Appeal No. 2002-0677
Application 09/257,899
roughening the surface of the lower electrode of a capacitor,
thereby increasing the surface area of the lower electrode
(abstract). The disclosed roughening techniques include anodic
oxidation, wet etching and dry etching. See id. Hirota also
discloses that the inventors in that patent have proposed two
methods for making a lower capacitor electrode having a surface
of hemispherical grains (col. 2, line 58 - col. 3, line 27). In
the first method dense hemispherical silicon grains are formed
using low pressure chemical vapor deposition and are patterned
using dry etching (col. 2, line 58 - col. 3, line 7). In the
second method a smooth amorphous silicon layer is deposited on a
substrate, patterned using lithography and etching, and heated to
form a crystallized, rough surface (col. 3, lines 8-27).
The portion of Fazan relied upon by the examiner discloses a
lower capacitor electrode formed by depositing a polycrystalline
silicon-germanium alloy (SixGe1-x) coating on a conformal
polysilicon layer by rapid thermal chemical vapor deposition
using SiH2Cl2 and GeH4 as precursor gases and H2 as a carrier gas
under conditions that favor macroscopic islanding of the
deposited alloy crystals (col. 4, line 46 - col. 5, line 5).
3
Page: Previous 1 2 3 4 5 6 7 8 Next
Last modified: November 3, 2007