1. Testbed for Plasma-Wall and Etch Product Studies
SFR Workshop
May 24, 2001
Matthew Radtke, John Coburn, David Graves
Berkeley, CA
2001 GOAL: Construction and testing of apparatus for
etching and etch byproduct studies by 9/30/2001.
5/24/2001

2. Motivation Etch products often play major role in etch chemistry
System designed to study role of etch products.
Plasma and surface diagnostics combined.
Model studies require data: system measures all neutral and ionic species impacting surfaces.
N2 and Ar/c-C4F8 plasma diagnostics reported.
5/24/2001

3. Experimental Apparatus
5/24/2001

4. Etch Chamber (side view)
5/24/2001

5. Measurement Diagnostic
Diagnostics
Measured Quantity
Measurement Diagnostic
pressure
pressure gauge
radical and neutral densities
quadrupole mass spectrometer
(appearance potential mass spectrometry)
ion composition
electron density
Langmuir probe
electron energy distribution
(electron temperature)
plasma potential
average neutral temperature
optical emission
wall temperature
thermocouple
* mass spectrometer measurements are at wall
* Langmuir probe can measure profile
5/24/2001

6. Illustration of Diagnostics:
N2 plasma
5/24/2001

7. Neutral Densities: Ar/c-C4F8 plasma
Radical densities from APMS
5/24/2001

8. Langmuir probe measurements: Ar/c-C4F8 plasma
Ion Densities and
Langmuir probe measurements: Ar/c-C4F8 plasma
P(mTorr)
<Te(eV)>
kdiss(10-8cm3/s) 1
6.42
2.93 3
4.87
1.86 10
3.38
0.776
* Morgan, L. (2000)
- theoretical C4F8 total dissociation cross section calculation
5/24/2001

9. 2002-2003 Milestones Studies of plasma-wall interactions
(e.g. Si/O/Cl for gate/trench etch)
Studies of new high-K and gate stack etching
(e.g. etch precursors, by-products, selectivity)
Studies of plasma surface interactions
(e.g. N2 plasma: PET; NF3 plasma: elastomer)
5/24/2001