AIMCAL CONFERENCE PRESENTATION: LAYER PROPERTIES OF HIPIMS SPUTTERED SILICON NITRIDE, ZINC TIN OXIDE, AND ITO October 2018 AIMCAL 2018
REPORT OUTLINE − Introduction and Goals ▪ HiPIMS (or HPPMS) − Test Equipment and Setup − Test Overview ▪ SiN ▪ ZnSnO ▪ ITO − Summary of Results October 2018 AIMCAL 2018
INTRODUCTION AND GOALS − Barrier coatings applied to polymer films are widely utilized to increase the lifetime of commercial products ranging from food packaging to OLED displays. − The best optically transparent barrier layers are stoichiometric films such as Silicon Nitride or ZnSnO that are free of defects that allow the migration of water vapor and oxygen. − The goal of this study was to compare the results of sputtered SiN films that were deposited on a R2R web coating machine using more common pulsed DC and HIPIMS power supply technology. − Measurements for performance included: ▪ Deposition rate ▪ Optical transmission ▪ WVTR October 2018 AIMCAL 2018
INTRODUCTION: HIPIMS hip-V Power Supplies 1, 6, 10 and 20kW Unipolar / Bipolar Standard / Positive Voltage Reversal HIPIMS power supplies with Positive Can be stacked up to 80 kW Voltage Reversal Synchronized pulsing/bias Coating development Contract R&D On site process implementation Founded 2012 Located in Madrid, Spain Developed and produced by Viesca Engineering Founded 2004 Producer of high power pulsed power supplies for trains October 2018 AIMCAL 2018
INTRODUCTION: HIPIMS • High peak powers (500-2000 W/cm 2 ) • Reasonable average power (up to 80kW) • Low duty factors (0.5-5%) October 2018 AIMCAL 2018
INTRODUCTION: HIPIMS Active V+ Passive V+ No V+ Option to control the voltage reversal October 2018 AIMCAL 2018
INTRODUCTION: HIPIMS Me + Ar + Me + Me + Me + Me + Positive Pulse Negative Pulse - Ion acceleration from the target surface (0-1000 eV) - Increase of plasma potential (bombardment of low V surfaces) E i = E 0 + Qe (V plasma - V surface ) October 2018 AIMCAL 2018
TEST EQUIPMENT AND SETUP − The coFlex R2R coater at FEP was utilized for these experiments. − Position 23 was used as the deposition zone. October 2018 AIMCAL 2018
TEST EQUIPMENT AND SETUP Schematic of the deposition zone: − Single rotatable magnetron was used with Si:Al target material. − Magnetrons are 1m in length. − Rotatable magnetron with Ti target was used as the anode. − Both unipolar pulsed DC and HIPIMS were utilized for comparison. October 2018 AIMCAL 2018
TEST EQUIPMENT AND SETUP Target preparation: − The silicon target was provided by GfE Fremat. − The target had been used for previous experiments for the OPTIPERM program. − Thus, the target was first prepared by grinding the outer edges to reduce the arc rate for this experiment. October 2018 AIMCAL 2018
TEST EQUIPMENT AND SETUP − Control of HIPIMS October 2018 AIMCAL 2018
TEST EQUIPMENT AND SETUP − Typical waveform − Note positive voltage reversal − Current is at a constant slope October 2018 AIMCAL 2018
TEST EQUIPMENT AND SETUP − Waveform capturing an arc event − Note: ▪ Change in current slope ▪ Switching response of power supply October 2018 AIMCAL 2018
