Coating apparatus – Gas or vapor deposition – Work support
Reexamination Certificate
2001-03-22
2004-03-09
Hassanzadeh, Parviz (Department: 1763)
Coating apparatus
Gas or vapor deposition
Work support
C156S345550, C216S058000, C427S346000, C034S359000, C034S058000
Reexamination Certificate
active
06702900
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a wafer chuck used in a semiconductor process chamber and more particularly, relates to a wafer chuck in a semiconductor process chamber that is capable of producing an inert gas blanket for insulating a wafer from harmful chemicals and a method for using the chuck.
BACKGROUND OF THE INVENTION
In the fabrication of semiconductor devices, a silicon wafer must be process by many processing steps, i.e. as many as several hundred, in order to produce a final product of an IC chip. In the various chemical or physical processes for performing the fabrication steps, a silicon wafer must be held onto a wafer carrying device, such as a wafer chuck securely in a process chamber such that an active surface of the wafer can be processed.
One or more of such numerous processing steps may be an etching or cleaning step in which a silicon wafer is etched in a spin etcher. In a typical spin etcher, a wafer is held on a wafer chuck that rotates at a predetermined rotational speed while an acid solution is sprayed on top of the wafer surface. For instance, in recent semiconductor processing technology, cobalt deposition is frequently used in forming transistor gates on the silicon surface. After the completion of a cobalt deposition process, the backside of the wafer must be cleaned due to the extreme mobility of the cobalt atoms during a sputtering process. A suitable cleaning process for removing the cobalt particles on the backside of a silicon wafer is by using the spin etching apparatus.
Many different types of spin etchers have been designed to suit specific etching requirements on a silicon wafer.
FIG. 1
illustrates a conventional spin etcher that has four-level etch chambers or etch stations formed in a single etcher.
Referring now to
FIG. 1
, wherein a conventional multi-leveled spin etcher
10
is shown. Spin etcher
10
is constructed by four different levels of reaction chambers
12
,
14
,
16
and
18
. Each of the reaction chambers are formed by a partitioning member
20
which cooperates with a wafer chuck
22
divides the cavity of the spin etcher in four different sub-cavities
22
,
24
,
26
and
28
. The conventional wafer chuck
22
is provided with an internal passageway
30
for passing an inert gas such as nitrogen into a cavity
32
formed between a wafer
34
and the top surface
36
of the wafer chuck
22
. The wafer
34
is supported by a plurality of mounting pins
38
as shown in FIG.
1
. The wafer chuck
22
is driven, or rotated, by shaft
40
to a suitable rotational speed during the etching process.
The multi-leveled spin etcher
10
shown in
FIG. 1
provides the benefit that a single etcher can be used to execute various etching steps by either using different etchant or the same etchant at different concentrations. During the etching process, an acid, or a diluted acid solution, is sprayed from the top of the chamber (not shown) to etch the backside of the wafer
34
, for instance, after a silicon wafer is sputter deposited with cobalt. The shaft
40
elevates or lowers the wafer chuck
22
between the various etch stations
12
,
14
,
16
and
18
. The rotation of the shaft
40
and the rotation of the wafer
34
situated on top of the wafer chuck
22
results in a more uniform etch reaction on the surface of the wafer, and thus a more satisfactory etch reaction.
In most spin etching reactions, a highly corrosive acid in a diluted form is sprayed into the chamber cavity
22
,
24
,
26
or
28
. While each of the chamber sub-cavities
22
~
28
is equipped with an exhaust conduit
42
to evacuate the sub-cavities after an etch reaction has been conducted, such withdrawal is not always effective such that residual acid vapor stays in the sub-cavities. In the multi-leveled spin etcher
10
, the upward/downward movement of the wafer chuck
22
further contributes to the migration of acid vapor from one sub-cavity into the sub-cavity above it. The acidic vapor therefore corrodes the backside of the wafer
34
by flowing into the cavity
32
formed between the wafer and the wafer chuck
22
. In the case of a backside cleaning after a cobalt deposition on a silicon wafer, the backside of the wafer
34
, i.e. the side that faces downwardly, is actually the active side of the wafer and thus, any corrosive effect on the active side of the wafer can produce detrimental effects. When the active surface of the wafer
34
is attacked by acid vapor, serious quality and reliability problems occur which greatly effects the throughput of the spin etching process.
It is therefore an object of the present invention to provide a wafer chuck in a semiconductor process chamber that can be used without the drawbacks or shortcomings of the conventional wafer chuck.
It is another object of the present invention to provide a wafer chuck for use in a semiconductor process chamber capable of producing an inert gas blanket shielding a wafer positioned thereon.
It is a further object of the present invention to provide a wafer chuck for use in a semiconductor process chamber that is equipped with inert gas passageways in the chuck for flowing an inert gas into an upper portion of the reaction chamber and forming an inert gas blanket.
It is another further object of the present invention to provide a wafer chuck for use in a semiconductor process chamber that is provided with a plurality of apertures in a sidewall of the wafer chuck for flowing an inert gas into the reaction chamber and thus insulate a wafer positioned on the chuck.
It is still another object of the present invention to provide a process chamber for processing semiconductor wafers that includes a wafer chuck capable of producing an inert gas blanket around a wafer positioned on the chuck and preventing the wafer from being damaged by residual chemical vapor in the chamber.
It is yet another object of the present invention to provide a process chamber for processing semiconductor wafers which is equipped with a multi-leveled sub-chamber for etching a semiconductor wafer and protecting the wafer from being damaged by residual chemical vapor in the process chamber.
It is still another further object of the present invention to provide a method for chemical treating a wafer topside without damaging the wafer backside by residual chemical vapor in a process chamber.
It is yet another further object of the present invention to provide a method for chemical treating a wafer topside without damaging the wafer backside by residual chemical vapor in a process chamber by providing a wafer chuck equipped with internal passageways for feeding an inert gas into the chamber cavity and thus blocking the wafer from the residual chemical vapor.
SUMMARY OF THE INVENTION
In accordance with the present invention, a wafer chuck for producing an inert gas blanket to insulate a wafer positioned on the chuck and a method for chemical treating a wafer topside without damaging the wafer backside by residual chemical vapor in the chamber are provided.
In a preferred embodiment, a method for chemical treating a wafer topside without damaging the wafer backside by residual chemical vapor in a process chamber can be carried out by the operating steps of first providing a wafer chuck for mounting a wafer thereon; positioning the wafer chuck in the process chamber wherein an upper surface of the chuck substantially separates an upper chamber and a lower chamber; and rotating the chuck and conducting a chemical process on the topside of the wafer while simultaneously flowing an inert gas through a sidewall of the wafer chuck into an upper portion of the lower chamber stopping chemical vapor from flowing from the lower chamber into the upper chamber and preventing the backside of the wafer from being attacked by the chemical vapor.
The method for chemical treating a wafer topside without damaging the wafer backside by residual chemical vapor in the process chamber may further include the steps of stopping a flow of the chemical into the upper chamber and withdrawing residual chemical
Lai Jun-Yang
Pan Cheng-Yang
Yang Huai-Tei
Yeh Su-Yu
Hassanzadeh Parviz
Moore Karla
Taiwan Semiconductor Manufacturing Co. Ltd.
Tung & Associates
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