Oerlikon PVD production solution for in-situ large scale
Oerlikon PVD production solution for in-situ large scale deposition of PZT 2nd International Workshop on Piezoelectric MEMS Materials - Processes - Tools - Devices Lausanne, 06./07.09.2011 M. Kratzer, L. Castaldi and B. Heinz D. Kaden, H.J. Quenzer A. Mazzalai, S. Harada, P. Muralt Oerlikon Systems R&D, Liechtenstein Fraunhofer ISIT, Germany EPFL, Switzerland Agenda § piezoVolume project § Sputter equipment § Key hardware factors § Results of in-situ PZT deposition process § Summary and outlook 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] EU project “piezoVolume” Sputter cooperation and goals Development of automated high volume sputter system M. Kratzer, L. Castaldi and B. Heinz F. Tyholdt - 14:00 FP7 piezoVolume Process development D. Kaden and H.J. Quenzer Process development A. Mazzalai, S. Harada and P. Muralt Overview Goal of this cooperation is to develop in-situ PZT processes on a Oerlikon sputter system which meet commercial production requirements Project goals High quality PZT films on 8” substrates § Dielectric constant ~ 1200 and dielectric loss tanδ < 0.03 § Piezoelectric coefficients d33,f > 100pm/V and - e31,f > 14 C/m2 § Thickness uniformity < ± 5% at max. thickness 4 - 5 µm § Throughput > 3.6 wafer/hr·µm (= 1nm/s) 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] Equipment for PZT in-situ sputtering RF magnetron sputtering from single ceramic target CLN200 sputter tool RF sputter module equipped with 8” Very Hot Chuck Robot handling D Support stations Aligner (A) Degasser (D) Cooler (C) A C Loadlocks 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] Key hardware factors Overview Anode & Shieldings RF cathode PZT sputter equipment Heated chuck RF Bias & master oscillator Magnet array & Target 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] Key hardware factors Very Hot Chuck Heated substrate holder for 6” and 8” wafer enable deposition process in the temperature range needed for in-situ sputtered PZT films 6” Very Hot Chuck Temperature sense w afer vs. Heater set point (6" and 8" Very Hot Chuck) 650 6" wafer Temperature_sense wafer [°C] 600 8" wafer 550 8” Very Hot Chuck 500 450 Operational range 400 350 450 500 550 600 650 700 750 800 850 He ate r se t point [°C] 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] Key hardware factors Temperature uniformity 8” Very Hot Chuck Optimization of process settings to achieve highest wafer temperatures and excellent temperature uniformity by § Back gas flow § ID / OD heating (Alpha factor) 100 Uniformity Temperature (Temperatur) uniformity 458.0-460.0 456.0-458.0 80 Measurement Statistics Uniform ity 2.44% Mean Range Max Min 430.76 10.50 434.70 424.20 454.0-456.0 60 452.0-454.0 450.0-452.0 40 448.0-450.0 446.0-448.0 0 y [mm] 20 -20 -40 [°C] [°C] [°C] [°C] 444.0-446.0 442.0-444.0 440.0-442.0 438.0-440.0 8” Very Hot Chuck 436.0-438.0 434.0-436.0 -60 -80 x [mm] 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 100 80 60 40 20 0 -20 -40 -60 -80 -100 Chuck temperature: 600°C Backside gas: 4 sccm Wafer temperature: 430 °C -100 432.0-434.0 430.0-432.0 428.0-430.0 426.0-428.0 424.0-426.0 422.0-424.0 420.0-422.0 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] Key hardware factors RF target self bias voltage 1. RF power 0 B RF A C 1 kW Plasma CS USB -100 -15 0 -200 -300 0 UB UA 3 kW -25 0 dB dA 2 kW -5 0 Target self bias voltage [V] Target self bias voltage influenced by § Process pressure § RF power § Anode area 10 20 30 40 50 60 70 80 90 100 110 Ar flow [sccm] 2. Anode area UPlasma Cathode area ~ Anode area Cathode area < Anode area UB UA USB USB = UA - UB UB = UPlasma UA / UB = (AreaB / AreaA)n Target self bias voltage [V] 0 Higher anode area -50 Lower anode area -100 -150 -200 -250 -300 0 10 20 30 40 50 60 70 80 90 100 Ar flow [sccm] 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] 110 Key hardware factors Magnetron design 1.10 Normalized Uniformity thickness PZT thickness and composition uniformity influenced