Korean Chem. Eng. Res., Vol. 45, No. 2, April, 2007, pp. 149-154 { m Š oi o ryl mk Ž z m mç Çoq Çmm Ç l o rq l 305-343 re o q 171 (2006 7o 19p r, 2006 9o 25p }ˆ) The Surface Treatment Effect for Nanoimprint Lithography using Vapor Deposition of Silane Coupling Agent Dong-Il Lee, Ki-Don kim, Jun-Ho Jeong, Eung-Sug Lee and Dae-Geun Choi Nano-Mechanical Systems Research Center, Korea Institute of Machinery & Materials, 171, Jang-dong Yuseong-gu, Daejeon 305-343, Korea (Received 19 July 2006; accepted 25 September 2006) k p r p s p Ž dš ( p ) pn l rr Ž ol s p r l Ž p r p. rp p rp o p p } k yp v vd pl r v (adhesion promoter) } n tn l p. l l q s e ƒ rp v p pn l p rl n r v } p m. p o ˆ (DUV-30J), v }, e ƒ r q s p l. e ƒ r q s p e p r~rp p p p p e s p r r m p 3-acryloxypropyl methyl dichlorosilane(apmds)p pn q s (SAMs) } ˆ v } r p v pl p rl r p k pl. h Abstract Nanoimprint lithography (NIL) is useful technique because of its low cost and high throughput capability for the fabrication of sub-micrometer patterns which has potential applications in micro-optics, magnetic memory devices, bio sensors, and photonic crystals. Usually, a chemical surface treatment of the stamp is needed to ensure a clean release after imprinting and to protect the expensive original master against contamination. Meanwhile, adhesion promoter between resin and substrate is also important in the nanoscale pattern. In this work, we have investigated the effect of surface treatment using silane coupling agent as release layer and adhesion promoter for UV-Nanoimprint lithography. Uniform SAM (self-assembled monolayer) could be fabricated by vapor deposition method. Vapor phase process eliminates the use of organic solvents and greatly simplifies the handling of the sample. It was also proven that 3-acryloxypropyl methyl dichlorosilane (APMDS) could strongly improve the adhesion force between resin and substrate compared with common planarization layer such as DUV-30J or oxygen plasma treatment. Key words: Nanoimprint, Silane Coupling Agent, Adhesion Promoter 1. p r ~ e rp p (nanoimprint lithography; NIL) r p l~ l q p ep p. p r p[1] s p Ž dš ( p ) pn l rr Ž o l s p r l Ž p r p. p rp 1995 d p Chou [1,2] rk mp, qn p (UV-NIL) rp 1996 To whom correspondence should be addressed. E-mail: lamcdg@kimm.re.kr Haisma l[3] p l rk l. p rp v ep p, lp pn thermal NIL(or hot embossing) e qn p pn UV-NIL ep p. Thermal NILp qn el d Š q Œ v kk l dš rp d n p v rp r qrp p., qn ep l el rkl rp p lv l v n qv ol Ž rel o rp r np qrp p., m d e p n v k l ql e p q rp v p [4]. 149
150 p pë Ërt Ëpp Ë s p Ž r o d dš q t m(quartz), (silicon (Si) or silicon dioxide(sio 2 ), ~ (GaAs) p t n lr m. p q l v k } lp n v l p mm p., Ž r el dš p mm v o p (release layer) } e n. p } t d p } l l v l r p eˆ p n. p rp q s q (self assembled monolayers, SAMs)p p kp p l v d sr p qrp v p l d l (F) q s q p v l r p tp l p v lm [4-7]. q s p p e -q s p e ƒ r(silane coupling agent) p - r(sol-gel) l r v, r v v, kr r, r pm vp r k n n l m. q rp s Fig. 1l m p p X m kˆ d ƒ(linker) o p R p lr pp X p t p p l p l (-OH) e pqm p v p -OH m p R