Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1998-12-30
2001-03-27
Paik, Sam (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C118S725000
Reexamination Certificate
active
06207932
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heater block for heating a wafer, and more particularly, to a heater block which provides a wafer, disposed in a process chamber for PVD (physical vapor deposition), with the proper temperature enviromnent in a thermal process by supplying the wafer with uniform heat.
2. Discussion of the Related Art
A process for fabricating a semiconductor device is accompanied with a plurality of steps requiring high temperature for effecting oxidation, deposition, diffusion and the like.
The heating means for these thermal processes are set up in the processing chamber where the PVD process, for example, is carried out. Thus, heat is transferred to a wafer by transforming electrical energy into thermal energy in the use of a heating device such as a hot-wire.
FIG. 1
shows a plan view of a heater block according to the prior art, and
FIG. 2
shows a cross-sectional view taken along line I-I′ of FIG.
1
.
As shown in FIG.
1
and
FIG. 2
, the heater block comprises a body
100
, a bellows
116
, a power supply
103
, a gas line
108
, a controller
101
for checking the temperature and a clamp ring
112
. The body
100
includes a heated element
106
wrapped with a hot wire
104
and a wafer support
102
for conveying the heat generated from the heated element
106
to the wafer support
102
, wherein the wafer support
102
is located on the upper part of the body
100
. The bellows
116
drives the body
100
in the upward and downward direction to position the body in a suitable location. The power supply
103
electrically connected to the hot-wire
104
selectively applies or cuts off electricity to the hot-wire
104
by turning the power on or off. The controller
101
monitors and controls the temperature of the wafer support
102
. The clamp ring
112
is utilized to fix the wafer
110
to the wafer support
102
.
The heater block according to a prior art is mounted on the lower part of the process chamber not shown in the drawings, and a gas supply pipe is installed at the upper part of the process chamber with an exhaust pipe being located at the lower part of the process chamber. Accordingly, while the processing gas is supplied to the inside of the processing chamber from the gas supply pipe, thermal processing such as deposition, diffusion and the like on the wafer heated by the heater block proceeds in accordance with the prior art. By-products from the process are exhausted through the exhaust pipe. The inside of the process chamber is constantly maintained at a pressure of 3 to 8 mTorr during the thermal process.
The procedure of heating the wafer with a heater block according to the prior art is a follows. To the heated element
106
is transferred the heat which is generated from the hot-wire
104
coruected to a power source when the power supply
103
is turned to the “on” position. The heated element
106
is made of a ceramic material and belongs to the body
100
under the wafer support
102
and is surrounded spirally by the hot-wire
104
.
The heat transmitted from the heated element
106
preheats the wafer support
102
controlled by the controller
101
for maintaining the proper temperature in the thermal process. Once the wafer support is preheated to the proper temperature, a wafer
110
is mounted on the wafer support
102
by a transporting means, such as a robot arm, etc. Then the wafer support
102
is moved to a suitable level by the bellows
116
connected to the body
100
.
Gas is supplied to the reverse face of the wafer
110
on which no device is being formed, wherein the gas line
108
is tunneled through the wafer support
102
and is connected to the discharge hole
118
formed in the wafer support
102
for carrying gas from the center to the ends of the wafer through the hole
118
. The gas supplied through the gas line
108
is identical to the process gas supplied from the gas supply pipe formed in the process chamber, thereby heating the reverse face of the wafer as well as the heated element
106
. This gas supply also contributes to the thermal process of diffusion, deposition, etc. on the wafer
110
together with the process gas which is supplied through the gas supply pipe. The gas supplied through the gas line
108
and the gas supply pipe is an inert gas, e.g., Ar. The gas introduced through the gas line
108
is maintained at a constant pressure as it contracts the reverse face of the wafer. The wafer
110
is fixed to the wafer support
102
by means of a clamp ring which clamps the top-side of the wafer to the support
102
, while the pressurized gas is supplied during the thermal process.
As only one controller for monitoring the temperature is installed for the heated clement for heating the wafer support of the prior art heater block, a temperature difference may occur due to the impossibility of controlling each section of the wafer support from the center to the extremities, particularly if the hot-wire wrapped along the heated clement becomes broken or is weakened in its function.
Accordingly, there is a problem that an uneven distribution of temperature along the wafer is caused during the thermal process by the inability of the controller to control the temperature difference throughout the entire wafer. Moreover, the device is contaminated at the contact area between the wafer and the clamp ring due to particles that attach to or are introduced by the clamp ring itself.
SUMMARY OF THE INVENTION
The present invention is directed to a heater block that substantially obviates one or more of the limitations and disadvantages of the related art. Accordingly, an object of the present invention is to provide a heater block which conducts heat uniformly within the wafer during a typical thermal process.
Another object of the present invention is to provide a heater block which minimizes particles which appear during a thermal process. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve these and other advantages and in accordance with the purposes of the present invention, as embodied and broadly described, a heater block for heating a wafer is provided which comprises a body and a wafer support disposed on said body, wherein a plurality of troughs are disposed in the surface of the wafer support, and a plurality of heated elements are positioned under the wafer support and in the body, said heated elements being wrapped with hot-wires so that the heat generated from each of the heated objects is conveyed to the wafer support. A gas line is connected to the wafer support so that the gas line can supply gas to the troughs. A power supply is electrically conlected to each of the hot-wires, and a controller for monitoring the temperature is connected to each of the heated elements, respectively, whereby the controllers control the temperature in each of the heated elements.
It is to be understood that both the foregoing description and the following detailed description are exemplary and explanatory and are intended to provide a further explanation of the present invention.
REFERENCES:
patent: 5059770 (1991-10-01), Mahawili
patent: 5294778 (1994-03-01), Carmen et al.
patent: 5854468 (1998-12-01), Muka
Hyundai Electronics Industries Co,. Ltd.
Paik Sam
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