Development and Optimization of highly transparent SiO 2 films by using Hot Wire CVD (HWCVD) 7 th European DoE User Meeting, Paris, June 7-8, 2018

Transcription

1 Development and Optimization of highly transparent SiO 2 films by using Hot Wire CVD (HWCVD) 7 th European DoE User Meeting, Paris, June 7-8, 2018 Markus Höfer Tino Harig Madeleine Justianto Hendrik Thiem Lothar Schäfer Volker Sittinger Michael Vergöhl Department Chemical Vapour Deposition Fraunhofer IST, Braunschweig, Germany This work was supported by the Fraunhofer Internal Programs under Grant No. Discover

2 Outline Introduction to Fraunhofer Motivation of the study The HWCVD process in the presence of oxygen Initial planning as Split-Plot-Design The most important factor not part of the design! Unexpected outcome allows huge simplification Augmentation and multi response optimization Application of optimized SiO 2 films in AR coating Conclusions

3 The Fraunhofer-Gesellschaft The Fraunhofer-Gesellschaft is the largest organization for applied research in Europe. It undertakes applied research of direct utility to private and public enterprise and of wide benefit to society. Page 3 Fraunhofer offen

4 The Fraunhofer-Gesellschaft at a Glance The Fraunhofer-Gesellschaft undertakes applied research of direct utility to private and public enterprise and of wide benefit to society staff 2.3 billion 2.0 billion Major infrastructure capital expenditure and defense research Almost 30% is contributed by the German federal and Länder Governments. 72 institutes and research units Finance volume Contract Research 2017 More than 70% is derived from contracts with industry and from publicly financed research projects. Page 4 Fraunhofer offen

5 Motivation High quality transparent thin films are used in many (optical) applications Barrier Electrical insulation, transparent conductive oxides Optical Filters (selective transmission/reflection, AR) I R 1 R 2 Interference: 2nd cos(α)=mλ (constructive) 2nd cos(α)=(m-1)λ (destructive) Interference condition only valid for one wavelength λ and/or one angle α Single Layer AR-Coating d, n Substrate

6 Motivation High quality transparent thin films are used in many (optical) applications Barrier Electrical insulation, transparent conductive oxides Optical Filters (selective transmission/reflection, AR) uncoated glass I R 1 R 2 R 3 R 4 R 5 Multi Layer AR-Coating low n high n low n high n SiO 2 n.a. Si 3 N 4 SiO 2 n.a. Si 3 N 4 1 layer 2 layers 4 layers Substrate

7 Motivation High quality transparent thin films are used in many (optical) applications Barrier Electrical insulation, transparent conductive oxides Optical Filters (selective transmission/reflection, AR) Combination HW-SiO 2 with HW-SiN films will allow to use HWCVD for the fabrication of optical filters

8 Hot wire CVD of silicon oxide films SiH 4 + O 2 p 1 mbar hot wires C SiH 4 (g)+o 2 (g) SiO 2 (s)+2h 2 (g) Oxidation of W wires 4W(s) + 12O 2 (g) 4WO 3 (g) SiO x (x=2?) substrate 500 C kinetics & transport SiO x film Page 8 Fraunhofer

9 Oxidation of Tungsten Light bulb with W-filament Page 9 Fraunhofer

10 Oxidation of Tungsten opening Light bulb with W-filament Page 10 Fraunhofer

11 Oxidation of Tungsten C 4W + 3O 2 (g) 2W 2 O 3 tungsten(iii)-oxide 2W 2 O 3 + O 2 (g) 4WO 2 tungsten(iv)-oxide, T m <1730 C 4WO 2 + 2O 2 (g) 4WO 3 tungsten(vi)-oxide, T m =1473 C Page 11 Fraunhofer

12 Oxidation of Tungsten C 4W + 3O 2 (g) 2W 2 O 3 tungsten(iii)-oxide 2W 2 O 3 + O 2 (g) 4WO 2 tungsten(iv)-oxide, T m <1730 C 4WO 2 + 2O 2 (g) 4WO 3 tungsten(vi)-oxide, T m =1473 C Page 12 Fraunhofer SiO 2 with HWCVD, a crazy idea?

