Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1999-04-20
2001-03-13
Utech, Benjamin L. (Department: 1765)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C438S745000
Reexamination Certificate
active
06200414
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circulation system for supplying chemicals for manufacturing semiconductor devices and a circulating method thereof, and more particularly, to a circulation system and a circulating method for supplying and re-circulating chemicals to a processing section for manufacturing semiconductor devices, and a bypass section for collecting the chemicals while the processing section is idle.
2. Description of the Related Art
In general, a silicon substrate passes through many fabrication steps in order to form semiconductor devices thereon. These fabrication steps utilize various types of chemicals for cleaning and etching procedures that are performed during the steps. For example, a wet-etch process is performed on the semiconductor substrate having specific layers and photoresist patterns formed thereon, in which a chemical is used to etch portions of the layers to create a desired pattern. The wet-etch process is controlled by a variety of parameters, including the etch rate (the rate that a layer is etched per unit of time), the selectivity ratio (the ratio of the etch rate of the etched layer to the etch rate of its underlying layer over a certain time period), and uniformity of the etching process.
The rate of removal of material in the etch process depends on, among other parameters, the processing time, the temperature of the etching solution, and the composition of the etching solution. The accuracy to which these parameters can be controlled affects the precise amount of material removed. The etching solution can be used at room temperature, but if necessary, it can be heated or cooled in order to improve the etch rate and the efficiency of the etch process.
FIG. 1
is a schematic diagram of a conventional circulation system for supplying chemicals for manufacturing semiconductor devices. The conventional circulation system includes a chemical tank
10
containing a certain amount of etching solution comprised of a mixture of various chemicals. The chemicals are supplied from the chemical tank
10
through a chemical supply line
12
and then to a processing section where a designated manufacturing process will be performed. In this example, the processing section includes a spin chuck
22
, which is rotated by the driving force of a motor
26
, having a wafer to be etched loaded thereon. A chemical collection container
24
surrounds the spin-chuck
22
and collects the etching solution while the process is being carried out.
The chemical supply line
12
has a supply nozzle
20
attached at a distal end. Also, along the chemical supply line
12
there are provided, in order, a supply pump
14
, a heat exchanger
16
, and a cut-off valve
18
. The length of the chemical supply line
12
from the front end of the heat exchanger
16
to the supply nozzle
20
is 15 m to 17 m. The portion of the chemical supply line
12
passing through the heat exchanger
16
is coil-shaped, such that the etching solution remains in the heat exchanger
16
for an extended time period. In addition, a cooling water supply may be used to further control the temperature of the etching solution passing through the chemical supply line
12
.
A chemical re-circulation line
30
branches off the chemical supply line
12
at a point between the heat exchanger
16
and the cut-off valve
18
, and connects to a top portion of the chemical tank
10
.
A chemical collection line
28
connects the bottom of the chemical collection container
24
to a top portion of the chemical tank
10
. A collection pump
29
is disposed along the chemical collection line
28
.
In operation, a wafer to be etched is loaded on spin chuck
22
inside the chemical container
24
, and a motor
26
is driven so as to rotate the spin chuck
22
. Thereafter, supply pump
14
in the chemical supply line
12
is driven, and a certain amount of the etching solution inside the chemical tank
10
is supplied into the heat exchanger
16
via the chemical supply line
12
. As the etching solution passes through the coil-shaped chemical supply line
12
in heat exchanger
16
, its temperature is changed by the cooling water interacting with the heat exchanger
16
.
Notice that a certain amount of the etching solution inside the heat exchanger
16
is re-circulated back to the chemical tank
10
via the chemical re-circulation line
30
by the pumping operation of the supply pump
14
.
The remaining etching solution passes from the heat exchanger
16
, through the cut-off valve
18
, and then through the supply nozzle
20
, where it is sprayed over the wafer to be etched while the wafer is rotating on the spin chuck
22
. Any excess etching solution from this process is collected and stored inside the chemical collection container
24
. The etching solution inside the chemical collection container
24
is re-circulated into the chemical tank
10
via the chemical collection line
28
by operating the collection pump
29
provided on the chemical collection line
28
.
When the wafer etching process is completed, the cut-off valve
18
is closed and the rotation of the spin chuck
22
is stopped. A new wafer is then placed on the spin chick
22
and rotated by the motor
26
, the cut-off valve
18
is then opened, and a new etching process commences.
While the new wafer is being prepared for etching, any etching solution collected and stored inside the chemical collection container
24
is re-circulated into the chemical tank
10
. However, when the cut-off valve
18
is closed, some of the etching solution remains in the chemical supply line
12
between the heat exchanger
16
and the cut-off valve
18
, which alters the temperature of the etching solution. When the new wafer is ready for etching and the cut-off valve is opened, the etching solution with the altered temperature is the first to contact the wafer, which could result in a process failure.
In addition, because of the coil-shape of the chemical supply line
12
inside the heat exchanger
16
, the length of the chemical supply line
12
from the front end of the heat exchanger
16
to the supply nozzle
20
(15 to 17 m) is so long that the control of the pumping pressure of the etching solution supplied by the supply pump
14
is very difficult, the temperature change of the etching solution while it is passing through the chemical supply line
12
is very large, and the possibility of chemical leaks or contamination is very high.
Another drawback of the conventional system is that a large amount of time is required to re-circulate the etching solution from the heat exchanger
16
, through the chemical re-circulation line
30
, and into the chemical tank
10
, so that the mixture efficiency of various chemicals is decreased and the uniformity of the chemical temperature in the entire circulation line is poor.
SUMMARY OF THE INVENTION
The present invention is directed to a circulation system for supplying chemicals for manufacturing semiconductor devices, and a circulating method thereof, which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.
One object of the present invention is to provide a circulation system, and a circulating method thereof, that prevents etching process failures caused by an etching solution encountering unsatisfactory temperature variations between etching processes for successive wafers.
Another object of the present invention is to provide a circulation system, and a circulating method thereof, that effectively controls the pumping pressure of the system, as well as reduces temperature changes and contamination of the etching solution, by shortening the length of the chemical supply line between the chemical tank and the supply nozzle.
A further object of the present invention is to provide a circulation system, and a circulating method thereof, that facilitates mixing of the etching solution comprising a plurality of chemicals inside the chemical tank.
A still further object of the present invention is
Hwang Kyung-Seuk
Kwag Gyu-hwan
Yun Young-hwan
Deo Duy-Vu
Jones Volentine, LLC
Samsung Electronics Co,. Ltd.
Utech Benjamin L.
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