KR20030056224A - a method for cleaning the surface of a wafer - Google Patents

Abstract

PURPOSE: A method for cleaning the surface of a wafer is provided to be capable of completely removing contaminants of the wafer surface by repeatedly growing a chemical oxide layer using ozonized water after etching a native oxide layer or a thermal oxide layer using diluted HF at least two time. CONSTITUTION: A wafer(1) is etched by using diluted HF. At this time, a native oxide layer(2) and contaminants(3) are partially removed. The first cleaning process is carried out at the wafer(1) by using deionized water. A chemical oxide layer is growed by using ozonized water. The second cleaning process is carried out at the wafer(1) by using the deionized water. Then, the chemical oxide layer and contaminants are partially removed by using the diluted HF. The processing steps are repeatedly carried out more than two times for completely removing contaminants. Preferably, the diluted HF is used until the native oxide layer is removed and the ozonized water is used until the chemical oxide layer is growed as much as about 5 angstrom.

Description

{A method for cleaning the surface of a wafer}

The present invention relates to a method for cleaning a wafer surface, more specifically, by etching a natural oxide film or a thermal oxide film with dilute hydrofluoric acid and repeating the process of growing the chemical oxide film using ozone water two or more times to completely remove the contaminant. The present invention relates to a method for cleaning a wafer surface that can improve wafer surface properties.

As the thickness of the gate oxide decreases as the semiconductor circuit line width becomes smaller and smaller, the quality of the gate oxide film becomes important enough to influence the quality of the semiconductor chip.

Since the quality of the gate oxide film varies depending on the degree of cleaning of the wafer surface before growth, it is necessary to remove contaminants such as metal ions and anions in the process of cleaning the wafer surface before growth of the gate oxide film. .

If the surface of the wafer is not sufficiently cleaned, hydrocarbons, etc., contaminated on the surface of the wafer may locally inhibit growth of the gate oxide layer, causing defects, and other silicon atoms on the surface of the wafer in the high temperature annealing process. It may also cause defects that cause the movement of.

The wafer surface cleaning process currently used is an oxide film caused by impurities in the atmosphere by etching a natural oxide film or a thermal oxide film using diluted hydrofluoric acid (Diluted HF, DHF) before growing the gate oxide film, and growing a chemical oxide film using ozone water. We are using a method to stop growth.

There are various cleaning processes used to remove natural or thermal oxide contaminants on the wafer surface before the gate oxide film growth.

1) Dilute hydrofluoric acid-Ultrapure water (DIW)-SC-1-Ultrapure water

2) Dilute hydrofluoric acid-Ultrapure water-COM (HCL + ozone water)-Ultrapure water

3) SC-1-Ultrapure water Dilute hydrofluoric acid-Ultrapure water

That is, the conventional cleaning process is to remove the native oxide film or thermal oxide film using dilute hydrofluoric acid and grow the chemical oxide film with SC-1 and ozone water, and to remove the oxide film using dilute hydrofluoric acid after the main cleaning. have.

However, such a conventional cleaning method can make the surface of the wafer considerably clean. However, when the surface of the wafer contains a lot of contamination such as metal ions, the next cleaning does not completely remove the source of contamination. There is a problem that can act as this impurity to degrade the oxide film.

An object of the present invention is to solve such a conventional problem, by completely etching the natural oxide film or thermal oxide film with dilute hydrofluoric acid and repeat the process of growing the chemical oxide film using ozone water two or more times to completely remove the source The present invention provides a method for cleaning a wafer surface that can improve wafer surface characteristics.

1A to 1D are schematic diagrams of a method for cleaning a wafer surface according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: wafer 2: natural oxide film

3: pollutant 4: chemical oxide film

As a means for achieving the above object, the configuration of the present invention comprises the steps of etching the wafer with dilute hydrofluoric acid, cleaning the wafer using ultrapure water, growing a chemical oxide film with ozone water, and using ultrapure water. Cleaning the wafer, and repeating the above process at least twice.

According to the present invention, in order to remove contaminants on the wafer surface, the process of ozone water treatment after dilute hydrofluoric acid treatment is performed once and the treatment time of dilute hydrofluoric acid and ozone water is reduced and repeated two or more times to remove the contamination of the wafer surface more effectively. You can do it.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings in order to describe in detail enough to enable those skilled in the art to easily carry out the present invention. . Other objects, features, and operational advantages, including the object, operation, and effect of the present invention will become more apparent from the description of the preferred embodiment.

For reference, the embodiments disclosed herein are only presented by selecting the most preferred examples to help those skilled in the art from the various possible examples, the technical spirit of the present invention is not necessarily limited or limited only to this embodiment. In addition, various changes, additions and changes are possible within the scope without departing from the spirit of the present invention, as well as other embodiments that are equally apparent.

As shown in FIGS. 1A to 1D, the configuration of the method for cleaning the wafer surface according to the embodiment of the present invention includes etching the wafer with dilute hydrofluoric acid, cleaning the wafer using ultrapure water, and ozone water. Growing a raw chemical oxide film, cleaning the wafer using ultrapure water, and repeating the above process at least two times.

The operation of the cleaning method of the wafer surface according to the embodiment of the present invention by the above configuration is as follows.

If there is an oxide film, all of the oxide film is etched, and then diluted hydrofluoric acid and ozone water treatment are repeated, and if only natural oxide film is present, the diluted hydrofluoric acid and ozone water treatment may be repeated 3-4 times.

The wafer is etched with dilute hydrofluoric acid. In the case of a thermal oxide film, the hydrofluoric acid treatment time is adjusted.

First, as shown in FIG. 1A, when contaminants 3 are present on the wafer 1, and the natural oxide film 2 is formed on the order of 10-20 ohms, it is diluted as shown in FIG. 1B. The native oxide film 2 on the wafer 1 is etched using hydrofluoric acid. In the case of thermal oxidation film, the treatment time of dilute hydrofluoric acid is adjusted.

Next, the wafer 1 in which the natural oxide film 2 is not etched is cleaned using ultrapure water.

Next, the chemical oxide film 4 is grown on the wafer 1 with ozone water.

Next, the wafer 1 in which the chemical oxide film 4 is grown is cleaned using ultrapure water.

Next, as shown in FIG. 1D, the cleaning and etching processes are repeated at least twice while etching the chemical oxide film 4 on the wafer 1 using dilute hydrofluoric acid.

At this time, in order to compensate for the disadvantage that the process time is long, the processing time of dilute hydrofluoric acid is performed only as long as the natural oxide film is etched, and the processing time of ozone water is only as long as the natural oxide film is grown on the wafer surface by about 5 ohms.

As described above, in the embodiment of the present invention, by etching the oxide film with dilute hydrofluoric acid and repeating the process of growing the chemical oxide film using ozone water two or more times, the contaminant may be completely removed to improve the wafer surface characteristics. It is possible to provide a method for cleaning a wafer surface having an effect. Such effects of the present invention can be applied to various applications within the scope of the technical spirit of the present invention in the field of cleaning.

Claims (2)

Etching the wafer with dilute hydrofluoric acid, Cleaning the wafer using ultrapure water, Growing a chemical oxide film with ozone water, Cleaning the wafer using ultrapure water, And repeating the above process at least twice. The method of claim 1, wherein the processing time of dilute hydrofluoric acid is performed only as long as the natural oxide film is etched, and the processing time of ozone water is also grown on the surface of the wafer by about 5 ohms. The cleaning method of the wafer surface, characterized in that only for a time.