JPH05259050A - Spin coating on semiconductor substrate and device - Google Patents

Abstract

PURPOSE:To prevent a coating solution from being concentrated on the central part of a coating layer and to make uniform the film thickness of the whole coating layer by a method wherein a coating solution is dripped on the central part of a semiconductor substrate and thereafter, while the central part of the substrate is covered with a solvent atmosphere, a rotating stage is rotated at high speed and a spin coating is performed. CONSTITUTION:A coating solution 5 is dripped on the central part 1a of a substrate 1 in a prescribed amount by a coating nozzle 4. Then, after the nozzle 4 is moved from the central part 1a of the substrate 1 to the side part of the substrate, a solvent spray nozzle 10 is moved to the central part 1a. Then, a rotating stage 2 is rotated at high speed and at the same time, a solvent is made to blow off in a spray form through a nozzle 12 via a piping part 11 and the interior of a cup 13 is filled with a solvent atmosphere. Whereupon, the rate of volatilization of the solvent in the solution 5 on the central part 1a of the substrate 1 is suppressed by this solvent atmosphere and the film thickness of a coating layer becomes thin. Thereby, the uniformity of the film thickness of the coating layer on the central part can be increased and the film thickness of the coating layer on the whole semiconductor substrate can be made even.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for spin coating a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, there has been a spin coating method as a typical method for coating a semiconductor substrate such as a silicon wafer or a mask substrate with a coating solution such as a photoresist or an adhesive wax. This spin coating method
As shown in FIG. 4, a coating solution 5 is applied by a coating nozzle 4 whose axis A is vertical on a semiconductor substrate (hereinafter, simply referred to as a substrate) 1 which is suction-fixed to a rotary table 2 by a wafer chuck 3 of a vacuum type or the like. Is dropped on the central portion 1a of the wafer 1,
This is a method in which the motor 7 is rotated at a high speed in the direction of the arrow F through the spindle shaft 6 to spread the solution by utilizing the centrifugal force that acts so as to obtain a coating layer 5a having a uniform thickness. The film thickness of the coating layer 5a at this time is determined by the solution concentration, the volatilization rate of the solvent, the spin rotation speed, etc., and the volatilization rate of the solvent is affected by the environmental temperature, humidity, the solution temperature, the temperature of the substrate 1, and the like.

[0003]

However, in the conventional spin coating method as described above, the central portion 1 of the substrate 1 is
In the case of a, the centrifugal force generated by the rotation is almost zero, so that the spread of the coating solution 5 becomes worse. Then, as shown in FIG. 5, the coating layer 5a has a drawback that it locally becomes thick and becomes a dead spot near the central portion 1a of the substrate 1.

By the way, as a countermeasure against such a thick film in the central portion of the substrate, a pipe for blowing a gas such as an inert gas to the central portion of the substrate as disclosed in, for example, JP-A-64-73618. A coating device having a section has been proposed. However, with this method, the average film thickness in the central part of the substrate is reduced, but the solvent is scattered due to the influence of the wind pressure of the gas to be sprayed, and a secondary dead spot is generated in the periphery thereof, and the film thickness also varies. There is a drawback that occurs.

An object of the present invention is to provide a method and apparatus for coating a semiconductor substrate, which solves the above problems of the prior art.

[0006]

The present invention is a method of spin coating a coating solution such as a photoresist or an adhesive wax onto a semiconductor substrate fixed to a turntable, wherein the coating solution is dropped onto the central portion of the semiconductor substrate. After that, the spin table is rotated at a high speed while the central part is covered with a solvent atmosphere, and the semiconductor substrate is spin-coated.

Further, the present invention is an apparatus for spin-coating a coating solution such as photoresist or adhesive wax onto a surface of a semiconductor substrate removably fixed to a rotary table through a coating nozzle, above the rotary table. A spin coating apparatus for a semiconductor substrate, characterized in that a solvent spray nozzle is provided on a side portion thereof so as to be movable to a central portion of the semiconductor substrate.

