Fast Vacuum for Optical Disc Metallization and Photovoltaic Coatings B. Cord, M. Hoffmann, O. Hohn, F. Martin SINGULUS Technologies AG, Kahl am Main SINGULUS TECHNOLOGIES June 2014
SINGULUS Overview 25-June-2014-2 - Replication CD, DVD, Blu-ray Vacuum coating, Thermal Treatment, Chemistry Vacuum (UHV) Multi-Layer Deposition
Content 25-June-2014-3 - Optical Disc: Dynamic Vacuum at Metallization Pirani-, Diaphragm-, Ion-Gauges Photovoltaics: Process Pressure Measurement for Plasma Enhanced Chemical Vapour Deposition (PE-CVD) Capacitance (Diaphragm) Gauges
Optical Disc Blu-ray ROM 25-June-2014-4 - BD-Dual Layer (50GB) Moisture Barrier: 10 nm SiN PC-Disc: 1.1 mm Reflector L0: 35 nm Ag (<60%R<85%) Laquer: 25 μm Semi Reflector L1: 25 nm Ag (<18%R<30%) Laquer: 72 μm Laquer Hardcoat: 3 µm Vacuum (Sputtering) Fully Automated Production: CD, DVD and Blu-ray
Single Station Magnetron Sputtering System 25-June-2014-5 - CD-Metallizer SINGULUS DVD-System Spaceline BD-System BLULINE Sputter Station: - Gassupply Ar - Turbomolecularpump - Ion gauge (10-4 to 1 Pa) Small volume Loadlock: - Volume about 100ccm - Prepump of about 20cbm/h - Piranitype vacuumsensor (1 to 10 +5 Pa) Cycletime 1,5-4,5s Turntable: - Rotation 180 and - Up and down
BLULINE: Vacuum Layout 25-June-2014-6 - Vacuum Schematics: Loadlock and process chamber Process chamber vacuum: (turbomolecular pump, ion gauge) 10-8 Pa base pressure Loadlock: (prepump, Pirani Gauge in pump line): Setting of pumpdown threshold (in mv of gauge reading) Display of evacuation time (ms) 500ms = 1mbar (= 6200mV) Prepump Loadlock Venting Loadlock Pumping Process Chamber
Metallizer: Dynamic Vacuum in Load lock 25-June-2014-7 - Load lock: Pump down Threshold vacuum trigger: 45 Pa Base pressure pump Opening of pump valve Closing of pump valve
Metallizer: Dynamic Vacuum in Load lock 25-June-2014-8 - Load lock: Pump down Threshold vacuum trigger: 45, 100, 200, 500 Pa Opening of pump valve Closing of pump valve
Metallizer: Dynamic Vacuum in Loadlock 25-June-2014-9 - Loadlock: Pumpdown; Pressure burst into Process chamber Start pump down Load lock 2s Load lock: Pirani Gauge Process chamber: Bayard Alpert Gauge Closing of pump valve and opening of load lock to process chamber Pressure burst Closing of load lock to process chamber
Metallizer: Dynamic Vacuum in Process Chamber 25-June-2014-10 - Process chamber: (one TMP) Process chamber: (two TMP s) Opening of load lock to process chamber (different thresholds)
Metallizer: Dynamic Vacuum in Process Chamber with Argon gas 25-June-2014-11 - Dynamic behaviour of different gauges Gauges: Pirani Bayard Alpert Ion Gauge Plurality of gauges at DN25 cross Air from load lock Argon gas
BLULINE: Dynamic Vacuum in Load lock 25-June-2014-12 - Pirani: Dynamic behaviour at high Pressures (>1000Pa) Loadlock vented Late reaction of Pirani after start pumpdown Additional Pirani gauge at loadlock (for experiment only) Base pressure pump Start pump down Pirani Gauge in pumpline
Loadlock: Dynamic Vacuum Measurement 25-June-2014-13 - Pirani: Study of Dynamic behaviour at high Pressures (>1000Pa); Comparison to combined Pirani/Diaphragm Pirani/Diaphragm gauge top of load lock Pirani gauge top of load lock Late reaction of Pirani after start pump down Pirani /Diaphragm gauge bottom of load lock Start pump down (opening of valve)
Loadlock: Dynamic Vacuum Measurement 25-June-2014-14 - Pirani: Study of Dynamic behaviour at high Pressures (>1000Pa); Comparison to combined Pirani/Diaphragm Pirani Combined Pirani/Diaphragm Slow venting Pirani Combined Pirani/Diaphragm Fast venting