13 Motivation High quality transparent thin films are used in many (optical) applications Barrier Electrical insulation, transparent conductive oxides Optical Filters (selective transmission/reflection, AR) Combination HW-SiO 2 with HW-SiN films will allow to use HWCVD for the fabrication of optical filters Risk of wire oxidation Incorporation of wire material into the growing films deterioration of film properties instable deposition processes

14 Previous studies n>2.4 Hot wire-cvd deposited a-sio x and its characterization Y. Matsumoto, Thin Solid Films 501 (2006) Only SiO x, x<2 films with high absorption and n >>1.47

15 HWCVD deposition system 7 chambers: 3 hot-wire reactors 600 mm x 500 mm length: 11.2 m Deposition of intrinsic and doped Si-based films in independent reactor chambers Investigation of production-like process chains

16 Design of Experiments Factors and Levels 4 different wire setups! split-plot design low high Type 1 Aa Wire-Diameter [mm] 0,25 0,5 hard to change 2 Bb Wire-Distance [mm] hard to change 3 C T_Wire [ C] easy to change 4 D SiH4-Flow [sccm] 50 easy to change 5 E Pressure [Pa] 1,5 3,5 easy to change 6 F T_Start [ C] easy to change Notice: O 2 gas flow as most important factor is not part of the design!

17 Wire setups influence on substrate temperature Deposition Area: 50 x 60 cm 2 Cold! Medium 50 mm (10 wires) S1 S3 b: wire distance 30 mm (17 wires) S2 S4 Medium 0.25 mm 0.50 mm a: wire diameter Hot!

18 Design of Experiments Split Plot Design: 2 (6-1) (4 Setups) Generator: I=abCDEF

19 Design of Experiments Power of 2 (6-1) Split-Plot-Designs

20 Design of Experiments Power of 2 (6-1) Split-Plot-Designs hard to change (8 sets) hard to change (4 sets)

21 S1 S3 S4 S2

22 Design of Experiments Alias Structure 2 (6-1) factorial, 32 Runs, Res V with generator I=abCDEF [a] = a [b] = b [C] = C Cold! Medium [D] = D [E] = E [F] = F [ab] = ab 50 mm (10 wires) S1 S3 [ac] = ac [ad] = ad [ae] = ae [af] = af b: wire distance [bc] = bc [bd] = bd [be] = be [bf] = bf 30 mm (17 wires) S2 S4 [CD] = CD [CE] = CE [CF] = CF [DE] = DE [DF] = DF [EF] = EF Medium 0.25 mm 0.50 mm a: wire diameter Hot!

23 Design of Experiments Alias Structure 2 (5-1) factorial, 16 Runs, Res V with generator I=bCDEF [b] = b [C] = C Cold! Medium [D] = D [E] = E [F] = F 50 mm (10 wires) S1 S3 [bc] = bc + DEF [bd] = bd + CEF [be] = be + CDF [bf] = bf + CDE [CD] = CD + bef [CE] = CE + bdf [CF] = CF + bde b: wire distance 30 mm (17 wires) S2 S4 [DE] = DE + bcf [DF] = DF + bce [EF] = EF + bcd Medium 0.25 mm 0.50 mm Hot! a: wire diameter

24 Design of Experiments Alias Structure 2 (5-1) factorial, 16 Runs, Res V with generator I=aCDEF [a] = a [C] = C Cold! Medium [D] = D [E] = E [F] = F 50 mm (10 wires) S1 S3 [ac] = ac + DEF [ad] = ad + CEF [ae] = ae + CDF [af] = af + CDE [CD] = CD + aef [CE] = CE + adf [CF] = CF + ade b: wire distance 30 mm (17 wires) S2 S4 [DE] = DE + acf [DF] = DF + ace [EF] = EF + acd Medium 0.25 mm 0.50 mm Hot! a: wire diameter

25 Design of Experiments Alias Structure 2 (4-1) factorial, 8 Runs, Res IV with generator I= CDEF [C] = C [D] = D Cold! Medium [E] = E [F] = F [CD] = CD - EF 50 mm (10 wires) S1 S3 [CE] = CE - DF [CF] = CF - DE b: wire distance 30 mm (17 wires) S2 S4 Medium 0.25 mm 0.50 mm a: wire diameter Hot!

