JPH06168928A - Wafer cleaning device and cleaning of wafer - Google Patents

Abstract

PURPOSE:To prevent particles from adhering again to a wafer at the time of carrying-out of a carrier by a method wherein a mechanism for changing the output of an ultrasonic wave during the time when the carrier having the wafer therein is in the inner bath of a cleaning device is added to the cleaning device. CONSTITUTION:A cleaning bath inner bath 1 is always filled with a cleaning liquid and is in a state that it is overflowed. The cleaning fluid, which enters a cleaning bath outer bath 2 by the overflow, is made to pass through a filter 4 by a circulating pump 3, particles are removed and the cleaning liquid is returned to the inner bath 1. When a carrier 6 having a wafer 7 therein is transferred to the inner bath 1, an ultrasonic oscillator 5 is operated, the output of the oscillator is adjusted sequentially and the output is changed. When the carrier 6 is carried out, the oscillator 5 is stopped. Accordingly, the particles, which have been trapped by ultrasonic waves in a low-output time zone, are discharged outside the inner tank 1 by the overflow and can be prevented from readhering to the wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a wafer cleaning apparatus and a method of cleaning a wafer which are widely used in semiconductor manufacturing.

[0002]

2. Description of the Related Art In a conventional wafer cleaning apparatus, an ultrasonic oscillator operates when a wafer is loaded into a cleaning tank, removes particles adhering to the wafer by vibration of ultrasonic waves, and the wafer is unloaded. The structure was such that the ultrasonic oscillator stopped.

FIG. 3 shows a sectional structure of a conventional wafer cleaning apparatus, and FIG. 4 shows an output of ultrasonic waves during cleaning. Cleaning tank inner tank 1
Is always filled with cleaning solution and is in an overflow condition. The cleaning liquid that has entered the cleaning tank outer tank 2 due to the overflow passes through the filter 4 by the circulation pump 3 to remove particles, and returns to the cleaning tank inner tank 1. When the carrier 6 containing the wafer 7 is transferred to the cleaning tank inner tank 1, the ultrasonic oscillator 5 operates, and when the carrier 6 is unloaded, the ultrasonic oscillator 5 stops. As shown in FIG. 4, the output of ultrasonic waves during this period was constant.

[0004]

By the way, in the above-mentioned wafer cleaning apparatus, even though the particles removed from the wafer by ultrasonic waves have a constant flow of the cleaning liquid in the inner tank of the cleaning tank, the inner tank is cleaned by ultrasonic waves. However, there is a drawback that it is reattached to the wafer when the carrier is carried out.

[0005]

In order to solve the above-mentioned problems, the wafer cleaning apparatus of the present invention is characterized by adding a mechanism for changing the ultrasonic output while the wafer is in the inner tank of the carrier cleaning apparatus. It is what

The cleaning method of the present invention removes particles from the cleaning liquid in the inner tank of the cleaning tank by changing the output of ultrasonic waves while the carrier containing the wafer is in the cleaning tank. Is characterized by.

[0007]

According to the above structure, the wafer is removed from the wafer,
The particles trapped in the cleaning liquid by the ultrasonic waves are removed from the cleaning tank inner tank by overflow of the cleaning tank inner tank when the ultrasonic output is reduced. Further, the number of particles in the cleaning liquid can be further reduced by increasing the number of changes in ultrasonic output. Therefore, it is possible to prevent the carrier from being attached again when the carrier is carried out.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a wafer cleaning apparatus according to an embodiment of the present invention, and FIG. 3 is the same as that of FIG. 3 except that the sequencer 8 is connected, and therefore, the same portions are denoted by the same reference numerals and the description thereof is omitted.

With the above structure, as shown in FIG. 2, the ultrasonic wave output is changed while the carrier containing the wafer is in the cleaning tank. Particles trapped by ultrasonic waves during the low output time period are discharged to the outside of the cleaning tank by overflow. As a result, the number of particles in the cleaning tank can be reduced, and the number of particles redeposited on the wafer can be reduced.

The output of ultrasonic waves may change intermittently as in this example, or may change continuously.

[0011]

As described above, the sequencer is connected to the ultrasonic oscillator, and the carrier containing the wafer can reduce the number of particles in the tank in the cleaning tank, and the particles reattached to the wafer can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural view of a wafer cleaning apparatus that employs an ultrasonic output changing mechanism according to an embodiment of the present invention.

FIG. 2 is an ultrasonic output diagram of a wafer cleaning apparatus that employs an ultrasonic output changing mechanism according to an embodiment of the present invention.

FIG. 3 is a sectional structural view of a conventional wafer cleaning apparatus.

FIG. 4 is an ultrasonic output diagram of a conventional wafer cleaning apparatus.

[Explanation of symbols]

 1 Cleaning tank inner tank 2 Cleaning tank outer tank 3 Circulation pump 4 Filter 5 Ultrasonic oscillator 6 Carrier 7 Wafer 8 Sequencer

Claims (3)

[Claims] 1. A wafer cleaning apparatus, wherein the wafer cleaning apparatus is provided with output adjusting means for sequentially adjusting the output of an ultrasonic oscillator used for cleaning. 2. A wafer cleaning apparatus characterized in that the output of an ultrasonic oscillator used for cleaning is switched during cleaning. 3. A method for cleaning a wafer, which comprises applying ultrasonic output intermittently during cleaning.