Browse Prior Art Database

Germanium as a Chem-Mech Polish Etch Stop

IP.com Disclosure Number: IPCOM000107920D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Blouse, JJ: AUTHOR [+6]

Abstract

Described is the use of germanium as an etch stop in chem-mech polishing processes, such as SiO2 and LPCVD TEOS. One of the problems associated with all etch stops, however, is their removal after the polishing process. Consider, for example, the polysilicon trend planarization process. The most common method for planarizing polysilicon filled trenches is to use a CVD oxide as a polish stop. After planarization, the oxide is removed by a wet etchant. Problems which arise in the underlying oxide layers, such as trench liners, are also etched during the etch stop removal. A material that is easily removed after the planarization step in an etch which does not affect the underlying layers is therefore highly desirable.

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Germanium as a Chem-Mech Polish Etch Stop

      Described is the use of germanium as an etch stop in chem-mech
polishing processes, such as SiO2 and LPCVD TEOS. One of the problems
associated with all etch stops, however, is their removal after the
polishing process.  Consider, for example, the polysilicon trend
planarization process. The most common method for planarizing
polysilicon filled trenches is to use a CVD oxide as a polish stop.
After planarization, the oxide is removed by a wet etchant. Problems
which arise in the underlying oxide layers, such as trench liners,
are also etched during the etch stop removal. A material that is
easily removed after the planarization step in an etch which does not
affect the underlying layers is therefore highly desirable.  The use
of germanium as a chem-mech polish etch stop is extremely favorable
since the germanium can be removed with a wide variety of wet
etchants, including hydrogen peroxide, which does not etch oxides.
In addition, it has been shown that the germanium: polysilicon
removal rate is 1:15 in a standard polysilicon polishing slurry.
Germanium could therefore be directly substituted for CVD oxide as
the etch stop in a polysilicon trench process.

      Disclosed anonymously.