Browse Prior Art Database

LOW ENCROACHMENT SELECTIVE PLANARIZATION PROCESS FOR TRENCH ISOLATION

IP.com Disclosure Number: IPCOM000009629D
Original Publication Date: 2000-Jan-01
Included in the Prior Art Database: 2002-Sep-05
Document File: 2 page(s) / 110K

Publishing Venue

Motorola

Related People

Anda McAfee: AUTHOR [+2]

Abstract

Deep trench isolation on submicron BiCMOS process results in oxide encroachment and defectivi- ty issues related to surface topography. Poor surface topography in trenches following cap oxidation causes a yield degrading stringer problems. Oxide encroachment limits cap oxide thickness forcing the use of an additional masking step to protect the cap oxide during stringer removal. Resulting integration is marginal. A new approach with deep trench side- wall nitride and high pressure argon sputter etch to smooth surface topography results in a low encroachment selective planarization process that alleviates both of these issues.

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0 M MOldRoLA Technical Developments

LOW ENCROACHMENT SELECTIVE PLANARIZATION PROCESS FOR TRENCH ISOLATION

by Anda McAfee and Gordy Grivna

ABSTRACT

  Deep trench isolation on submicron BiCMOS process results in oxide encroachment and defectivi- ty issues related to surface topography. Poor surface topography in trenches following cap oxidation causes a yield degrading stringer problems. Oxide encroachment limits cap oxide thickness forcing the use of an additional masking step to protect the cap oxide during stringer removal. Resulting integration is marginal. A new approach with deep trench side- wall nitride and high pressure argon sputter etch to smooth surface topography results in a low encroachment selective planarization process that alleviates both of these issues.

PROBLEM

  In order to minimize stress from deep trench isolation, the deep trench structures are typically formed after field oxide growth. A deep trench etch, liner oxidation, channel stop implant, polysilicon till and trench polysilicon oxidation complete the struc- ture.

  The trench polysilicon oxidation step serves the purpose of isolating the trench polysilicon and the lens shaped oxide growth brings the surface oxide

up to the level of the adjacent field oxidation. However, excess surface topography is created at the trench edges that can act as stringer traps and sources of contamination. Additionally, in submi- cron applications where the trench is very close to the emitter and collector regions' catastrophic enhancement of lat...