Plasma and Dry Micro/Nanotechnologies 10. Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková Faculty of Science, Masaryk University, Brno & Central European Institute of Technology - CEITEC lenkaz@physics.muni.cz spring semester 2023 Central European Institute of Technology BRNO I CZECH REPUBLIC rit • Plasma Enhanced Chemical Vapor Deposition 10.1 Introduction to PECVD 10.2 PECVD of Si-based Films 10.3 PECVD of Hard Carbon Films 10.4 Amine Plasma Polymers 10.5 Anhydride/Carboxyl PPs 10.6 Plasma Polymers in Immunosensing 10.7 Plasma Coating of Polymer Nanofibers Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 3/34 10.1 Introduction to PECVD plasma enhanced chemical vapor deposition (PECVD) ► from gases and vapors ► very easy for organic materials and Si compounds (SiH4, variety of volatile organosilicon compounds) ► for metals - necessary to find sufficiently volatile compounds (organometallic) Si2H6 Si3H3 Radicals Oligomers Ions Substrate + electrodes + chamber walls physical vapor deposition (PVD), namely magnetron sputtering ► gasification of solid targets by ion sputtering deposition ► simple method for metals ► a bit more complex for oxides, nitrides, carbides (reactive sputtering) i Anode Substrate „ Plasma Ground shield " Cathode (target) OOOOOOOOOOOO Q waler coohng Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 4/34 thermally driven chemical deposition from gas phase: 1. transport of reactants to the deposition space 2. diffusion of reactants to the substrate surface 3. adsorption of reactants 4. phys.-chem. processes ^ film growth by-products 5. desorption of by-products 6. diffusion of by-products in gas flow 7. transport of by-products from deposition space Low Pressure CVD (LPCVD) is often used in microelectronics or in applications requiring excellent control over impurities Plasma & Dry Technologies 'lasma Enhanced Chemical Vapor Deposition ka Zajíčková 5/34 lagram CVD method in which discharge is ignited in the gas mixture: ^ collisions of energetic electrons with heavy gas particles ^ production of highy reactive species ^ more competing processes take place, deposition can be generally divided into thermal and plasma branches Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 6/34 CVD versus PECVD - example PECVD x CVD reaction branch: thermal ^^^9 plasma IMffM 3SiH4 + 4NH3 -> Si3N4 + 12H2 SiH 4 + NH 3 -> -> SiNH + 3H,, plasma reaction branch at PECVĎ is much more importan 250-350°C because: ^ sticking coefficient is much higher for reactive radicals and activated surface ^ activation energies of chemical reactions are lower for excited reactants PECVD - lower deposition temperature, novel reaction schemes leading to new materials, replacement of toxic and dangerous reactants but high complexity of chemical reactions and processes, worse selectivity and reaction control, possibility of damages by energetic ions, UV radiation or electrostaticaly (charge accumulation) Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 7/34 Plasma Polymerization - subset of PECVD Plasma polymerization is a subset of plasma enhanced CVD It produces organic thin films with specific functional groups originating from the monomer structure. Plasma polymers do not have the typical structure of polymers (impossible to find a repeated unit, structure is highly branched and cross-linked). Yasuda scheme: I'l.i-n.i cxdiaiion 1st pathway (M») - similar to a standard free radical polymerization mechanism, 2nd pathway (#M») - difunctional mechanism, "polymer" can grow in multiple directions by multiple pathways off one species a very rapid step-growth