26 Design of Experiments Alias Structure 2 (4-1) factorial, 8 Runs, Res IV with generator I=+CDEF [C] = C [D] = D Cold! Medium [E] = E [F] = F [CD] = CD + EF 50 mm (10 wires) S1 S3 [CE] = CE + DF [CF] = CF + DE b: wire distance 30 mm (17 wires) S2 S4 Medium 0.25 mm 0.50 mm a: wire diameter Hot!

27 Design of Experiments Alias Structure 2 (4-1) factorial, 8 Runs, Res IV with generator I=+CDEF [C] = C [D] = D Cold! Medium [E] = E [F] = F [CD] = CD + EF 50 mm (10 wires) S1 S3 [CE] = CE + DF [CF] = CF + DE b: wire distance 30 mm (17 wires) S2 S4 Medium 0.25 mm 0.50 mm a: wire diameter Hot!

28 Design of Experiments Alias Structure 2 (4-1) factorial, 8 Runs, Res IV with generator I= CDEF [C] = C [D] = D Cold! Medium [E] = E [F] = F [CD] = CD - EF 50 mm (10 wires) S1 S3 [CE] = CE - DF [CF] = CF - DE b: wire distance Let s start with the most attractive but most challenging wire setup and see what happens! Randomized 2 (4-1) factorial 30 mm (17 wires) Medium S2 S mm 0.50 mm a: wire diameter Hot!

29 Design of Experiments - Results FACTORS Opt. Transm. Dektak Spectrometer Ellipsometrie EPMA AFM Transmission Quarz Run# Process# T wire SiH4 flow p T 0 O2 flow O2 / SiH4 t dep thickness rate T 250 MW n 550 k 550 Roughness film stress [W] Ra MW MW T350 [ C] [sccm] [Pa] [ C] [sccm] [%] [s] [nm] [nm/s] [%] [%] - - [nm] [Mpa] [mass%] [nm] %T %T % 1 IL , ,54 80,79 92,04 1,4875 0,0022 8,4-225,8 0,43 2,22 91,02 92,44 91,38 2 IL , ,88 74,93 91,23 1,485 0, ,9-172,2 4,26 2,94 90,91 92,27 90,79 3 IL , ,60 75,84 91,31 1,497 0,0023 7,8-313,3 2,68 2,28 89,96 91,59 88,95 4 IL , , ,03 65,23 89,58 1,398 0, ,0 20,0 11,72 6,44 89,09 91,69 87,15 5 IL , ,69 83,36 92,14 1,491 0,0013 6,5-260,1 2,27 2,25 91,96 92,78 91,7 6 IL , ,00 77,31 91,07 1,481 0,0048 8,5-309,1 3,62 2,33 90,39 91,83 89,86 7 IL , ,98 84,98 92,46 1,484 0,0006 8,3-250,4 1,32 1,98 92,14 92,75 91,73 8 IL , ,45 83,81 92,37 1,479 0, ,0-177,4 2,34 2,46 92,21 92,93 91,85 9 IL , ,54 63,23 87,95 1,493 0, ,8-142,0 9,72 3,04 88,44 91,09 86,94 10 IL , ,13 88,94 93,11 1,466 0, ,3-168,7 0,08 2,34 92,98 93,22 92,89 11 IL , ,67 84,84 92,14 1,484 0,0010 4,3-244,3 1,56 1,92 91,97 92,61 91,91 For each factor setting O 2 gas flow is varied to achieve optimum transmission!

