Browse Prior Art Database

Process for Organic Fill of Deep Trench Structures

IP.com Disclosure Number: IPCOM000061445D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 94K

Publishing Venue

IBM

Related People

Cservak, NR: AUTHOR [+4]

Abstract

Disclosed is a change in the process sequence during polyimide fill of deep trenches for semiconductor devices which eliminates seams and/or voids between that organic fill material and trench sidewalls. The method involves reversing the sequence of curing the polyimide and reactive ion etching (RIE). Seams and/or voids between organic fill material and deep trench sidewalls may entrap contaminants. These may cause electrical leakage and insulator and metal defects due to outgassing in subsequent processing. In the previous process, an organic layer was applied, soft- baked at a moderate temperature, reflowed and baked at a higher temperature, followed by cross-linking of the polymer at >300ŒC. This was then followed by RIE using O2 plasma.

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Process for Organic Fill of Deep Trench Structures

Disclosed is a change in the process sequence during polyimide fill of deep trenches for semiconductor devices which eliminates seams and/or voids between that organic fill material and trench sidewalls. The method involves reversing the sequence of curing the polyimide and reactive ion etching (RIE). Seams and/or voids between organic fill material and deep trench sidewalls may entrap contaminants. These may cause electrical leakage and insulator and metal defects due to outgassing in subsequent processing. In the previous process, an organic layer was applied, soft- baked at a moderate temperature, reflowed and baked at a higher temperature, followed by cross-linking of the polymer at >300OEC. This was then followed by RIE using O2 plasma. In the sequence described, polyimide fill separated from Si3N4 trench sidewalls with the poor adhesion being evidenced by the negative wetting angle. This permitted voids to form that entrapped contaminants. Scanning electron microscopic (SEM) photographs (Figs. 1A-1D) indicate these conditions. The present method changes the process sequence by having the RIE etch occur immediately following the reflow bake. This is then followed by curing of the polymer as before. The result is an improved adhesion of the polyimide to the sidewall, reduced residue after O2 RIE and elimination of cracks and voids in the finished product. SEM photos of the polyimide-filled trench using the ne...