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Polymer Residue Removal Method in Poly Si Gate Self Alignment Process

IP.com Disclosure Number: IPCOM000111022D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Imai, A: AUTHOR [+2]

Abstract

Disclosed is a process for removing polymer residue on ploy Si gate sidewall spacers with the use of UV assisted ozone whereby short between the poly Si gate and diffused regions is prevented in self alignment process (especially Ti silicide process).

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Polymer Residue Removal Method in Poly Si Gate Self Alignment Process

      Disclosed is a process for removing polymer residue on ploy Si
gate sidewall spacers with the use of UV assisted ozone whereby short
between the poly Si gate and diffused regions is prevented in self
alignment process (especially Ti silicide process).

      The Figure shows the process flow of the present self alignment
process.  As is conventional in the art, poly Si gate sidewall
spacers are formed by dry etching a conformal sidewall film deposited
over the poly si gate structure.  It has been found that the dry
etching produces a polymer film on the sidewall spacers which is hard
to remove and remains as polymr residue.  The polyer residue acts to
adsorb or hold Ti on the sidewall spacers in the subsequent Ti
silicide process.  That is, in the final step, a Ti layer is
deposited over the poly Si gate and silicided to form a TiSix layer
on the poly Si gate.  Ti on the sidewall spacers not silicided is
etched away.  However, with the polymer residue existing on the
sidewall spacers, Ti cannot be removed completely from the sidewall
spacers because of adsorpton or holding by the polymer, resulting in
short or leakage between the poly Si gate and diffused regions.

      The problem can be solved by inserting, after the poly Si dry
etching, a step of UV (Ultra Violet) assisted ozone treatment to
remove such polymer residue.

      O radical generated by UV assisted ozone reacts...