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Lift Off Technique for High Temperature Metal Depositions

IP.com Disclosure Number: IPCOM000078385D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Gardiner, JR: AUTHOR [+3]

Abstract

This technique for depositing a metal interconnection system on a substrate by the lift-off technique, utilizes a glass masking layer having a varying composition to promote undercutting.

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Lift Off Technique for High Temperature Metal Depositions

This technique for depositing a metal interconnection system on a substrate by the lift-off technique, utilizes a glass masking layer having a varying composition to promote undercutting.

Lift-off techniques for fabricating metal patterns on substrates normally utilize a photoresist layer or etchable metals, such as aluminum, as a pattern having Portions removed in the areas where the subsequently deposited metal film must be retained. Such techniques are temperature limited. Further, such techniques are limited to relatively thin films of metal, since there is a tendency for metal to form over the mask step-down.

In this technique, a layer of glass 10 having a lower portion 14 that etches faster than the upper portion is deposited on the substrate 12. Preferably. The masking layer 10 has a lower base portion such as phosphosilicate glass 14 that has a high-etch rate, and an upper layer 16 of glass having a slower etch rate such as SiO(2). This composite glass layer 10 can be conveniently deposited using pyrolytic vapor deposition techniques, by injecting PH(3) into a SiH(4), O(2) and H(2) stream during the initial forming period during which layer portion 14 is formed, and subsequently turning off the PH(3) stream during the formation of layer portion 16. The glass pattern is then covered with a photoresist, exposed, and the exposed portions removed with a suitable etchant. As shown in Fig. 2, the lower p...