Refrigeration – Using electrical or magnetic effect – Thermoelectric; e.g. – peltier effect
Reexamination Certificate
2000-02-23
2002-01-01
Bennett, Henry (Department: 3744)
Refrigeration
Using electrical or magnetic effect
Thermoelectric; e.g., peltier effect
C062S003700, C136S201000
Reexamination Certificate
active
06334311
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermoelectric-cooling temperature control apparatus located in a clean room for maintaining a constant temperature inside a semiconductor device fabrication facility.
2. Description of the Related Art
In general, semiconductor devices are fabricated by executing various processes repeatedly. The conditions in the semiconductor device fabrication facility must be well regulated in order for the fabrication processes to be carried out precisely and efficiently. These conditions include temperature, vacuum pressure, radio frequency power, gas flow rate, etc. However, if any one of the above conditions is not kept stable during the respective process carried out thereunder, productivity is adversely affected, e.g., the production yield, etch rate, uniformity, etc., is reduced.
Recently, wafers having a large diameter(greater than 300 mm) have been used for mass producing highly integrated semiconductor devices. Accordingly, each piece of processing equipment has been adapted for use with such wafers. Also, accessory equipment is required for regulating the process conditions appropriately for the processing of the large wafers.
In particular, the semiconductor device fabrication processes include a dry etch process in which a wafer is etched by activating process gas inside a process chamber, whereby the process gas assumes the state of plasma. In the dry etch process, a certain portion of a layer grown on the wafer is selectively etched by the process gas in a plasma state, using a photoresist as a mask. Dry etching is an important step for fabricating high-capacity and highly integrated semiconductor devices. The types of plasma which are used are referred to as Capacitive Coupled Plasma (CCP) and Inductive Coupled Plasma (ICP).
Capacitive Coupled Plasma is produced by an electric field generated by selectively applying high frequency power to a plurality of electrodes installed inside the process chamber. On the other hand, Inductive Coupled Plasma is produced by magnetic and electric fields respectively generated by selectively applying high frequency power to coils wound around the outside of the process chamber and to a plurality of electrodes installed inside the process chamber. In addition to the dry etch process, plasma is also typically used in a Chemical Vapor Deposition (CVD) process to form a good thin layer on a wafer inside a process chamber.
In the above-described processes for manufacturing semiconductor devices, at least two electrodes are required to form the plasma, and a wafer is mounted on either one of the two electrodes. Most important, though, the process conditions, i.e., process temperature, must be regulated appropriately if the process is to impart the desired characteristics to the semiconductor device. Therefore, a chiller as a heat exchanger is provided outside the semiconductor device fabrication facility for automatically controlling the temperature within the chamber.
The chiller is of critical importance in the dry etch process. The chiller prevents the electrodes (cathode or anode) from overheating during the etch process and maintains the temperature inside the chamber to within a certain temperature range, thereby preventing the dry etch apparatus from malfunctioning due to temperature fluctuations.
FIG. 6
schematically illustrates a chiller (heat exchanger) of a semiconductor device fabrication facility in which plasma is produced.
The semiconductor device fabrication facility (F) includes an electrode
132
provided at the bottom of a chamber
130
, a pedestal
134
on top of the electrode
132
, and a second electrode
131
. The pedestal
134
is provided with the same electric potential as the electrode
132
. An electric state chuck (not shown) is incorporated into the pedestal
134
and supports a wafer
2
thereon. The electrode
131
surrounds the electrode
132
and the pedestal
134
to form a sealed space therebetween. An insulator
133
is disposed around the electrode
132
and the pedestal
134
to provide electrical insulation between the electrode
131
and the electrode
132
.
In addition, a vacuum port
135
is provided on one side of the electrode
131
. The vacuum port
135
is selectively opened to maintain a vacuum in the sealed space. A vacuum pump (not shown) is connected to the vacuum port
135
to create the vacuum in the chamber
130
. A gas supply line (not shown) is open at one side of the chamber
130
to fill the sealed space with process gas. A high frequency power source (RF) is connected to the bottom of the electrode
132
, and the electrode
131
is connected to ground.
As the vacuum pump is operated to produce a high vacuum state in the chamber
130
, process gas fills the sealed space of the chamber
130
. The wafer
2
is processed by the process gas when high frequency power is applied to the electrode
132
, and the process gas is transformed into plasma by the resultant electric field.
A coolant circulation line
102
extends through the electrode
132
, on which the wafer
2
is mounted, or through the pedestal
134
to directly control the temperature of the wafer
2
. The coolant is circulated through the line
102
with constant fluid pressure and fluid quantity while being cooled (or heated) by a chiller
100
. The coolant may be an inert solution consisting of deionized water, an immobile solution diluted at a constant rate, or a Fluorinert solution such as a colorless and odorless Fluoro Carbon solution.
The chiller
100
provides a typical cooling cycle. The chiller
100
comprises a compressor to transform gas coolant at a low temperature and low pressure to gas coolant having a high temperature and high pressure, a condenser to transform the gas coolant having a high temperature and high pressure to fluid coolant at room temperature and having a high pressure, an expander to transform the fluid coolant at room temperature and high pressure to fluid coolant having a low temperature and low pressure, and an evaporator to absorb heat from the outside while transforming the fluid coolant at low temperature and low pressure to gas. With the operation of the compressor, the coolant is successively compressed and evaporated so that the coolant, in turn, radiates and absorbs heat. The cooled (or heated) coolant circulating through the coolant circulation line
102
passes through the inside of the electrode
132
so that a heat exchange is effected.
As described above, a temperature controlling apparatus (chiller) is disposed outside the semiconductor device fabrication facility F in which the wafer
2
is processed. The chiller
100
thus occupies a large amount of otherwise free space, and contributes to the expense necessary for maintaining the clean room in which the semiconductor fabrication facility is provided. Moreover, although the conventional chiller
100
is installed adjacent to the semiconductor device fabrication facility F to minimize the temperature losses, such temperature losses are inevitable because the coolant is circulated to and from the facility via the coolant circulation line
102
. These temperature losses become especially significant when large-diametered wafers are processed because the chiller
100
must have a large cooling capacity in this case. Moreover, such a large chiller
100
requires so much space inside a clean room that a significant part of the cost associated with building the clean room can be attributed to the space necessary for accommodating the chiller.
In addition, any problem with the operation of the chiller
100
destabilizes the temperature of the wafer
2
, thereby causing failures in the processing of the wafer
2
. Also, the leakage of coolant adversely affects the chips on the wafer, thereby decreasing production yield and contaminating the clean room environment.
In addition, because the chiller
100
comprises a compressor, a condenser, an expander, and an evaporator, etc., the chiller requires a large amount of maintenance and hence, the expense a
Kim Byung-chul
Kim Tae-hoon
Kim Tae-ryong
Lee Young-woo
Bennett Henry
Jones Melvin
Samsung Electronics Co,. Ltd.
Volentine & Francos, PLLC
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