30 OFAT: Influence of O 2 gas flow on transparency 0% (120 sccm SiH sccm O 2 ) 33% (120 sccm SiH sccm O 2 ) 67% (120 sccm SiH sccm O 2 ) Evaluation by UV-VIS- Spectrometer (O 2 flow) / (SiH 4 flow)=% (120 sccm SiH sccm O 2 )

31 Influence of O 2 gas flow on transparency Quartz opt. O 2 flow T wire =1900 C, SiH 4 flow= 50 sccm, p=3.5 Pa, T 0 =140 C

32 Influence of process parameters on transparency Quartz opt. O 2 flow

33 Influence of process parameters on W concentration x50 opt. O 2 flow

34 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm nm Half-Normal Plot W-Concentration Half-Normal Plot Half-Normal % Probability Design-Expert Software T(250 nm) [%] Error estimates A: Tfil [ C] B: SiH4 flow [sccm] C: p [Pa] D: T_0 [ C] Positive Effects Negative Effects CD+AB B-SiH4 flow [sccm] C-p [Pa] D-T_0 [ C] BC+AD Half-Normal % Probability Design-Expert Software [W] [mass%] Error estimates Shapiro-Wilk test W-value = 0,826 p-value = 0,158 A: Tfil [ C] B: SiH4 flow [sccm] C: p [Pa] D: T_0 [ C] Positive Effects Negative Effects A C-p [Pa] B-SiH4 flow [sccm] BC+AD A ,00 2,35 4,69 7,04 9,38 0,00 0,60 1,19 1,79 2,38 2,98 3,57 4,17 4,76 Standardized Effect Standardized Effect

35 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm nm W-Concentration T(250 nm) [%] [W] [mass%] B: SiH4 flow [sccm] D: T_0 [ C] B: SiH4 flow [sccm] D: T_0 [ C] T fil =1900 C, P=3.5 Pa

36 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm nm W-Concentration T(250 nm) [%] [W] [mass%] B: SiH4 flow [sccm] D: T_0 [ C] B: SiH4 flow [sccm] D: T_0 [ C] T fil =2 C, P=3.5 Pa

37 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm nm W-Concentration T(250 nm) [%] [W] [mass%] B: SiH4 flow [sccm] D: T_0 [ C] B: SiH4 flow [sccm] D: T_0 [ C] T fil =2 C, P=1.5 Pa

38 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm nm W-Concentration very nice! T(250 nm) [%] [W] [mass%] 10 8 very nice! B: SiH4 flow [sccm] D: T_0 [ C] B: SiH4 flow [sccm] D: T_0 [ C] T fil =1900 C, P=1.5 Pa

39 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm nm W-Concentration 3 Centers above! T(250 nm) [%] [W] [mass%] Centers below! B: SiH4 flow [sccm] p-value for curvature: D: T_0 [ C] B: SiH4 flow [sccm] T fil =2000 C, P=2.5 Pa D: T_0 [ C] p-value for curvature: 0.02

40 DOE analysis of 2 (4-1) factorial for 10 wires with 0,25 mm Results Setup with 0.25 mm Wires works stable and enables SiO 2 films with very high transparencies even in UV (comparable to quartz substrates!) and low tungsten contaminations Increase of substrate temperature reduces transparency! Wire setups with thicker or more wires do not make any sense! De-aliasing of 2FI is required! Investigation of non-linear effects for predictive models! Enlargement of design space to higher SiH 4 gas flows recommended (higher deposition rates!)

