Chemistry: analytical and immunological testing – Rate of reaction determination
Patent
1994-01-31
1995-08-01
Warden, Robert J.
Chemistry: analytical and immunological testing
Rate of reaction determination
436 72, 20419213, 20419233, 422 89, G01N 3006
Patent
active
054380014
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and device for accurately measuring the decomposition rate of various special material gases which are necessary for semiconductor manufacturing, in relation to reaction time, impurity concentration, atmospheric temperature, and the like.
BACKGROUND OF THE INVENTION
In recent semiconductor manufacturing technology, for example, in the case in which a silicon substrate is manufactured, the handling of special material gases (for example, silane gas, disilane gas, diborane gas, and the like) is extremely important, and an elucidation of the chemical and physical properties thereof would lead to great developments in such manufacturing technology. Such special material gases are corrosive, spontaneously combustive, and toxic; such properties make the handling thereof inconvenient, and they decompose as the result of specified temperatures or discharges; for example, in the case in which this special material gas comprises silane gas (SiH.sub.4), it is known that this gas decomposes into Si and 2H.sub.2, and the decomposition temperatures thereof have been measured.
Conventionally, the component analyses of such special material gases were carried out using concentration analyzers utilizing gas chromatography.
However, conventionally, only approximate values were known for the decomposition temperatures of special material gases, and no useful data could be obtained with respect to the relationship between various reaction conditions and variations in the decomposition rate. Accordingly, in particular with respect to manufacture of semiconductors having hyperfine structures, sufficient understanding of these relationships is necessary.
The present invention was created in light of the above-described problems in the background art; it has as an object thereof to provide a method and device for easily and accurately measuring the relationship between the decomposition rate of special material gasses which present difficulties in handling, and reaction conditions such as reaction time, impurity concentration, and atmospheric temperature.
SUMMARY OF THE INVENTION
In order to achieve the above object, the invention relates to a method for measuring variation in a decomposition rate of a special material gas, which comprises a first step, in which an inert gas of ultrahigh purity is caused to flow in a reaction pipe, an inner surface of which has been subjected to electrolytic polishing so as to be stable with respect to at least special material gases; a second step, in which the interior of this reaction pipe is baked so as to achieve a specified purity level; a third step, wherein the interior of the reaction pipe is placed in an atmosphere having a specified temperature; a fourth step, in which a special material gas having a specified purity is supplied at a specified flow rate into the reaction pipe; and a fifth step, in which the decomposition rate of the special material gas within the reaction pipe is measured under varying flow rate, purity, and reaction pipe atmospheric temperature conditions; silane gas is used as a representative special material gas.
The invention also relates to a device for measuring variation in a decomposition rate of a special material gas, which comprises a first gas supply source for supplying an inert gas of high purity, a second gas supply source for supplying a special material gas at adjustable concentrations and flow rates, a purity adjustment mechanism which is capable of adjusting an amount of impurities added to this special material gas, changeover valves which are capable of selective changeover between an inert gas and a special material gas flow, a support mechanism for supporting a reaction vessel, one end opening of which is connected to a valve, a concentration analyzer, which is connected to the other end opening of the reaction pipe, and a heating mechanism which is capable of controlling the interior of the reaction pipe so as to maintain a freely selected fixed temperature; gas chromatogr
REFERENCES:
patent: 3578404 (1971-05-01), Walles et al.
patent: 4810654 (1989-03-01), Tao
Bhat N.
Warden Robert J.
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