Novel olyphenol Base Molecular Resist Having High Thermal Resistance Taku Hirayama, Takeyoshi Mimura, Jun Iwashita, Makiko Irie, Daiju hiono, Hideo Hada and Takeshi Iwai TKY KA KGY C., LTD. 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#2 Contents Introduction Concept Evaluation results of new molecular glasses Thermal property Dissolution curve Resolution on EB exposure ummary 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
Key lithography-related characteristics and resist requirements on the ITR 2007 Table Key lithography-related characteristics and resist requirements on the ITR 2007. #3 Year of production 2007 2010 2013 2016 DRAM half pitch (nm) 65 45 32 22 MU Gate in resist (nm) 42 30 21 15 MU hysical Gate Length (nm) 25 18 13 9 Gate CD control (3 sigma) (nm) 2.6 1.9 1.3 0.9 Low frequency line width roughness 3.4 2.4 1.7 1.2 (3 sigma, <8% of CD) (nm) 193 nm immersion with water 193 nm immersion double patterning 193 nm immersion double patterning EUV 193 nm immersion with other fluids and lens materials ML2, Imprint EUV Innovative 193 nm immersion ML2, Imprint, Innovative technoligy Yellow character : Manufacturable solutions are known ink character : Interim solutions are known Red character : Manufacturable solutions are NT known ML2: maskless lithography EUV: extreme ultraviolet 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#4 Molecular size comparison approx. 4 nm approx. 2 nm olymer ize * * 50 Calculation method : MM2 Bond energy : 669.5 kcal/mol (a) olymer resists (b) Molecular resists (MG) ubstrate ubstrate Figure chematic illustrations of cross sectional resist pattern based on (a) the conventional polymeric material and (b) the low molecular base matrix. T. Kadota, et.al., roc. IE, 4345 (2001) 891. 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#5 Molecular glass (MG) candidates on our work so far <ositive tone type resist> -tboc H 3 C R R R = H 3 C R R R R T. Hirayama et. al., IE 6153-18 (2006). H Jpn. Kokai Tokkyo Koho J 08 33102 R R R = H or R R H 3 C R R H D. hiono et. al., Jpn. J. Appl. hys. 45 (2006) 5435. <Negative tone type resist> T. Hirayama et. al., J. hotopolym. ci. Technol. 17 (2004) 435. R R R = H or H 3 C R R R R K. Kojima et. al., J. hotopolym. ci. Technol. 19 (2006) 373. 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#6 Distribution of protecting group number R R R R H R R R R where R is H or protecting group R R R R where R is H or protecting group 100 artially protected 25X-MBA (25X-MBA-) rotecting ratio is determined to be approx. 32 mol% by using 13 C-NMR Fractionated 25X-MBA- rotecting ratio is determined to be approx. 33 mol% by using 13 C-NMR and HLC 100 rot-mad-2 riginally designed to have two protecting groups onto the core 100 80 80 80 Content (%) 60 40 20 Content (%) 60 40 20 Content (%) 60 40 20 0 0 1 2 3 4 5 Number of protecting group in a molecule 0 0 1 2 3 4 5 Number of protecting group in a molecule 0 0 1 2 3 4 5 Number of protecting group in a molecule C/N EUV : rocess 2120809051 Technology LER(3 sigma) =9.9 nm LER(3 sigma) =5.8 nm 100nm hp feature on EB 100nm hp feature on EB 100nm hp feature on EB Film thickness;100nm Exposure;HL800D (70kV) Development;NMD-3 2.38% of 0.26 N TMAH for 60s puddle The resist consisting of Tek25X-DCADM achieved 28 nm resolution and 3.6 nm of LER on 45 nm feature including low frequency roughness region on EUV exposure by using HiNA3 of AET, Japan D. hiono et al., roc. IE, 6519 (2007) 65193U. 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK LER(3 sigma) =5.6 nm Thickness : 58 nm Dose : 12.2 mj/cm 2
#7 Concept To achieve better resolution using MG material Number of protecting group increases, and position of protecting groups should be defined in the structure in order to increase dissolution contrast to be comparable to common polymeric materials Higher thermal resistance should be realized, also to be similar to polymeric materials LER (nm) 14 12 10 8 6 0 Number of deproteciton reaction required for solubility change (contrast) 10 20 5 10 15 20 Variation (Distribution of deprotection reaction) LER strongly depends on the number of deprotection reaction for solubility change and its distribution. H. Fukuda: Jpn. J. Appl. hys., 42 (2003) 3748. 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#8 MGs based on polyphenol In many of papers concerning MG material and also our previous reports, some of un-protected MG show enough high glass transition temperature, Tg, but after protection reaction, the Tg of (partially or fully) protected MGs was usually getting lower than that of unprotected due to, maybe, lack of hydrogen bonding and intermolecular interaction A. D. ilval et al., roc. IE, 6923 (2008) 69231L-1. T. Hirayama et. al., J. hotopolym. ci. Technol., 17 (2004) 435. According to our concept for MGs which have polyphenol cores and protecting groups of precise number at the specific position in the structure, we prepared several candidates to increase number of protecting group and thermal resistance by increasing number of protecting groups and molecular weight R R R R R R where R is H or protecting group artially protected 25X-MBA (25X-MBA-) H rot-quad-4 M=~2K H rot-mad-2 M=1238 H H H rot-quad-3 M=~1.5K rot-ct-4 M=~2.5K : rotecting group 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
