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Tapered Well Insulation Process

IP.com Disclosure Number: IPCOM000119546D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Harmon, D: AUTHOR [+2]

Abstract

Electron cyclotron resonance (ECR) oxidation is used to oxidize walls of a trench in silicon (Si). The oxide layer thickness may be varied by nearly an order of magnitude from thinnest near the bottom to thickest near the top of the trench. The process is found to be especially useful as a replacement for multiple process steps to form a thin insulator in the lower part of a trench and a thick "collar" insulator at the top.

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Tapered Well Insulation Process

      Electron cyclotron resonance (ECR) oxidation is used to oxidize
walls of a trench in silicon (Si).  The oxide layer thickness may be
varied by nearly an order of magnitude from thinnest near the bottom
to thickest near the top of the trench.  The process is found to be
especially useful as a replacement for multiple process steps to form
a thin insulator in the lower part of a trench and a thick "collar"
insulator at the top.

      With oxygen pressure in the one milli-torr range, substrate
temperature near 350 degrees centigrade, and other conditions, e.g.,
magnet current of the system, to create an ECR condition at the
source midplane, oxide is formed on sidewalls and bottom of a deep
trench in silicon.  With these conditions, an oxide is formed which
increases in thickness from bottom to top of a 0.4 micron wide by 8.0
micron deep trench by approximately an order of magnitude. The
thickness increase is quite gradual in the lower two thirds of the
trench depth and more rapid in the upper third of the trench.  Thus,
additional processing to form thick collar insulation at the top of a
trench becomes unnecessary.

      Additional insulator film layers, e.g., nitride plus more
oxide, may be deposited by standard processing.

      Anonymous.