pt as a release layer for ixo thermally formed glass optics: preliminary results s. romaine, r....

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)