Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – Amorphous semiconductor
Reexamination Certificate
1995-05-18
2001-06-12
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Formation of semiconductive active region on any substrate
Amorphous semiconductor
C438S694000, C438S710000, C438S758000, C438S907000
Reexamination Certificate
active
06245648
ABSTRACT:
BACKGROUND OF THE INVENTION
Hydrogenated amorphous silicon films, hereinafter called a-Si, which are suitable for semiconductor applications have been prepared by a variety of techniques. Chittick, Alexander, and Sterling reported in the
Journal of the Electrochemical Society,
Vol 116, No. 1 (January 1969) pages 77-81, in an article entitled “The Preparation and Properties of Amorphous Silicon”, that an inductively coupled, RF glow-discharge in silane (SiH
4
) gas produced low-conductivity a-Si films that could be doped with both donor and acceptor impurities, thereby changing the a-Si conductivity over a wide range of values. More recently, a-Si films were produced by evaporating silicon in an atmosphere of hydrogen (H
2
) and by sputtering silicon in an atmosphere of H
2
+Ar which exhibited similar semiconductor characteristics to those films made from silane in a glow-discharge.
Presently, several commercial projects related to the development of Schottky barrier solar cells using crystal, polycrystal, and amorphous semiconductor materials were described in a recent book entitled
Twelfth IEEE Photovoltaic Specialists Conference
-1976, published by the Institute of Electronic and Electrical Engineers Inc., New York, N.Y., 10017. On pages 893-895 of this book, Carlson et al reported in an article entitled “Solar Cells Using Schottky Barriers on Amorphous Silicon” that he formed a solar cell by applying a transparent electrode with appropriate work-function to one side of an a-Si film and an ohmic contact to the other. Also, this article stated output voltages increased initially by 100 mV when the thin metal electrode was evaporated in residual oxygen background in the vacuum system, producing a metal-insulator-semiconductor (MIS) structure. More recently, Carlson reported in Vol 77-2
Extended Abstracts, Fall Meeting, Atlanta, Ga., Oct.
9-14 1977 of the Electrochemical Society, Princeton, N.J., 08540, pages 791-792, that these MIS cells were generally unstable. Furthermore, Carlson reported that his electrodes were less than 0.02 cm
2
in area—a value too small for commercial use. Also, an article by Godfrey & Green in
Applied Physics Letters
Vol 31, No. 10, (Nov. 15, 1977) pages 705-707, indicates that such small areas lead to erroneous data.
My prior glow-discharge coating processes are covered in U.S. Pat. Nos. 3,068,283, 3,068,510 (Dec. 18, 1962) and 3,600,122 (Aug. 17, 1971). These processes generally related to polymeric coatings which have resistivities greater than 10
12
ohm-cm High-resistivity coatings act as blocking capacitance in series with the glow-discharge thereby assisting in regulation of coating uniformity. However, neither 60 Hz line transformers nor DC power supplies can be used with my prior processes. The present process, on the other hand, produce semiconducting films which act primarily as resistances in series with the glow discharge and which require different process concepts.
SUMMARY OF THE INVENTION
The present coating process is related to producing semiconductor films which have electrical resistivities generally less than about 10
12
ohm-cm at room-temperature, and preferably between 10
12
and 10
6
ohm-cm. The present process is designed to produce uniform semiconducting coating over a large area by means of a glow-discharge in which pressure and electric field are controlled. Also, the present process relates to the treatment of a semiconductor surface to increase the Schottky barrier voltage when an active conducting coating is applied. Such treatment may be used on any semiconductor material, including crystal semiconductors which have conductivities of 100 and 0.01 ohm cm. and higher. My coating process and barrier treatment is particularly useful for producing a Schottky barrier solar cell.
The principle object of the process is to produce a semiconductor and barrier for use in a solar cell. Another object of the invention is to coat a large-area substrate with amorphous semiconducting material. Yet another object is to form a Schottky barrier between a semiconducting material and an active electrode. Another object is to dope large area amorphous semiconductor materials to form an ohmic contact with a conducting substrate. Another object is to introduce semiconductor material from a solid-source into a coating being formed by glow-discharge deposition from the gas-phase.
REFERENCES:
patent: 3869322 (1975-03-01), Cuomo et al.
patent: 3979271 (1976-09-01), Noreika et al.
patent: 4015558 (1977-04-01), Small et al.
patent: 4046659 (1977-09-01), Cormia et al.
patent: 4064521 (1977-12-01), Carlson
patent: 4066037 (1978-01-01), Jacob
patent: 4123316 (1978-10-01), Tsuchimoto
patent: 2 114 470 (1972-09-01), None
patent: 49-79782 (1974-08-01), None
Advertisements,Solid State Technology,Dec. 1977, pp 10 & 76.
N. Kawahara et al., “Plasma Deposition: Appartus for producing silicon nitride films,” published inIONICS,Aug. 1, 1976, pp. 34-39 (original and English translation provided).
A. Madan et al., “Investigation of the Density of Localized States in a-Si Using the Field Effect Technique,” published inJournal of Non-Crystalline Solids 20,1976, pp. 239-257.
Bowers Charles
Fish & Neave
Nguyen Thanh
Plasma Physics Corporation
LandOfFree
Method of forming semiconducting materials and barriers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of forming semiconducting materials and barriers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of forming semiconducting materials and barriers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2498285