Thin Films Deposition F4280: An appendix for a plasma deposition cookbook Miroslav Michlfcek michlicekm@mail. muni, cz F4280 PECVD deposition Repetition Miroslav Michlicek 2/17 What was already said ► What is plasma and how to generate it, sheath and what kind reactions are there ► Kinetics and collisions reactions, cross sections distribution functions ► Types of plasma sources with typical basic plasma parameters -LP/AP ► Plasma treatment and PECVD ► Plasma polymers - low energy organic PECVD F4280 PECVD deposition Appendix 1A Miroslav Michlicek 3/17 Why an appendix for a plasma deposition cookbook? ► "Baking - a simple process where a command like place in a 350 ° F oven for 15 minutes' leads to a lot of chemistry and a bit of physics as the many chemical compounds that make up cake batter react. A recipe doesn't specify all of the reactions that occur, because they will happen on their own when you introduce heat." ► But first you sort of need to know where to find things and how to use them! F4280 PECVD deposition Appendix 1A Miroslav Michlicek 4/17 So prepare F4280 PECVD deposition Appendix 1A Miroslav Michlicek 5/17 Chamber ► What will be the pressure? - LP - glass, PMMA, stainless steel., all with appropriate sealings - KF and CF standards, swagelok ► design is more of an engineering problem - size of samples, windows + much more ► geometry affects electric fields, gas flow patterns, possibly temperature distribution ► =>Chamber itself influences process - standard - GEC reference cell To ground insulator Torf power Insulator F4280 PECVD deposition Appendix 1A Miroslav Michlicek 6/17 Vacuum sealing ► KF/QF/DN - Klein Flange (KF), Quick Flange (QF) - elastomer O-rign + clamp, lower vacuum ► CF - Conflat - single-use copper gasket - bakeable - UHV vacuum F4280 PECVD deposition Appendix 1A Miroslav Michlicek 7/17 Vacuum sealing II ► swagelok systems - mainly for gas delivery - bevare of American sizes ► others - ISO flange, Wheeler flange F4280 PECVD deposition Appendix 1A Miroslav Michlicek 8/17 Pumping ► what types of pumps do we have? Which of them are relevant? ► oil vs dry pumps - tricks? ► it is rather useful to know principle and limitations of different types of pumps... there is not enough space for that. Vacuum Pump Pressure Ranges Ultra-High Vacuum High Vacuum Rough Vacuum ROTARY VANE ROTARY PISTON MECHANICAL PU DRY MECHAN MECHANICAL PUMP SORPTION PUMP B LOW E F .'BOOST E F. PUMP IMP ICAL Y/SSs Y/S///S VENTURI PUMP Y/SA vrssssssA LIQUID NITROGEN TRAP ÚP Y////////A DIFFUSION PU YSS/S/S/SSS* Y//S/////////7m CRYOPUMP Y////////* TURBOPLfMP ION PUMP Tl SUBLIMATION PUMP -12 -10 -8 -6 -4 -2 0 +2 Pressure in Torr (units are exponents of ten) F4280 PECVD deposition Appendix 1A Miroslav Michlicek 9/17 Pumping II example ► what type of pump is this? ► can it pump atmospheric pressure? RPS Systems / MS-301 - Pumping Speed I 600 200 D 10 10 ■2 101 1 ID1 10s Pressure (mbar) 10^ 104 RPS 751/301 RPS-1001/301 RPS 1401/301 65 F4280 PECVD deposition Appendix 1A Miroslav Michlicek 10/17 Pressure measurement ► U tube? Absolute vs relative gauges ► a single wide range gauge is often used (usually consists of Pirani + Ionization) ► additionally, absolute measurement by a capacitron (Baratron) -zero error McLeod Convection/Pirani__ nometer Thermocouple Cold Cathode Hot Cathode (Ionization Residual Gas AialvzerfRG e-Range Combination F4280 PECVD deposition Appendix 1A Miroslav Michlicek 11 IM ► how to deliver gases? gas bottle « 200 bar ► mass flow meters - K-factors ► Internal structure Flaw rate sensor Bypass -v. Power supply Flow rate output signal Flow rate setting signal Inlet \ Driver/ Receiver D/A ■ A/D converter =1- : PU Valve drive circuit A/D converter Piezo actuator Flow rate control valve Metal diaphragm li'iii]nr;itiiitE._— Sensor?. r~ — To .Solenoid Operated Control Ifoitvr Outlet LmniiiLi I Urn M;i in fLim for a high flow - a floating ball flow meter rd^nd 'Lt-r I P.I ■ —■ ■ IBHI PkttH * nufniMafl Ijl r-if ► homogeneity of the gas mixture - gas mixers ► inlet of gases into the chamber - shower head ► depending on the gas, pressure and geometry we can distinguish degree of mixing ► plug flow ► back-mixing flow ► well mixed flow ► Throttling valves to adjust pumping speed and working pressure For independent measurement of the gas flow (leak rate, liquid vapors): (1) (2) F4280 PECVD deposition Electric Power Appendix 1A Miroslav Michlicek 13/17 ► Choosing a frequency - DC and AC Aston Dark Space (AD) Cathode Negative Glow (NG) Faraday Space self-bias F4280 PECVD deposition Appendix 1A Miroslav Michlicek 16/17 Optional accessories ► Temperature control - both cooling and heating + feedback ► Leak detection ► Various characterization and process control techniques ► Light - spectroscopy using emission or absorption ► Charged particles + electric fields - ► Neutral species - mass spectrometry laser induced fluorescence ► Power signal ► Sample movement and manipulation - mechanical clamping and electrostatic chuck WafaivConductive Substrata + + + + + + + Dielectric _ — v — ±5000V ±600V '— V —' '□' Electrodes (Thick Film) Concentric Rings (Thin Film) F4280 PECVD deposition Appendix 1A Miroslav Michlíček 17/17 Additional reading and info Books covering similar topics: ► General thin film deposition (easy) - Thin-Film Deposition: Principles and Practise, D. Smith ► General plasma (easy) - Principles of Plasma Processing, F Chen and J. Chang ► General plasma (hard) - Principles Of Plasma Discharges And Materials Processing, Lieberman M. and Lichtenberg A. ► CCP (hard) - Physics of Radio-Frequency Plasmas, Pascal Chabert Courses - Vakuová fyzika 1, 2 (Czech only), Fyzika plazmatu 3 (CCP mainly)