p p pp o p l p. X p ql X p (X 3 ) k ee (trialkoxysilane)p X p k ee (monoalkoxysilane)p., R l,, pm l v vp l p., rp p rp o p p } k yp v ol v vd pl r v (adhesion promoter) } n tn l p (Fig. 2). p n p } m r v } n. v v vd m p p e p q o p p n lr mp q r v o v SAMsp ep p. sp p rp r v p ˆ (planarization)p p n l. ˆ p e p pl p l Ž r o p pm e (RIE) p e e p rl q p qn e e v e p r l m p t [6-9]. q s p p kp p r p v e t p pm e p e e p rl k m Fig. 2. (a) Schematic of major components in nanoimprint lithography (b) Reaction mechanism of resist and APMDS as adhesion layer. p tv kk e e p eˆ e p r p p., Ž rr qkvl, dš vd mp rp v r p v l Ž r r p lvv k r e [10]. l l q s e ƒ rp v p pn l p rl n r v } p m. p o ˆ (DUV-30J), v }, e ƒ r q p l. p rp p p n v p o n n k v l e p, dš p Œ np qrp pl p rp } l r. 2. 2-1. m z (release layer) n dš p qvp m(quartz) p. p } o dš - (3:1 vol ratio) nkl e r v } m. p r Trichloro-(1H,1H,2H,2Hperfluorooctyl) silane(fots) Dichlorodimethylsilane(DDMS)p n l. p p o n v q Fig. 3. v r, v, l} q p p~ p rq p } kl rp rq m. Fig. 1. The basic structure of silane coupling agent and an illustration of gas phase deposition of silane SAM. o45 o2 2007 4k 2-2. oy r z (adhesion promotor) e op - (piranha solution)l 1~2e r l e op p r m r (DI water) IPA Dryer r l ml 2e k s
p rl e ƒ r v p pn } 151 2-5. Š ~o m q s p e op p p AFM(atomic force microscope)p l r m. r p tapping mode digital instruments(di, USA) p AFM q pn l r m. q s p op n l p, p SEM(scanning electron microscope, FEI)p l r m. rq q XPS(X-ray/ultraviolet photoelectron spectroscopy, KRATOS) l rqp l v r ˆ r m. 3. y Fig. 3. Automatic Vapor SAM coater for release layer. (drying) e. p SAMs } p v (N 2 ) d tp e } (chamber) p r, SAMs } nkp 100 µl tpe } l v (evaporation)e e op l SAMs nkp v e. SAMs nkp r v o 3- acryloxypropyl methyl dichlorosilane(apmds)p n m. SAMs } ql vp r o acetone, IPA, DI water, IPA dryer r l ml se. e ƒ r p p ˆ (DUV-30J, Brewscience) v } p l. 2-3. m Š l l p l n m(quartz) dš rs o l rq (HITACHI) n l. (Cr) Ž Ž l kp ql vd r m l l p Ž p o ICP(inductive coupled plasma) n m. Ž p l del p n l vd ICP n l 200 nm p m Ž p m. srp p r r l d rq m. p rq d l Trichloro-(1H,1H,2H,2H-perfluorooctyl) silane p p } l r p l p e op l EVG 620-NIL q pn l p e p m. d o l UV vd d e(dispensing) ep pr p vd krp r p e op m k l p rp m. p r k p 125 mbar, k e p 120 s, e (exposure time) 180 s, (exposure intensity) 12 mw/cm 2 p s p qn p m. 2-4. PDMS mk o Sylgard Am B 10:1p p p p e op ol p 60 o Cl 2e k e PDMS(poyl(dimethylsiloxane)) l. 3-1. ny s (release layer) p re dš p l v l vl p mmp tp p } n tn rp. rp r v p e -ƒ rp psp Trichloro- (1H,1H,2H,2H-perfluorooctyl) silane (FOTS)p t n lr m p, v p l- r(lb) Ž(dip-coating)p pn k p t p n lr m. v, k l t n Š l(toluene), (hexane) p o n dš p p Ž (, 100 nm p )p l Œ q v Ž p r v p sv rp v p., p n p o v mm vp p rp p. l l Silane SAMs p p p sk p pnp q t (polymerization) l r p pq rp v p k p rp k q o n n l p pn e op dš l q s p m [11-13]. Fig. 4l p } e p r ˆ l. } v kp e p r p 40 o n k 40~50 dyne/cm pp l v p p rp (Fig. 4a). l l e SAMp v rl o v } k 1 p t p p l p mr r (Fig. 4b). p l v k 80~90 dyne/cm p. Ž (-CH 3 )m (-CF 3 ) p DDMSm Fig. 4. Water contact angle on the different surface. Korean Chem. Eng. Res., Vol. 45, No. 2, April, 2007
