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Process Scheme to Make Shallow Trench Isolation without Chemical Mechanical Polishing

IP.com Disclosure Number: IPCOM000109566D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 3 page(s) / 107K

Publishing Venue

IBM

Related People

Rajeevakumar, TV: AUTHOR

Abstract

A selective oxide deposition method that allows oxide to grow on the surface of oxide surface may be used (1,2) to form self-planarized STI, without using any Chemical Mechanical Polishing or the additional resist planarization mask. Proposed process flow

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Process Scheme to Make Shallow Trench Isolation without Chemical Mechanical Polishing

       A selective oxide deposition method that allows oxide to
grow on the surface of oxide surface may be used (1,2) to form
self-planarized STI, without using any Chemical Mechanical Polishing
or the additional resist planarization mask.
Proposed process flow

      The proposed process flow is described below.
1.   First, a 10 nm thick pad oxide is formed followed by 200 nm
Si3N4 deposition.  After  exposure of the photoresist (Fig. 1) the
Shallow Trench is etched into the silicon, as shown in Fig. 2.
2.   The photoresist is then stripped off, and the exposed silicon
surface is then oxidized, as shown in Fig. 3.
3.   Now the wafer is immersed in a solution of hydroflurosilicic
acid (H2SiF6) solution saturated with silica (SiO2).  Continuous
addition of boric acid (H3BO3) causes oxide deposition at the oxide
surface at room temperature (2).  The rate of addition of boric acid
and SiO2 concentration may be adjusted to prevent the formation of
any oxide residue on nitride surface.  The oxide deposition time is
now adjusted so that the shallow trench is now completely filled with
oxide (Fig. 4).
4.   The Si3N4 layer is now removed using phosphoric acid etch, as
shown in Fig. 5.  Any oxide residue formed on the nitride layer also
gets lifted off with the nitride.

      References
(1)  T. Homma, T. Kato, Y. Yamada, J. Shimizu and Y. Murao, "A new
interlayer forma...