41 2 (4-1) factorial for 10 wires with 0,25 mm Cube T(250 nm) [%] 79, ,3241 B+: ,668 82,2859 Original 2 (4-1) factorial I= ABCD B: SiH4 flow [sccm] 72, ,9254 C+: 3,5 C: p [Pa] B-: 50 79, ,8873 C-: 1,5 D-: 140 D+: 360 D: T_0 [ C] T fil =1900 C

42 Augmentation of 2 (4-1) factorial for 10 wires with 0,25 mm Augmentation I=+ABCD Original 2 (4-1) factorial I= ABCD B+: 150 B: SiH4 flow [sccm] 86,668 Cube T(250 nm) [%] 79, , , , ,9254 B-: 50 79, ,8873 C-: 1,5 D-: 140 D+: 360 D: T_0 [ C] T fil =1900 C C: p [Pa] C+: 3,5 Term VIF A 1,13 B 1,09 C 1,13 D 1,13 AB 1,06 AC 1,13 AD 1,13 BC 1,06 BD 1,06 CD 1,13 B 2 1,05

43 Augmentation of 2 (4-1) factorial for 10 wires with 0,25 mm FACTORS Opt. Transm. Dektak Spectrometer Ellipsometrie EPMA Run# Process# T wire SiH4 flow p T 0 O2 flow O2 / SiH4 t dep thickness rate T 250 MW n 550 k 550 [ C] [sccm] [Pa] [ C] [sccm] [%] [s] [nm] [nm/s] [%] [%] - - [nm] [Mpa] [mass%] 1 IL , ,54 80,79 92,04 1,4875 0,0022 8,4-225,8 0,43 2 IL , ,88 74,93 91,23 1,485 0, ,9-172,2 4,26 3 IL , ,60 75,84 91,31 1,497 0,0023 7,8-313,3 2,68 4 IL , , ,03 65,23 89,58 1,398 0, ,0 20,0 11,72 5 IL , ,69 83,36 92,14 1,491 0,0013 6,5-260,1 2,27 6 IL , ,00 77,31 91,07 1,481 0,0048 8,5-309,1 3,62 7 IL , ,98 84,98 92,46 1,484 0,0006 8,3-250,4 1,32 8 IL , ,45 83,81 92,37 1,479 0, ,0-177,4 2,34 9 IL , ,54 63,23 87,95 1,493 0, ,8-142,0 9,72 10 IL , ,13 88,94 93,11 1,466 0, ,3-168,7 0,08 11 IL , ,67 84,84 92,14 1,484 0,0010 4,3-244,3 1,56 Roughness film stress [W] Term VIF A 1,13 B 1,09 C 1,13 D 1,13 AB 1,06 AC 1,13 AD 1,13 BC 1,06 12 IL , ,76 84,54 93,27 1,464 0, ,3-167,4 1,09 13 IL , ,02 80,76 92,96 1,484 0,0006 6,9-284,8 0,63 14 IL , ,09 68,58 92,02 1,514 0,0024 9,3-353,9 3,92 15 IL , ,67 88,35 93,28 1,477 8,8 231,8 0,22 16 IL , ,91 87,14 93,41 1,469 0, ,9-175,3 0,01 17 IL , ,62 79,51 92,85 1,495 0,0013 9,9-253,5 BD 1,06 CD 1,13 B 2 1,05

