Metal-Carbonyl Organometallic Polymers, PFpP, for High- Resolution Positive and Negative Electron Beam Lithography Resist

Transcription

1 Electronic Supplementry Mteril (ESI) for ChemComm. This journl is The Royl Society of Chemistry 2015 Supporting informtion Metl-Crbonyl Orgnometllic Polymers, PFpP, for High- Resolution Positive nd Negtive Electron Bem Lithogrphy Resist J. Zhng, K. Co, X. Wng *, nd B. Cui *,b Mterils nd instrumenttion All experiments were performed under dry nitrogen tmosphere using stndrd Schlenk techniques unless otherwise indicted. THF ws freshly distilled under nitrogen from N/benzophenone. Toluene ws dried with moleculr sieves before use. Sodium (N), 1-bromo-3-chloropropne, potssium (K) were purchsed from Sigm- Aldrich. Cyclopentdienyl iron dicrbonyl dimers (Fp 2 ) were purchsed from Strem Chemicls Inc. Chlorodiphenylphosphine ws purchsed from Tokyo Chemicl Industry (TCI). Benzophenone ws purchsed from Fisher Scientific. All chemicls were used s received unless otherwise indicted. 1 H, 31 P NMR spectr were obtined on Bruker Avnce 300 ( 1 H NMR: 300 MHz, 31 P NMR: 120 MHz) spectrometer t mbient temperture using pproprite solvents. NMR smples were prepred under dry nitrogen tmosphere unless otherwise indicted. Fourier trnsform infrred spectroscopies (FT-IR) were recorded using Perkin Elmer Spectrum RX I FT-IR system. The smples were ground with KBr nd then pressed into trnsprent pellet. Moleculr weights nd moleculr weight distributions, M w /M n, were chrcterized using GPC nlysis t room temperture with THF s eluent t flow rte of 1.0 ml/min. The Viscotek GPC mx unit used ws equipped with VE 2001 GPC, three PolyAnlytik orgnic mixed bed columns, PAS-103-L, PAS-104-L, nd PAS-105-L, with dimension of 8 mm (ID) 300 mm (L) ech nd Viscotek triple detector rry, including refrctive index, viscosity, nd dul-ngle light scttering detectors. Synthesis of nd chrcteriztion PFpP PFpP is prepred vi migrtion insertion polymeriztion (MIP) of CpFe(CO) 2 (CH 2 )PPh 2 in bulk t 105 o C. After 20 h, the polymeriztion ws terminted by cooling down the rection flsk to room temperture. Smll mount of THF ws dded to dissolve the crude product; the crude product ws purified vi

2 precipittion into lrge mount of hexne nd this precipittion procedure ws repeted for three times. Finlly, the product ws collected by filtrtion nd dried under vcuum t room temperture for 24 h. 1 H NMR (CDCl 3 ): ppm (b, 10H, C 6 H 5 ), ppm (b, 5H, C 5 H 5 ), ppm (b, 1H, COCH 2 ), ppm (b, 1H, COCH 2 ), ppm (b, 2H, CH2P), nd ppm (b, 2H, CH2CH2CH2). 31 P NMR (CDCl3): 73 ppm, 35 ppm. FT-IR: terminl CO stretching frequency is 2000 nd 1911 cm -1, cyl CO stretching frequency is 1600 cm -1. FT-IR nd 31 PNMR of the resultnt polymers re shown in Figure S1(). Upon the polymeriztion, the two peks t 2007 cm -1 nd corresponding to terminl CO in FpP monomer shift to lower frequencies. Prticulrly, one CO signl ppers t 1600 cm -1, suggesting cyl CO ws formed s result of migrtion insertion rection. 31 P NMR shown in Figure S1(b) lso illustrtes tht the coordintion of phosphine to Fe occurred, s chemicl resonnce for the phosphine in FpP shifts from -15 ppm to 73 ppm. The very wek chemicl shift t 35 ppm is ttributed to the oxidized phosphorus t PFpP chin end. As such, both FT-IR nd 31 P NMR results confirmed the occurrence of migrtion insertion rection. FpP b -15 PFpP 2007 cm cm -1 FpP cm cm cm -1 PFpP Wvenumber/cm /ppm Figure S1. () FT-IR of FpP nd PFpP; (b) 31 P NMR of FpP nd PFpP. in CDCl 3.

3 Fe CO O b c P n Ph Cp H 2 O,c b /ppm Figure S2. 1 H NMR of PFpP produced from bulk polymeriztion t 105 o C in CDCl 3. The chemicl structure of the polymers ws lso chrcterized by 1 H NMR in CDCl 3. As shown in Figure S2, the chemicl shift t ppm corresponds to the phenyl group; nd the resonnce signl due to the protons in the Cp ring ppers t 4.3 ppm. The integrtion rtio for these two peks is 2.2, which is closed to the theoreticl vlue of 2.0. The chemicl shift for the propyl spcer ppered t ppm, within which the peks t 2.8 nd 2.4 ppm represent distereotopic protons from CH 2 djcent to cyl group. GPC nlysis revels tht the polymer hs M n of 8200 g/mol with PDI of Preprtion of PFpP film by spin coting nd electron bem lithogrphy. To prepre PFpP thin film by spin-coting, the polymer ws dissolved in toluene (1 % by weight) nd the solution ws filtered by PTFR membrne with pore size of 0.22 μm. Then the resist ws spin-coted on clened silicon substrte nd bked t 100 o C for 5 min, which gve uniform film with thickness of 67 nm. Electron bem lithogrphy ws crried out using Rith 150 TWO system with 20 kv ccelertion voltges nd 1.4 na bem current. To obtin contrst curve, the resist film ws exposed with n re dose from 0.1 mc/cm 2 to 10 mc/cm 2. To explore its resolution cpbility, line rrys with period from 20 nm to 500 nm were exposed with line dose rnging from 15 nc/cm to 150 nc/cm, nd from 3 nc/cm to 30 nc/cm, for negtive nd positive tone, respectively. Investigtion of PFpP s negtive nd positive resist To study its negtive tone behvior, the developer should be ble to dissolve the unexposed re, but not the exposed nd thus cross-linked re. Mny solvents stisfy

4 this criterion, nd we developed the resist using THF nd nisole, both for 1 min, followed by rinsing with 2-propnol (IPA). As for positive tone, the developer should be strong enough to dissolve the exposed re hving drsticlly reduced moleculr weight due to chin scission upon exposure to electron bem, yet wek enough to not severely ttck the unexposed re. To strt with, we exmined the two most populr developers used respectively for positive resist PMMA nd ZEP-520 (Zeon Corportion), nmely methyl isobutyl ketone (MIBK) : IPA = 1:3 nd myl cette. The exposed resist ws developed for 30 sec for MIBK : IPA nd 1 min for myl cette, followed by rinsing with IPA before drying. After development, the contrst curve ws obtined from mesurement using Dektk 8 Stylus Profilometer, nd the high resolute structure ws imged using scnning electron microscope (SEM) nd tomic force microscope (AFM). PFpP s resistnce to dry plsm etching. To study PFpP s resistnce to dry plsm etching, O 2 rective ion etching (RIE, 20 sccm O 2 gs flow, 20 mtorr pressure nd 20 W RF power) ws crried out using Phntom II RIE system (Trion Technology Inc.). The etching rte of the synthesized PFpP resist ws compred with the most populr EBL resist PMMA nd ZEP-520A under the sme etching condition. Figure S3. Contrst curve of PFpP showing negtive tone

5 Figure S4. SEM imge of exposed line rry pttern with 80 nm period developed by MIBK: IPA= 1: 3