pt as a release layer for ixo thermally formed glass optics: preliminary results s. romaine, r....
TRANSCRIPT
Pt as a release layer for IXO thermally formed glass optics: preliminary results
S. Romaine, R. Bruni, P. Gorenstein, S. Park, P.ReidHarvard-Smithsonian Center for Astrophysics
Platinum and boron nitride are two of the materials being considered as release layers for thermally slumping glass substrates for IXO. SAO is investigating the use of platinum as a release layer for IXO glass substrates. Recent experimental results using dc magnetron sputtered platinum coatings will be presented.
Process• Clean substrates• dc magnetron deposit ~ 450 Å Pt on glass• Characterize (XRR, AFM, WYKO)• Thermal anneal – flat mandrel (fused silica)• Characterize (XRR, AFM, WYKO)
Test Substrates: D263 schott glass
400 µm thick
5cm diameter
SAO Coating Facility
R&D chamber – small substratesChamber I.D. = 23.5 in. ; height = 13 inTurbo pump, base pressure = 1x10-7 Torr
RandD Chamber Cross Section
Magnetron1 Magnetron2
Substrate1 Substrate2
Variable Height Rotary Platen
D263 Slumping Temperature Profiles
50
150
250
350
450
550
650
0 5 10 15 20 25 30 35 40 45 50
Time (Hrs)
Tem
per
atu
re (
C)
Elongated (Post-08Aug07)
54 hour slumping cycle
17.5 cm diameter fused silica flat mandrel
5 cm diameter D263 coated glass
Max temp = 580
Pre vs. Post slumped 8 keV XRR data
Graze angle (deg)
Red = pre-slump data; Green = post-slump data
8 keV XRR data - taken at SAO XRR facility
Data Fit using D. Windt IMD software
8 keV XRR data+ models 525 Å thick Pt film on D263 400 µr thick glass substrate
Model:
µr(Pt) = 5.5 Å
µr(sub) =4.0 Å
Model:
µr(Pt) = 14.0 Å
µr(sub) = 7.0 Å
Pre-slump Post-slump
Graze angle (deg) Graze angle (deg)R
efle
ctiv
ity
Ref
lect
ivity
Red = data
Green = model
Red = data
Green = model
3 µm AFM scans: uncoated, pre-slump, post-slump
Uncoated D263, µr =2.1
Pt coated, pre-slump, µr =4.0
Pt coated, post-slump, µr =9.1
AFM 1 µm scans: Uncoated, Pre-slump, Post-slump
Uncoated D263
Pt coated, pre-slump
Pt coated, post-slump
XRR
(Å)
**WYKO
(Å)
AFM
(Å)Pre Post Pre post Pre-slumped Post-slumped
1µm scan
3µm
scan
10µm scan
1µm
scan
3µm
scan
10µm
scan
1a 5.5 14 1.9 2.1 -- 3.2 3.5 7 7 10
2a 5.0 15.5 1.7 2.0 3.4 3.2 3.1 7.5 10 13
3a 5.0 14.0 2.3 1.8 -- 4.4 3.1 7 9 11
6b 4.5 13 1.3 1.6 -- 2.8 2.6 7.5 7 14
*5b 4.5 n/a 1.6 1.8* 4.1 4.1 4.1 4 4 4.5
D263-bare
3.0 1.7 1.6 2 2 2.6 n/a n/a n/a
*Sample 5b was a control sample. It was coated with Pt and characterized, but was not slumped** all WYKO data taken at MSFC (B.Ramsey, T. Kester)
Microroughness data for Pt films pre and post slumping
Summary
• These are first – preliminary - results of this study• Obvious advantages if release layer is also X-ray reflector –• M.Ghigo/G. Pareschi found smaller effect (of roughness) with
thicker substrates• Work continues …….
END
XRR
Z (Å) ρPt (%) ρsub (%) σPt (Å) σsub(Å)
1a pre 526 99 100 5.5 4.0
post 522 97 100 14.0 7.0
2a pre 448 99 100 5.0 5.0
post 441 91 100 14.7 7.0
3a pre 466 99 100 5.0 5.0
post 465 97 100 14.0 7.0
6b pre 483 99 100 4.5 5.0
post 485 97 100 13 7.0
5b 378 99 100 4.5 5.0
Pt on 400 µm D263
3 µm scan 10 µm scan(Preslumped)