JPH05259054A - Spin coating on semiconductor wafer - Google Patents

Abstract

(57) [Summary] [Object] To provide a spin coating method for a semiconductor wafer. [Structure] Semiconductor wafer 1 via solvent supply nozzle 4
After the solvent 5 is dropped on the surface of the wafer 1, while the wafer 1 is rotated at a high speed, a gas is blown to a position 1c intermediate between the central portion 1a and the peripheral portion 1b through a gas injection nozzle,
It is possible to obtain the coating layer 5a having a film thickness with little variation.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art When a semiconductor wafer (hereinafter simply referred to as a wafer) is spin-coated with a solvent such as a photoresist or an adhesive wax, conventionally, as shown in FIG. 3, a wafer 1 provided with a forming layer 2 is vacuumed. After being attached to the holder 3 via a chuck or the like, the solvent 5 is dropped from the solvent supply nozzle 4 in a fixed amount of 4 to 5 cc, for example, and then the holder 3 is rotated at a high speed around the spin shaft 3a via the motor 6 so that the wafer The coating layer 5a such as a resist film having a uniform thickness is formed on the upper surface.

[0003]

However, in the conventional spin coating method as described above, the thickness of the coating layer 5a becomes thicker at the central portion 1a of the wafer 1 and its peripheral portion 1b as shown in FIG. There is a drawback. By the way, as a countermeasure against such a thick film of a wafer, in the case of the central portion thereof, for example, as shown in JP-A-64-73618, coating with a piping portion for blowing gas to the central portion of the wafer is provided. A device has been proposed,
As a measure against the peripheral edge, for example, as disclosed in Japanese Patent Laid-Open No. 62-13029, a method has been proposed in which gas is blown to the peripheral edge of the substrate to scatter the resist to the outside. But,
With these means, the average film thickness of the central part and the peripheral part of the wafer is reduced, but in any case, the solvent such as the resist that is scattered by the physical force adheres to other parts of the wafer surface, There is a drawback that the film thickness varies.

An object of the present invention is to provide a method for coating a semiconductor wafer, which solves the above problems.

[0005]

The present invention is a method of spin-coating a semiconductor wafer with a solvent such as a photoresist or an adhesive wax, after dropping a predetermined amount of the solvent onto the center of the surface of the semiconductor wafer. And a method of spin coating a semiconductor wafer, which comprises spin-spinning while spraying a gas on an intermediate portion of a peripheral portion.

[0006]

[Operation] First, the structure of the present invention will be described. As shown in FIG. 1, a plurality of gas injection nozzles 7 are arranged on an intermediate position 1c between the central portion 1a of the wafer 1 and its peripheral portion 1b. Then, after a predetermined amount of the solvent 5 is dropped onto the wafer 1 from the solvent supply nozzle 4, the holder 3 is passed through the motor 6.
When the coating layer 5a is formed by rotating the
A gas such as Ar gas is sprayed from the gas injection nozzle 7 under predetermined conditions.

The conditions of the gas to be sprayed will now be described. Generally, the faster the moving speed of the gas on the free surface of the solvent 5, that is, the higher the flow velocity, the faster the evaporation rate of the solvent in the solvent. Then, as the evaporation rate of the solvent increases, the solute remaining on the wafer 1 increases and the film thickness increases. However, if the flow velocity of the gas becomes too fast, the solvent itself will move due to the physical force of the gas, and if it becomes faster, the solvent will start to scatter and the variation in the film thickness will become large. If the gas pressure is too weak, the evaporation rate of the solvent does not increase and the film thickness does not increase. Therefore, the condition is that the gas is blown at a pressure and a flow velocity at which the solvent does not move.

[0008]

[Example] After dropping 5 cc of photoresist onto the center of the wafer 1, Ar gas at a pressure of 1.5 kg was applied to the middle portion of the wafer 1.
A resist film was formed by spin coating at a high speed of 2500 rpm while spraying at f / cm ² and a flow rate of 100 cm / sec. The result of the film thickness distribution at that time is shown in FIG. For comparison, the film thickness distribution in the conventional method without gas blowing is also shown in the same figure. As is clear from this figure, in the method of the present invention, the difference in film thickness between the central portion, the peripheral portion and the intermediate portion thereof is smaller than that in the conventional method.

[0009]

As described above, according to the present invention, the gas is blown to the intermediate portion between the central portion and the peripheral portion of the wafer surface at a pressure and a flow velocity at which the solvent does not move. A coating layer with less variation can be obtained, which contributes to improvement of wafer quality and yield.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a spin coating apparatus of the present invention.

FIG. 2 is a characteristic diagram showing a film thickness distribution of a coating layer obtained by the present invention.

FIG. 3 is a schematic diagram showing a configuration of a conventional spin coating apparatus.

FIG. 4 is an explanatory diagram of a film thickness distribution of a conventional coating layer.

[Explanation of symbols]

 1 Wafer (Semiconductor Wafer) 2 Forming Layer 3 Holder 4 Solvent Supply Nozzle 5 Solvent 5a Coating Layer 6 Motor 7 Gas Injection Nozzle

Claims (1)

[Claims] 1. A method of spin-coating a semiconductor wafer with a solvent such as a photoresist or an adhesive wax, which comprises dropping a predetermined amount of the solvent onto the center of the surface of the semiconductor wafer and then applying a gas to the middle of the center and the peripheral edge. A method for spin-coating a semiconductor wafer, which comprises spin spinning while spraying.