152 p pë Ërt Ëpp Ë FOTS } p n r p 100 o p p l v 20 dyne/cm p lr rp p r n p k p (Fig. 4c, 4d). p rp p r p ˆ p k p r p p v p p l m p p FOTSp n p rp r p k 120 o } k r p. ~pp wp DDMS np po p rp Trichloro silanel p p p qn 2 l rp r- o p r p. dš } p d l v p p l p rp p p ˆ l. 3-2. oy r p rl v p r p v eˆ o op ˆ (k 50 nm)p p n m. p ˆ p r v k vp p l o n n lr m. v v rrp p Ž p pn l Ž r e k p Žp l p p rp q (residual layer)p qn Ž p l e r l rp p. l l p rp k q Fig. 2m p SAMs nkp pn l nmp kp r (adhesion layer)p m. r p r v p pn l p m. Fig. 5. Contact angel of resin on the different surface treatment. p ˆ (DUV 3OJ), v, e ƒ rp APMDS l. p rp p el dš p } Ž } v kp rp p š., v Ž p r p sv kp n dš yl vp mm p e pl. p p } p p e p nl dš mmlp Ž p q r l. po, ˆ p nl p } dš y r v p } vp r p. v p rp p kk o v p r r Fig. 5l ˆ l. Fig. 5l p p dš yl FOTS l vp r p 75 o n v v r v ol vp rp(wetting)p q p k p., APMDS l k pl e l n k p p v o p p qrp p. APMDSm p e ƒ r r l n o p p v e t l p p dš p v l p e dš p mmp v l p. Fig. 6p 15 min k k p m l q s v AFMp r p. l p r~rp q s p e op p nm op p ov l p rl rn rpp lt plp, p m 80 o Cp 0.254 nm q r ˆ r~rp q s p k l p rl rn q s p l. Fig. 7p p m l APMDS e op o l q s v rq q (XPS) l rqp l vm r ˆ kk k. Sim oxide p pm l pv kv carbonp p m l l v(binding energy) v p k pl. Si e op ˆ oxide q s p o r} rp SPM ep cleaningp l oxide l p m m lp pr l v v pl. carbon p pm kv v p k pl. p pm v e op ol q s p v kp kr Fig. 6. AFM images of the silicon wafer surface after APMDS vapor deposition at different reaction temperature. (a) 60 o C, (b) 80 o C, (c) 100 o C. o45 o2 2007 4k
p rl e ƒ r v p pn } 153 Fig. 7. XPS data at the different reaction temperature of APMDS. Fig. 8. SEM images of various patterns made by nanoimprint lithography (NIL) using APMDS SAM as adhesion layer. (a) Planar SEM images of imprinted patterns (b) Cross-sectional SEM image of imprinted pattern. p. p rp, e ƒ r q p p l v kp v o, e l } q p p v ˆl }p n v p r n v p qp o. q s p e op SAMs nk e op p oxide l 285.0 ev l CH 3 -Cp ˆ ˆ lp, 288.9 evl O-C(=O)- Op ˆ ˆ l. pm p ˆ p -C=O-p l v v l p p k p., rm pp n p p o l} rp t p v. Fig. 8p APMDS e op ol q s p v l p p. Fig. 8a p sub-micron p k SEM p v p Fig. 8b p Ž p SEM ˆ l. Fig. 8bl p k 50 nmp q pnl rp q p l p qrp. ˆ p n ˆ q p v rp p. l p APMDS q s p e op p e s p r r mp APMDS v p rp r (adhesion) v p n p k p l. Fig. 9. Photographs of adhesion test using PDMS replication method. Korean Chem. Eng. Res., Vol. 45, No. 2, April, 2007
154 p pë Ërt Ëpp Ë Fig. 9 e op ol r p v p v } l p r q p PDMS(poly (dimethylsiloxane)) pn l r p p. l p ˆ v } l p r e p n, p Ž p rp lp PDMS re r p k p Ž p PDMSyp lr rp r p l v l. APMDS q s (SAMs)p pn l p Ž r e p n, vp p APMDSm k p o p pl r p j Ž p elp PDMS r rp pl. v, APMDS q s (SAMs) } ˆ v } r p v pl p Ž p PDMS rel r vpp k pl. 4. l l l p v e ƒ r q s p pn l p n } l m p kk k. l p dš p p } p lr r v p APMDS pn l q s (SAMs) l l v m. APMDSp r r p ˆ v d l. (1) p rp k v o FOTS e ƒ r k Ž p lv DDMSp n p p l rp p r