44 2 nd Augmentation of 2 (4-1) factorial for 10 wires with 0,25 mm FACTORS Opt. Transm. Dektak Spectrometer Ellipsometrie EPMA Run# Process# T wire SiH4 flow p T 0 O2 flow O2 / SiH4 t dep thickness rate T 250 MW n 550 k 550 [ C] [sccm] [Pa] [ C] [sccm] [%] [s] [nm] [nm/s] [%] [%] - - [nm] [Mpa] [mass%] 1 IL , ,54 80,79 92,04 1,4875 0,0022 8,4-225,8 0,43 2 IL , ,88 74,93 91,23 1,485 0, ,9-172,2 4,26 3 IL , ,60 75,84 91,31 1,497 0,0023 7,8-313,3 2,68 4 IL , , ,03 65,23 89,58 1,398 0, ,0 20,0 11,72 5 IL , ,69 83,36 92,14 1,491 0,0013 6,5-260,1 2,27 6 IL , ,00 77,31 91,07 1,481 0,0048 8,5-309,1 3,62 7 IL , ,98 84,98 92,46 1,484 0,0006 8,3-250,4 1,32 8 IL , ,45 83,81 92,37 1,479 0, ,0-177,4 2,34 9 IL , ,54 63,23 87,95 1,493 0, ,8-142,0 9,72 10 IL , ,13 88,94 93,11 1,466 0, ,3-168,7 0,08 11 IL , ,67 84,84 92,14 1,484 0,0010 4,3-244,3 1,56 12 IL , ,76 84,54 93,27 1,464 0, ,3-167,4 1,09 13 IL , ,02 80,76 92,96 1,484 0,0006 6,9-284,8 0,63 14 IL , ,09 68,58 92,02 1,514 0,0024 9,3-353,9 3,92 15 IL , ,67 88,35 93,28 1,477 8,8 231,8 0,22 16 IL , ,91 87,14 93,41 1,469 0, ,9-175,3 0,01 17 IL , ,62 79,51 92,85 1,495 0,0013 9,9-253,5 18 IL , ,15 77,94 92,71 1,502 0,0016 8,0-262,6 19 IL , ,96 81,23 92,98 1,494 0,0011 8,9-256,5 20 IL , ,96 79,71 92,78 1,503 0,0011 6,9-267,1 21 IL , ,25 73,48 92,41 1,499 0,0022 9,8 22 IL , ,60 78,16 92,67 1,498 0,0014 5,3-246,5 Roughness film stress [W] Term VIF A 1,18 B 1,12 C 1,19 D 1,19 AB 1,13 AC 1,12 AD 1,12 BC 1,08 BD 1,08 CD 1,13 A 2 2,47 B 2 1,35 C 2 3,51 D 2 3,51

45 2 nd Augmentation of 2 (4-1) factorial for 10 wires with 0,25 mm FACTORS Opt. Transm. Dektak Spectrometer Ellipsometrie EPMA Run# x Process# T wire SiH4 flow p T 0 O2 flow O2 / SiH4 t dep thickness rate T 250 MW n 550 k 550 [ C] [sccm] [Pa] [ C] [sccm] [%] [s] [nm] [nm/s] [%] [%] - - [nm] [Mpa] [mass%] 1 IL , ,54 80,79 92,04 1,4875 0,0022 8,4-225,8 0,43 2 IL , ,88 74,93 91,23 1,485 0, ,9-172,2 4,26 3 IL , ,60 75,84 91,31 1,497 0,0023 7,8-313,3 2,68 4 IL , , ,03 65,23 89,58 1,398 0, ,0 20,0 11,72 x5 IL , ,69 83,36 92,14 1,491 0,0013 6,5-260,1 2,27 6 IL , ,00 77,31 91,07 1,481 0,0048 8,5-309,1 3,62 7 IL , ,98 84,98 92,46 1,484 0,0006 8,3-250,4 1,32 8 IL , ,45 83,81 92,37 1,479 0, ,0-177,4 2,34 9 IL , ,54 63,23 87,95 1,493 0, ,8-142,0 9,72 10 IL , ,13 88,94 93,11 1,466 0, ,3-168,7 0,08 11 IL , ,67 84,84 92,14 1,484 0,0010 4,3-244,3 1,56 x 12 IL , ,76 84,54 93,27 1,464 0, ,3-167,4 1,09 13 IL , ,02 80,76 92,96 1,484 0,0006 6,9-284,8 0,63 14 IL , ,09 68,58 92,02 1,514 0,0024 9,3-353,9 3,92 15 IL , ,67 88,35 93,28 1,477 8,8 231,8 0,22 16 IL , ,91 87,14 93,41 1,469 0, ,9-175,3 0,01 17 IL , ,62 79,51 92,85 1,495 0,0013 9,9-253,5 x 18 IL , ,15 77,94 92,71 1,502 0,0016 8,0-262,6 19 IL , ,96 81,23 92,98 1,494 0,0011 8,9-256,5 20 IL , ,96 79,71 92,78 1,503 0,0011 6,9-267,1 21 IL , ,25 73,48 92,41 1,499 0,0022 9,8 22 IL , ,60 78,16 92,67 1,498 0,0014 5,3-246,5 x Roughness film stress [W] Term VIF A 1,18 B 1,15 C 1,22 D 1,22 AB 1,13 AC 1,12 AD 1,12 BC 1,09 BD 1,09 CD 1,12 A 2 1,32 B 2 1,19 C 2 1,79 D 2 1,79