polymerization: Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition ka Zajíčková 8/34 E itterent i rypes o i asma Polymers Organosilicon plasma polymers hexamethyldisiloxane CH3 CH3 H3C-Si-0-Si-CH3 1 1 CH3 CH3 Amine films allylamine NH2 cyclopropylamine NH2 diaminocyclohexane ethylenediamine ► interfacial adhesion, ► grafting of molecules with specific functionalities (reverse adhesion), ► improvement of cell colonization (tissue engineering), ► immobilization of biomolecules (biosensors, drug delivery systems). ► barrier and protective coatings ► hydrophilic/hydrophobic surface ► cross-linking improvement (stabilization of organic functionalities by co-polymerization) deposition from gas mixtures: NH3/CH4 ► NH3/C2H4 Carboxyl/ester/anhydride films acrylic acid o HO II CH2 ► H2O/CO2 ► C2H4/CO2 methyl methacrvlate 0 y 0CH3 CH3 maleic anhydride Plasma & Dry Technologies lasma Enhanced Chemical Vapor Deposition ka Zajíčková 9/34 Plasma Polymerization in Pulsed RF Discharges Quest for retaining monomer structure in plasma polymers - too much energy in plasmas! ► decreasing power (some limits apply) ► excluding ion energy flux (higher pressures, atmospheric pressure namely) ► pulsed CCP discharges pulse repetition frequency fpuls = 1/(fcn + W) O Q_ on toff duty cycle (DC) DC _ ^on řon+ř0ff x 100% Simplification (1 parameter instead of 2): mean RF power Paver = Pon x DC time Macroscopic approach uses P, aver W/F = aver Q [J/cm3] Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 10/34 10.2 PECVD of materials with Si O dielectric films for microelectronics silicon nitride: SiH4+NH3 or SiH4+N2 (find protective T=250-400 °C passivation for integrated circuit) silicon oxide: (insulating film - el. separation) SiH4+N20/NO/C02/02 T= 200-400 °C Si(OC2H5)4+02 \ tetraetoxysilane (TEOS) sheath feature Silicon Plasma & Dry Technologies 'lasma Enhanced Chemical Vapor Deposition of materials with Si ka Zajíčková 11/34 O more dielectric films for microelectronics low-k dielektrics: organosilicons + Ozl... + ... (el. separation for ULSI) ^¥ organosilicon glass O semiconducting films for microelectronics (^SG) epitaxial silicon: SiH4+H2 T=800 °C polycrystalline silicon: SiH4/SiH2CI2+H2/Ar T=450-700 °C (gate electrode, connections in MOS i.e., solar energy pannels) O SiOx and SiOxCyHz for many other applications scratch resistant films for plastics, anticorrosion films for metals, barrier films for packaging and pharmacy, biocompatible films mixtures with organosilicons (TEOS, HMDSO, HMDSZ) Plasma & Dry Technologies 'lasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 12/34 of films from H M D SO (hexamethyldisiloxane) CH3 CH3 source of Si-O-Si bonds \7 CH3-Si — i —Si-CH3 CH CH source of CH3 groups Si02-like films SiOxCyHz plasma polymers • concentration of HMDSO in the gas feed, especially oxygen • power • bias voltage / ion energy • pressure • pulsing Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 13 / 34 Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 14/34 Variation of film composition 5 % HMDSO in CX 0) Ü c CO -Q s_ O (f) CO O CCP 40 Pa ICP 0.4 Pa _i_i_i_i_ 05 O co -Q i_ O C/3 .Q CO O c 1000 2000 3000 wavenumber [cm1] _i_i_i_i_ 4000 CCP 2.5Pa, 0ms CCP2.5Pa, 15ms •CCP40Pa, 0ms ■CCP40Pa, 15ms A Si-(CH3)X 600 800 1000 1200 wavenumber [cm1] 1400 ^> 0.4 Pa: Si02 structure, almost no impurities ^> 2.5 Pa: Si02 structure, OH groups and H20 ^> 40 Pa: organosilicon films Plasma & Dry Technologies 3lasma Enhanced Chemical Vapor Deposition mm ka Zajíčková 15/34 Domains of stresses two different coatings choosen for treatment testing: ■ P=100W, Q02 = 45 seem, d = 0.5 |um ■ P = 400W, QG2= 10 seem, d = 1.2 um Plasma & Dry