How to define the thermal resistance of protected base matrix #9 The Tg is a good indicator for thermal resistance property of the resist on realistic lithography process and is one of the important factor for not only polymeric resist but MG resist In some case, MG material of which alkaline soluble group is fully or partially protected doesn t show apparent glass transition behavior on thermal analysis such as DC so that we considered how we could define the thermal property and decided to measure thermal flow starting temperature on contact hole feature by the following procedure; Development ost bake CD hrink is observed by CD-EM The resist film is exposed by 248nm light and baked as EB treatment Note; the resist solution used is formulated with protected base resin, AG, amine and solvent, meaning that those are model REIT solutions, not Un-protected base resin solution ost bake temperature No post bake The exposed film is developed and 170 nm of isolated hole feature is obtained 150 C 155 C ost bake is applied at various temperature and the CD is measured. The post bake temperature where 10% of CD shrink occurs, is defined as thermal flow starting temperature 160 C Common polymeric resist (H/Acryl hybrid) 10% of CD shrink is observed at 159 C from the fitting curve of post bake temperature-cd plots 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
Relationship between Tg of unprotected MGs and thermal flow temperature #10 Thermal flow starting temperature ( C) 170 160 150 140 130 120 110 100 100 120 140 160 180 200 220 Various common polymeric resists based on H/Acryl polymer shows 130 to 160 C of thermal flow temperature through same investigation procedure H H Tg of unprotected MG ( C) rot-ct-4 M=~2.5K H H H Note that for thermal flow measurement, test resists are formulated with rotected MG, AG and amine rot-mad-2 M=1238 rot-quad-3 M=~1.5K rot-quad-4 M=~2K 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#11 Tg dependency on molecular weight 240 Tg of unprotected MG ( C) 220 200 180 160 140 120 H H 100 500 2500 Molecular weight Unprot-ct-4 H H H H Unprot-Mad-2 M=941 Unprot-Quad-3 Unprot-Quad-4 : Alkaline soluble group 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#12 Contrast curve 1.2 1.0 Normalized film hickness 0.8 0.6 0.4 0.2 rot-mad-2 rot-quad-3 rot-ct-4 1123 0.0 1.0 10.0 100.0 Dose (µm/cm 2 ) ubstrate:i HMD treated 90-36s, Thickness:100nm Tool: HL800D 70keV AG and amine formulation is the same among all the test samples including rot-mad-2, rot-quad-3 and rot-ct-4. EUVR-1123 is TK s EUV resist of which formulation has been optimized for the process The resist consisting of rot-ct-4 shows good dissolution contrast as well as that with rot-quad-3 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#13 Exposure results on EB tool ample LWR EL ensitivity Beam size (nm) 100 EUVR-1123 11.9 nm 8.0% 48.0 µc/cm 2 Test resist using rot-ct-4 11.3 nm 7.3% 30.0 µc/cm 2 90 80 70 60 50 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK EUVR-1123 is TK s EUV resist of which formulation has been optimized for the process ubstrate: Bare-ili n (HMD treatment, 90 C-36 sec) Resist Film Thickness: 60 nm EB Writer: Hitachi HL-800D (VB, 70 kv, 7 A/cm 2 ) Target pattern: 100 nm L (duty ratio, 1:1) Development: NMD-3, 2.38 wt% TMAHaq., 60 sec, LD-nozzle Rinse: Distilled water, 15 sec
#14 ummary We have synthesized polyohenol base molecular glass (MG) candidates based on the concept to increase number of protecting groups and molecular weight and to attach the protecting groups in the specific positions of the MG structure In order to define thermal resistance of base materials, measurement of thermal flow starting temperature using contact hole feature is utilized rot-ct-4 which has four protecting group showed enough high thermal flow starting temperature ~154 C, comparable to that of common polymeric material Test resist formulated with rot-ct-4 partially achieved 50 nm resolution on EB exposure tool (70 kv, VB) and it seems to be comparable to the result of EUVR-1123. EUV exposure test is needed to confirm the performance of this material 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#15 Appendix; EUV exposure result of EUVR-1123 at I LWR 6.0nm 50nm L RCD 50.9nm Dose 23.6mJ/cm 2 45nm L RCD 46.7nm Dose 24.3mJ/cm 2 40nm L RCD 39.4nm Dose 26.0mJ/cm 2 32.5nm L RCD 31.4nm Dose 29.6mJ/cm 2 30.0nm L RCD 29.0nm Dose 35.4mJ/cm 2 25nm L RCD 28.5nm Dose 41.0mJ/cm 2 rocess conditions ubstrate i Resist EUVR-1123, 80nm FT AB 120 C for 60 sec EUV tool Interferometer@I EB 100 C for 60 sec Data courtesy of IMEC 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK
#16 Acknowledgements The authors would like to thank Mr.Akira Yoshitomo and Mr.Tatsuya Iwai of Honshu Chemical Industry co., Ltd. for their experimental supports. 2008 International ymposium, 1st of ctober 2008, Lake Tahoe, California T.Hirayama, TK