by § Erosion profile § Emission characteristic of sputtered atoms § Scattering (~ pressure · distance) § Substrate temperature Thickness uniformity of PZT films on Pt substrates Thickness uniformity 1.15 1.05 1.00 0.95 Standard § Standard setup Improved § Improved setup 0.90 0.85 0 10 20 30 40 50 60 70 80 90 Radius [mm] Composition uniformity 1.03 Composition (normalized) Actual sputter performance § Deposition rate > 40 nm/min § Estimated target life time ~ 1600 µm film thickness for 4mm target 1.02 1.01 ID OD 620°C, ID 620°C, OD 1.00 0.99 0.98 0.97 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 Pb/(Zr+Ti) 1.000 1.004 Zr/(Zr+Ti) 1.000 0.989 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] 100 In-situ PZT deposition process General trends Variation of substrate temperature 1.40 Relative Pb content can be influenced § Pb decrease with Ar flow increase § Pb increase with RF power increase Composition (normalized) § Pb decrease with temperature increase 1.20 1.00 0.80 0.60 0.40 Pb/(Zr+Ti) Zr/(Zr+Ti) 0.20 0.00 500° C 550° C 600° C Variation of RF power Variation of Ar flow 2.00 1.40 1.80 650° C 700° C 750° C 1.20 1.40 Pb/(Zr+Ti) 1.20 Zr/(Zr+Ti) 1.00 0.80 0.60 Composition (normalized) Composition (normalized) 1.60 1.00 0.80 0.60 0.40 0.40 Pb/(Zr+Ti) Zr/(Zr+Ti) 0.20 0.20 0.00 0.00 1.5 kW 2.0 kW 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 2.5 kW 50 sccm 100 sccm 250 sccm 350 sccm M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] In-situ PZT deposition process 6” PZT with PTO seed layer § Best PZT films achieved with a PTO seed layer to promote the nucleation of the PZT perovskite structure Performance of films deposited at 2 kW § For films sputtered at 1 kW § ε ~ 1500 § tanδ = 3.2% § d33,f = 100pm/V § -e31,f = 7.5 C/m2 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] 2 Polarisation [µC/cm ] 30 Intensity [a.u] 10 0 -10 -20 Ec (avg) P rem (avg) = 23.5 µC/cm2 -40 P max (avg) = 42.5 µC/cm -250 -200 -150 -100 -50 0 50 150 200 250 300 25 30 35 40 45 50 55 60 65 70 75 80 85 90 2 Theta Polarisation vs. displacement 4.0 0.05 T h = 600°C 0.04 Th = 600°C 2.5 2.0 1.5 1.0 => d33,f = 120 pm/V 0.5 => d33,f = 120 pm/V Polarisation [µC/cm2] 0.03 3.0 Displacement [nm] 100 2 Field [kV/cm] Displacement vs. voltage 3.5 = 49.6 kV/cm -30 -50 -300 38.25, PZT (111) § Similar performance for films without TiO2 seed layer 20 85.71, Pt (222) Th = 600°C 55.47, PZT (211) 40 40.02, Pt (111) 50 44.88, PZT (200) § Best piezoelectric data § ε ~ 1200 § tanδ = 3% § d33,f = 120 pm/V § -e31,f = 12.6 C/m2 69.132, Si (400) In-situ PZT deposition process 8” PZT with TiO2 seed layer 0.02 0.01 0.00 -0.01 -0.02 -0.04 -0.5 -0.05 -30 -25 -20 -15 -10 -5 0 5 Voltage [V] 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 10 15 20 25 30 -2000 2 = 12.6 C/m 2 => -e31,f=>=e 12.6 C/m -0.03 0.0 31,f -1500 -1000 -500 0 500 1000 1500 2000 Displacement [nm] M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] In-situ PZT deposition process Summary § The existing sputter equipment is capable to deposit PZT films in-situ with the required perovskite structure § Therefore no additional annealing step is needed in the process sequence § Electrodes and PZT films can be deposited consecutively in a cluster tool without breaking the vacuum § Piezoelectric performance of best films comparable to state-of-the-art films deposited by chemical solution deposition (CSD) § Further improvements achievable by § Magnetron design § Target properties § Process optimization 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 => Thickness and composition uniformity, deposition rate => Deposition rate => Piezoelectric properties M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected] The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2010-2013) under grant agreement n° 229196 Thank you for your attention 2nd International Workshop on Piezoelectric MEMS - Lausanne, 06./07.09.2011 M. Kratzer, Oerlikon Systems R&D, e-mail: [email protected]
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