Computer-aided design and analysis of circuits and semiconductor – Nanotechnology related integrated circuit design
Reexamination Certificate
2000-06-30
2003-09-16
Siek, Vuthe (Department: 2825)
Computer-aided design and analysis of circuits and semiconductor
Nanotechnology related integrated circuit design
C716S030000, C700S121000
Reexamination Certificate
active
06622286
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to plasma processing of semiconductor devices. More particularly, the present invention relates to an apparatus for integrating sensors and hardware controls used in a semiconductor manufacturing equipment, specifically, in a plasma etching system.
2. Background Art
Various forms of processing with ionized gases, such as plasma etching/deposition and reactive ion etching/deposition, are increasing in importance particularly in the area of semiconductor device manufacturing. Of particular interest are the devices used in the etching process.
FIG. 1
illustrates a conventional inductively coupled plasma etching system
100
that may be used in the processing and fabrication of semiconductor devices. Inductively coupled plasma processing system
100
includes a plasma reactor
102
having a plasma chamber
104
therein. A transformer coupled power (TCP) controller
106
and a bias power controller
108
respectively control a TCP power supply
110
and a bias power supply
112
influencing the plasma created within plasma chamber
104
.
TCP power controller
106
sets a set point for TCP power supply
110
configured to supply a radio frequency (RF) signal, tuned by a TCP match network
114
, to a TCP coil
116
located near plasma chamber
104
. A RF transparent window
118
is typically provided to separate TCP coil
116
from plasma chamber
104
while allowing energy to pass from TCP coil
116
to plasma chamber
104
.
Bias power controller
108
sets a set point for bias power supply
112
configured to supply a RF signal, tuned by a bias match network
120
, to an electrode
122
located within the plasma reactor
104
creating a direct current (DC) bias above electrode
122
which is adapted to receive a substrate
124
, such as a semi-conductor wafer, being processed.
A gas supply mechanism
126
, such as a pendulum control valve, typically supplies the proper chemistry required for the manufacturing process to the interior of plasma reactor
104
. A gas exhaust mechanism
128
removes particles from within plasma chamber
104
and maintains a particular pressure within plasma chamber
104
. A pressure controller
130
controls both gas supply mechanism
126
and gas exhaust mechanism
128
.
A temperature controller
134
controls the temperature of plasma chamber
104
to a selected temperature setpoint using heaters
136
, such as heating cartridges, around plasma chamber
104
.
In plasma chamber
104
, substrate etching is achieved by exposing substrate
104
to ionized gas compounds (plasma) under vacuum. The etching process starts when the gases are conveyed into plasma chamber
104
. The RF power delivered by TCP coil
116
and tuned by TCP match network
110
ionizes the gases. The RF power, delivered by electrode
122
and tuned by bias match network
120
, induces a DC bias on substrate
124
to control the direction and energy of ion bombardment of substrate
124
. During the etching process, the plasma reacts chemically with the surface of substrate
124
to remove material not covered by a photoresistive mask.
Primary parameters such as plasma reactor settings are of fundamental importance in plasma processing. The amount of actual TCP power, bias power, gas pressure, gas temperature, and gas flow within plasma chamber
104
greatly affects the process conditions. Significant variance in actual power delivered to plasma chamber
104
may unexpectedly change the anticipated value of other process variable parameters such as neutral and ionized particle density, temperature, and etch rate.
In existing plasma etch systems, however, primary parameters are controlled through separate standalone controllers that do not directly communicate with each other in real-time.
FIG. 2
illustrates a conventional plasma etching control hardware system. A TCP match
200
includes a TCP controller
202
. A bias match
204
includes a bias controller
206
. A pressure control valve
208
includes a pressure controller
210
. An optical emission spectrometer (OES) or interferometer (INTRF)
212
includes an OES or INTRF controller
214
. A VME chassis
216
communicates with standalone controllers
202
,
206
,
210
, and
214
via serial links
218
. Thus, reactor settings are controlled separately through standalone controllers with a relatively slow communication link between each other.
In plasma etching systems, a change in one of the parameters may affect the other parameters. For example, during a process, chemical reactions in the chamber cause the plasma impedance to vary affecting the power delivery, temperature, and pressure. Thus, elaborate discreet recipe steps need to be developed by an operator to effectively de-couple these effects. This generally limits the operating process window, and increases the processing time, affecting the plasma etching system throughput potential. Furthermore, the first wafer effect (the process of a first wafer within a same plasma reactor causes changes in the plasma reactor that affect subsequent processes), and the ever present process drift over time (plasma reactors used over a period of time lose their accuracy because of their prolonged usage) are also indications that the control of reactor settings do not solely control what happens inside the chamber and at the wafer.
A need therefore exists for a method and a device that would centralize all the controls with an open architecture allowing real-time communication between the various controllers. Such a device would allow an operator to significantly improve the stability and repeatability of the etch process, and eventually control the parameters directly relevant to the process therefore directly controlling wafer features.
BRIEF DESCRIPTION OF THE INVENTION
A central controller for use in a semiconductor manufacturing equipment integrates a plurality of controllers with an open architecture allowing real-time communication between the various control loops. The central controller includes at least one central processing unit (cpu) executing high level input output (i/o) and control algorithms and at least one integrated i/o controller providing integrated interface to sensors and control hardware. The integrated i/o controller performs basic i/o and low level control functions and communicates with the CPU through a bus to perform or enable controls of various subsystems of the semiconductor manufacturing equipment.
A method for controlling a plurality of sensors and a plurality of control hardware for use in a semiconductor manufacturing equipment loads an application software onto a cpu board that is plugged in a bus. Sensors and control hardware are linked to electrical controllers that are mounted onto a single circuit board which occupies an address block in a memory space of the bus. The single circuit board is then plugged in the bus and the sensors and control hardware are controlled via the application software.
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Kim et al, “Real-Time Diagnosis of Semiconductor Manufacturing Equipment Using a Hybrid Neural Network Expert System,” IEEE, Jan. 1997, pp. 39-47.*
Vivek Bakshi, “Benchmarking Of Commercial Software For Fault Detection and Classification (FDC) Of Plasma Etchers for Semiconductor Manufacturing Equipment,” IEEE, Jun. 1997, pp. 15-79-1582.*
Rashap et al, “Control of Semiconductor Manufacturing Equipment: Real-Time Feedback Control of a Reactive Ion Etcher,” IEEE Aug. 1995, pp. 286-297.
Huang Chung-Ho
Kaveh Farro
Lam Connie
Le Anthony T.
Ngo Tuan
Lam Research Corporation
Lo Thierry K.
Siek Vuthe
Thelen Reid & Priest LLP
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