n p k pl. (2) APMDS q s p, vl r p r rp p sp p dš p v l p e dš p mmp v pl. (3) p m v q s carbonp l v v p k pl. SAMs nk e op p oxide l 285.0 evl CH 3 -Cp ˆ ˆ lp, 288.9 evl O-C(=O)-Op ˆ ˆ l. (4) APMDS q s p e op p nm op p ov l p l rn rpp k pl. (5) APMDS pn q s (SAMs) } ˆ v } r p v pl p PDMS rl r p k pl. l 21 Žl l lp d l p l vo(m102kn010001)p k m d. y 1. Chou, S. Y., Krauss, P. R. and Renstrom, P. J., Imprint Lithography with 25-nanometer Resolution, Science, 272(5258), 85-87 (1996). 2. Chou, S. Y., Krauss, P. R. and Renstrom, P. J., Nanoimprint Lithography, J. Vac. Sci. Tech. B., 14(6), 4129-4133(1996). 3. Haisma, J., Verheijen, M. and Heuvel, K., Mold-Assisted Nanolithography: A Process for Reliable Pattern Replication, J. Vac. Sci. Tech. B., 14(6), 4124-4128(1996). 4. Resnick, D. J., Sreenivasan, S. V. and Willson, C. G., Step & Flash Imprint Lithography, Materialstoday, 8(2), 34-42(2005). 5. Austin, M. D., Ge, H., Wu, W., Li, M., Yu, Z., Wasserman, D., Lyon, S. A. and Chou, S. Y., Fabrication of 5 nm Line Width and 14nm Pitch Features by Nanoimprint Lithography, Appl. Phys. Lett., 84(26), 5299-5301(2006). 6. Jeong, J. H., Sim, Y. S., Sohn, H. K. and Lee, E. S., UV-nanoimprint Lithography Using an Elementwise Patterned Stamp, Microelectron. Eng., 75(2), 165-171(2004). 7. Choi, D. G., Jeong, J. H., Sim. Y. S., Lee, E. S., Kim, W, S. and Bea, B. S., Fluorinated Organic-inorganic Hybrid Mold as a New Stamp for Nanoimprint and Soft Lithography, Langmuir, 21(21), 9390-9392(2005). 8. Bailey, T., Choi, B. J., Colburn, M., Meissl, M., Shaya, S,. Ekerdt, J. G., Sreenivasan, S. V. and Willson, C. G., Step and Flash Imprint Lithography: Template Surface Treatment and Defect Analysis, J. Vac. Sci. Tech. B., 18(6), 3572-3577(2000). 9. Ruchhoeft, P., Colburn, M., Choi, B., Nounu, H., Johnson, S., Bailey, T., Damle, S. and Willson, C. G., Patterning Curved Surfaces : Template Generation by Ion Beam Proximity Lithography and Relief Transfer by Step and Flash Imprint Lithography, J. Vac. Sci. Tech. B., 17(6), 2965-2969(1999). 10. Colburn, M., Johnson, S., Stewart, M., Damle, S., Bailey, T., Choi, B., Wedlake, M., Michealsom, T., Sreenivasan, S. V., Ekerdt, J. and Willson, C. G., Step and Flash Imprint Lithography: A New Approach to High-resolution Patterning, Proc. SPIE., 3676(1), 379-389(1999). 11. Jung, G. Y., Li, Z., Wu, W., Ganapathiappan, S., Li, X., Olynick, L. D., Wang, S. Y., Tong, W. M. and Williams, R. S., Improved Pattern Transfer in Nanoimprint Lithography at 30 nm Half- Pitch by Substrate-Surface Functionalization, Langmuir, 21(14), 6127-6130(2005). 12. Kawai, A., Adhesion and Cohesion Properties of dot Resist Patterns Ranging from 84 to 364 nm Diameter Analyzed by Direct Peeling Method with Atomic Force Microscope Tip, J. Photopolym. Sci. Technol., 15(1), 121-126(2002). 13. Bunker, B. C., Carpick, R. W., Assink, R. A., Thomas, M. L., Hankins, M. G., Voigt, J. A., Sipola, D., De bore, M. P. and Gulley, G. L., The Impact of Solution Agglomeration on the Deposition of Self-Assembled Monolayer, Langmuir, 16(20), 7742-7751(2000). o45 o2 2007 4k