JPH056884A - Cleaning method for silicon wafer - Google Patents

Abstract

PURPOSE:To prevent adherence of contaminant substance in the case of moving between tanks in a step of cleaning a silicon wafer. CONSTITUTION:In order to remove contaminant substance adhered to the surface of a silicon wafer, the wafer is cleaned with treating solution containing NH4OH +H2O2+H2O, and further cleaned with treating solution containing HF+HCl+ H2O2+ H2O.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method which is particularly useful when cleaning a silicon wafer which is a substrate for semiconductor devices and the like.

[0002]

2. Description of the Related Art Generally, in cleaning a silicon wafer, in order to remove inorganic and residual organic contaminants on the surface of the wafer, it is first immersed in a treatment solution of NH ₄ OH + H ₂ O ₂ + H ₂ O and washed. Then, immerse it in a treatment liquid consisting of HF to remove the natural oxide film such as SiO ₂ , and further dip it in a treatment liquid consisting of HCl + H ₂ O ₂ + H ₂ O to remove residual heavy metals on the surface. An RCA wash consisting of a three-step wash was applied.

Recently, in order to minimize particle adhesion on the surface of a silicon wafer, a heavy metal removal method using a treatment liquid of HF + H ₂ O ₂ has been proposed (VLSI LSI Ultra Clean Technology Workshop No. 1). , See Ultra Clean Technology in Submicron ULSI Manufacturing, Proceeding).

[0004]

By the way, the conventional RCA
In cleaning, it was unavoidable that contaminants adhered to the wafer surface when the silicon wafer was moved from one processing tank to the next processing tank. Especially after washing with HF treatment liquid, the hydrophobic surface without natural oxide film is exposed on the wafer surface, so that impurity particles are likely to adhere firmly to the wafer surface during subsequent washing with water or transfer between tanks. ,
The attachment of such impurity particles has been a cause of pinholes and deterioration of device characteristics.

It is an object of the present invention to propose a novel method for cleaning a silicon wafer which does not cause the above-mentioned problems that may occur during the water washing process between wafers after cleaning and the transfer of wafers.

[0006]

The present invention is directed to removing contaminants adhering to the surface of a silicon wafer.
After cleaning the above silicon wafer with a treatment liquid consisting of NH ₄ OH + H ₂ O ₂ + H ₂ O, HF + HCl + H ₂ O ₂ + H ₂ O
The method for cleaning a silicon wafer is characterized by performing a cleaning process with a processing liquid containing

[0007]

According to the present invention, when cleaning a silicon wafer, cleaning with a treatment liquid composed of NH ₄ OH + H ₂ O ₂ + H ₂ O and cleaning with a treatment liquid composed of HF + HCl + H ₂ O ₂ + H ₂ O is performed. Since the stepwise treatment eliminates the movement of the wafer between tanks, especially when there is no natural oxide film on the surface, it is possible to advantageously avoid the attachment of pollutants, which was difficult to avoid during this movement between tanks. .

Next, a concrete procedure for cleaning a silicon wafer will be described. First, in cleaning by dipping NH ₄ OH + H ₂ O ₂ + H ₂ O in the treatment liquid, NH ₄ OH + H ₂ O ₂ + H ₂ O
= 1: 1: 5 to 20 capacity ratio can be applied, 60 to
It is desirable to perform the washing treatment under the condition of 80 ° C. Also HF +
For washing with HCl + H ₂ O ₂ + H ₂ O, use HF + HCl + H ₂
O ₂ + H ₂ O = 0.1 to 10: 125: 125: 750 with a volume ratio can be applied, and it is desirable to perform the cleaning treatment at 20 to 30 ° C.

[0009]

Example: NH ₄ O with a volume ratio of 1: 1: 5 and a temperature of 70 ° C.
A 6-inch silicon wafer is immersed in a treatment tank containing H + H ₂ O ₂ + H ₂ O for 10 minutes, and the first cleaning process is performed, followed by QDR (quick dump rinse) with pure water. After dropping enough, the capacity ratio is 1:
125: 125: 750, HF + HCl + H ₂ O ₂ + at a temperature of 24 ° C
The wafer was immersed in a treatment tank containing H ₂ O for 10 minutes to perform a cleaning treatment, and further, the chemical solution was completely removed by cleaning using an overflow method after QDR, and the surface condition of the obtained cleaned silicon wafer was investigated. As a result, it was found that the adhesion of contaminants on the surface of the silicon wafer was significantly reduced. The surface condition of the cleaned wafer was examined by measuring fine particles on the wafer surface of 0.2 μm or more using an automatic surface defect inspection device (WIS-600, manufactured by ESTEK).

[0010]

As described above, according to the present invention, the process steps for cleaning a silicon wafer can be simplified and the number of times of movement between tanks is reduced, so that contaminants adhere to the hydrophobic surface of the silicon wafer. The ratio of doing this is extremely small, and the yield can be improved.

Claims (1)

Claim: What is claimed is: 1. When removing contaminants adhering to the surface of a silicon wafer,
_A method for cleaning a silicon wafer, which comprises cleaning with a treatment liquid composed of ₄ OH + H ₂ O ₂ + H ₂ O, and then further cleaning with a treatment liquid composed of HF + HCl + H ₂ O ₂ + H ₂ O.