investigation of laser ablation of cvd diamond film
TRANSCRIPT
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7/31/2019 Investigation of Laser Ablation of CVD Diamond Film
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 1
C. L. CHAO
Investigation of Laser Ablation of CVD
diamond film
1 Tam-Kang University, 2 Chung-Hwa University,
Taiwan, R.O.C
C.L. Chao1*, W.C. Chou1, K.J. Ma2 and Y.T. Chen2
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 2
C. L. CHAO
Application of Diamond Films
Applications Surface Requirement
SAW device Polished surface required
X-ray windows, UV to IR
windows, radomes
Polished surface required
Thermal Spreader for laser,
IC
Polished surface required
Precision cutting tools Smooth/Polished surface required
MEMS Polished surface required
Biological devices Polished surface required
Wear resistant coating on
die.
Polished surface required
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7/31/2019 Investigation of Laser Ablation of CVD Diamond Film
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 3
C. L. CHAO
Comparison of various CVD methods of growing diamond
Method Rate(m/hr) /
Area(cm2)
Adv. Drawbacks
Hot Fi lament
(HFCVD)
0.5~8 / >250 Si mpl e, large
area
Stability,
contamination
Microwave
(MWCVD)
0.1~3 / >6 Quality, Area Expensive, rate
Arc plasma jet
(APJ)
25~ 930 /
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 5
C. L. CHAO
Comparison of Methods
Processing
Temp.Limit. On
dimension
Shape of
processing
cost of process.
equipment/
running cost
Processing
time
Mechanical
lapping
RT Lapping
Pad
Planar L/H days
Thermo-
chemical
Polishing
HT
>650oC
Heating
Zone
Planar depends Hours
Laser
Smoothing
RT Stage Planar/
non-planar
H/H Hours
RIE/Plasma
Assisted
Polishing
HT
>700oC
Chamber Planar/
non-planar
H/H Hours
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 6
C. L. CHAO
Mechanical polishing
10hrs
25hrs
30hrs
20hrs
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7/31/2019 Investigation of Laser Ablation of CVD Diamond Film
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 7
C. L. CHAO
diamond
graphite
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 8
C. L. CHAO
Thermo-mechanically polished CVD Diamond Film
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7/31/2019 Investigation of Laser Ablation of CVD Diamond Film
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 9
C. L. CHAO
Surface morphology of TC-polished CVD diamond film
Polishing Temp. is low, and/or C% of the pad is high
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 10
C. L. CHAO
Surface morphology of TC-polished CVD diamond film
Polishing Temp. is high, and/or C% of the pad is low
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 11
C. L. CHAO
Excimer Laser Machining
Facilities: ArF(193nm) lasers (LPX210)
(1)Laser source (2)45Mirror (3)Homogenizer (4)Field Lens (5)Mask
(6)Condenser Lens (7)Stage (8)Fan (9)Gas Handling (10)Optical Table
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 12
C. L. CHAO
Laser ablated surface
SEM micrographs of the graphitic structure on the surface after ablated by
laser for 8000 shots with a fluence of 2.8 J/cm2 and at a repetition rate of (L)
10Hz and (R) 20Hz.
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 13
C. L. CHAO
Raman spectra of laser ablated diamond film
9 00 1 00 0 1 10 0 1 20 0 1 30 0 1 40 0 1 50 0 1 60 0 1 70 0Raman shift (cm-1)
0
500
1 0 0 0
1 5 0 0
2 0 0 0
2 5 0 0
Intensity,a.u.
As Grown
9 00 1 00 0 1 10 0 1 20 0 1 30 0 1 40 0 1 50 0 1 6 00 1 70 0
Raman shift (cm-1)
0
500
1000
1500
2000
2500
Intensity,a.u.
Laser Ablated (370mj-5hz-8ks )
1332 diamond peak 1332 diamond peak
Raman: Ar+, 514nm, 2m spot size, 2W
Graphite,
Amorphous
Carbon
Nanocrystalline
diamond
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 14
C. L. CHAO
Laser ablated surface
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 15
C. L. CHAO
Excimer laser polished CVD diamond surface(diamond film of 25m thick, repetition rate:10Hz , fluence: 2.9 J/cm2 )
As grown
100 shots 500 shots1000 shots 3000 shots5000 shots 10000 shots
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 16
C. L. CHAO
Roughness vs Shot Number
0 100 500 1000 3000 5000 1 0000
Shot Number
0.08
0.09
0.1
0.110.12
0.13
0.14
0.15
0.16
0.17
0.18
Ra(um)
Ra vs Shot Number
0 100 500 1000 3000 5000 10000
Shot Number
0.5
1
1.5
2
2.5
3
Rt(um)
Rt vs Shot Number
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 17
C. L. CHAO
Excimer laser polished CVD diamond surface(diamond film of 25m thick, repetition rate:10Hz , fluence: 2.9 J/cm2 )
5HzRa:0.14m
Rt:2.5m
10HzRa:0.12m
Rt:1.31m
20HzRa:0.11m
Rt:1.37m
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 18
C. L. CHAO
Excimer laser polished CVD diamond surface(diamond film of 120m thick, fluence: 2.5 J/cm2 )
2Hz,
3000 s hots
As grown4Hz,
3000 shots
6Hz,
3000 shots
10Hz,
3000 shots
8Hz,
3000 shots
10Hz,
5000 shots
10Hz,
4000 shots
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 19
C. L. CHAO
Laser ablated surface
With KOH
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Dept. of Mechanical EngineeringTam-Kang University
Pr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering GroupPr ecision Engineering Group 20
C. L. CHAO
Summary
The higher the fluence and/or the laser pulsenumbers, the higher the ablation rate
Graphitization plays an important role in CVDdiamond films material removal
In the case of CVD diamond film of 25mthickness, laser ablation could improve the surfaceroughness from above 0.4m to around 0.1m ina minute, however scanning would be required tocover a large area,
Unless ventilation system is improved, addingKOH makes the laser ablation a rather messyprocess.