Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
1999-11-10
2001-03-13
McDonald, Rodney (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192170, C204S192150, C427S398100, C427S398200, C427S444000, C438S584000, C438S660000, C438S685000, C438S688000
Reexamination Certificate
active
06200432
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a film deposition technique using sputtering, and particularly to a technique of handling a substrate after sputtering.
2. Description of the Related Art
Film deposition techniques include vacuum evaporation, sputtering, chemical vapor deposition (CVD), and the like. In a process of manufacturing a semiconductor integrated circuit or the like, sputtering is frequently used to deposit a film for a wiring material and the like.
FIG. 12
is a view illustrating the configuration of an example of a conventional sputtering apparatus. The sputtering apparatus of
FIG. 12
mainly comprises: a sputter chamber
1
having a vacuum pump system
11
; a cathode
12
and a substrate holder
13
which are disposed so as to oppose each other in the sputter chamber
1
; a gas introducing system
14
which introduces a gas into the sputter chamber
1
; a sputter power source
15
which applies a given voltage to the cathode
12
; a load-lock chamber
2
and an unload-lock chamber
3
which are disposed before and after the sputter chamber
1
through gate valves
22
and
32
; a transferring mechanism (not shown) which transfers a substrate
10
in the sequence of the load-lock chamber
2
, the sputter chamber
1
, and the unload-lock chamber
3
. The load-lock chamber
2
has a vacuum pump system
201
, and the unload-lock chamber
3
has a vacuum pump system
301
.
A number of substrates
10
are housed in a substrate cassette
21
and then placed in the load-lock chamber
2
. The load-lock chamber
2
is exhausted to a pressure similar to that of the sputter chamber
1
, the gate valve
22
is then opened, and one of the substrates
10
is transferred into the sputter chamber
1
and placed on the substrate holder
13
.
After the gate valve
22
is closed, the gas introducing system
14
is operated so as to introduce the gas, and the sputter power source
15
is operated, whereby sputtering is conducted so that a thin film is deposited on the substrate
10
. In this case, the substrate
10
is heated to a temperature by heating means
131
disposed in the substrate holder
13
. For example, it is known that, when sputtering is conducted in a process of forming a tungsten wiring on an Si foundation while heating the substrate to about 400° C., the resistivity of the tungsten thin film is stabilized at a given value. Consequently, sputtering is conducted while heating the substrate
10
to a temperature of this level.
When the thin film is deposited to a desired thickness, the operations of the gas introducing system
14
and the sputter power source
15
are stopped, and the gate valve
32
is then opened. The transferring mechanism takes out the substrate
10
and the taken-out substrate is housed in a substrate cassette
31
disposed in the unload-lock chamber
3
. In this case, also the unload-lock chamber
3
is exhausted to a pressure similar to that of the sputter chamber
1
.
In this way, the substrates
10
are transferred one by one from the load-lock chamber
2
into the sputter chamber
1
, subjected to sputtering, and then housed in the substrate cassette
31
of the unload-lock chamber
3
. When all the substrates
10
which have been housed in the substrate cassette
21
of the load-lock chamber
2
are housed in the substrate cassette
31
of the unload-lock chamber
3
after the film deposition, a vent valve
352
is opened so that a vent gas is introduced into the unload-lock chamber
3
, thereby returning the interior of the unload-lock chamber
3
to the atmospheric pressure. Thereafter, the substrates
10
are taken out from the unload-lock chamber
3
.
One of the important problems raised in film deposition techniques including sputtering is that the film quality is to be stabilized. In an integrated circuit such as an LSI, particularly, even low-degree degradation of the film quality causes circuit characteristics to be changed, so that the performance of a product is largely affected. In sputtering for a wiring material, for example, the resistivity of a film is required to be stabilized at an expected value.
In the above-described conventional sputtering apparatus, it was ascertained that last several ones of the substrates housed in the substrate cassette of the unload-lock chamber are varied in properties such as the resistivity.
The inventors of the invention have vigorously studied the cause of this phenomenon, and found that the phenomenon is caused by exposing a substrate of a high temperature to the ambient atmospheric pressure. Specifically, with respect to last several ones of the substrates housed in the substrate cassette of the unload-lock chamber, the time period from the timing when the substrates are housed in the substrate cassette to that when the unload-lock chamber is ventilated is short. In other words, these substrates are exposed to the ambient atmospheric pressure after a lapse of a relatively short time period from the timing when the substrates are taken out from the sputter chamber under a high temperature condition. Consequently, it seems that the film of a high temperature captures oxygen, water vapor, and the like contained in the vent gas, and this causes the properties to be varied.
SUMMARY OF THE INVENTION
In order to solve the above problem, the invention provides a method of handling a substrate after sputtering, comprising the steps of: depositing a thin film on a substrate while heating the substrate in a vacuum; placing the substrate on a cooling stage so as to forcedly cool the substrate; and returning the substrate to an atmospheric pressure ambient after a temperature of the substrate is lowered to a temperature or lower.
Also, the invention provides a sputtering apparatus comprising: a sputter chamber which has a vacuum pump system and which deposits a thin film on a substrate by means of sputtering; heating means, disposed in the sputter chamber, for heating the substrate to a first temperature during sputtering; an unload-lock chamber which is adjacent to the sputter chamber and which has a vacuum pump system and a vent gas introducing system; and-a cooling stage, disposed in the unload-lock chamber, for making surface contact with the substrate which has been subjected to sputtering and taken out from the sputter chamber so as to forcedly cool the substrate to a second temperature.
REFERENCES:
patent: 4913790 (1990-04-01), Narita et al.
patent: 5203958 (1993-04-01), Arai et al.
patent: 5267607 (1993-12-01), Wada
patent: 5388944 (1995-02-01), Takanabe et al.
patent: 5460684 (1995-10-01), Saeki et al.
patent: 5707500 (1998-01-01), Shimamura et al.
patent: 4-141587 (1992-05-01), None
Kobayashi Masahiko
Takahashi Nobuyuki
Anelva Corporation
McDonald Rodney
Sughrue Mion Zinn Macpeak & Seas, PLLC
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