Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1998-11-23
2001-01-09
Mills, Gregory (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C118S728000
Reexamination Certificate
active
06171437
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor manufacturing device for performing wet etching only on one main surface of a semiconductor substrate, particularly a semiconductor manufacturing device suitable for producing a cantilever used for a probe of a scanning probe microscope.
In a scanning probe microscope represented by an atomic force microscope (AFM), a cantilever in which an exploring needle is formed at a free end of a beam portion is used as a scanning probe. In the configuration, because attraction or repulsion based on interatomic force appears between a surface of a sample and the exploring needle by scanning the exploring needle on the surface of the sample, a shape of the surface of the sample can be measured by detecting the interatomic force as a deflection of the cantilever.
FIGS. 7A
to
7
D are sectional views showing a method of processing the conventional cantilever as a specimen. First as shown in FIG.
7
a
, layered substrate
3
is prepared, which is layered with a SiO
2
film
30
, a silicon thin film
31
acting as a beam portion of the cantilever and an exploring needle, a SiO
2
film
32
as an intermediate layer, a silicon substrate
33
acting as a supporting table of the cantilever, and a SiO
2
film
34
.
Next, a beam portion
31
a
of the cantilever and an exploring needle
31
b
are formed on a surface of the SiO
2
film
34
by etching SiO
2
film
30
into a proper shape so as to become a protecting film and by etching the silicon substrate
31
as the mask of the protecting film as shown in FIG.
7
B. Moreover, SiO
2
film
34
is properly etched so as to form a protecting film
34
a
, and surface <100> of the silicon substrate
33
is exposed.
Next, an end portion of layered substrate
3
is supported with a jig (etching holder)
50
sealed with an O-ring
51
for preventing inflow of liquid so that only the other main surface where said beam portion
31
a
and the exploring needle
31
b
of the layered substrate
3
is not formed is exposed by etching solution as shown in FIG.
7
C. SiO
2
film
32
exposes by etching the silicon substrate
33
as a mask of the protecting film
34
(
34
a
) using anisotropic wet-etching.
For the etching solution, a potassium hydroxide (KOH) aqueous solution of 40 percentage by weight at 60 to 80° C. a tetraalkylammonium hydroxide (TMAH) aqueous solution of 20 percentage by weight at 80 to 90° C., and so on can be used. With these etching solutions, plane <100> of the silicon substrate
33
is etched much faster than plane <111> so that the protecting film
34
a
is not actually etched. Therefore, anisotropic wet-etching actually stops at plane <111> referenced with the end of the protecting film
34
a
. At the end, the extra SiO
2
film
32
is removed as shown in FIG.
7
D. By the above-described process, a cantilever is completed which has an exploring needle
31
b
at one end of the beam portion
31
a
and the other portion thereof is supported by a cantilever-like supporting table
60
.
In the above-mentioned prior art, pressure increases corresponding to the depth of the etching solution at a processing plane of layered substrate
3
while pressure in the etching holder
50
is substantially at atmospheric pressure when the etching holder
50
holding the layered substrate
3
is sunk in the etching solution. Because of that, there has been problems that etching is performed unevenly and the substrate itself is broken by stress corresponding to a difference in pressure applied to both main surfaces.
When temperature of etching solution, gas in the etching holder
50
gradually expands thermally, and pressure applying to non-processing surface of the layered substrate
3
gradually increases. There has been a problem that stress toward reverse direction to the above-mentioned appears at the layered substrate
3
when pressure applied to the non-processing surface becomes higher than pressure applied to a processing surface corresponding to depth in the etching solution.
An object of the present invention is to provide a semiconductor manufacturing device substantially adjusting pressure applied to a non-processing surface to a processing surface of a semiconductor substrate in wet-etching in which the processing surface of the semiconductor substrate is exposed outside and the non-processing surface is sunk in etching solution so as to be sealed from outside preventing from inflow of the solution to solve the above-mentioned problem in the prior art.
SUMMARY OF THE INVENTION
To achieve the above-mentioned object, the present invention is characterized by providing a substrate holding member for holding the semiconductor substrate so that one main surface of the substrate exposes outside and the other main surface exposes in a space sealed to prevent inflow of liquid from outside, and a pressure control means for controlling pressure in said space so that similar pressure as pressure applied to the one main surface of said semiconductor substrate is applied to the other main surface in performing wet etching only on the one main surface of the semiconductor substrate.
According to the above-mentioned configuration, since similar pressure as pressure applied to one main surface is applied to the other main surface of the semiconductor substrate, stress caused by difference of pressure applying to each main surface does not appear at the semiconductor substrate.
REFERENCES:
patent: 5275690 (1994-01-01), Garwood, Jr.
patent: 5437757 (1995-08-01), Rice et al.
patent: 5542559 (1996-08-01), Kawakami et al.
patent: 5695566 (1997-12-01), Suzuki et al.
Inoue Akira
Shimizu Nobuhiro
Shirakawabe Yoshiharu
Adams & Wilks
Hassanzadeh Parviz
Mills Gregory
Seiko Instruments Inc.
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