Method of producing pure water, system therefor and cleaning met

Details Method of producing pure water, system therefor and cleaning met Method of producing pure water, system therefor and cleaning met

1994-01-27

1995-08-08

McCarthy, Neil

Liquid purification or separation

Processes

Utilizing electrical or wave energy directly applied to...

134 2, 134 42, 250436, 2504922, 422 21, 422186, C02F 130

Patent

active

054395968

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a method of producing pure water, a system therefor, and a cleaning method, and in particular, relates to a method of producing pure water, a system therefor, and a cleaning method which are preferably used in cleaning processes in LSI manufacturing processes.


BACKGROUND ART

The conventional technology will be explained using the cleaning process of an LSI process as an example.
In an LSI manufacturing process, an oxide film is formed on a silicon wafer, window-opening having a predetermined pattern is conducted in the oxide film, and then cleaning is conducted, and depending on the purpose, p-type or n-type chemical elements are introduced, and a procedure, in which the above impurities are diffused or annealed in the silicon, is repeatedly conducted in a thermal diffusion furnace, and elements are thus formed.
When conducting heat treatment such as thermal diffusion or annealing or the like, if even a small amount of impurities such as, for example, metals or the like, adhere to the silicon surface, then the characteristics of the element which is formed worsen; for example, a drop in the base collector withstand voltage, an increase in leak currents, or the like, is experienced.
Accordingly, in semiconductor manufacturing processes, cleaning processes are extremely important in order to manufacture high-performance elements, and it is necessary to completely remove the contaminants on the silicon.
However, after the removal of an oxide film, the silicon surface is hydrophobic, and the wettability thereof with water is normally poor, so that, in other words, it is difficult to bring the pure water and the contaminant impurities into contact, and it is difficult to completely clean away the very small amount of impurities adhering to the silicon surface. As a result, it is impossible to obtain elements having higher performance, as explained above, and this represents a great hindrance to the attainment of a shift to high performance elements.
The present invention has as an object thereof to provide a method of and system for producing pure water which is capable of completely cleaning away impurities on silicon by improving the wettability with pure water of a substrate body surface, and in particular, a silicon wafer substrate body from which an oxide film has been removed, and bringing pure water into contact with the silicon surface, and to provide a cleaning method.


DISCLOSURE OF THE INVENTION

A first gist of the present invention resides in a pure water production method, wherein microwaves are applied in the state in which water is brought into contact with a catalyst.
A second gist of the present invention resides in a pure water production apparatus, wherein a catalyst holding mechanism for holding a catalyst so as to come into contact with water introduced into the interior thereof, and a microwave producing mechanism for applying microwaves to the water introduced into the catalyst holding mechanism, are disposed in an intermediate portion of a piping for supplying pure water to a use point.
A third gist of the present invention resides in a substrate body cleaning method, wherein a substrate body is cleaned using pure water produced by means of the method described in gist 1 above.


(Embodiment Examples)

Hereinbelow, embodiment examples of the present invention will be explained.
The pure water of the present invention has a degree of purity suitable for use in cleaning procedures of semiconductor manufacturing processes. This pure water removes impurities as shown, for example, in Table 1; however, in cases of use in processes other than LSI manufacturing processes, other pure water may be used.


TABLE 1 ______________________________________ Specific Resistance 18 M.OMEGA. .multidot. cm or more ______________________________________ TOC .ltoreq.1 ppb Silica .ltoreq.1 ppb Particles (0.07 .mu.m) .ltoreq.1/ml Evaporation Residue .ltoreq.1 ppb ______________________________________
A structural example of the pure

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patent: 4345983 (1982-08-01), Wan
patent: 4456512 (1984-06-01), Bieler et al.
patent: 4582629 (1986-04-01), Wolf
patent: 5068030 (1991-11-01), Chen
patent: 5215634 (1993-06-01), Wan et al.

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