JPS6072233A - Washing device for semiconductor wafer - Google Patents

Abstract

PURPOSE:To effectively remove organic contaminant deposited on the surface of a wafer by a method wherein the title device is composed of a washing bath in which a washing chemical solution is contained, a hold carrier for semiconductor wafers dipped therein, an ultrasonic wave generator that gives oscillation, an irradiator with ultraviolet rays to wafers, etc. CONSTITUTION:The wafer carrier 2 holding the semiconductor wafers 1 to be washed is contained in the wafer washing bath 3 made of transparent quartz surrounded by a casing 13, and many ultraviolet ray lamps 9 are arranged in the gap between the carrier 2 and the bath 3. Chemical solution supply ports 4-7 are made opposed to the upper surface of the bath 3, and the ultrasonic wave generator 10 surrounding a valve 11 and a duct is installed outside the bottom. The device being thus constructed, hydrofluoric acid, hydrogen peroxide, hydrochloric acid, aqueous ammonia, persulfuric acid, etc. are poured from the supply ports 4-7, respectively; at the same time the bath 3 is filled with the chemical solution 8 obtained by feed of pure water from the duct 12. Thereafter, the lamps 9 and the generator 10 are set in motion at the same time, and the deposited organic substance is thus removed.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a semiconductor wafer for removing surface contaminants from semiconductor wafers (including those cut from a single crystal to those that have undergone wafer processing such as oxidation and diffusion). The present invention relates to a cleaning device.

[Technical background of the invention]

In recent years, as the performance and density of semiconductor devices have increased, more and more highly accurate microfabrication technology has been required. By the way, surface contaminants such as particulate deposits and film-like deposits that are mixed in and remain during the wafer processing process can reduce process precision and reliability of device characteristics (therefore, it is necessary to remove these surface contaminants). It has become essential for improving device yield.

The conventional wafer cleaning process consists of a simple combination of the elementary steps (1) to (4) below. Namely, ■ Removal of surface organic contamination by organic solvent treatment, ■ Removal of surface organic contamination by oxidizing acid and alkali treatment, ■ Removal of natural oxide film by dilute hydrofluoric acid treatment, ■ Removal of residual heavy metals on the surface by oxidizing acid treatment, and ■ Surface activity. These include removal of fine particles by combined use of chemical agents, alkali, or mechanical action, ■cleaning with pure water, etc. Semiconductor wafer cleaning apparatuses that meet these objectives have also been put into practical use.

[Problems with background technology]

However, the conventional techniques described above cannot adequately remove organic surface contaminants. That is, strong surface deposits cannot be completely removed only by physical cleaning, desorption, and dissolution by dipping the wafer in an organic solvent. Also,
The organic solvent itself used for organic matter removal treatment, or the contamination of organic components (e.g., organic matter in acid or alkaline chemicals, contaminants from the working environment, etc.) during a series of subsequent steps. The adhering carbon components cannot be sufficiently removed using conventional techniques.

However, carbon atoms attached to semiconductor wafers may precipitate in crystals, oxide films, or at interfaces, or cause crystal defects or Si
This results in the formation of C, resulting in a decrease in dielectric strength, an increase in leakage current, and a deterioration in junction characteristics. Also, Si
Heavy metals are immobilized in the crystal distortion around C, resulting in drawbacks such as poor characteristics.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a semiconductor wafer cleaning device that can effectively remove organic contaminants attached to the surface of a semiconductor wafer. .

[Summary of the invention]

In order to achieve the above object, the present invention provides a wafer cleaning tank in which a semiconductor wafer is immersed in a cleaning chemical solution, which is equipped with an ultrasonic generator and an ultraviolet irradiator, thereby making it possible to easily remove organic matter from the surface of the wafer 71. The present invention provides a wafer cleaning device.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of the same embodiment. A cleaned semiconductor wafer 1 is held in a wafer carrier 2 and placed in a wafer cleaning tank 3 made of transparent quartz. The cleaning chemical is supplied from the chemical supply port 4°5.6.7 to the wafer cleaning tank 3 as shown by the arrow, and the semiconductor wafer 1 is immersed in the accumulated chemical 8.
A plurality of ultraviolet lamps 9 are attached to the side surface of the wafer cleaning tank 3, and an ultrasonic generator 10 is provided at the bottom of the wafer cleaning tank 3.