TESTING OVERVIEW − Silicon Nitride was chosen due to it being a relatively common material for optical and barrier properties. It also lacks a strong hysteresis curve so that this will not be a strong influence on test set-up and results. − The power level was chosen to be 4-5 kW to avoid thermal issues due to high power. Parameter HIPIMS Unipolar Pulse Frequency 1.5 kHz 50 kHz Pulse on time 55 µs 15 µs Discharge voltage 760 V 400 V Maximum current 100 A 10 A Power 4 kW 4.5 kW Argon flow 200 sccm 200 sccm 0 – 70 sccm 0 – 70 sccm Nitrogen flow October 2018 AIMCAL 2018
TESTING OVERVIEW − Current comparison ▪ HIPIMS is independent of nitrogen flow ▪ Unipolar pulsed increases with nitrogen flow ~ 10% October 2018 AIMCAL 2018
TEST OVERVIEW − Transmission of HIPIMS is higher for relative Nitrogen flow − The top of the curve was not discovered October 2018 AIMCAL 2018
OTHER MATERIALS – ZINC TIN OXIDE − A conductive ceramic ZnSnO x target from GfE Fremat was tested. − Almost transparent when sputtered with Argon and more transparent with additional oxygen gas. − Ability to sputter at higher power – 9.5 kW with less concerns related to arcing. − A comparison of the waveforms between HIPIMS and Unipolar pulsed: October 2018 AIMCAL 2018
OTHER MATERIALS – ZINC TIN OXIDE Summary of deposition parameters Parameters HIPIMS Unipolar pulsed Frequency 1.5 kHz 50 kHz Pulse on time 30 µs 15 µs Peak Voltage 1000 V 1100 V Voltage Discharge 760 V 351 V Max Current 400 A 26.7 A Power 9.5 kW 9.5 kW DDR 37 nm*m/min 55 nm*m/min Argon flow 200 sccm 200 sccm Oxygen flow 10 sccm 10 sccm October 2018 AIMCAL 2018
OTHER MATERIALS – ZINC TIN OXIDE Summary of HIPIMS deposition parameters: − Lowest diffusion rate was with HIPIMS − Barrier properties seem to be low at lower film thickness − Deposition rate approximately 67% of unipolar pulsed DC Look up published data for comparison October 2018 AIMCAL 2018
OTHER MATERIALS - ITO − A Soleras target composition of 95% Indium Oxide and 5% Tin Oxide was utilized − Only an small amount of additional oxygen is needed for optimum film performance Parameter HIPIMS Unipolar Pulsed Frequency 1.4 kHz DC Huh? Pulse on time 40 µs 15 µs Discharge Voltage 700 V 319 V Max Current 200 A 15.4 A Power 5 kW 5 kW DDR 22 nm*m/min 25 nm*m/min Argon flow 200 sccm 200 sccm Oxygen flow 3-9 sccm 3-9 sccm October 2018 AIMCAL 2018
OTHER MATERIALS - ITO − A Soleras target composition of 95% Indium Oxide and 5% Tin Oxide was utilized − Only an small amount of additional oxygen is needed for optimum film performance October 2018 AIMCAL 2018
OTHER MATERIALS - ITO − Note that the hysteresis curve is shifted October 2018 AIMCAL 2018
CONCLUSIONS − Deposition rate is lower for HIPIMS than p-DC. ▪ Approximately 67% − SiN ▪ The transmission of HIPIMS is higher for relative Nitrogen flow. − Need data on higher flows… − ZnSnO ▪ Barrier performance shows an improvement for a specific thickness. ▪ Approximately 0.011 vs. 0.046 g/m 2 /day for 150 nm thick layer. − ITO ▪ Results seem to be comparable, but at a reduced oxygen flow. ▪ Need to confirm thickness for resistivity. October 2018 AIMCAL 2018
A SPECIAL THANK YOU TO: − FEP: Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology ▪ Matthias Fahland ▪ Tobias Vogt − Nano4energy ▪ Ivan Fernandez ▪ Frank Papa October 2018 AIMCAL 2018
DANKE FÜR IHRE AUFMERKSAMKEIT! TH THANK ANK YOU OU FOR FOR YOUR OUR ATT TTENTI ENTION ON. October 2018 AIMCAL 2018
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