Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With measuring – sensing – detection or process control means
Reexamination Certificate
2000-11-09
2002-10-22
Mills, Gregory (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With measuring, sensing, detection or process control means
C156S345240, C118S7230ER
Reexamination Certificate
active
06468384
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to plasma processing systems, and more particularly to plasma processing systems for maintaining a constant set-point temperature from wafer to wafer in plasma processing.
2. Description of the Related Art
High density plasma (HDP) processing systems are used to process semiconductor wafers or substrates for fabrication of integrated circuits. For example, high density plasma processes are commonly used in etching, oxidation, chemical vapor deposition (CVD), etc. The high density plasma processes are typically carried out by means of plasma processing systems and generally include a plasma processing chamber to provide a controlled setting.
FIG. 1
illustrates a schematic diagram of a conventional high density plasma processing system
100
for processing a wafer
106
. The plasma processing system
100
includes a plasma processing chamber
102
and a pair of RF power generators
104
A and
104
B. The plasma processing chamber
102
includes an electrostatic chuck (ESC)
108
for holding and clamping the wafer
106
in place during plasma processing. The RF power generator
104
A generates and provides RF power to an electrode
114
provided in the electrostatic chuck
108
. An ESC power supply
122
is arranged to generate and provide a DC voltage to the electrode
114
to clamp the wafer
106
to the electrostatic chuck
108
.
The plasma processing chamber
102
is configured to receive RF power from the RF power generator
104
B and a source gas
116
. When the RF power generators
104
A and
104
B are energized after the source gas
116
has been introduced into the plasma processing chamber
102
, plasma
118
is generated from the source gas
116
over the wafer
106
and diffuses down to the wafer
106
. In addition, the RF power provided to the electrode
114
produces ions
120
that bombard the wafer
106
. In this manner, the plasma
120
and the ions
122
process the wafer
106
to produce desired plasma processing characteristics on the wafer
106
.
During plasma processing, a heat transfer gas
110
such as helium is provided to the wafer
106
via a port
112
through the electrostatic chuck
112
. The heat transfer gas
112
functions as a heat transfer medium between the wafer
106
and the electrostatic chuck
108
to keep the wafer
106
at a constant temperature during plasma processing. In general, this scheme keeps the wafer
106
at a reasonably constant temperature for plasma processing.
Conventional plasma processing chambers are typically used to process batches of wafers. For example, when a batch of wafers are processed, one after another, to produce integrated chips, it is desirable to keep the temperature of the wafers at a constant value. The uniformity in temperature helps to ensure fabrication of chips of uniform features across the batch of wafers.
Unfortunately, however, the conventional plasma processing system
100
often suffers from variation in wafer temperature during plasma processing from wafer to wafer due to several factors. For example, different wafers typically exhibit different resistivity, resulting in varying emissivity of RF radiation. Furthermore, the backside roughness of wafers is generally non-uniform for the wafers. On the other hand, various coatings on the front surfaces, i.e., surface being processed, of the wafers vary from wafer to wafer. In addition, different structures, devices, and materials on wafers and the aforementioned factors typically lead to varying wafer temperatures during plasma processing. As can be appreciated, the processing of wafers at such varying temperatures leads to different process performance.
In view of the foregoing, what is needed is a system and method for processing wafers at a constant temperature from wafer to wafer during plasma processing.
SUMMARY OF THE INVENTION
The present invention fills these needs by providing a system and method for providing a set-point temperature during plasma processing from substrate to substrate. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, a method, or a computer readable medium. Several inventive embodiments of the present invention are described below.
In one aspect of the invention, the present invention provides a plasma processing system for providing a set-point temperature for substrates during plasma processing by controlling clamping force. The plasma processing system includes a plasma chamber, a controller, and an electrostatic power supply. The plasma chamber is arranged to receive an RF power and a source gas for producing plasma. The plasma chamber includes an electrostatic chuck for clamping a substrate in place during plasma processing. The electrostatic chuck includes an electrode and a sensor, which is arranged to monitor temperature of the substrate being processed. The controller is coupled to the sensor to receive the substrate temperature and is configured to generate a control signal for driving the substrate temperature to the set-point temperature. The electrostatic power supply is coupled between the controller and the electrode in the electrostatic chuck. The electrostatic power supply receives the control signal from the controller and generates a voltage adapted to clamp the substrate with a clamping force. In this configuration, the electrostatic power supply provides the voltage to the electrode to clamp the substrate such that the substrate temperature is driven to the set-point temperature.
In another aspect of the invention, the present invention provides a plasma processing system for providing a set-point temperature for substrates during plasma processing by controlling RF power. The plasma processing system includes a plasma chamber, an electrostatic power supply, a controller, and an RF power generator. The plasma chamber is arranged to receive a source gas for producing plasma and includes an electrostatic chuck for clamping a substrate in place during plasma processing. The electrostatic chuck includes an electrode and a sensor, which monitors the temperature of the substrate. The electrostatic power supply is coupled to the electrode to provide a voltage signal for generating a clamping force to clamp the substrate. The controller is coupled to the sensor to receive the substrate temperature and is configured to generate a control signal for driving the substrate temperature to the set-point temperature. The RF power generator is coupled between the controller and the plasma chamber. In this configuration, the RF power generator receives the control signal from the controller and generates an RF power adapted to control heat input to the substrate in response to the control signal. The RF power generator provides the RF power to the plasma chamber such that the substrate temperature is driven to the set-point temperature while generating the plasma from the source gas.
In yet another aspect of the invention, the present invention provides a method for providing a set-point temperature for substrates during plasma processing in a plasma processing system by controlling clamping force. The plasma processing system is arranged to receive an RF power and a source gas for producing plasma and includes an electrostatic chuck for clamping a substrate in place during plasma processing. The electrostatic chuck includes an electrode coupled to an electrostatic power supply to generate a clamping force for clamping the substrate. In this method, temperatures of a substrate being processed is monitored and received. In response to the monitored temperatures, a control signal is generated for driving the substrate temperature to the set-point temperature. The control signal is then provided to the electrostatic power supply to generate a clamping voltage. The clamping voltage is then provided to the electrode to generate a clamping force adapted to drive the substrate temperature to the set-point temperature.
In another aspect of the
Saproo Ajay
Shufflebotham Paul K.
Singh Vikram
Whiting Robert J.
Mills Gregory
Novellus Systems Inc.
Zervigon Rudy
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