JPH04116928A - How to clean semiconductor wafers - Google Patents

Abstract

PURPOSE:To clean a wafer with high detergency without using the matter which exerts the adverse effect in human body and environment by soaking the surface of a semiconductor wafer in liquid nitrogen. CONSTITUTION:When the surface of a semiconductor wafer 3 is exposed in liquid nitrogen 2, the organic film adhering to the surface of the wafer 3 hardens, and also the liquid nitrogen at the surface of the semiconductor wafer or its vicinity boils, and the adhering organic film exfoliates efficiently. Accordingly, it becomes the effective cleaning method for a wafer, etc., where the detergency is enhanced without using a solvent harmful to human body or environment such as Freon, trichloroethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of cleaning a semiconductor wafer in a semiconductor integrated circuit manufacturing process. In particular, the present invention relates to a method for removing organic matter adhering to a wafer surface.

<Prior Art> In the manufacturing process of semiconductor integrated circuits, semiconductor wafers are cleaned to remove foreign matter from their surfaces.

Conventionally, organic substances have been removed from semiconductor wafers by cleaning them in a mixture of sulfuric acid and hydrogen peroxide heated to 100°C to 150°C. . In addition, if a film of aluminum or the like that dissolves in sulfuric acid is formed on the wafer, the above-mentioned mixture of sulfuric acid and hydrogen peroxide cannot be used, and CFCs,
Cleaning has been performed with a solvent such as trichlorethylene to remove organic matter.

<Problem to be solved by the invention> By the way, the use of CFCs used in conventional cleaning products is being regulated because they destroy the earth's ozone layer and increase ultraviolet rays that cause skin cancer. It is in.

In addition, chlorine-based solvents such as trichlorethylene are carcinogenic and have a negative impact on the human body and the environment.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a method for cleaning semiconductor wafers that does not use substances that have an adverse effect on the human body and the environment and has high cleaning power.

<Means for Solving the Problems> In order to solve the above object, the semiconductor wafer cleaning method of the present invention is a method for removing foreign matter on the surface of a semiconductor wafer, the method comprising: immersing the surface of the semiconductor wafer in liquid nitrogen. It is characterized by immersion.

Another feature is that the semiconductor wafer surface is not exposed to liquid nitrogen and an external force is applied to the semiconductor wafer surface.

<Operation> When the semiconductor wafer surface is exposed to liquid nitrogen (77 or less), the organic film adhering to the semiconductor wafer surface is hardened, and at the same time, the liquid nitrogen near the semiconductor wafer surface is boiled. By applying an external force due to boiling of liquid nitrogen to the cured organic film, the organic film adhering to the semiconductor wafer is efficiently peeled off.

Further, by exposing the semiconductor wafer surface to liquid nitrogen and applying an external force to the semiconductor wafer surface, the organic film adhering to the wafer surface is easily peeled off, and the removal of the organic film is promoted.

<Example> FIG. 1 is a schematic configuration diagram of an apparatus used in an example of the present invention.

A wafer 3 to be cleaned is immersed in liquid nitrogen 2 injected into a cleaning tank 1 . Liquid nitrogen is constantly supplied from a liquid nitrogen supply pipe 4, a circulation pump 5 circulates the liquid nitrogen, and the liquid nitrogen is passed through a filter 6 to the cleaning tank 1.
is supplied to That is, the liquid nitrogen circulated through the circulation pump 5 is filtered by the filter 6 and is supplied to the cleaning tank 1 in a clean state in which impurities such as peeled organic films are removed. As mentioned above, liquid nitrogen in a clean state is constantly supplied, and even if the liquid nitrogen evaporates, a sufficient amount of liquid nitrogen 2 to clean the wafer 3 is always maintained in the cleaning tank 1. has been done.

The wafer 3 is cleaned using the apparatus having the above configuration.

That is, when the surface of the semiconductor wafer 3 is exposed to the liquid nitrogen 2 supplied to the cleaning tank 1, the organic film adhering to the surface of the semiconductor wafer 3 is cured, and at the same time, the liquid nitrogen 2 near the surface of the semiconductor wafer 3 is cured. Boil. By applying an external force due to boiling of liquid nitrogen 2 to the cured organic film, the organic film adhering to the semiconductor wafer 3 is efficiently peeled off.

For example, most of the attached oil marker can be removed by immersing the wafer to which the oil marker has adhered for 10 minutes.

Moreover, FIG. 2 is a schematic configuration diagram of an apparatus used in another embodiment of the present invention.

This example is characterized in that an ultrasonic diaphragm 7 is attached to the lower part of the cleaning tank 1 in the apparatus having the configuration shown in FIG.

If a device having this configuration is used, the vibrations generated by the operation of the ultrasonic diaphragm 7 are propagated to the liquid nitrogen 2 in the cleaning tank 1, and the vibrations are further transmitted onto the surface of the wafer 3 immersed in the liquid nitrogen 2. As the organic film spreads, the organic film on the surface of the wafer 3 hardened by the liquid nitrogen 2 is easily peeled off and effectively cleaned.

Moreover, FIG. 3 is a schematic configuration diagram of an apparatus used in another embodiment of the present invention.

Liquid nitrogen 2 is sprayed onto the surface of wafer 3 by spray 8 . At the same time as this injection, the brush 9 moves while gradually rotating on the surface of the wafer 3 in the direction shown with an arrow,
Configured to scrub over a surface.

If an apparatus having this configuration is used, the organic film on the surface of the wafer 3 is hardened by the liquid nitrogen 2 sprayed onto the surface of the wafer 3, and the surface 3 is further scrubbed by the brush 9, so that the organic film is effectively removed. Can be removed.

<Effects of the Invention> As explained above, if the present invention is used, there is no need to use solvents that are harmful to the human body and the environment, such as fluorocarbons and trichlorethylene, so the environment will not be polluted. That is, by using liquid nitrogen to clean the wafer, the organic film on the wafer can be easily removed. Further, by exposing the wafer surface to liquid nitrogen and using an ultrasonic diaphragm, a brush, etc., the cleaning power is improved and the organic film on the wafer can be removed more effectively.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of the device used in the embodiment of the present invention, Figure 2
3 to 3 are schematic configuration diagrams of devices used in other embodiments of the present invention. 1...Cleaning tank 2...Liquid nitrogen 3...Wafer 4...Liquid nitrogen supply pipe 5...Circulation pump 6...Filter 7...Ultrasonic diaphragm 8...Spray 9 ···brush

Claims (2)

[Claims] (1) A method for cleaning a semiconductor wafer, which is a method for removing foreign matter on the surface of a semiconductor wafer, the method comprising immersing the surface of the semiconductor wafer in liquid nitrogen. (2) A method for removing foreign matter on the surface of a semiconductor wafer, the method comprising: not exposing the semiconductor wafer surface to liquid nitrogen;
A method for cleaning a semiconductor wafer, which comprises applying an external force to the surface of the semiconductor wafer.