The application of negative tone development for small contact hole and resolution enhancement

Transcription

1 , ~22 Kobe The application of negative tone development for small contact hole and resolution enhancement Kyoung-Seon Kim, Shi-yong Yi, Seok-Hwan Oh, Jeong-Ho Yeo Samsung Electronics Co., LTD.

2 Contents Brief Summary of Lithography Extensions NTD dense L/S pattern Evaluation NTD Application : Contact hole Summary

3 Contents Brief Summary of Lithography Extensions NTD dense L/S pattern Evaluation NTD Application : Contact hole Summary

4 Lithography Technology SET DET DPT NGL Stitching Trimming Sidewall LELE DSA ML2 X-Contact Pattern Splitting NIL Low Cost DPT NTD LFLE SET : Single Exposure Tech. DET : Double Exposure Tech. DPT : Double Patterning Tech. SW : Sidewall LELE : Litho Etch Litho Etch NTD : Negative Tone Develop LFLE : Litho Freezing Litho Etch NGL: Next Generation Lithography DSA : Direct Self Assembly ML2 : Mask less Lithography NIL : Nano Imprint Lithography

5 Low Cost DPT : LFLE and NTD Process Cap- Freezing Thermal Freezing Implant freezing Dual solvent UV-Cure freezing Amine-vapor Freezing Negative tone develop Resist Conventional / dedicated Dedicated Conventional Dedicated Conventional Dedicated Dedicated New chemical Needed Not needed Not needed Not needed Not needed Needed Needed Special module Needed Not needed Needed Not needed Needed Needed Needed CD-Shift Need optimization Need optimization Too large Need optimization Too large Need optimization - Defect Risky Throughput Low Middle Middle Middle Middle Middle High Low cost DPT is important for cost reduction of memory device.

6 Low Cost DPT : Process Process scheme LFLE NTD Substrate 1 st Pattern Substrate 1 st Exposure Substrate Substrate Substrate Freezing CAP or Hard Bake 2 nd Pattern Substrate Substrate Substrate Freezing CAP X-linked Layer 2 nd Pattern A simplified process can be realized using NTD sans freezing step. Masafumi Hori,SPIE Vol. 6923, 69230H-1 L.Van Look, SPIE Vol.7640, Shinji Tarutani, 4 th International symposium on immersion Lithography

7 Low Cost DPT : Dense contact hole - Dense contact hole double line exposure -1.2 NA (Dipole 35X/Y-pol, Dipoe 35Y/X-pol) -1:1 L/S Mask Low cost Double Patterning (LFLE) DET Cap Freezing Dual Solvent Thermal Freezing NTD Method Cap coating solubility Hard bake Nega-tone develop Image CD (mean) X bar: 43 / Y bar: 45 X bar: 41 / Y bar: 43 X bar: 44 / Y bar: ** Total CDU(3σ)* X : 3.5 / Y : 3.4 X : 3.4 / Y : 5.5 X : 4.4 / Y : Total CDU: 8 shots around center x 9 holes per shot = 72 points ** Hole diameter DPT & NTD Process were evaluated for dense contact holes. However, CD uniformity was poor.

8 Contents Brief Summary of Lithography Extensions NTD dense L/S pattern Evaluation NTD Application : Contact hole Summary

9 L/S Pattern feasibility Evaluation conditions Substrate : Stack wafer ARC : O-ARC 250A PR : 1000A NTD Sample A3 / NTD Sample B1 / Positive PR Illumination condition : 1.2NA (immersion tool) Dipole 35X (Y-pol) 1:1 L/S Mask Develop : Organic develop solvent, Organic rinse solvent@ NTD Single exposure 2.38wt% TMAH@ Positive PR

10 Dense L/S pattern : Resolution CD [nm] NTD Sample A3 vs Positive L/S NTD A3 y = 2.11 x R 2 = 0.94 Posi PR y = -1.06x NTD Sample A3 R 2 = PR L/S Pattern Bridge Target CD 51nm NTD Sample A3 L/S Pattern Collapse dose [mj/cm2] -The resolution limit of NTD is 51nm using 1:1 L/S mask.

11 Dense L/S pattern : LWR LWR - LWR vs CD Variation LWR: NTD A3 vs NTD B1 vs Positive PR NTD B1 Positive PR NTD A CD [nm] A Comparison of results between positive PR and NTD PR for pitch 94nm 1: 1L/S pattern show that LWR is high in case of NTD PR.

12 Dense L/S pattern : vertical profile Positive Process NTD Sample B1 NTD Sample A3 Positive PR@ Normal develop Target CD 55 nm target 26.0 mj/cm 2 %EL (10%CD) % Dose sensitivity 0.40 nm/%dose LWR 3.11 nm NTD Sample B1 Target CD 55 nm target 28.6 mj/cm 2 %EL (10%CD) % Dose sensitivity 0.30 nm/%dose LWR 3.4 nm NTD Sample A3 Target CD 55 nm target 25.3 mj/cm 2 %EL (10%CD) % Dose sensitivity 0.62 nm/%dose LWR 4.23 nm Height 76nm Height 75nm

13 Contents Brief Summary of Lithography Extensions NTD dense L/S pattern Evaluation NTD Application : Contact hole Summary

14 Application Narrow trench pattern Random logic contact layer Dense small contact hole Shinji Tarutani, SPIE Vol. 7273, 72730C-1 L.Van Look, SPIE Vol.7640, V. Truffert, SPIE Vol.7274, 76400N-1

15 Dense contact hole feasibility Evaluation conditions Substrate : Stack wafer ARC : O-ARC 250A PR : 1000A NTD Sample A3 Illumination condition : 1.2NA (immersion tool) Dipole 35X, Y-Polarization Dipole 35Y, X-Polarization 1:1 L/S Mask Develop : Organic develop solvent, Organic rinse solvent@ NTD Double line exposure

16 Dense contact hole NTD Sample A3 Height 77.87nm 43nm -% EL : 10.4 % -Process step is simple; 45nm dense contact holes were successfully patterned. - Uniformity & profile needs improvement.

17 Logic contact layer feasibility Evaluation conditions Substrate : Stack wafer ARC : O-ARC 250A PR : 1000A NTD Sample A3 Illumination condition : 1.35NA Annular (TE-pol) Rectangle Dot shape mask Develop : Organic develop solvent, Organic rinse solvent@ NTD Single exposure

18 Rectangle contact hole Positive PR NTD Sample A3 54 nm -% EL : 16.5% -Resolution limit 53nm 45nm -% EL : 7.81% - Resolution limit 43nm

19 Rectangle contact hole - Sub 50nm contact hole formation using positive PR process is difficult/complex. - Moreover, additional steps are required for small size C/Hs if positive process is employed. - Comparing Positive PR feasibility, a 10 nm gain in resolution margin is achieved by NTD. - DoF margin improves by ~20nm. - X axis 45nm achieved using single exposure.

20 Contents Brief Summary of Lithography Extensions NTD dense L/S pattern Evaluation NTD Application : Contact hole Summary

21 Summary Resolution Defect control Low cost Throughput Printing of smaller pitches and feature. : Sub 45nm contact hole was demonstrated. Uniformity control : Significant uniformity control required if this process is to evolve as a powerful technology. A more cost effective process : NTD is highly attractive compared to alternative DPT processes Simple process step : Resist coating once exposure develop. Resist property : Continuous improvement

22 Thank you for your attention!!! And the authors would like to thank FUJIFILM for NTD materials.