Technologies 'lasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 16/34 of films from H M D S O/O 2 in CCP or ICP (13.56 MHz) Plasma & Dry Technologies 'lasma Enhanced Chemical Vapor Deposition ka Zajíčková 17/34 .3 PECVD of Hard Carbon Films Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition nka Zajíčková 18/34 e in RF (13.56 MHz) capacitively coupled discharges ► continuous wave and pulsed modes ► ton = 660 fj,s, ton = 1340 /xs ► fpuls = 500 Hz, DC = 33% reactor R3, substrate at floating potential gas mixture blocking matching rf generator capacitor unit ► Ar 28 seem, CPA 0.1-1.0 seem ► pressure 120 Pa RF power 20-30 W ► electrode diameter 80 mm ► interelectrode distance 185 mm ► in CPA/Ar mixtures NH2 reactor R2, substrate at RF electrode gas mixture rf generator (Jv)-1 |_C =±= blocking capacitor matching unit Q(Ar) = 28 seem, Q(CPA) = 2.0 seem ► pressure 50 Pa ► RF power 30-250 W electrode diameter 420 mm ► interelectrode distance 55 mm Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 19/34 Comparison of Floating (R3) x RF Biased (R2) Substrate o 0.26 R3, fixed power of 20 W 1000 2000 3000 4000 5000 6000 W/F (J/cm3) O 0.26 0.24 0.22 0.20 0.18 0.16 0.14 0.12 R2, fixed CPA flow rate 2 seem a pulsed mode (10%) a pulsed mode (33%) •a—continuous wave mode 1000 2000 3000 4000 5000 6000 7000 8000 W/F (J/cm3) CD O) c JZ o to to CD c o CD or 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 ^ t~~S)- -▲ • --■ // N/C=0.22 ^^>^S^ ii) / - N/C=0.25 // -a- pw 1 h - // -•-PW 24h // -■-PW48h // -a- CW 1 h L // -•-CW 24h 4 - CW 48h m '.................. ....... CD CO o to to CD c J£ o CD a: 15 10 o CN 5 N/C=0 0 -5 -10 -15 -20 -25 a PW(10%), 216h -*^PW (33%), 216h ■A-CW, 216h 0 1000 2000 3000 4000 5000 6000 1000 2000 3000 4000 5000 6000 7000 8000 W/F (J/cm') W/F (J/cm3) /I. Manakhov et al. Plasma Process. & Polym. 11 (2014) 532 & 14 (2017) 1600123 Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 20/34 10.5 Anhydride/Carboxyl PPs Co-polymerization of maleic anhydride (MA) with C2H2 in Ar dielectric barrier discharge (DBD) at atmospheric pressure chamber °YOy° + HC CH L. Zajíčková et al. Plasma Phys. Control. Fusion 59 (2017) 034003 A. Obrusnik et al. Surf. Coat. Technol. 314 (2017) 139 1.1 1.0 0.9 ~ 0.8 CO f 0.7 0.6 0.5 MA:C2H2= 0.06:3 = 0.020 0.11:3 = 0.037 0.11:2=0.055 OH sp3C-H 0.33:3 = 0.11 sp2C-H C=0 anhydride 3500 3000 2500 2000 1500 1000 Wavenumbers (cm"1) HV generator 6 - -1- -o/c -♦-ch : X ♦ -*-c(0)0 : 7- *-- -▲ - ______4 __------- A" _1_1_1_1_1_l_ 1 55 - 50 - 45 - 40 - 35 ■,30 at.% - 15 X 10 0.02 0.04 0.06 0.08 0.10 0.12 ma:c2h2 ratio Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 21 /34 [COOH] by Chemical Derivatization and Water Stability Increasing MA => t C1s peak at 289.1 eV, i.e. carboxyls (COOH) / esters (COOR). =>- important to quantify „true" concentration of COOH - derivatization with trifluoroethanol u in in c _^ u 60 - 40 - 20 - 0) cn c 03 0 -20 -40 -60 I— -80 - -100 - lh in H20 - ■ 24hinH20 - a 128h in H20 - t [COOH] before H20 [COOH] after 128h in H20 * *: -^ =5: j_i_i_i_ 0.02 0.04 0.06 0.08 0.10 MA:C2H2 ratio 10 9 8 7 6 5 4 3 2 1 0 0.12 -i—3 03 O O u A. Manakhov et al. Surf. Coat. Technol. 