46 Results of the augmented D-optimal design T fil =2 C p=3.5 Pa T fil =2 C T(250 nm) [%] [W] [mass%] D: T0 [ C] D: T0 [ C] B: SiH4 flow [sccm] B: SiH4 flow [sccm]

47 Results of the augmented D-optimal design T fil =1900 C p=3.5 Pa T fil =1900/2 C T(250 nm) [%] [W] [mass%] D: T0 [ C] D: T0 [ C] B: SiH4 flow [sccm] B: SiH4 flow [sccm]

48 Results of the augmented D-optimal design T fil =1900 C p=2.5 Pa T fil =1900/2 C T(250 nm) [%] [W] [mass%] D: T0 [ C] D: T0 [ C] B: SiH4 flow [sccm] B: SiH4 flow [sccm]

49 Results of the augmented D-optimal design T fil =1900 C p=1.5 Pa T fil =1900/2 C T(250 nm) [%] optimum 360 [W] [mass%] D: T0 [ C] 150 optimum 250 D: T0 [ C] B: SiH4 flow [sccm] B: SiH4 flow [sccm]

50 Results of the augmented D-optimal design T fil =1900 C p=1.5 Pa T fil =1900/2 C 4,0 90 3,0 T(250 nm) [%] optimum 360 Rate [nm] 2,0 local 1,0 optimum 0, D: T0 [ C] D: T0 [ C] B: SiH4 flow [sccm] B: SiH4 flow [sccm]

51 Results of the augmented D-optimal design T fil =1900 C p=3.5 Pa T fil =1900/2 C 4,0 90 3,0 T(250 nm) [%] Rate [nm] 2,0 1,0 0, D: T0 [ C] D: T0 [ C] B: SiH4 flow [sccm] B: SiH4 flow [sccm]

52 Multi-response optimization Wanted film properties 150 Overlay Plot T(250 nm)>88% [W]<0.2mass% [W] [mass%]: 0,2 T(250 nm) [%] : 88 Rate [nm]: 2 n= Rate>2 nm/s -σ<190 MPa B: SiH4 flow [sccm] n(550 nm): 1,48 film stress [MPa]: -190 p=1.5 Pa T fil =1900 C D: T0 [ C]

53 Transmission after optimization of deposition factors Film stress σ(d=380 nm) =-170 MPa σ(d=2600 nm)= MPa T wire =1900 C, SiH 4 flow= sccm, p=1.5 Pa, T 0 =140 C

54 SIMS depth profile of 4 layer anti antireflection stack SiO 2 SiN SiO 2 SiN Quartz

55 4 layer AR stack: SiN-SiO 2 -SiN-SiO 2 uncoated uncoated coated coated

56 Summary HWCVD applicable for the deposition of highly transparent SiO 2 films for optical applications Depositions conditions found combining high transmission (T(250 nm) 89% on quartz) low compressive film stress (-σ 170 MPa) low W contamination ([W] 0.2 atom%) high deposition rate ( 2.1 nm/s) In combination with SiN film as high index material first full-hwcvd 4 layer anti reflection stack was successfully demonstrated This work was supported by the Fraunhofer Internal Programs under Grant No. Discover

57 THANK YOU FOR YOUR ATTENTION! Page 57 Fraunhofer offen This work was supported by the Fraunhofer Internal Programs under Grant No. Discover