Semiconductor device manufacturing: process – Chemical etching – Liquid phase etching
Reexamination Certificate
1996-12-27
2001-07-17
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Liquid phase etching
C438S753000, C438S756000, C252S079100, C252S079200, C252S079300, C252S079400
Reexamination Certificate
active
06261969
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for manufacturing a semiconductor apparatus, and more particularly to a method of separating a semiconductor film and a substrate from each other.
2. Related Art
FIG. 10
shows a conventional method of manufacturing a semiconductor apparatus, and in particular, a method of separating a semiconductor film and a substrate from each other. The method has been disclosed in Japanese Patent Application No. 6-162452. Referring to
FIG. 10
, reference numeral
100
represents a semiconductor film,
120
represents a separation layer,
140
represents a substrate, and
110
represents a through hole reaching to the separation layer
120
. Reference numeral
130
represents etchant and
130
B represents water.
A method of separating the semiconductor film and the substrate from each other will now be described. The substrate
140
is made of silicon and formed into, for example, a single crystal silicon wafer. The thickness of the single crystal silicon wafer is usually 625 &mgr;m in a case where the diameter of the wafer is 6 inches. A separation layer is provided which is made of a silicon oxide film formed by, for example, oxidizing the substrate
140
with heat or a silicon oxide film deposited by CVD or the like. The thickness of the separation layer is, for example, 1 &mgr;m. The semiconductor film
100
is a polycrystal silicon film deposited on the separation layer by the CVD or the like. The semiconductor film
100
may be a semiconductor film having an improved electric characteristic by enlarging the crystal particle size by zone melting recrystallization or by solid phase epitaxy.
As shown in
FIG. 10A
, a semiconductor apparatus having the foregoing structure is, initially, immersed in, for example, hydrofluoric acid etchant
130
A to introduce the hydrofluoric acid etchant
130
A through the through holes
110
so as to remove the separation layer
120
by etching. Then, the semiconductor apparatus is washed with water, and then the space between the semiconductor film
100
and the substrate
140
is replaced with water
130
B, as shown in FIG.
10
B. In this state, water
130
B acts like an adhesive agent between the semiconductor film
100
and the substrate
140
to prevent easy separation of the semiconductor film
100
from the substrate
140
. If water
130
B between the semiconductor film
100
and the substrate
140
is removed by allowing the semiconductor apparatus to stand or by drying the same with heat, the bonding state established between the semiconductor film
100
and the substrate
140
prevents natural separation of the semiconductor film
100
.
Accordingly, when horizontal force is applied to the semiconductor film
100
along the surface of the substrate
140
as indicated by an arrow shown in
FIG. 10B
in a state as shown in
FIG. 10B
where the substrate
140
is fixedly held, water
130
B between the semiconductor film
100
and the substrate
140
serves as a lubricant which permits the semiconductor film
100
to slide on the substrate
140
. As described above, the semiconductor film
100
is drawn out from the position above the substrate
140
so that the semiconductor film
100
is separated from the substrate
140
(see FIG.
10
C). The above-mentioned method permits the semiconductor film
100
to be divided into sections each having a thickness of 10 &mgr;m and a size of 10 cm×10 cm.
FIG. 11
is a structural view showing a conventional manufacturing apparatus for embodying the method of manufacturing the semiconductor apparatus. Similarly to the foregoing method, the apparatus has been disclosed in Japanese Patent Application No. 6-162452. Referring to
FIG. 11
, reference numeral
100
represents a semiconductor film,
110
represents a through hole,
140
represents a substrate,
210
represents a first container and
211
represents an upper portion of the first container
210
. Reference numeral
212
represents a taper of the first container
210
. Reference numeral
213
represents a lower portion of the first container
210
. Reference numeral
300
represents an upper room,
310
represents a lower room,
400
represents a second container and
410
represents a cover for sealing up the second container
400
.
In a case where the semiconductor film
100
is larger than the substrate
140
as shown in
FIG. 11
, the width of the lower room
310
is made to be smaller than the width of the upper room
300
so that introduction of the semiconductor film
100
is permitted and that of the substrate
140
is inhibited. Since force for fixing the semiconductor film
100
to the substrate
140
is lost after the separation layer has been removed by etching, the semiconductor film
100
is, attributable to the gravity, moved along the surface of the substrate
140
toward the lower room
310
. Since the substrate
140
has a size with which the movement of the substrate
140
into the lower room
310
is inhibited, only the semiconductor film
100
is moved into the lower room
310
. As a result, the separation of the semiconductor film
100
from the substrate
140
can be performed.
Since the conventional method and apparatus for manufacturing a semiconductor apparatus have been structured as described above, completion of the process for etching the separation layer does not result in the semiconductor film and the substrate being completely separated from each other. Since the semiconductor film and the substrate are, in many cases, in close contact with each other, an external force has been required to be applied to completely separate the semiconductor film and the substrate from each other. There arises another problem in that time required to complete the process cannot be shortened and the surface of the semiconductor film is roughened excessively because the semiconductor film is immersed in the etchant for a long time. Since the conventional manufacturing apparatus is not provided with a function for again liquefying vapor of the hydrofluoric acid etchant, there arise problems in that the life of the etchant is unsatisfactorily short and that an excessively large quantity of the etchant is required.
As a result, the cost performance has been unsatisfactory in a case where the semiconductor film and the substrate are separated from each other in the mass production level.
SUMMARY OF THE INVENTION
In view of the foregoing, a first object of the present invention is to provide a method and an apparatus for manufacturing a semiconductor apparatus capable of smoothly separating a semiconductor film and a substrate from each other.
Further, a second object of the present invention is to provide a method and an apparatus for shortening time required to complete the process.
Furthermore, a third object of the present invention is to provide a method and an apparatus for reducing consumption of etchant and thus exhibiting excellent cost performance.
According to one aspect of the present invention, there is provided a method of manufacturing a semiconductor apparatus having a process in which etchant is introduced into through holes formed in a semiconductor film formed on a substrate through a separation layer to remove the separation layer by etching so as to separate the substrate and the semiconductor film from each other, the method of manufacturing a semiconductor apparatus comprising the step of: etching the separation layer by using etchant to which an additive for improving an etching rate is added.
The separation layer may be made of a silicon oxide film. The semiconductor film may be made of silicon.
The concentration of p-type impurity contained in the substrate may be 1E17 cm
−3
or lower.
The surface of the semiconductor film separated from the substrate may be etched by 0.1 &mgr;m to 4.0 &mgr;m.
Hydrofluoric acid solution may be employed as the etchant for etching the separation layer. Ammonium fluoride may be employed as the additive.
Another additive which reacts with the etchant and forms bubb
Matsuno Yoshinori
Morikawa Hiroaki
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Umez-Eronini Lynette T.
Utech Benjamin L.
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