295 (2016) 37-45 Plasma & Dry Technologies lasma Enhanced Chemical Vapor Deposition ka Zajíčková 22/34 10.6 Plasma Polymers in Immunosensing Reactivity of primary amine and carboxyl R1 \ H H is important for ► immobilization of biomolecules for immunosensing Human serum albumin (HSA) chosen for the demonstration of immunosensing application: gold electrode coated with CPA-PR covalent attachment of antibody AL-01 by 3 coupling methods, the most robust being glutaraldehyde (GA) groups P xOH Plasma & Dry Technologies lasma Enhanced Chemical Vapor Deposition ka Zajíčková 23/34 Immunosensing - Two Principles, Same Material Needs Different principles/transducers but same material is needed - gold electrode coated with a functional film Quartz crystal microbalance Surface plasmon resonance o 3\ Flow channel Flow channel S. uaitz Crystal \ Receptor Quartz Ci>stal , MASS LOADING I écettoáe t\ Sauerbrey equation for change of oscillator frequency Af = 2.26 x 10"6f2AA7?//\ f resonant frequency, A electrode area, Am mass change o o \. _ X o o Q Flow channel / q Sensing rarn Sensor chip with gotd film Reflected ttght Angle Time change of resonance angle / reflectance at given angle Plasma & Dry Technologies lasma Enhanced Chemical Vapor Deposition ka Zajíčková 24/34 Chemically Prepared Amine Films versus Plasma Polymers SAM of cysteamine NH2 (3-Aminopropyl)triethoxysilane (APTES) l-s I I -s NH2 NH2 NH2 ^ -O 1 RO^Si—NH2 -O -°\ -O—Si—NH2 RQ/ Polyethyleneimine (PEI) NH- ^n-L^nJ-4n—|nh2 O L HJ™ ^NH2 ^nJ----isi-j—[-n^-—\nh2 O i HJm ^NHz Ni ----TNH2 Hjm Plasma polymerization - alternative to the conventional methods NH __^ Example of plasma polymerized cyclopropylamine optimized for sensing performace a) c 03 0,98 0,96- Z3 3, (D O 03 £i 0,94- 1380 C"H bend. 0,92- 0,90 3500 3000 2500 2000 1500 wavenumber (cm") Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition ka Zajíčková 25 / 34 ■ elected Films for Immunosensors CPA/Ar mixtures, Qat = 28 seem pulsed RF discharges: U = 660 ms, foff = 1340 ms =>- fpuis = 500 Hz, DC = 33% conditions C N 0 C-NHX NH* NH+ [NH2] Ad/d [at%] [at%] [at%] [at%] [at%] [at%] [at.%] [%] floating, I W/F 78.3 20.1 1.6 18.9 5.1 2.6 3.4 -53 floating, t W/F 79.5 19.0 1.5 22.8 6.4 0 1.5 -18 RF biased, t W/F 80.3 17.2 2.5 16.2 4.6 0 1.3 -2 difference in atomic composition relatively small but water stability quite different ► IR spectra reflect different film structure ► SIMS analyses reveal different degree of film cross-linking ► confirmed by different stability in water Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 26/34 QCM immunosensing with CPA PPs: 1. 5% glutaraldehyde in PBS, 1 h at room temperature 2. 100 /zg/ml AL-01 in PBS, 18 hours at 4 °C =>- baseline stable for both the CPA PPs (t W/F, floating & RF) SPR immunotests with optimized PP-CPA (t W/F, floating) sensor: immersed in PBS prior to activation by GA and immobilization of antibody: 1 hour in PBS 10 ng/ml solution of HSA 10 20 30 40 time (min) 50 18 hours in PBS CD CD CĹ 10 ng/ml solution of HSA 10 15 20 time (min) 25 30 18 h in antibody/PBS solution CD CD "D CD u) c o Cl ui CD 10 |ig/ml solution of HSA - binding channel - reference channel 20 30 time (min) ► longer immersion in PBS improved baseline stability while keeping sensor performace ► longer immersion in antibody/PBS also improves baseline stability but detection of antigen is not efficient Plasma & Dry Technologies 'lasma Enhanced Chemical Vapor Deposition ka Zajíčková 27/34 ensitivity o Is a perfect water stability of film thickness necessary for succesful immobilization of biomolecules and surpression of drifts? sensor reactor W/F Ad/d [NH2] NHX C=N [%] [at.%] [at.%] [at.