Browse Prior Art Database

Complementary Subcollector Process with Self Aligned Trench Iso Isolation

IP.com Disclosure Number: IPCOM000107290D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Galli, CA: AUTHOR [+4]

Abstract

Disclosed is a new method for the formation of N+/P+ subcollectors employing solid-state diffusion sources and a self-aligned trench isolation.

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This is the abbreviated version, containing approximately 58% of the total text.

Complementary Subcollector Process with Self Aligned Trench Iso Isolation

       Disclosed is a new method for the formation of N+/P+
subcollectors employing solid-state diffusion sources and a
self-aligned trench isolation.

      Existing methods for forming complementary subcollectors and
subsequent isolation between them generally requires several mask
alignments.  This leads to increased device spacing due to overlay
tolerances. Furthermore, non-self-aligned methods must allow for
spacing between the N+ and P+ regions to prevent overlap.  Finally,
most methods use ion implantation for buried layer formation which is
known to cause defects in the silicon substrate. The process
described below avoids these problems while providing a reduced
ground rule structure.

      A nitride/oxide layer is first formed and patterned in the
areas where trench isolation is desired.  The thin (15 nm) oxide 1
provides the buffer for the 50 nm nitride 2 during oxidation (Fig.
1).  A non- critical block-out mask is used where the subcollectors
of the first dopant type (e.g., arsenic) would be formed.  After
removal of the oxide 1 in the open areas of resist, a solid source
arsenosilicate or phosphosilicate glass 3 is deposited and the dopant
is diffused into the silicon with a thermal anneal to form doped
region 4.  The resultant structure is shown in Fig. 2.

      After removal of the glass 3, an oxide layer 5 is grown on the
exposed silicon.  A second block-out...