinner. CONSTITUTION:The resist liquid 1 of a prescribed concn. is fed by a resist supplying pump 3 and a diluent soln. 2 is fed by a diluent supplying pump 4. After these liquids are mixed in a piping coupling part 5, the liquids are uniformly mixed in a mixing coil 6 and are supplied to a nozzle 7, from which the resist is applied on a substrate 8 on a substrate installing base 9 rotating at the specified speed. The concn. of the resist liquid to be supplied is continuously changed by continuously changing the supplying rates of the pumps 3, 4. The deviation in the resist film thickness is decreased by continuously changing the viscosity of the resist liquids to be supplied, i.e., by supplying the resist liquids first at the low concn. then gradually increasing the concn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of spin-coating a resist using a spinner method.

[Prior Art] Conventionally, in the manufacturing process of a stub bar for molding a substrate of an information recording medium (hereinafter referred to as an information recording medium, etc.) for recording and reproducing information such as a CD, a video disc, or a magneto-optical disc, a glass substrate is used. There is a process for applying resist, and the so-called spinner method is mainly used, in which a glass substrate is placed on a turntable and rotated, while the resist is ejected from a nozzle onto the main surface of the substrate to form a thin film of resist. There is. However, it has been pointed out that in such a spinner method, there is a difference in the coating thickness of the resist between the central portion of the substrate and the peripheral portion of the substrate. When such a difference in film thickness is extreme, there is a problem in that it becomes difficult to set an appropriate development time in the subsequent development step.

To solve the above problem, there is a method in which the substrate is rotated around an axis perpendicular to its surface and at the same time revolved around an axis parallel to the axis of rotation (Japanese Unexamined Patent Publications No. 51-65883, No. 54-14487).
7) has been proposed. Although these methods have the effect of reducing the thickness difference, it is necessary to provide two driving parts for the substrate, which increases the size of the device.
At the same time, there was a tendency for the frequency of board defects due to dust generated from the drive unit to increase.

[Problems to be Solved by the Invention] An object of the present invention is to reduce the film thickness difference between the center portion of the substrate and the peripheral portion of the resist that occurs in the resist spinner coating method, and the above-mentioned method is used to reduce the difference in film thickness of the resist between the center portion of the substrate and the peripheral portion. The object of the present invention is to provide a resist coating force method that can achieve the objective without modifying the substrate drive unit as described above.

[Means for Solving the Problems] The present invention, which can achieve the above object, is a method of applying resist liquid to a rotating substrate while continuously changing the concentration of a resist liquid to be applied in a resist applying force method using a spinner. It is characterized by:

The resist coating method according to the present invention will be explained in detail below.6 In the spinner coating method, the resist film thickness is determined by the rotation speed of the spinner and the viscosity of the resist solution, and the viscosity of the resist solution is determined by the mixing ratio with the diluent. be done. Therefore, the difference in resist film thickness between the center and peripheral parts of the substrate, which occurs when the rotational speed of the spinner is constant, is considered to be due to the change in the viscosity of the resist liquid after being dropped onto the substrate. Therefore, by continuously changing the viscosity of the resist liquid to be supplied, that is, by supplying it at a low concentration initially and gradually increasing the concentration, it is possible to reduce the deviation in resist thickness. be.

FIG. 1 shows a schematic diagram of a Subinoner coating apparatus for carrying out the method of the present invention. 6 A resist solution 1 of a predetermined concentration is fed by a resist supply bomb 3, and a diluent solution 2 is supplied.
A is sent by the diluent supply knob 4 and mixed at the piping joint 5, and then uniformly mixed by the combination coil 6.
"N, the resist is applied to the substrate 8 of 9L, which is not supplied to the nozzle 7 and rotates at a constant speed. By continuously changing the supply amount of the bombs 3 and 4, The concentration of the supplied resist solution can be changed continuously, and the above-mentioned object can be achieved quickly.3 [Examples] The present invention will be specifically explained below based on Examples.

Using the resist coating 'AM' shown in Figure 1, apply the resist solution to AZ1.350 (trade name, manufactured by Hoechst) and use AZ thinner (trade name, manufactured by Hoechst) as a diluent solution. The resist solution supply amount, diluent solution supply amount, and substrate rotation speed were set so that the film thickness at a point 30 mm from the center of the substrate was approximately 5000 A at a predetermined concentration. The predetermined concentration is 1
(arbitrary unit), and the concentration of the resist solution to be supplied is the initial g
Jlo. By supplying the resist solution to the substrate in a continuous manner from 95 to 1, the resist solution is applied to the center of the substrate (30 mm from the center) and the periphery (120 mm from the center) as shown in FIG. ) The difference in resist film thickness is approximately 3
0 people, and it was possible to reduce the deviation in film thickness.

Comparison 11 A resist was applied in the same manner without changing the predetermined density. The results are shown in Figure 2. As shown in the figure, the difference in resist film thickness between the center of the substrate (30mm from the center) and the periphery (120mm from the center) is approximately 2.
00 people, and it can be seen that there is a large deviation in film thickness.

[Effects of the Invention] As explained above, by implementing the coating method of the present invention, the difference in film thickness between the center and peripheral parts of the substrate can be reduced, and proper development can be achieved in the subsequent development process. This makes it easy to set the time.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a resist coating apparatus that can be used in the present invention, and FIG. 2 is a graph showing the relationship between the thickness of resist films coated in Examples and Comparative Examples and the distance ah from the center of the substrate. . 1... Resist solution 2... Diluent solution 3... Resist solution supply bomb 4... Diluent solution supply bomb

Claims (1)

[Claims] 1. A resist coating method using a spinner, which comprises supplying a resist solution to a rotating substrate while continuously changing the concentration of a resist solution to be coated.