Semiconductor device manufacturing: process – Formation of electrically isolated lateral semiconductive... – Having air-gap dielectric
Reexamination Certificate
2000-04-07
2003-12-30
Everhart, Caridad (Department: 2825)
Semiconductor device manufacturing: process
Formation of electrically isolated lateral semiconductive...
Having air-gap dielectric
C438S700000, C438S456000
Reexamination Certificate
active
06670257
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for forming horizontal buried channels or cavities in wafers of monocrystalline semiconductor material.
BACKGROUND OF THE INVENTION
In many applications it is necessary to form cavities inside a monocrystalline silicon substrate, for example to obtain suspended masses of microactuators and/or sensors of various types, such as speed, acceleration and pressure sensors, or to isolate electronic components.
Buried cavities can be formed substantially in two ways. According to a first solution, shown in
FIG. 1
, two monocrystalline silicon wafers
1
, suitably excavated and presenting each a half-cavity, are bonded to one another, using an adhesive layer (for example silicon oxide
2
), so that the two half-cavities form a buried cavity
3
.
According to a second solution, shown in
FIG. 2
, a monocrystalline silicon wafer
1
, suitably excavated and comprising final cavities
4
, is bonded to a glass layer
5
(anodic bonding process).
These solutions are costly, have a high criticality and low productivity, and are not fully compatible with the usual technological steps of microelectronics processing. In addition, the buried cavities or channels can be arranged only on a single plane, represented by line
7
in
FIG. 3
, and it is not possible to form cavities or channels at different heights, as shown in FIG.
4
.
SUMMARY OF THE INVENTION
The embodiments of the present invention provide a method for overcoming the disadvantages of the known solutions.
According to an embodiment of the present invention, there are provided a method for forming buried cavities in wafers of monocrystalline semiconductor material, and a wafer of monocrystalline semiconductor material. The method includes forming a cavity in a substrate and growing an epitaxial layer on the substrate and in the cavity. In one embodiment, the walls of the cavity are coated with material inhibiting epitaxial growth.
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Barlocchi Gabriele
Villa Flavio
Everhart Caridad
Jorgenson Lisa K.
Lee Calvin
SEED IP LAw Group
STMicroelectronics S.r.l.
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