Important challenge for the extension of Spacer DP process

Transcription

1 Important challenge for the extension of Spacer DP process H. Yaegashi Tokyo Electron Limited Leading-edge Process development center Kobe, JAPAN 21 October

2 Outline Background Lithographic scaling by Self-aligned DP(SADP) SADP Applicability -Gridded design for poly-level and metal level Fundamental techniques for DP process Resist slimming process Hole-shrink process Summary 2

3 Photolithography Trend nm 500nm Minimum feature (nm) nm 248nm 350nm 250nm 180nm 130nm 90nm 193nm 65nm 45nm 32nm 22nm 15nm 11nm year 13.5nm 3

4 Various DP schemes 1,LELE for line 2,LELE for trench/hole 3,LLE 4,Self-aligned Spacer DP 4

5 Process scheme of Self aligned DP Post Litho BARC trim SiO2 depo SiO2 Etch-back & core strip H/M Etch PR:80nm BARC:37nm Poly-Si:100nm 40nm hp 20nm hp 5

6 Pitch Quadrupling Litho 1 st HM etch Depo. Etch-back 2 nd HM etch Depo. Etch-back H/M Etch 45nm hp 23nm hp 11nm hp 23nm Pitch 6

7 Spacer & Cut Process 40nm hp Photo-resist BARC 20nm hp Poly 20nm Core PR SADP Cut mask CD Shrink Final etch 40nm hp 20nm hp 20nm cut 7

8 2006/LELE Historical examination results V. Wiaux et al., imec IIAP (2006) C.bencher, et al., SPIE 7274 (2009) K. Oyama, et al., SPIE 7639 (2010) 8

9 Spacer & Cut Process for trench pattern Core PR PR slimming Spacer Depo Spacer etchback 2nd PR (Bar) BARC&SiARC etch HM etch PR SiARC=30nm SOH=180nm SiN=50nm 48nm hp Dry slimming Etch back 24nm hp BARC 9

10 Spacer &Cut process for random layout post Litho. Pitch-doubling Cutting 50nm hp 25nm hp Random cut 10

11 Image comparison Positive / negative tone resist Positive tone resist Mask Aerial image Negative tone resist Mask Aerial image (Bias+0/Serif+5) (Bias+5/Serif+10) Resist image Resist image 68.9nm 44.7nm NA1.3S0.98CP0.63 XYpolarized 6%attPSM 11

12 Resolution improvement Posi-type resist + ALD/SiO2 shrink Nega-type resist Cut mask PR (Posi resist) ALD SiO2 depo(6nm) Cut mask PR (Nega resist) 12

13 Image comparison Positive tone resist Negative tone resist 13

14 Short Summary ~ 193 Extension 193-i Resolution Limit Pitch-Doubling Pitch-Quadrupling 40nmhp 20nmhp 11nmhp Down scaling for gate 20nmhp for trench 24nmhp for Random 25nmhp Lay-out modification 14

15 Fundamental techniques for DP 15

16 CD bias control in DP schemes 1,LELE for line Trim Trim 2,LELE for trench/hole Shrink Shrink 3,LLE Trim Trim 4,Self-aligned DP Trim 16

17 Effective PR slimming control 1 Process time (a.u.) A/R=2.4 A/R=3.2 A/R=3.4 A/R=3.5 A/R=4.3 CD=39.8nm CD=28.0nm CD=25.0nm CD=22.8nm CD=18.1nm Height=94.2nm Height=89.2nm Height=84.1nm Height=79.3nm Height=78.4nm 17

18 Merit of CD bias control (Slimming) Dose control with Slimming Process window EL(%) DOF(um) 18

19 PR slimming for 2D pattern 19

20 Chemical assist Deposition Tapered Etching Hole shrink Schemes Litho. Chem. Apply Bake Litho. Film depo. Etch back Litho. Taper Etch Strip 20

21 Control (0nm) Hole-shrink ~ SiO2 deposition SiO2 deposition thickness 5nm 10nm 15nm 25nm CD=65nm CD=55nm CD=45nm CD=35nm CD=15nm 21

22 CD bias control ~ ALD SiO2 Control : As Litho. Depo = 3nm Depo = 5nm Depo = 10nm Depo = 20nm Depo = 30nm y = x R 2 = Thickness (Å) Thickness[A] cycle# Process cycle# 22

23 Shrink property comparison control 20nm 25nm 30~35nm 40nm Chemical Assist Y=54.5nm X=118.8nm Y=34.4nm X=93.5nm Y=30.7nm X=81.3nm Y=25.3nm X=54.4nm SiO2 deposition Y=54.5nm X=118.8nm skip Y=30.1nm X=87.7nm Y=21.2nm X=79.7nm Y=14.5nm X=65.8nm 23

24 X-Y diameter linearity Hole size (nm) X Y : Chem. assist : SiO2 depo Shrink ammount (nm) 24

25 Pattern transfer reliability (1) Post-Litho. Hole shrink on TEOS Control w/o shrink Chemical Assist SiO2 Depo. 25

26 Pattern transfer reliability (2) Post-Litho. Hole shrink on TEOS Control w/o shrink Chemical Assist D=47.7nm SiO2 Depo. D=30.4nm 26

27 Summary H2O base immersion 193nm is still major exposure technique, and will be able to extend lithographic scaling combined with Double Patterning process SADP (Self-aligned spacer DP) can be modified easily to match well with restricted design rule. -SADP & Cut process for island, trench and complex 2D pattern Resist slimming is essential in any DP scheme to maintain wide process window. Hole shrink process with low-temp. SiO2 deposition can control the hole size precisely, and it may reduce the defect after etching. 27

28 Acknowledgement The author would like to express appreciation to Tokyo Electron / Leading-edge Process Development Center Tokyo Electron AT / Technical Development Center Tokyo Electron Kyushu / SPE process technology dept. Tokyo Electron Tohoku / Development dept. for their support in carrying out the experiments described in this paper. 28

29 Double Patterning Process TOKYO ELECTRON 29