Passivation coating for flexible substrate mirrors

[54] PASSIVATION COATING FOR FLEXIBLE SUBSTRATE MIRRORS

[75] Inventors: C. Edwin Tracy; David K. Benson,

both of Golden, Colo.

[73] Assignee: The United States of America as represented by the United States Department of Energy, Washington, D.C.

[21] Appl. No.: 259,634
[22] Filed: Oct. 19,1988

Related U.S. Application Data

[63] Continuation-in-part of Ser. No. 873,069, Jun. 4, 1986, Pat No. 4,780,372, which is a continuation of Ser. No. 632,742, Jul. 20, 1984, abandoned.

[51] Int. CI.5 G02B 5/08; G02B 7/18

[52] U.S. a 350/641; 350/164;

350/166; 350/320

[58] Field of Search 350/641, 642, 582, 164-166,

350/320; 428/428, 434, 460-463

[56] References Cited

U.S. PATENT DOCUMENTS

4,097,889 6/1978 Kern et al 427/94

4,273,828 6/1981 Tracy et al 428/136

4,341,841 7/1982 Ohno et al 350/641

4,451,119 5/1984 Meyers et al 350/641

4,482,209 11/1984 Grewal et al 350/642

4,487,196 12/1984 Murphy 126/438

4,517,217 5/1985 Hoffman 428/428

4,780,372 10/1988 Tracy et al 350/641

OTHER PUBLICATIONS

Kern & Rosier, Advances in Deposition Process for Passivation Films, J. of Vac.Sci & Techno, vol. 13, No. 5, pp. 1082-1099, 1977.

Milek, Silicon Nitride for Microelectronic Applica

tions, Handbook of Electronic Materials, vol. 3, IFI/Plenuj. NY, N.Y., pp. 10-13 (1971), SERI/TR-31-042. SERI Materials Branch Semiannual Report, Jan. 1, 1978-Jun. 30, 1978, Solar Energy Research Institute, Golden, Colo. (1978).

SERI/RR-31-145, Solar Glass Mirror Program A Planning Report on Near-Term Mirror Development Activities, Solar Energy Research Institute, Golden, Colo. (1979).

Vossen and Kern, Thin Film Processes, Academic Press, NY, N.Y. (1978).

R. B. Pettit & C. J. Brinker, Use of Sol-Gel Thin Films in Solar Energy Applications, SPIE vol, 562, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion IV, pp. 256-268 (1985).

Primary Examiner—Bruce Y. Arnold

Assistant Examiner—Thong Nguyen

Attorney, Agent, or Firm—Kenneth Richardson; John

M. Albrecht; William R. Moser

[57] ABSTRACT

A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate before metal deposition thereon to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors. Also, the silver or other reflective metal layer on mirrors comprising thin, lightweight, flexible substrates of metal or polymer sheets coated with glassy layers can be protected with silicon nitride according to this invention.

25 Claims, 6 Drawing Sheets