Vacuum plasma processor and method of operating same

Details Vacuum plasma processor and method of operating same Vacuum plasma processor and method of operating same

2001-03-30

2004-05-25

Sircus, Brian (Department: 2836)

Electricity: electrical systems and devices

Electric charge generating or conducting means

Use of forces of electric charge or field

Reexamination Certificate

active

06741446

ABSTRACT:

FIELD OF INVENTION
The present invention relates generally to vacuum plasma processors and more particularly to a vacuum plasma processor including an electrode array with plural mutually-insulated electrodes forming a bottom or top electrode of the plasma processor.
Another aspect of the invention relates to a vacuum plasma processor including a thermoelectric, Peltier effect arrangement for localized temperature control of workpieces.
An additional aspect of the invention relates to a vacuum plasma processor including a sensor arrangement and method for determining at least one localized processing parameter at different locations of a workpiece and/or plasma.
A further aspect of the invention relates to a vacuum plasma processor for controlling at least one localized electric parameter of a plasma processing workpiece.
Still another aspect of the invention relates to a vacuum plasma processor with control of at least one localized electric parameter of plasma coupled to different locations of a workpiece.
An added aspect of the invention relates to a plasma processor with sensing of workpiece position relative to a chucking electrode array with plural mutually insulated electrodes.
BACKGROUND ART
FIGS. 1 and 2
are schematic diagrams of two types of prior art vacuum plasma processors. The workpiece processor illustrated in
FIG. 1
includes vacuum plasma processing chamber assembly
10
, a first circuit
12
for driving a reactance for exciting ionizable gas in chamber assembly
10
to a plasma state, a second circuit
14
for applying RF bias to a workpiece holder in chamber assembly
10
, and a controller arrangement
16
responsive to sensors for various parameters associated with chamber assembly
10
for deriving control signals for devices affecting the plasma in chamber assembly
10
. Controller
16
includes microprocessor
20
which responds to various sensors associated with chamber assembly
10
, as well as circuits
12
and
14
, and signals from operator input
22
, which can be in the form, for example, of a keyboard. Microprocessor
20
is coupled with memory system
24
including hard disk
26
, random access memory (RAM)
28
and read only memory (ROM)
30
. Microprocessor
20
responds to the various signals supplied to it to drive display
32
, usually a typical computer monitor.
Hard disk
26
and ROM
30
store programs for controlling the operation of microprocessor
20
and preset data associated with different recipes for the processes performed in chamber assembly
10
. The different recipes concern gas species and flow rates applied to chamber assembly
10
during different processes, the output power of AC sources included in circuits
12
and
14
, the vacuum applied to the interior of chamber assembly
10
, and initial values of variable reactances included in matching networks of circuits
12
and
14
.
Plasma chamber assembly
10
includes chamber
40
having metal, non-magnetic cylindrical side wall
42
and metal, non-magnetic base
44
, both of which are electrically grounded. Dielectric, typically quartz, window
46
is fixedly positioned on the top edge of wall
42
. Wall
42
, base
44
and window
46
are rigidly connected to each other by suitable gaskets to enable a vacuum to be established within the interior of chamber
40
. Planar plasma excitation coil
48
, for example, as configured in Ogle, U.S. Pat. No. 4,948,458 or Holland et al., U.S. Pat. No. 5,759,280, sits on or in very close proximity to the upper face of window
46
. Coil
48
, an electric reactance, reactively supplies magnetic and electric AC fields usually at an RF frequency, such as 13.56 MHz, to the interior of chamber
40
, to excite ionizable gas in the chamber to a plasma, schematically illustrated in
FIG. 1
by reference numeral
50
. In other configurations, coil
48
is replaced with a powered or grounded electrode
55
that extends parallel to electrode
56
, typically located in window
46
in close proximity to chamber
40
as illustrated in FIG.
2
.
The upper face of base
44
carries holder, i.e. chuck,
52
for workpiece
54
, which is typically a circular semiconductor wafer or a rectangular dielectric plate such as used in flat panel displays. Robotic arm
53
inside chamber
40
or coupled through a suitable air lab to the chamber interior responds to position control signals microprocessor
20
derives to correctly position workpiece
54
on chuck
52
so the center of the workpiece and chuck are vertically aligned. Microprocessor
20
derives the position control signals in response to position sensors (e.g., photodetectors) for sensing the relative positions of workpiece
54
and chuck
52
. Chuck
52
typically includes metal plate
56
that forms an electrode (a reactive element). Electrode
56
carries dielectric layer
58
and sits on dielectric layer
60
, which is carried by the upper face of base
44
. Workpiece
54
is cooled by supplying helium from a suitable source
62
to the underside of dielectric layer
58
via conduit
64
and grooves (not shown) in electrode
56
and by supplying a liquid from a suitable source (not shown) to conduits (not shown) in chuck
52
. With workpiece
54
in place on dielectric layer
58
, DC source
66
supplies a suitable voltage through a switch (not shown) to electrode
56
to clamp, i.e., chuck, workpiece
54
to chuck
52
. Chuck
52
can be monopolar or bipolar. When chuck
52
is bipolar, and designed for use with semiconductor wafers, electrode
56
includes two or more concentric, mutually-insulated circular metal elements having differing DC voltages applied to them.
With workpiece
54
secured in place on chuck
52
, one or more ionizable gases from one or more sources
68
flow into the interior of chamber
40
through conduit
70
and port
72
. For convenience, port
72
is shown as being in sidewall
42
but it is to be understood that gas usually is distributed by a manifold in the top of chamber
40
. For convenience, only one gas source
68
is shown in
FIG. 1
, but it is to be understood that usually there are several gas sources of different species, e.g. etchants, such as SF
6
, CH
4
, C
12
and HBr, dilutants such as Ar or He, and O
2
as a passivation gas. The interior of conduit
70
includes valve
74
and flow rate gauge
76
for respectively controlling the flow rate of gas flowing through port
72
into chamber
40
and measuring the gas flow rate through port
72
. Valve
74
responds to a signal microprocessor
20
derives, while gauge
76
supplies the microprocessor with an electric signal indicative of the gas flow rate in conduit
70
. Memory system
24
stores for each recipe step of each workpiece
54
processed in chamber
40
a signal indicative of desired gas flow rate in conduit
70
. Microprocessor
20
responds to the signal that memory system
24
stores for desired flow rate and the monitored flow rate signal gauge
76
derives to control valve
74
accordingly.
Vacuum pump
80
, connected to port
82
in base
44
of chamber
40
by conduit
84
, evacuates the interior of the chamber to a suitable pressure, typically in the range of one to one hundred millitorr. Pressure gauge
86
, in the interior of chamber
40
, supplies microprocessor
20
with a signal indicative of the vacuum pressure in chamber
40
. Memory system
24
stores for each step of a particular workpiece processing recipe a signal indicative of desired vacuum pressure for the interior of chamber
40
. Microprocessor
20
responds to the stored desired pressure signal memory system
24
derives for each recipe step and an electric signal from pressure gauge
86
to supply an electric signal to a drive for a gate valve (i.e. variable constriction)
87
in conduit
84
to maintain the pressure in chamber
40
at the set point or predetermined value for each recipe step.
Optical spectrometer
90
monitors the optical emission of plasma
50
by responding to optical energy emitted by the plasma and coupled to the spectrometer via window
92
in side wall
42
. Spectrometer
90
responds to the

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