Semiconductor wafer and production method therefor

Semiconductor device manufacturing: process – Formation of semiconductive active region on any substrate – Fluid growth from gaseous state combined with preceding...

Reexamination Certificate

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C438S508000, C117S084000, C117S086000, C117S093000

Reexamination Certificate

active

06746941

ABSTRACT:

TECHNICAL FIELD
This invention relates to a semiconductor wafer and a production method therefor and particularly, a semiconductor wafer obtained by forming a semiconductor thin film having a uniform resistivity distribution on a main surface of a large diameter semiconductor substrate and a production method therefor.
BACKGROUND ART
In company with recent miniaturization of an electronic device, not only has the use of semiconductor wafers each obtained by forming a silicon single crystal thin film on a main surface of a silicon single crystal substrate increased, but a more uniform resistivity distribution of the silicon single crystal thin film has also been required. The term uniform resistivity distributions used here, to be detailed, means that a resistivity distribution across the surface of the silicon single crystal thin film is uniform. Further, a larger diameter has also been demanded on a semiconductor wafer together with the uniform resistivity distribution. A horizontal, single wafer vapor phase growth apparatus has been mainly employed as an apparatus for growing a silicon single crystal thin film on a main surface of a silicon single crystal substrate keeping pace with use of a large diameter semiconductor wafer.
Description will be below given of a horizontal, single wafer vapor phase growth apparatus generally employed with reference to
FIGS. 5 and 6
, wherein
FIG. 5
is a sectional view in a horizontal plane showing a conventional horizontal, single wafer vapor phase growth apparatus in a simplified manner and
FIG. 6
is a vertical sectional view showing the apparatus in a simplified manner. As shown in
FIGS. 5 and 6
, in a conventional horizontal, single wafer vapor phase growth apparatus, a susceptor
14
on which a silicon single crystal substrate
12
is horizontally placed is disposed at the bottom of the middle portion of a transparent quartz glass reaction chamber
10
installed along a horizontal direction and the susceptor
14
is coupled with a rotation unit (not shown) through a rotary shaft
16
.
Further, a gas inlet port
18
is provided atone end in a length direction of the reaction chamber
10
and a gas outlet port
20
is provided at the other end thereof. With this construction, a flow of a gas which is introduced through the gas inlet port
18
into the reaction chamber
10
and discharged through the gas outlet port
20
to the outside passes over a main surface of the silicon single crystal substrate
12
placed on the susceptor
14
almost along a length direction of the reaction chamber
10
. Further, the gas inlet port
18
of the reaction chamber
10
is constructed of six inlet ports
18
a
to
18
f
spread in a width direction of the reaction chamber
10
. Among the six inlet ports
18
a
to
18
f
, a pair of two inlet ports at the innermost side (hereinafter simply referred to as inner inlet ports)
18
a
and
18
b
are arranged in symmetry with respect to an imaginary central axis along a length direction of the reaction chamber
10
, passing through the center of the main surface of the silicon single crystal substrate
12
on the susceptor
14
, and this arrangement of the inner inlet ports
18
a
and
18
b
applies to not only a pair of two inlet ports at the outermost side (hereinafter simply referred to as outer inlet ports)
18
e
and
18
f
, but also a pair of two inlet ports each between one of the two inner inlet ports and the corresponding one of the two outer inlet ports (hereinafter simply referred to as middle inlet ports) in the same way.
To be more detailed, the inner inlet ports
18
a
and
18
b
are directed toward points in the vicinity of the center of the main surface of the silicon single crystal substrate
12
on an imaginary central axis along a width direction of the reaction chamber
10
, passing through the center of the main surface of the silicon single crystal substrate
12
on the susceptor
14
, and the outer inlet ports
18
e
and
18
f
are directed toward points in the vicinity of the outer periphery of the main surface of the silicon single crystal substrate
12
on the imaginary central axis line and the middle inlet ports
18
c
and
18
d
are directed toward points between the central portion and the outer peripheral portion of the main surface of the silicon single crystal substrate
12
on the imaginary central axis line.
Further, the six inlet ports
18
a
to
18
f
are all connected to a common gas pipe
22
. The common gas pipe
22
are branched in three ways and the branches are connected to a gas source (not shown) of hydrogen (H
2
) gas as a carrier gas, a gas source (not shown) of a semiconductor raw material gas and a gas source (not shown) of a dopant gas through mass flow controllers MFC
24
,
26
and
28
, respectively, as gas flow rate regulators.
Further, outside of the reaction chamber
10
, an infrared radiation lamp
30
, for example, as a heat source heating the silicon single crystal substrate
12
placed on the susceptor
14
is disposed and by supplying a power to the infrared radiation lamp
30
, the main surface of the silicon single crystal substrate
12
is heated to a predetermined temperature. In addition, cooling means (not shown) for cooling the infrared radiation lamp
30
and an outer wall of the reaction chamber
10
is equipped.
Then, description will be made of a method for forming a silicon single crystal thin film on the main surface of the silicon single crystal substrate
12
using the conventional horizontal, single wafer vapor growth apparatus shown in
FIGS. 5 and 6
.
First, the silicon single crystal substrate
12
is horizontally placed on the susceptor
14
of the reaction chamber
10
. Following this, H
2
gas is supplied into the reaction chamber
10
from the gas source of H
2
gas through MFC
24
, the common gas pipe
22
and through the six inlet ports
18
a
to
18
f
to replace the atmosphere in the reaction chamber
10
with hydrogen. Further, with the rotation device, the susceptor
14
is rotated through the rotary shaft
16
clockwise as shown by arrow marks of
FIGS. 5 and 6
while the silicon single crystal substrate
12
is horizontally placed on the susceptor
14
. Then, with the infrared radiation lamp
30
, the silicon single crystal substrate
12
on the susceptor
14
is heated to raise a temperature of the main surface thereof to a predetermined one.
After doing so, the semiconductor raw material gas and the dopant gas are supplied into the reaction chamber
10
from the respective gas sources of the semiconductor raw material gas and the dopant gas through MFC
26
and
28
, the common gas pipe
22
and the six inlet ports
18
a
to
18
f.
At this time, not only are flow rates of H
2
gas as a carrier gas, the semiconductor raw material gas and the dopant gas controlled individually and precisely by MFC
24
,
26
and
28
, respectively, but the gases are mixed after the individual control and introduced into the reaction chamber
10
as a process gas having the raw material gas and the dopant gas of respective constant concentrations with almost no diffusion in a width direction through the six inlet ports
18
a
to
18
f
disposed in a width direction of the reaction chamber
10
.
The process gas introduced into the reaction chamber
10
passes over the main surface of the silicon single crystal substrate
12
placed horizontally on the susceptor
14
rotating about the rotary shaft
16
as a center in one direction and in almost parallel to the main surface. During the passage over the main surface, a chemical reaction arises to grow the silicon single crystal thin film
32
in vapor phase on the main surface of the silicon single crystal substrate
12
.
In a case where a silicon single crystal thin film
32
was formed on the main surface of the silicon single crystal substrate
12
using the conventional horizontal, single wafer vapor phase growth apparatus shown in
FIGS. 5 and 6
as described above, and when the diameter of a silicon single crystal substrate
12
was 200 mm or less, a resistivity distribution al

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