Browse Prior Art Database

Smoothening of Sacrificial Si in BESOI Wafers

IP.com Disclosure Number: IPCOM000104710D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Iyer, SS: AUTHOR [+2]

Abstract

The bonded etch-back (BE) silicon-on-insulator (SOI) method can create roughness of >= 100angstrom on the surface of the sacrificial Si. The smoothening of the surface can be achieved by a high temperature (1200 - 1350ºC) annealing/oxidation treatment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 87% of the total text.

Smoothening of Sacrificial Si in BESOI Wafers

      The  bonded etch-back (BE) silicon-on-insulator (SOI) method
can create roughness of >=  100angstrom on the surface of the
sacrificial  Si.  The smoothening of the surface can be achieved by a
high temperature (1200 - 1350ºC) annealing/oxidation treatment.

      The figure illustrates schematically  the conventional BESOI
process.  Due to etching steps of (d) and (e) in the figure,
roughening of the superficial Si occurs.  Surface undulations of
>=  100angstrom are typically present on the surface of the Si
after the etching.  For high speed CMOS applications, extremely thin
Si layers (<=  700angstrom) with thickness uniformity of
<=  30angstrom are required.

      This invention utilizes a high temperature annealing/oxidation
treatment of the BESOI structure after step (e) of the figure so that
severity of the undulations is minimized.  The smoothening of
undulated SOI surfaces in SIMOX  has already been demonstrated after
a 1320ºC/5hr treatment in Ar + 0.5 % O&sub2.  [1,2].  It is
proposed that a heat treatment similar to that used for SIMOX in Fig.
2 be used on etched back SOI wafers to achieve smoothening of the
sacrificial Si surface in BESOI wafers.

      The process can be easily implemented for a product line as it
requires only a heat treatment.  However, a special high temperature
furnace will be required.

      The process would be quite beneficial for the fabrication of...