Heating – Processes of heating or heater operation – Including preparing or arranging work for heating
Reexamination Certificate
2001-03-05
2004-09-28
Wilson, Gregory (Department: 3749)
Heating
Processes of heating or heater operation
Including preparing or arranging work for heating
C219S390000, C118S725000
Reexamination Certificate
active
06796795
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for loading a substrate in a semiconductor manufacturing apparatus. More particularly, it relates to a method and apparatus for loading a substrate on a substrate-loading section so that a temperature difference between the substrate and the section becomes smaller in a vacuum-processing chamber.
2. Description of the Related Art
Conventionally, a sputtering apparatus for depositing a thin film on a substrate, a chemical vapor deposition (CVD) apparatus, an etching apparatus for etching a thin film deposited on a substrate using plasma and the like have been well-known. They are semiconductor manufacturing apparatuses for processing a substrate carried into a vacuum processing chamber. In these semiconductor manufacturing apparatuses, films are deposited or films are etched, so it is widely known that originally undesirable films or etching products from the substrate deposit on a processing table loading the substrate.
Next an example of the conventional CVD apparatus will be explained referring to FIG.
9
. This CVD apparatus is a cold-wall type vacuum processing apparatus heating only the substrate to be processed. In this CVD apparatus, the vacuum-processing chamber is comprised of a water-cooled chamber
11
. The vacuum-processing chamber is provided with a heat reflecting plate
12
and a processing table
13
housing a heating source. The vacuum-processing chamber is structured so that only the substrate to be processed is heated. The processing table
13
is a substrate holder with a top surface serving as a substrate-loading surface. The processing table
13
is provided with three lift pins
14
arranged in a vertically movable structure, for example. A lift pin drive mechanism
15
for raising and lowering the lift pins
14
and a controller
16
for controlling the operation of the lift pin drive mechanism
15
are provided with respect to the lift pins
14
. The lift pin drive mechanism
15
is comprised of a support
15
a
linked with the plurality of lift pins
14
, a movable member
15
b
supporting the support
15
a
, and a drive member
15
c
raising and lowering the movable member
15
b
. The support
15
a
is arranged passing through the bottom of the vacuum-processing chamber, so the support
15
a
is covered by a bellows
15
d
so as to maintain the vacuum seal of the vacuum-processing chamber and deal with the operation of raising and lowering the support
15
a
. A substrate
10
to be processed is carried into the vacuum-processing chamber by a transport robot (not shown) through a transport gate
17
and is first placed on the raised lift pins
15
. Next, the lift pins
14
are made to descend, whereby the substrate
10
is loaded on the substrate-loading surface of the processing table
13
. The processing table
13
houses a heater
18
and is heated to a fixed temperature of 600° C., for example. Illustration of the mechanism for supplying power to the heater
18
, and the control mechanism for measuring the temperature of the heater
18
using a thermocouple and controlling the amount of power supplied by the power supply mechanism are omitted. Note that the above vacuum-processing chamber is provided with turbo molecular pumps
19
and
20
, for example, at a side-wall and bottom for evacuating the inside thereof to a required vacuum state. The inside of the vacuum-processing chamber is divided into a top chamber positioned above the processing table
13
and a bottom chamber positioned below it. The turbo molecular pumps
19
and
20
are used to evacuate the top chamber and bottom chamber to the required pressure, respectively.
After the substrate
10
is loaded on the substrate-loading surface of the processing table
13
, a heat stabilization time of 180 seconds is waited for allowing the temperature of the substrate
10
to approach the temperature of the processing table
13
and stabilize, then a heat decomposing gas, Si
2
H
6
gas, is introduced from a gas nozzle
21
at a rate of 12 sccm, for example. Due to this, Si films are deposited on the heated substrate
10
. The temperature of the inside-walls of the vacuum-processing chamber is adjusted by water circulating in the water-cooled chamber
11
to become about the water temperature, so the Si
2
H
6
gas does not decompose at the walls and consequently no silicon films are deposited. On the other hand, since the processing table
13
is heated to 600° C. by the heater
18
, silicon films are deposited at this portion. The silicon films deposited on the processing table
13
increase in thickness along with the number of substrates
10
processed.
In the above conventional CVD apparatus, experience has shown that the silicon films increased in thickness along with the number of substrates processed are subject to heat stress produced by the heat expansion of the substrate and easily peel off from the deposited surface.
Referring to
FIG. 10
, the action of the peeling of the silicon films due to the heat expansion of the substrate will be explained. As explained above, the processing table
13
is heated to 600° C. by the heater
18
. As opposed to this, the substrate
10
carried into the vacuum-processing chamber by the transport robot and loaded on the processing table
13
is placed on the substrate-loading surface of the processing table at a relatively low temperature compared with the processing table
13
. A silicon film
22
is deposited on the processing table
13
and at the outer circumference of the substrate
10
. The substrate
10
in this state is heated by the heat from the processing table
13
and rises in temperature too close to the temperature of the processing table
13
.
Here, an explanation will be given of the case where the substrate
10
is at room temperature when loaded in the vacuum-processing chamber. The heat from the processing table
13
rapidly heats the substrate
10
loaded on the processing table
13
. When the substrate to be processed is a silicon substrate, and if it has a diameter of 200 mm and a thermal expansion coefficient of 4.1×10
−6
/° C., while being heated from room temperature 25° C. to 600° C., the substrate expands by exactly 200 (mm)×4.1×10
−6
(1/° C.)×(600-25) (° C.)=0.47 (mm). At this time, the substrate
10
slides on the substrate-loading surface of the processing table
13
, so force is applied to the silicon film
22
deposited on the processing table
13
and peeling is promoted.
The silicon film peeled off due to this action scatters over the substrate as foreign particle and causes originally undesirable defects in the substrate.
Therefore, to prevent this peeling, in the past, the practice had been to allow the temperature of the processing table
13
to sufficiently fall, load the substrate
10
, then allow sufficient time to heat it to a predetermined temperature.
With this method, however, a large amount of time was required until the substrate
10
reaches the predetermined temperature and therefore the productivity was remarkably reduced.
The above-mentioned problem also arises in a case that the temperature of the substrate is relatively high compared with the processing table being in a cooled state (or a low temperature state).
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and apparatus for loading a substrate in a semiconductor manufacturing apparatus designed to load the substrate on a heated or cooled processing table in a manner by which the temperature difference between the processing table and the substrate becomes smaller so as to prevent peeling of thin films deposited on the processing table.
The method and apparatus for loading a substrate in a semiconductor manufacturing apparatus according to the present invention are comprised as follows to achieve the above object.
The method of loading a substrate according to the present invention is applied to a semiconductor manufacturing apparatus in which a substrate is ca
Ide Yosuke
Inaba Shin-ichi
Anelva Corporation
Wilson Gregory
LandOfFree
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