Further, pure water is sent to the wafer cleaning tank 3 via the pulp 11 and the conduit 12. Then, the above device is housed in the housing 13.
be accommodated in.

Next, the operation of the apparatus shown in FIG. 1 will be explained. A series of cleaning steps is performed by combining the above-mentioned material diameters, and at that time, the necessary high-purity chemical solutions (e.g., hepatic acid, hydrogen peroxide,
Hydrochloric acid, aqueous ammonia, etc.) are supplied from chemical solution supply ports 4 to 7.

Removal of organic contaminants adhering to the surface is also performed as one of the above-mentioned basic steps. That is, a mixture of persulfuric acid and pure water is supplied from the chemical supply lower, ultraviolet light is irradiated from the ultraviolet lamp 9, and ultrasonic vibration is applied from the ultrasonic generator. In this way, a great cleaning effect can be obtained by the synergy of the activation effect of ultraviolet rays, the physical cleaning effect of ultrasonic vibration, and the chemical cleaning effect of persulfuric acid (active sulfate group).

An outline of the above-mentioned cleaning action is as follows. First, persulfate ions in the persulfuric acid solution become active sulfuric acid groups by ultraviolet rays, and organic contaminants on the wafer surface are excited. The excited organic matter is oxidized by active sulfuric acid groups, and carbon is removed as carbon dioxide gas. The chemical formula for the above reaction is as follows.

52o8"-+h, -→280."R+h,-→R" R%+2 SO4" +H2O-+nc02+-...During such activation and chemical cleaning action, ultrasonic imaging is given, Uniform cleaning action and easier dust removal can be achieved.

Incidentally, cleaning with pure water is not carried out between these raw materials in order to remove the chemical solution, etc. Pure water is supplied via a valve 11 and a conduit 12, and flows beyond the cleaning tank 3 to the housing 13.
Overflowing inside.

FIG. 2 is a graph illustrating the contamination removal effect when Si wafer 1 is treated using the embodiment shown in FIG.
aj shows the case of sharpening by the conventional device, and FIG. 2(b) shows the case of the present embodiment. As shown in FIG. 2(a), after cleaning a Si wafer with conventional equipment ft and VC, an S + 02 film was formed to a thickness of 300 mm and the withstand voltage of the oxide film was measured. On the other hand, as shown in FIG. 2 (1)), after cleaning the Si wafer according to the embodiment shown in FIG.
When a film is formed and its withstand voltage is measured, most of the films have a withstand voltage of about 8 to 9 MV/d.
: 1=6 mixed liquid treatment→pure water treatment→dilute HF treatment−pure water treatment−−+HC1:l−I202:H2O=1:
1:6 mixed solution treatment→pure water treatment→Ih5zOs 8 dilution solution (5 to 30%) treatment−→pure water treatment.

〔Effect of the invention〕

As described above, according to the present invention, since the wafer cleaning tank is provided with an ultraviolet irradiator and an ultrasonic generator, chemical solutions using ultraviolet rays,
It is possible to obtain a semiconductor wafer cleaning device that can effectively remove organic surface contaminants by synergizing the activation effect of dirt, the physical cleaning effect of ultrasonic vibration, and the chemical cleaning effect of a chemical solution. By this means, the yield of LSI can be improved. Furthermore, by using the apparatus according to the present invention, the process of removing organic contaminants can be performed as one process in a series of other elementary processes.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a graph comparing and explaining the contaminant removal effect of the conventional apparatus and the contaminant removal effect of the embodiment of FIG. 1. 1... Semiconductor wafer, 2... Wafer gearia,
3... Wafer cleaning tank, 4, 5, 6.7... Chemical solution supply port, 8... Chemical solution, 9... Ultraviolet lamp, 10... Ultrasonic generator, 11... Valve , 12... conduit, 13
...Housing. Applicant's agent Kiyoshi Inomata

Claims (1)

[Scope of Claims] A wafer cleaning tank for containing a cleaning chemical solution, a wafer carrier holding a semiconductor wafer immersed in the cleaning chemical solution, and an ultrasonic generator for applying ultrasonic vibrations into the wafer cleaning tank. A cleaning device for semiconductor wafers, comprising an ultraviolet irradiator for irradiating the semiconductor wafer with ultraviolet rays, and removing contaminants adhering to the surface of the semiconductor wafer.