Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – For liquid etchant
Reexamination Certificate
2001-04-30
2004-01-13
Hassonzadeh, Parriz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
For liquid etchant
C438S690000, C438S706000
Reexamination Certificate
active
06676801
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 90109734, filed on Apr. 24, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to a pressure suppression device for a chemical mechanical polishing machine and method thereof. More particularly, this invention relates to a pressure suppression device to suppress a pressure applied to a wafer until the pressure is smaller than a pressure applied to a polishing pad and the method thereof
2. Description of the Related Art
Chemical mechanical polishing (CMP) is a technique that provides a global planarization for very large semiconductor integration (VLSI) or ultra large semiconductor integration (ULSI). The technique makes use of a grinder-like mechanical polishing theory, so that an uneven surface profile of a wafer can be planarized when assisted with an appropriate reagent.
FIG. 1
shows a layout of a chemical mechanical polishing equipment. As shown in
FIG. 1
, the chemical mechanical polishing equipment comprises a polishing table
10
on which sits a wafer
14
and a polishing head
16
for holding the wafer
14
ready to be polished, wherein the polishing head holds a back face of the wafer
14
, while a front to be polished, wherein the polishing head holds a back face of the wafer
14
, while a front face of the wafer is pressed against is disposed on the polishing table
10
for performing the chemical mechanical polishing step.
While performing the chemical mechanical polishing process, the polishing table
10
and the polishing head
16
are rotating along a certain direction. A reagent (not shown) is continuously supplied onto the polishing table
10
to provide a chemical reaction for polishing. So, with the chemical reaction and the mechanical polishing applied to the wafer
14
on the polishing table
10
, a portion of the deposited layer that protrudes from the wafer
14
is gradually removed.
When the wafer
14
is polished, a gas known as polishing gas is charged from a polishing gas input
11
. The polishing gas generates a polishing pressure applied to the polishing pad
12
. The polishing gas shown as Polish P/I
2
is output by the polishing table
10
to a transducer (not shown) in a pressure controller (not shown). Being converted into a current signal, the pressure is measured. A wafer gas input
15
of the polishing head
16
also charge with a wafer gas. The wafer gas generates a wafer pressure on the wafer
14
for performing the chemical mechanical polishing between the wafer
14
and the polishing pad
12
.
FIG. 2
shows a block diagram for controlling chemical mechanical polishing pressure. In
FIG. 2
, the voltage signal of the polishing pressure setting point is sent to the polishing pressure regulator
20
. When the polishing pressure regulator
20
receives the voltage signal, the polishing pressure regulator
20
convert the voltage signal into a corresponding pressure and output it from the polishing pressure output. The polishing pressure transducer
22
inspects the pressure output from the polishing pressure regulator
20
. The inspected pressure is converted into a current signal and compared to that of the polishing pressure setting point, so that a stable polishing pressure can be output.
A voltage signal of a &Dgr;P setting point is sent to a &Dgr;P regulator
26
. While receiving the voltage signal, the &Dgr;P regulator
26
transforms it into a corresponding pressure to be output from a &Dgr;P output. The &Dgr;P transducer
24
inspects the output pressure from the &Dgr;P regulator
26
and transforms the current signal output from the polishing pressure transducer
22
. After comparing the current signal with that of the polishing pressure setting point, a stable &Dgr;P pressure can be output.
While performing a chemical mechanical polishing planarization process, the polishing pressure by applying a force on the polishing pad has to be larger than the wafer pressure by applying a force on the wafer to provide a normal operation. That is, &Dgr;P=W
p
−P
p
<0, wherein W
p
is the wafer pressure, P
p
is the polishing pressure, and &Dgr;P is a difference between the wafer pressure and the polishing pressure.
In the above controlling method, once the outputs of the regulator and transducer are abnormal, the polishing pressure is smaller than the wafer pressure. So, the wafer is easily blown off from the polishing head to cause the wafer slippage or breakage.
SUMMARY OF THE INVENTION
The invention provides a pressure suppression device for a chemical mechanical polishing machine and a method thereof. The wafer pressure is controlled to be larger than the polishing pressure to avoid the wafer slippage and damage.
The invention provides a pressure suppression device of a chemical mechanical polishing machine. The chemical mechanical polishing machine comprises a polishing table and a polishing head. The polishing table further comprises a polishing pad and a polishing gas input to be charged with a polishing gas. The polishing gas generates a polishing pressure applied to the polishing pad. The polishing head is used to hold a wafer and comprises a wafer gas input to charge the wafer with a wafer gas. The wafer gas generates a wafer pressure applied to the wafer, so as to perform a chemical mechanical polishing between the wafer and the polishing pad. The pressure suppression device comprises a pressure releasing component which further comprises a spring. An gas input tube is coupled to the wafer gas input and the pressure releasing component, so that the wafer gas can be input to the pressure releasing component. When the polishing pressure applied to the polishing pad is smaller than the wafer pressure applied to the wafer, the spring in the pressure releasing component is deformed to release a part of the wafer pressure until the wafer pressure is smaller than the polishing pressure.
The invention further provides a pressure suppression method for a chemical mechanical polishing machine. The chemical mechanical polishing machine comprises a polishing table and a polishing head, wherein the polishing table has a polishing pad and the polishing head can hold a wafer. The pressure suppression method begins by charging the polishing table with a polishing gas, wherein the polishing gas generates a polishing pressure applied to the polishing pad. The polishing head is then charged the wafer with a wafer gas, wherein the wafer gas generates a wafer pressure applied to the wafer, so that a chemical mechanical polishing is performed between the wafer and the polishing pad. A pressure suppression device is installed, wherein the pressure releasing component further comprises a spring and an gas input tube coupled to the wafer gas input and the pressure releasing component, so that the wafer gas can be input to the pressure releasing component. When the polishing pressure applied to the polishing pad is smaller than the wafer pressure applied to the wafer, the spring in the pressure releasing component is deformed to release a part of the wafer pressure until the wafer pressure is smaller than the polishing pressure.
According to the present invention, a pressure suppression device for a chemical mechanical polishing machine and a method thereof are provided, where the pressure suppression device controls the polishing pressure to be larger than the wafer pressure when the wafer is polished. But, if the polishing pressure is smaller than the wafer pressure, the pressure releasing component will release an excessive part of the wafer pressure to prevent a huge wafer pressure. As a result, the slippage and breakage of wafers as occur in the conventional device and method can be avoided.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
REFERENCES:
patent: 6057245 (2000-05-01), Annapragada et al.
patent: 2000058521 (2000-02-01), None
Lai Chien-Hsin
Lin Huang-Yi
Tseng Jung-Nan
Yu Fu-Yang
Hassonzadeh Parriz
J.C. Patents
MacArthur Sylvia R.
United Microelectronics Corp.
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