Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – Amorphous semiconductor
Reexamination Certificate
2001-01-31
2003-05-13
Dang, Trung (Department: 2823)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
Amorphous semiconductor
C438S046000, C438S047000, C438S093000, C438S094000, C438S485000
Reexamination Certificate
active
06562702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method and apparatus for manufacturing a semiconductor device, and, particularly, to a nitride compound semiconductor device and a method and apparatus for manufacturing the nitride compound semiconductor device.
2. Description of the Related Art
In recent years, semiconductor compounds having a large bandgap, such as AlN, GaN, AlGaN, GaInN and InN, have attracted considerable attention as materials such applications as blue LEDs, blue LDs and visible light-emitting elements. In the production of these nitride-type group IIIA (Group number 13 in a revised edition of Inorganic Chemistry Nomenclature in 1989 by IUPAC (International Union of Pure and Applied Chemistry))-VA (Group number 15 in a revised edition of Inorganic Chemistry Nomenclature in 1989 by IUPAC) semiconductor compounds, NH
3
gas or N
2
gas is used as the VA element source. These NH
3
gas and N
2
gas are however more stable and hence more inactive than the VA element sources, e.g., AsH
3
gas and PH
3
gas which are used in the production of other III-V compound semiconductors. When a film of the nitride-type III-V semiconductor compound is formed on a substrate by a metal organic chemical vapor deposition method (MOCVD), the temperature of the substrate is therefore adjusted to 900 to 1200° C.
The materials which can be used at this substrate temperature are, however, limited. Bulk crystal substrates which are usually used for III-V compound semiconductors, e.g., GaAs, cannot be used but expensive substrate materials such as sapphire and SiC crystal are used. However, almost no In is incorporated into crystals at substrate temperatures as high as 900 to 1200° C. at which GaN of high quality grows and hence the substrate temperature is lowered in the production of mixed crystals containing In. In this method, however, the film quality of a compound semiconductor is sacrificed and it is therefore difficult to obtain a high quality mixed crystal containing 10% or more of In. Also, the method of changing the substrate temperature, when a film is formed at high temperatures, may cause, for instance, the diffusion of elements in the film formed at low temperatures and it is therefore difficult in practice to produce multi-layer film or super lattice elements.
To make growth at low temperatures, there is a method in which NH
3
gas or N
2
gas used as a VA element source is made into the form of plasma by glow discharge (J. M. Van Hore et al.,
J. Cryst. Growth
150 (1995) 908), microwave discharge, or electron cyclotron resonance and an organic metal compound containing a IIIA element is introduced into the remote plasma to form a film (A. Yoshida,
New Functionality materials,
Vol. C. 183-188 (1993), S. Zembutsuet al.,
App. Phys. Lett.
48, 870). It is reported that the formation of a GaN film using this method at temperatures between 600 and 900° C. results in the production of crystals exhibiting a strong UV photoluminescence when the film is formed at 900° C. (Tokuda, Wakahara, Sasaki,
Shingaku Technical Report ED,
95-120p 25 (1995-11).
Well-known apparatuses for the production of a semiconductor device using this type of remote plasma include those comprising one activating means connected to a reactor, a first supply means for supplying the element source of the group VA, e.g., N
2
gas to the activating means from the side opposite to the reactor and a second supply means for supplying an organic metal compound containing a IIIA element to the reactor side of the activating means.
It is, however, reported that, in the crystals grown at temperatures as low as 600° C. or less using such an apparatus for the production of semiconductor devices, the crystallinity is reduced and hence only peaks from a deep level are observed. An increase in the amount of the raw materials to improve the growth rate results in the inclusion of a large amount of hydrogen in the film bringing about a further reduction in the crystallinity. Moreover, when a mixed crystal is produced using this apparatus for production of semiconductor device, a mixed gas containing two or more organic metal compounds, for example, trimethylgallium and trimethylindium is supplied by the second supply means. However, since the binding energies of these organic metal compounds differ from each other, one of either of these metal compounds tends to be selectively decomposed when these compounds are introduced into the plasma, giving rise to the problems that, even if the ratio of the two compounds in the mixed gas is regulated, the composition of the resulting film is controlled with difficulty, the crystallinity of the mixed crystal film is reduced and carbon impurities derived from the more undecomposable organic metal compound get mixed in the resulting film.
The cause of these problems is considered to be in the fact that, at such low temperature conditions that the raw material of the organic metal compound containing the IIIA element which takes a three-coordinate form in a gaseous state has difficulty in decomposing, releasing, and rearranging on the growth surface, the IIIA element either remains on the growth surface in the three-coordinate state while it contains hydrogen or is left as an element having a binding defect in the film as it has difficulty forming a four-coordinate network with a nitrogen atom.
An object of the present invention is to improve these drawbacks of the conventional method and apparatus using this type of a remote plasma for the production of a semiconductor device and to provide a method and apparatus for producing a semiconductor device having high quality and performance at a low temperature efficiently and also to provide a semiconductor device produced using these method and apparatus.
SUMMARY OF THE INVENTION
The inventors of the present invention have made earnest efforts and, as a result, have found that it is possible to produce a microcrystal film and crystal film having high quality by controlling a film forming step and reaction step using plasma and repeating a step of the formation of a IIIA element
itrogen layer from an activated IIIA element atom and an activated nitrogen atom, and a step subsequent to this type of growth of a nitrogen layer containing nitrogen or nitrogen and hydrogen, a step of the passivation of defects and a step of the extraction of hydrogen, thereby solving the above problem, to complete the present invention. The present invention is characterized in that crystal growth is forwarded while the growth surface of a binding layer formed of a IIIA element atom and a nitrogen atom is restored and grown by the aid of a nitrogen atom and a hydrogen atom.
Accordingly, the features of the present invention to solve the aforementioned problem reside in:
<1> A semiconductor device produced by forming a film of a nitride compound on a substrate having heat resistance at 600° C. or less, wherein the nitride compound includes one or more elements selected from group IIIA elements of the periodic table and a nitrogen atom and produces photoluminescence at the band edges at room temperature;
<2> A semiconductor device according to <1>, wherein the substrate is constituted of a base material selected from the group consisting of an electroconductive material, a semiconductor material and an insulating material;
<3> A semiconductor device according to <1>, wherein the substrate is transparent;
<4> A semiconductor device according to <2>, wherein the substrate is transparent;
<5> A semiconductor device produced by forming a film of a nitride compound on a substrate having heat resistance at 600° C. or less, the nitride compound including one or more elements selected from group IIIA elements of the periodic table and a nitrogen atom, wherein the absorption wavelength for the nitride compound in an infrared absorption spectrum ranges between 3000 cm
−1
and 700 cm
−1
;
<6> A semiconductor device according to <5&
Dang Trung
Fuji 'Xerox Co., Ltd.
Oliff & Berridg,e PLC
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