Electric heating – Heating devices – With power supply and voltage or current regulation or...
Reexamination Certificate
2000-10-10
2003-06-17
Paschall, Mark (Department: 3742)
Electric heating
Heating devices
With power supply and voltage or current regulation or...
C219S483000, C219S501000, C219S508000, C219S497000, C392S416000
Reexamination Certificate
active
06580059
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a control apparatus for a light radiation-type rapid heating and processing device for rapidly heating a processed workpiece such as a semiconductor wafer by radiating light including infrared rays to perform processing such as a film formation, dispersion and annealing or the like.
2. Description of the Related Art
In recent years, a high integration and a fine formation of a semiconductor integrated circuit have been required more and more, and a stage for implanting impurities into the Si crystal of a semiconductor wafer through an ion implantation process, for example, has required the formation of a thin dispersed layer of the impurities and the necessity of forming a more shallow junction plane has increased.
In the case of dispersing impurities through an ion implantation process, an implantation stage for accelerating the ionized impurities through an electric field and implanting them into the Si crystal as well as an annealing stage for dispersing the impurities in the crystal while recovering damages applied to the crystal through the implantation process are carried out. A rapid thermal processing (RTP) is necessary for forming a shallow dispersion layer. It is further necessary to rapidly increase the temperature while the surface temperature of the semiconductor wafer is being kept uniform. If the film thickness of the dispersion layer has to be about 0.13 to 0.15 &mgr;&mgr;m, it becomes necessary to attain a temperature increasing speed of about 150 to 200° C./sec.
A light radiation-type rapid heating and processing device for radiating light including infrared rays which radiates light from filament lamps for heating a workpiece such as a semiconductor wafer and the like is preferable for the aforesaid rapid thermal processing (RTP), and it is possible to increase the temperature of the heated substrate up to a temperature of 1000° C. or more within several seconds.
FIG. 17
is a view showing a sectional configuration of a light radiation-type rapid heating and processing device (hereinafter abbreviated as a heating and processing device).
A plurality of filament lamps
1
(hereinafter abbreviated as lamps) are arranged in a lamp chamber
2
, and a mirror
3
is arranged at the rear surfaces of the lamps
1
. A workpiece carrier
5
is installed within a processing chamber
4
, and a workpiece to be heated and processed, such as a semiconductor wafer or the like, (hereinafter called a workpiece W) is mounted on the workpiece carrier
5
. In addition, the lamp chamber
2
and the processing chamber
4
may be separated by a window
6
such as a crystal window or the like.
FIG. 18
shows a possible configuration of the lamp
1
. The lamp
1
is comprised of a circular light emitting tube
1
a
and a pair of feeding tubes
1
b
extending in a substantially right angle from end parts of the light emitting tube
1
a
. A coil-like filament
1
c
is arranged within the light emitting tube
1
a
. An end part of the feeding tube
1
b
is provided with a seal part
1
d
, and a lead wire
1
e
is connected to an end portion of the filament
1
c
through a molybdenum foil
1
f
as shown in FIG.
18
.
In
FIG. 17
, circular lamps
1
as shown in
FIG. 18
are arranged in a concentric manner, for example, and the aforesaid plurality of lamps
1
are lit to cause light including infrared rays radiated from the lamps
1
to be emitted through the crystal window
6
onto the workpiece W installed in the processing chamber. With such an arrangement as above, the workpiece W is rapidly heated and in turn the lamps
1
are turned off to cause the workpiece W to be rapidly cooled.
A control apparatus (not shown) may control the amount of electrical power supplied to each of the lamps
1
in such a manner that the entire workpiece W is uniformly heated, and, for example, the workpiece W is heated to a temperature of 1000° C. or more within several seconds.
FIGS. 19 and 20
show an example of the prior art configuration of the control apparatus for controlling the aforesaid lamps.
FIG. 19
shows an entire configuration, and
FIG. 20
shows a more detailed configuration of the controlling apparatus for controlling each of the lamps.
In
FIGS. 19 and 20
, reference number
100
denotes a control section constituted by a CPU and the like;
101
is a temperature adjusting device (hereinafter called a temperature adjuster);
102
a thyristor unit;
1
is a lamp and
103
a temperature sensor. As shown in these figures, each of the temperature adjusters
101
, thyristor units
102
and temperature sensors
103
is arranged in correspondence with a lamp
1
(or in correspondence with an assembly of lamps). The temperature sensor
103
detects the temperature of the workpiece W to be heated through the light radiated from each of the lamps
1
. The temperature detected by the temperature sensor
103
is fed back to the temperature adjuster
101
which feeds the temperature set value (either an analog signal or a digital signal) sent from the control section
100
and the control signal (an analog signal) corresponding to a deviation of the temperature detected by the temperature sensor
103
to the thyristor unit
102
.
Each of voltage and current supplied to the lamp
1
is fed back to the thyristor unit
102
. The thyristor unit
102
controls the electrical power supplied to the lamp
1
dependent on the aforesaid control signal.
The thyristor unit
102
may have the configuration shown in
FIG. 21
where the electrical power supplied to the lamp
1
is controlled by changing the timing during which a gate current flows from SCR
2
.
As regards the electrical power control by the thyristor, it is possible to apply the following two methods, namely a conductive angle control and a zero-cross control.
(a) Conductive Angle Control
In
FIG. 21
, an alternating current is supplied to the thyristor unit
102
from an AC commercial power supply
21
. The thyristor unit
102
is provided with a lamp control circuit
200
comprised of a first thyristor SCR
1
and a second thyristor SCR
2
. When a gate current flows in gates G
1
, G
2
of the thyristors SCR
1
and SCR
2
of the lamp control circuit
200
, the thyristors SCR
1
and SCR
2
become conductive and a current is outputted from the thyristor unit
102
to the lamp
1
until the current supplied to the thyristors SCR
1
and SCR
2
becomes
0
.
FIG.
22
(
a
) shows an input voltage waveform of the thyristor unit
102
. FIG.
22
(
b
) shows an example of the timing of a gate current supplied to gates G
1
, G
2
of the thyristors SCR
1
, SCR
2
, wherein
1
indicates a gate current of the first thyristor SCR
1
, and
2
indicates a gate current of the second thyristor SCR
2
, respectively. FIG.
22
(
c
) indicates a waveform of an output current when a gate current is provided with the timing illustrated in FIG.
22
(
a
).
The output current from the thyristor unit
102
is a current with an output voltage waveform and an output current waveform as indicated by the hatched sections in FIG.
22
(
c
) being multiplied with each other. When the timing of the gate current applied to each of the thyristors SCR
1
, SCR
2
is changed the output current waveform and the output voltage waveform are changed resulting in that the output power of the thyristor unit, i.e., the lamp input power, are changed.
(b) Zero Cross Control
The control circuit configuration is the same as that shown in FIG.
21
. The timing of the gate current of each of SCR
1
and SCR
2
corresponds to that shown in FIG.
23
(
b
). In this case,
1
indicates the gate current of the first thyristor SCR
1
and
2
indicates the gate current of the second thyristor SCR
2
.
In
FIG. 23
, the output current and the output voltage when the gate current is supplied with the timing shown in FIG.
23
(
b
) correspond to that shown in FIG.
23
(
c
). That is, as indicated in FIG.
23
(
c
), it is possible to change the lamp input power by outputting a current and voltage with their waveforms being deleted.
Howev
Paschall Mark
Safran David S.
Ushiodenki Kabushiki Kaisha
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