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63rd GEC & 7th ICRP, QR2_2
Thurs. 7th Oct. '10, 16:30
Simulations of an Ar/HBr microwave source etch
process and the effect of SiBr and SiBr2 cross-sections.
Dr. James Munro
Dr. Song-Yun Kang
Prof. Jonathan Tennyson,
Mr. Stephen Harrison
Global Model
Electron Chemistry
Reactor Model
Process and Tool
Development
Measurement,
Experimentation
Data Data
Informs Informs Validates Validates
Modeling polyatomic electron-molecule interactionsWhat does Quantemol-N do? Elastic cross sections Electronic excitation cross sections Electron impact dissociation Rates Resonance parameters Eigenphase sums Ionisation cross sections Dissociative electron attachment Differential cross sections Momentum transfer cross sections Vibrational excitation cross sections
Tennyson et. al., J. Phys. Conf. Ser. 86, 012001 (2007)
The R-Matrix Method• The sphere, of radius a, has
the centre of mass of the molecule as its origin;
• the sphere contains the electron cloud of the molecule;
• equations of motion are solved in the body-fixed frame (fixed nuclei approximation)
r
e-
How does Quantemol-N work?
Tennyson, Phys. Rep. 491 (2010) 29-76
CF2 C6H6 C5H12 SiH4
Cl2 C3H4 NO2 C2H6
O2 C2 NO C3H8
H2O C3H6 O3 HCN
H3+ CaF+ PH3 HNC
CH4 CaF BF3 SiO
C3N CF N2 CS
Cl2O CO2 CO F2
CONH3 BF3 H2 HBr
Progress...
... and more.
CF2
CF4/O2 CCP etch
0-D plasma simulation CCP etching chamberSCCM
Simulation
0.0E+00
2.0E+11
4.0E+11
6.0E+11
8.0E+11
1.0E+12
1.2E+12
1.4E+12
1.6E+12
1.8E+12
2.0E+12
0 500 1000 1500 2000
Power (W)
CF2 (
#/cm
3)
Original
CF2*
0.0E+00
1.0E+11
2.0E+11
3.0E+11
4.0E+11
5.0E+11
6.0E+11
7.0E+11
8.0E+11
9.0E+11
0 500 1000 1500 2000
Power (W)
CF (
#/cm
3)
Original
CF2*
0.0E+00
2.0E+13
4.0E+13
6.0E+13
8.0E+13
1.0E+14
1.2E+14
1.4E+14
0 500 1000 1500 2000
Power (W)
F (
#/cm
3)
Original
CF2*
CF2
CF
F
T. Mori, M.Sasaki, T Nishizuka and T. Nozawa, 55th AVS, PS-TuM10
T. Mori, M.Sasaki, T Nishizuka and T. Nozawa, 55th AVS, PS-TuM10
12Reaction model
-Charged species: e-, Br-, Ar+, HBr+, Br+, Br2+, SiBr2
+, and SiBr+
-Neutral species: Ar, Ar*, HBr, Br, Br2, H2, H, SiBr2, SiBr, and Si
-Electron impact reactions: Ionization, excitation, dissociation,
attachment, and recombination
-Ion – neutral reactions
-Ion – ion reactions
-Molecule – molecule reactions
SiBr2+, SiBr+, SiBr, and Si are omitted in case
without SiBrx reactions.
13
SiBr49 Electrons
Bond length: 2.641 Ang.
0.1
1
10
100
1000
0 2 4 6 8 10 12 14 16 18 20
Cross -
secti
on
(an
g.
sq
rd
.)
Energy (eV)
Ionisation Elastic
Dissociative impact Dissociative Attachment
e + SiBr >
SiBr284 Electrons
Bond length: 2.039 Ang.
Bond Angle: 122.8 Deg.
1E-06
1E-05
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
0 2 4 6 8 10 12 14 16 18 20
Cro
ss
-secti
on
(an
g.
sq
rd.)
Energy (eV)
Elastic Dissociative impact
Dissociative Attachment Ionisation
e + SiBr2 >
17
Open
H
Br
H
H
Br
H
Br
Br
H2
HBr
HBr
Br2
Surface reactions with Walls
18
Si
SiBrSiBr2
SiBr
Br
H HBr
Ion SiBrIon SiBr2
SiBr2
Br2
SiH
SiBr
Br
Br2 Br
H HBr
SiBr SiBr2
Si SiBr
HH H2
Br HBr
Surface reactions with wafer
SiBrSiBrSiSiSiBrSiBrSiSiBrSiBriisER 22
/
19
Simulation model
• Comsol
• Gas flow
• Electron temperature
• Charged particles
• Neutral particles
Jozef Brcka, Song-Yun Kang,
Plasma Process. Polym. 2009, 6, S776–S783
20
Microwave
Wafer
Stage with rf bias
Gases
inlet
Pumping
out
Gas flow
21e- Br- SiBr2
With
SiBrx
reactions
Without
SiBrx
reactions
Electron distributions are localized near top, because microwave heat comes from top.
Br negative ion produced both inlet and near wafer because of attachment reaction of SiBrx.
SiBr2 in case with SiBrx reactions is localized near wafer because there are reactions of SiBr2.
5.0e11
Number is
maximum
[#/cm3]
1.6e13
4.6e111.5e13
1.9e13
6.6e13
100 mTorr
22 SiBr Si
SiBr2+ SiBr+
SiBr2
SiBr and Si are produced from SiBr2 and SiBr respectively.
Ions produced from byproducts are localized near wafer which is dominant ions attack to
wafer.
1.8e13
Number is
maximum
[#/cm3]
1.9e13
2.3e11
5.7e12
4.7e11
100 mTorr
23
0.0E+00
1.0E+15
2.0E+15
3.0E+15
4.0E+15
5.0E+15
Ar+ Br+ HBr+ SiBr+ Br2+ SiBr2+
Flu
x (#
/cm
2 s
)
40
70
80
100
0.0E+00
5.0E+15
1.0E+16
1.5E+16
2.0E+16
2.5E+16
Ar+ Br+ HBr+ SiBr+ Br2+ SiBr2+
Flu
x (#
/cm
2 s
)
40
70
80
100
Ion fluxes on wafer
Including SiBrx
reactions
Without SiBrx
reactions
24
o Ion mass gets heavier as pressure
increases
o Ion fluxes and energies will change
significantly with pressure in this
collisional sheath.
0
30
60
90
120
150
180
0 50 100 150
Pressure (mTorr)
Ave
rage
mas
s of
ions
with SiBr2 reaction
without SiBr2reactions
25
Specific conclusions:
o SiBr1,2 molecular data is critical in the correct understanding
of this etch process.
o SiBr1,2 ions are important in determining the etch profile and
have pressure dependant concentrations (and therefore
fluxes and energies).
o Cross-sections with SiBr4 and SiBr3 could be included.
o SiBr3,4 are not expected to be important etch products
o Ions of SiBr3,4 could be important however.
General conclusions:
o The availability of molecular data is critical to understanding
the gas-phase.
o ...and therefore what arrives at the surface.
o Cross-sections can and have been calculated on demand for
these applications.
Thank you for listening
With thanks also to:
Dr. Josef Brcka (for 2D Comsol model)
T. Mori, M.Sasaki, T Nishizuka and T. Nozawa (for experiment)
Brought to you by:
Dr. James Munro
Prof. Jonathan Tennyson,
Mr. Stephen Harrison
Dr. Song-Yun Kang
Methane