%] a b R3, floating 18 R2, RF driven 2 1.5 1.3 6.4 4.6 11.8 8.2 Response of QCM sensors with films (a) and (b) to HSA (film thickness 40 nm): N < -20- -30 -40 -50 whole time in flowing PBS RF potential CPA-PP sensor with floating potential CPA-PP -r- 10 15 20 25 I 30 Better response for the sensor (a) Response of SPR sensor with film (a) thickness 40 nm CD CD TD E 40 35 30 25 20 15 CD co c o CO 10 CD time (min) E. Makhneva etal. Surf Coat. Tech no I. 290 (2016) 116 ■ blank ■ 1 ng/mL ■ 5 ng/mL 15 20 time (min) Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 28/34 0 5 10 15 20 25 105 106 107 10 /(min) c(CFU/ml_) Plasma & Dry Technologies lasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 29/34 combination leading to novel nanomaterials ► electrospinning of polymer nanofibers ► + plasma processing Plasma coating of polymer micro/nanofibers can bring additional functionality for smart textiles ► tissue engineering ► filtration of liquids/gases ► drug delivery ► battery separators Nozzle-less electrospinning by Nanospider™ from ELMARCO (Czech Rep.) and plasma processing of polymer nanofibers water contact angle before Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 30/34 PP-Coated Nanofibers in Health Care tissue eng. requires suitable scaffold CELLS TISSUE ENGINEERING y j- nanofibrous polymer mats are ideal also for wound dressina EpidermH- Dermis — Hypodermts- Electrospun polymer nano/microfibers ► can be prepared in the form of flexible foil ► from biodegradable polymers ► provide moist environment ► allow gas exchange ► avoid bacteria infiltration ► resembles the structure of extracellular matrix (ECM) [S.R Miguel et al., Colloids & Surf. B 2018] ► deliver bioactive molecules - high surface area but a need of surface modifications creating reactive groups Plasma & Dry Technologies onaing o Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 31 /34 Plasma co-polymerization of maleic anhydride and C2H2 in atmospheric pressure plasma films with anhydrides (6.3% rel. to total C) spontaneously creating -COOH at air. Two different approaches for gentamicin bonding were tested: h^^^nh, covalent bonding 9H3 XX (with addition of N,N-Dicyclohexylcarbodiimide) gentamicin sulfate hN CH-, cha h2nv^vnhz COOH J COOH I DCC in water hň coo- nh, Plasma Polymer Plasma Polymer ■ PCL nanofibers PCL nanofibers H3JN h-.SO,, S0v«'T°ro el stati c bonding Oh NH2 HŇ. gentamicin sulfate CH3 + COOH COOH Plasma Polymer PCL nanofibers in water R T Plasma Polymer PCL nanofibers RcoliK-19 EcoliK-261 E. coli K-41 MIC=0.12ma/L MJC=128mg/L MIC=256inaL E. Permyakova et al. Antibacterial biocompatible PCL nanofibers modified by COOH-anhydride plasma polymers and gentamicin immobilization, Materials & Design 153 (2018) 60. Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 32/34 Cells on PCL Mats with PPs anhydride/carboxyl PP PCL-ppMA:C2H.-F < 1500 3000 wavenumber [cm1] 20|im I amine PP 0,98 0,96 3 CD CD Ü C CO Hi 0,94 E w 0,90 3350; 3200 N-H itr 2970: 2930: 2870 1380 C-Hh Ml C-R\ 1650 1630 0 -CH, =CH2 C=Nstr.C=Cstr. A-H2 )CH2 ^CH ^CH H- 3500 3000 2500 2000 1500 Pav = 10 W (18% water soluble, N/C=0.22) wavenumber (cm"1) Pav = 150W (5% water swelling, N/C=0.15) "CPA-2 20nm * A. Manakhov et al. Materials & Design 132 (2017) 257-265 sřS»řv*'«-rii y 20|im I : ■ Plasma & Dry Technologies Plasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 33 / 34 Trypsinization time [min] =>- Adhered non-endothelial cells cannot be removed by trypsin P. Černochová et al. Sci. Reports 10 (2020) 9357 Plasma & Dry Technologies lasma Enhanced Chemical Vapor Deposition Lenka Zajíčková 34/34 Vascular smooth muscle cells (VSMC) on polystyrene culture dishes (PS), polycaprolactone nanofibers (PCL) and amine-PP coated surfaces (CPA-10, 33, 150) VSMCs can be utilized for reconstruction Initial adhesion (24 h) tu -Q E 18-15-12-9-6 3 0 O -9- PP-CPA on polystyrene dishes CPA-10 CPA-33CPA-150 PS ° 6 £ = 4 to o — (0 Wo. C * TJ M <Ľ> i- (/) 0 Cell spreading (24 h) CT** CPA-10 CPA-33CPA-150 PS 40- 30- O o 2°H PP-CPA on PCL nanofibers Q) 1 1(H =^= E _s_ » a m jay ^ -1-w-1- b 6 u i AJ