Browse Prior Art Database

Combined Nitride/Polyimide Mask Process

IP.com Disclosure Number: IPCOM000039309D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Boettiger, U: AUTHOR [+3]

Abstract

In the CMOS process, the first metal layer 2, deposited on semiconductor substrate 1, is separated from the second metal layer 3 by a nitride layer 4 and a polyimide layer 5. The first and the second metal layers are conductively connected through via holes 6 in the nitride and polyimide layers. For that purpose, via holes 6 are photolithographically opened in nitride layer 4 after its deposition. Then, polyimide layer 5 is deposited, baked and provided with via holes. To prevent the first metal layer 2, which is unprotected after the opening of the nitride via holes, from being corroded in the subsequent process steps, in particular in the bake step of polyimide layer 5, the process described below is used. As shown in Fig.

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Combined Nitride/Polyimide Mask Process

In the CMOS process, the first metal layer 2, deposited on semiconductor substrate 1, is separated from the second metal layer 3 by a nitride layer 4 and a polyimide layer 5. The first and the second metal layers are conductively connected through via holes 6 in the nitride and polyimide layers. For that purpose, via holes 6 are photolithographically opened in nitride layer 4 after its deposition. Then, polyimide layer 5 is deposited, baked and provided with via holes. To prevent the first metal layer 2, which is unprotected after the opening of the nitride via holes, from being corroded in the subsequent process steps, in particular in the bake step of polyimide layer 5, the process described below is used. As shown in Fig. 1, nitride layer 4 is initially etched only down to a depth of about 80%, so that there is a sufficiently thick protective nitride layer 4' overlying the first metal layer 2. After resist strip, polyimide layer 5 is deposited and baked, and via holes are opened therein. As shown in Fig. 2, the protective nitride layer 4' in the region of the via holes is etched, using polyimide layer 5 as a mask, and the second metal layer 3 is deposited.

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