Optical Discs: Pirani Diaphragm Ion Gauges 25-June-2014-15 - Summary of Gauges for rough and high vacuum Pirani: Gauge of choice for 100Pa level with good time resolution Pirani shows large deviations for dynamic vacuum measurement at levels of >1000Pa Combined Pirani/Diaphragm gauge good solution up to 1000hPa Ion gauges seem to be fastest Absolute, precise pressure measurement with ion gauges needs careful integration and calibration
Photovoltaics: Coating of Si-wafer with Si-Nitride 25-June-2014-16 - SINGULAR multi chamber coating tool Inductively coupled plasma source Deposition by Plasma assisted chemical vapor deposition (PECVD) Process gases like NH3, SiH4, N2,. Modular design for various processes (e.g. SiN x, AlO x, a-si) Four identical PECVD Process stations
TECHNOLOGY: ICP - PECVD 25-June-2014-17 - Pressure Measurement of Process gases for PECVD: Usage of gas independent sensors (Diaphragm Capacitance Gauges) Range 0,01 to 100 Pa Avoid decomposition of gases at hot filaments (no ion gauges) Issue of sensor contaminations Pump Process pressure Measurement: Direct Pressure gauges (Diaphragm, Capacitance) Substrate Plasma chamber
TECHNOLOGY: ICP - PECVD 25-June-2014-18 - Plasma: Inductively coupled plasma (ICP) Vacuum: 0,01 to 100 Pa Static SiNx Process: Process on 9s, transport 3s with no gas going into chamber (avoid chamber crosscontamination) Gas Valves Additional Gas Valves Flowcontroller NH 3 SiH 4
Photovoltaics: PECVD Stations with Capacitance Gauges 25-June-2014-19 - Topic: Actual pressure in chamber after gasflow switching SINGULAR: Pressures in Chamber without plasma Flowmeter on Flows NH3 Pressures NH3 Pressures SiH4 Flowmeter on Different SiH4 Flows Valve opening
Photovoltaics: PECVD Stations with Capacitance Gauges 25-June-2014-20 - Topic: Station to station comparison of process pressure at identical gas flows SiH 4 SINGULAR Machine#1: Pressure versus Flow relation: - Measurement at four stations - Machine to machine comparison NH 3
Photovoltaics: PECVD Stations with Capacitance Gauges 25-June-2014-21 - Topic: Station to station comparison of process pressure at identical gas flows SiH 4 SINGULAR Machine#2: Pressure versus Flow relation: Measurement at four stations NH 3 Pressure Deviation at Station 4 (No#2)
Photovoltaics: PECVD Stations with Capacitance Gauges 25-June-2014-22 - Topic: Machine to machine comparison of process pressure at identical gas flows SiH 4 SINGULAR Machine #1 and #2: Comparison NH 3 Precise and stable pressure measurement over time and from sensor to sensor required
Photovoltaics: PECVD Stations with Capacitance Gauges 25-June-2014-23 - Topic: Actual pressure in chamber after gasflow switching SINGULAR Pressures in Chamber without plasma Different gas valve opening times Optimizing the gas inlet for shortest pressure stabilization time
Photovoltaics: PECVD Stations with Capacitance Gauges 25-June-2014-24 - Summary Capacitance Gauges for PECVD Accuracy of absolute pressure measurement good (but not perfect) Often zeroing of gauge required Signal rise/fall times in the range of some hundred milliseconds, but difficult to judge due to gas filling times for the vacuum chamber
Smart Solutions to Drive the Future 25-June-2014-25 - Question: Operation of the Capacitance Gauges: Absolute pressure accuracy over time? What is best routine for the often required zeroing? Thanks for your attention