JPH04124824A - Washing method of semiconductor wafer - Google Patents

Abstract

PURPOSE:To obtain a washing method, in which the re-adhesion of dust at the time of washing can be prevented easily, by making a liquid overflow from the upper periphery of a treating tank under the state in which a wafer is dipped in the liquid, flowing out the liquid to a spare tank installed to the upper periphery of the treating tank and removing dust floating in the liquid from the treating tank. CONSTITUTION:A liquid 8 etching or washing a semiconductor wafer 7 is fed through a piping 3 from the lower section of a treating tank 1, the treating tank 1 is filled with the liquid 8, the liquid 8 is made to overflow from the upper periphery of the treating tank 1 under the state in which the semiconductor wafer 7 is dipped in the liquid 8, and the liquid 8 is let out to a spare tank 5 mounted on the upper periphery of the treating tank 1, thus removing dust 9 floating in the liquid 8 from the treating tank 1. For example, the semiconductor wafer 7 is washed by the chemicals 8, the chemicals 8 are made to overflow from the treating tank 1 by the successive supply of the chemicals 8 from the lower section of the treating tank 1, and dust 9 floating on the surface of the chemicals is carried to the spare tank 5. The chemicals 8 are discharged from the lower section of the treating tank 1, and pure water 10 is fed from a piping 3 and the treating tank 1 is filled with pure water in order to exchange the chemicals 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to a semiconductor manufacturing process, and particularly to a semiconductor wafer cleaning method for etching or cleaning a semiconductor wafer.

(Prior Art) Conventionally, a method for cleaning a semiconductor wafer is as follows. Third
As shown in FIG. 2A, a semiconductor wafer 22 is set on a carrier 23 in a processing tank 21. As shown in FIG. Processing tank 2
A chemical solution 25 is supplied into the container 1 from a lower piping 24, a valve 26 is closed, and the ueno\22 is immersed in the chemical solution 25. After the chemical treatment, as shown in FIG. 2(b), the valve 26 is opened to discharge the chemical in the processing tank 21 through the pipe 24.

Therefore, as shown in FIG. 3(a), the dust 27 detached from the wafer 22 during cleaning floats on the chemical liquid surface.

When the chemical solution 25 is discharged as shown in FIG. 3(b), this dust descends with the chemical solution level and re-attaches to the inner wall surface of the processing tank 21 and the wafer 22.

Especially when etched with HF, the surface state of the silicon wafer is very active and easily absorbs dust, which is difficult to remove. Semiconductor wafers with dust attached may cause defects, leading to a decrease in the yield of semiconductor devices.

(Problems to be Solved by the Invention) As described above, conventionally, when the dust or chemical liquid that has come off from the semiconductor wafer during cleaning is discharged, the dust or chemical liquid descends with the level of the chemical liquid and re-adheres to the inner wall surface of the processing tank and the wafer. This has the drawback of causing defects in the semiconductor device and lowering the yield.

The present invention has been made in consideration of the above-mentioned circumstances, and an object thereof is to provide a method for cleaning semiconductor wafers that can easily prevent dust from re-adhering during cleaning.

[Structure of the Invention (Means for Solving the Problems)] In the semiconductor wafer cleaning method of the present invention, a liquid for etching or cleaning the semiconductor wafer is supplied from the lower part of the processing tank through piping, and the processing tank is connected to the The liquid is filled with a liquid, and the liquid overflows from the upper periphery of the processing tank while the semiconductor wafer is in the liquid, and the liquid is allowed to flow into a reserve tank provided at the upper periphery of the processing tank. It is characterized in that dust suspended therein is removed from the processing tank.

(Function) In the method of the second invention, the dust floating on the surface of the chemical solution in the processing tank is taken into the preliminary tank and discharged, so that the dust that re-adheres to the wafer surface and the wall of the processing tank during the processing sequence can be easily removed. It can be prevented.

(Examples) Hereinafter, the present invention will be explained by examples with reference to the drawings.

FIGS. 1(a) to 1(d) are block diagrams illustrating a semiconductor wafer cleaning method according to an embodiment of the present invention in the order of steps.