[0008]

[Operation] According to the present invention, the spin coating of the coating solution on the substrate covers the center of rotation of the substrate with the solvent atmosphere, so that the evaporation rate of the solvent in the coating solution at the center of the substrate is suppressed. And the coating layer becomes thinner,
As a result, it is possible to prevent the coating solution from being concentrated in the central portion of the coating layer and to make the film thickness of the entire coating layer uniform.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same members as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. FIG. 1 is a side view schematically showing the configuration of the embodiment of the present invention. As shown in the figure, the solvent spray nozzle 10 used in the present invention is disposed on the upper side of the turntable 2 and is composed of a pipe portion 11, a nozzle 12 attached to the tip portion thereof, and a cup 13.

Then, spin coating is performed according to the following procedure. First, a predetermined amount of the coating solution 5 is dropped onto the central portion 1a of the substrate 1 by the coating nozzle 4. Next, as shown in FIG. 2, after moving the coating nozzle 4 from the central portion 1a of the substrate 1 to the side portion, a solvent spray nozzle
10 is moved to the central portion 1a and positioned. The rotary table 2 is rotated at a high speed in the arrow F direction via the spindle shaft 6 and, at the same time, the solvent is nozzled via the piping section 11.
It is blown out from 12 in a spray form and the inside of the cup 13 is filled with a solvent atmosphere. The solvent atmosphere suppresses the volatilization rate of the solvent in the coating solution 5 in the central portion 1a of the substrate 1 and reduces the thickness of the coating layer 5a. After a lapse of a predetermined time, the rotary table 2 is stopped to complete the spin coating, and the solvent spray nozzle 10
Is retracted to a predetermined position. Thereby, the coating layer 5a having a uniform thickness can be formed on the entire surface of the substrate 1.

The method of the present invention was used when spin-coating a silicon wafer using an adhesive wax as the coating solution 5. First, about 2.4 cc of liquid wax was dropped on the center of the silicon wafer, and then the rotary table was rotated at high speed at 4000 rpm while the center was covered with a solvent atmosphere to form a wax film on the surface of the silicon wafer. . The result of the film thickness distribution at that time is shown in FIG. For comparison, the film thickness distribution in the conventional method is also shown in the same figure. As is clear from this figure, the difference between the maximum value and the minimum value in the conventional method is 419 Å, whereas in the method of the present invention, it is 221 Å, which is about 47%.
Is also small, and it can be seen that the uniformity is improved.

[0012]

As described above, according to the present invention, since the central portion of the coating layer is covered with the solvent atmosphere during spin coating, it is possible to enhance the uniformity of the thickness of the central portion. As a result, the film thickness of the entire semiconductor substrate can be made uniform.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a configuration of a spin coating apparatus of the present invention.

FIG. 2 is an explanatory diagram of the operation of the present invention.

FIG. 3 is a characteristic diagram showing a film thickness distribution of a coating layer obtained by the present invention.

FIG. 4 is a side view schematically showing the configuration of a conventional spin coating apparatus.

FIG. 5 is an explanatory diagram of a film thickness distribution of a conventional coating layer.

[Explanation of symbols]

 1 substrate (semiconductor substrate) 2 turntable 3 wafer chuck 4 coating nozzle 5 coating solution 5a coating layer 6 spindle shaft 10 solvent spray nozzle 11 piping part 12 nozzle 13 cup

Claims (2)

[Claims] 1. A method of spin-coating a coating solution such as a photoresist or an adhesive wax onto a semiconductor substrate fixed on a turntable, wherein the coating solution is dropped onto the central portion of the semiconductor substrate and then the central portion is covered with a solvent. A spin coating method for a semiconductor substrate, characterized in that the rotary table is rotated at a high speed while being covered with an atmosphere. 2. An apparatus for spin-coating a coating solution such as a photoresist or an adhesive wax on a surface of a semiconductor substrate removably fixed to a rotary table through a coating nozzle, wherein the upper side portion of the rotary table is provided with the coating solution. A spin coating apparatus for a semiconductor substrate, comprising a solvent spray nozzle that is movable in the center of the semiconductor substrate.