Browse Prior Art Database

Mask Substrate Surface Shield

IP.com Disclosure Number: IPCOM000078045D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+3]

Abstract

The spiking that occurs during the epitaxial layer growth in silicon processing causes defects or "starring" in the glass contact masks, which reduces the useful lifetime of the masks. In the article appearing in this issue of the IBM Technical Disclosure Bulletin on page 1726, a method is suggested to obtain a surface shield by coating the glass substrate surface with thin layers of hard, transparent oxide materials. In this article, the properties of AlN and Si(3)N(4) relevant for mask substrate surface shield applications are described.

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Mask Substrate Surface Shield

The spiking that occurs during the epitaxial layer growth in silicon processing causes defects or "starring" in the glass contact masks, which reduces the useful lifetime of the masks. In the article appearing in this issue of the IBM Technical Disclosure Bulletin on page 1726, a method is suggested to obtain a surface shield by coating the glass substrate surface with thin layers of hard, transparent oxide materials. In this article, the properties of AlN and Si(3)N(4) relevant for mask substrate surface shield applications are described.

Properties which make AlN particularly significant for mask substrate surface shield applications are:
1) High hardness value of approx. 8-9 mho compared to approx. 7

mho of silicon.
2) Insulating nature of AlN; it has an energy gap

of 3.8 ev, which puts its optical absorption

edge close to approx. 0.32 Mu and it is transparent in

the 4000 Angstrom region, where the photoresist

technology is being used.
3) The thermal expansion coefficient Alpha of AlN is

approx. 4.03 x 10/-6//degrees C in the 25-250 degrees C

range. The Alpha of soda lime glass in this range is

approx. 9.2 x 10/-6//degrees C.

A desirable of AlN is attainable with the following

glass compositions:

a) CORNING* 7740 alkaliborosilicate glass,

Alpha = 3.25 x 10/-6//degrees C.

b) CORNING 1715 or 1723; alkali-free, lime alumino

silicate glass, Alpha = 3.5, 4.6 x 10/-6//degrees C.

c) CORNING 7059, barium alumino silicate glass,

Alpha = 4.5 x 10/-6//degrees C.
4) The thermal expansion coefficient of AlN

Alpha = 4.5 x 10/-6//degrees C is compatible with t...