First, the configuration of the processing bath 1 for etching or cleaning semiconductor wafers with liquid will be explained. The processing tank 1 includes a carrier 2 for holding semiconductor wafers, and a pipe 3 for supplying and discharging chemical solutions and pure water from the bottom. The pipe 3 has a valve 4, which controls the supply and discharge of chemical liquid and pure water from the pipe 3. Furthermore, a preliminary tank 5 is provided around the processing tank 1. The reserve tank 5 is configured to collect an overflow of chemical solution or pure water supplied from the bottom of the processing tank I. This preliminary tank 5 is also provided with a pipe 6 through which the chemical solution or pure water is discharged.

The cleaning process for semiconductor wafers will be explained below.

As shown in FIG. 1(a), a chemical solution 8 is supplied to the processing tank 1 by opening the valve 4 of the piping 3 provided at the bottom. The semiconductor wafer 7 supported by the carrier 2 is
Cleaned with chemical solution 8.

After the chemical solution treatment, dust 9 separated from the wafer 7 floats on the surface of the chemical solution.

Next, as shown in FIG. 1(b), the chemical solution 8 is caused to overflow from the processing tank 1 by further supplying the chemical solution 8 (or pure water) from the lower part of the processing tank 1. As a result, the dust 9 floating on the surface of the chemical solution flows into the preliminary tank 5.

Thereafter, the dust 9 is discharged via the pipe 6 of the preliminary tank 5.

Next, as shown in FIG. 1(c), the valve 4 of the piping 3 of the processing tank 1 is opened, and the chemical solution 8 is discharged from the lower part. In this way, the dust 9 will not re-adhere to the surface of the wafer 7.

Next, as shown in FIG. 1(d), in order to replace the chemical solution 8,
Pure water 10 is supplied from the pipe 3 to fill the treatment tank 1. At this time, if the pure water overflows, the preliminary tank 5 can be washed at the same time.

According to the method of the above embodiment, the chemical solution 8 in the treatment tank l
The dust 9 floating on the surface is taken into the preliminary tank 5 and discharged. Therefore, when the chemical solution 8 in the processing tank 1 is discharged, the separated dust is processed so that it does not adhere to the wafer surface or the wall surface of the processing tank 1 again.

FIG. 2 is a dust adhesion distribution diagram showing a comparison between the method of the above embodiment and the conventional method. Dilute HF using dilute HF as a chemical solution
The method of the invention was carried out on Si wafers in process mode.

As a result, dust of 0.3 μm or more was removed by 67
The number of dust particles of 0.2 μm or more decreased from 204 particles/wafer to 1] particles/wafer, and the dust removal performance was significantly improved.

[Effects of the Invention] As explained above, according to the present invention, the dust floating on the surface of the chemical solution in the processing tank is taken into the preliminary tank and discharged, so that it is easily prevented from re-adhering to the wafer surface and the processing tank wall during the processing sequence. It is possible to suppress the dust caused by Therefore, it is possible to provide a semiconductor wafer cleaning method that can reduce the factors that lead to defects in semiconductor manufacturing and enable manufacturing of semiconductor devices with high production efficiency and high reliability.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are block diagrams showing a semiconductor wafer cleaning method according to an embodiment of the present invention in the order of steps, and FIG. 2 is a diagram showing a comparison between the method of the above embodiment and a conventional method. The distribution diagram and FIGS. 3(a) and 3(b) are block diagrams showing a conventional semiconductor wafer cleaning method in the order of steps. J... Processing tank, 2... Carrier, 3, 6... Piping, 4... Hartz, 5... Preliminary tank, 7... Wafer Death...
Chemical solution, dust, 10...pure water.

Claims (1)

[Scope of Claims] A liquid for etching or cleaning the semiconductor wafer is supplied from the lower part of the processing tank through piping, and the processing tank is filled with the liquid and the semiconductor wafer is placed in the liquid. Dust suspended in the liquid is removed from the processing tank by overflowing the liquid from the upper periphery of the processing tank and draining the liquid into a preliminary tank provided at the upper periphery of the processing tank. How to clean wafers.