Performances of fluoropolymer resists for 157-nm lithography

Transcription

1 1 Performances of fluoropolymer resists for 157-nm lithography Seiichi Ishikawa, Naomi Shida, Tamio Yamazaki, Hiroyuki Watanabe, Seiro Miyoshi, Takamitsu Furukawa, Minoru Toriumi and Toshiro Itani

2 Contents 2 Introduction Characterization of base resin Summary Target properties for single-layer resists Structures of fluoropolymers Transparency RIE resistance Alkaline solubility Outgassing Imaging and pattern transfer Imaging by 0.85NA microstepper L/S and C/H pattern transfer

3 3 Target performances for single-layer resists Optical properties ; Absorbance < 1.5µm -1 RIE resistance ; Rate < 1.0X to ArF resist Dissolution property ; No swelling, Rmax > 200nm/s Imaging performance ; Resolution limit < 65nm

4 4 Target performances for single-layer resists Optical properties ; Absorbance < 1.5µm -1 RIE resistance ; Rate < 1.0X to ArF resist Dissolution property ; No swelling, Rmax > 200nm/s Imaging performance ; Resolution limit < 65nm Main-chain fluorinated polymers

5 5 Absorbance of fluoropolymers Frequency Main-chain fluorination Other fluorination Absorption coefficient mm [µm -1 ] -1 ]

6 6 Main-chain fluorinated polymer TFE-NB Monocyclic polymer F F F F F F F F F F F k l m O O R F F HO CF 3 m F F RO CF 3 n FP1 FP2 - Superior optical transparencies - Suitable dissolution behavior into alkaline developer - Proper RIE resistance

7 FP1 : TFE + NB + α-fluoroolefin 7 CF 2 CF 2 x y CH 2 CF C z O luorinated backbones High transmittance Norbornene RIE resistance O R Alkaline soluble group Protecting group Imaging, Adhesion R = H, tboc, etc

8 FP2 : Monocyclic polymer 8 CF 2 CF CH 2 x CF 2 CF CH 2 y CF 2 CF 2 CF 3 OH Fluorinated backbones High transmittance Cyclic structure RIE resistance CF 3 O R R=t-BOC,THP,etc Alkaline soluble group Protecting group Imaging, Adhesion

9 9 Characterization of base resin Transparency RIE resistance Alkaline solubility Outgassing

10 10 Absorption coefficient on F contents Absorption coefficient [µm -1 ] FP1 FP Fluorine atom content [wt%] %T thickness [nm] FP1,FP2 were archived Abs. < 1.5 µm -1

11 3 RIE rate on F contents 11 RIE rate [vs. ArF resist] FP1 FP Fluorine atom content [wt%] FP1 = same as ArF resist FP2 = Low durability

12 12 Dissolution behavior 250 FP1 150 FP Thickness / nm Development time / s Rmax = 240 nm/s Development time / s Rmax = 30 nm/s No swelling

13 Outgassing from resist (GC-MS chart) 13 Total ion intensity / urb.unit Total Dose 100 mj/cm 2 Pulse energy 0.1 mj/cm 2 -pulse Laser frequency 10 Hz Irradiation area 1.2 cm x 2.4 cm Nb-HFIPA FP1 FP2 PAG:TPSOTf, 5wt% Retention time / min

14 14 Total amount of outgassing from resist 500 Amount of outgas / ng Nb-HFIPA FP1 FP2

15 15 Contents of outgassing from resist Amount of outgas / ng 500 Others 400 C-F Blocking Gr. 300 PAG Nb-HFIPA FP1 FP2

16 16 Characterization summary FP1 FP2 Absorbance µm µm -1 RIE (vs. ArF) X X Dissolution rate (R max ) 240 nm/s nm/s Outgassing < 430 ng < 50 ng

17 17 Imaging Resolution limit by 0.85NA microstepper Resolution of thick film imaging of FP2 based resist

18 18 FP1-based resist Substrate : BARC/85nm Si Reticle : Alt. PSM Illumination : 0.85NA / 0.30σ 70 nm L/S 65 nm L/S 60 nm L/S Thickness = 120 nm

19 19 FP2-based resist Substrate : BARC/85nm Si Reticle : Alt. PSM Illumination : 0.85NA / 0.30σ 70 nm L/S 65 nm L/S 60 nm L/S Thickness = 150 nm

20 20 Thick film imaging by FP2 based resist 90 nm L/S 85 nm L/S Substrate : BARC/85nm Si Reticle : Alt. PSM Illumination : 0.85NA / 0.30σ 80 nm L/S Thickness = 250 nm

21 21 Pattern transfer L/S pattern C/H pattern

22 22 Film structure Resist Organic BARC = 30nm SiN = 70nm (L/S) 100nm (C/H) Substrate for L/S pattern for C/H pattern

23 Pattern transfer of 130nm L/S pattern 23 Development BARC/SiN RIE Ashing FP1 50nm t.) FP2 50nm t.) The pattern profiles of of SiN were fairly good

24 Pattern transfer of 150nm C/H pattern using by FP2 based resist 24 Development BARC/SiN RIE Resist/BARC ashing TEOS SiO 2 RIE FP2 0nm t.) C/H pattern was successfully fabricated

25 Summary Two main-chain fluorinated polymer families (FP1,FP2) were evaluated ; FP1 show high transmittance, good RIE resistance, suitable dissolution and much outgassing. FP2 show excellently high transmittance, lower RIE resistance, relatively slow dissolution and extremely small outgassing. 2. Fluoropolymer based resists were evaluated by 0.85NA microstepper ; FP1 resolved 65nmL/S (120nm t). FP2 resolved 65nmL/S (150nm t) and 85nmL/S (250nm t). L/S pattern transfer were succeeded by FP1 and FP2. C/H pattern transfer were succeeded by FP2. More improvement of polymer characteristics, resist resolution and fabrication process are now underway.

26 Acknowledgements 26