Coating apparatus – With vacuum or fluid pressure chamber – With means to apply electrical and/or radiant energy to work...
Patent
1990-04-10
1993-02-16
Hearn, Brian E.
Coating apparatus
With vacuum or fluid pressure chamber
With means to apply electrical and/or radiant energy to work...
118726, 437173, 437936, C23C 1600, H01L 21203
Patent
active
051867508
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for forming, on any portion of a substrate, a thin film of a compound semiconductor having a controlled composition, and a semiconductor thin film forming apparatus for forming a partially thick or only partially grown thin film of a semiconductor by irradiating the substrate with light during growing the thin film of the semiconductor to thus promote the thin film growth reaction.
BACKGROUND OF THE INVENTION
It is a recent tendency to impart greater accuracy and higher function to semiconductor elements. Accordingly, the structure of such semiconductor elements has become more and more precise and complicated. Accordingly, to meet such requirements, a film of a uniform thickness and composition is formed on the surface of a substrate, and then a structure of elements having complicated unevenness on the surface is realized utilizing a highly accurate lithography technique. Recently, for the purpose of simplifying the complicated processing steps for fabricating these elements, it has been tried to control the thickness of a part of a film to be formed on the surface of a substrate during the formation of the film. For instance, in Applied Physics Letters, Vol. 47, 1985, p. 95, there is disclosed a technique which comprises irradiating a substrate with light from an argon laser while forming a GaAs film according to metalorganic chemical vapor desposition method (hereunder referred to as "MOCVD"), to thus form a film only on the portions irradiated with the argon laser rays. The reason why the film is selectively grown on the irradiation portions is that the growth of the film is enhanced by the decomposition of an organometal as a starting material by irradiating it with light. It has been reported that a low pressure mercury lamp, an excimer laser or the like is also effective as a light source other than the argon laser.
As the accuracy and the function of semiconductor elements such as those for optoelectronics become higher, the complexity of the process for fabricating the semiconductor elements has steadily increased.
Recently, there has been developed a metalorganic molecular beam epitaxial growth technique as a novel film growth method. The method is characterized by the use of such a molecular beam.
The molecular beam will now be explained below. The molecular beam refers to the condition that a molecule discharged from a source of the molecular beam reaches a substrate without causing any collisions with molecules remaining in a vacuum chamber. To realize such a condition, the inside of a deposition chamber should be maintained at a high vacuum. In general, the distance between the source of a molecular beam and a substrate ranges from 10 to 20 cm. The mean distance that a molecule proceeds between two consecutive collisions, i.e., the mean free path L can be expressed by the following equation as a function of an internal pressure p of the vacuum chamber: L (cm)=10.sup.-2 /p (Torr). Therefore, to establish the mean free path L of 10 cm, it is necessary to maintain the inside of the growth chamber at a pressure of not more than 10.sup.-3 Torr.
For the purpose of simplifying processes in fabricating semiconductor devices according to this method, there have been proposed not only structures of such devices but also processes for fabricating semiconductor films. For instance, in Applied Physics Letters, Vol. 52, No. 13, 1988 (Mar. 28), p. 1065, there is disclosed a technique for forming a semiconductor film by partially irradiating a semiconductor substrate placed in a metalorganic molecular beam epitaxial (hereunder referred to as "MOMBE") system with, for instance, excimer laser rays during the fabrication of a semiconductor film to thus selectively form such a semiconductor film on a part of the semiconductor substrate which is irradiated with the laser rays.
However, the excimer laser principally suffers from the following two disadvantages. First, since the wavelength of the laser agrees with that of the light absorbed by an
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Iga Ryuzo
Sugiura Hideo
Yamada Takeshi
Fleck Linda J.
Hearn Brian E.
Nippon Telegraph and Telephone Corporation
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