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Seamless Polysilicon Formation in the Field Regions of Isolated Device Regions

IP.com Disclosure Number: IPCOM000105120D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 82K

Publishing Venue

IBM

Related People

Burghartz, JN: AUTHOR [+2]

Abstract

The quality of epitaxially grown silicon films depends largely on the preclean conditions prior to epitaxy. The optimum conditions are given if a wafer pulls hydrophobic out of the final water rinse so that it can be loaded without an extra drying step into the epitaxy reactor. Device isolation, however, leads to wafers which are to a high fraction covered with silicon oxide or nitride so that the wafer pulls hydrophillic. Therefore, device isolation combined with a sacrificial polysilicon film covering the field-oxide is very desirable if the transition from the poly layer to the single-crystalline device region can be configured seamless.

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Seamless Polysilicon Formation in the Field Regions of Isolated Device Regions

      The  quality  of  epitaxially  grown  silicon  films depends
largely on the preclean conditions  prior  to  epitaxy.  The optimum
conditions  are  given if a wafer pulls hydrophobic out of the final
water  rinse  so  that  it  can  be  loaded without  an  extra
drying  step  into  the epitaxy reactor.  Device isolation, however,
leads to wafers which  are  to  a high  fraction covered with silicon
oxide or nitride so that the wafer pulls hydrophillic.  Therefore,
device  isolation combined  with  a  sacrificial polysilicon film
covering the field-oxide is very desirable if  the  transition  from
the poly  layer  to  the single-crystalline device region can be
configured seamless.

      A  structure  which   provides   seamless   polysilicon
formation  in  the field-oxide regions is disclosed here and is shown
in Fig. 1.  A stack of one or more dielectric  films (Fig. 1a, 1,2,4)
and  polysilicon (Fig. 1a, 2) is deposited.  Next, the top dielectric
films  (3,4)  and  the  polysilicon film  (2)  are  patterned.
Within  this window a narrower opening is etched into the bottom
dielectric film  (1)  down to  the  silicon  substrate.  This
opening  is  epitaxially refilled (5) by using a selective epitaxy
process  (Fig. 1b).  During the selective epitaxy poly nucelation (6)
takes place at  the  exposed  poly  side...