High Power, High Repetition Rate F 2 Laser for 157 nm Lithography

Transcription

1 High Power, High Repetition Rate F 2 Laser R. Pätzel a, S. Spratte a, F. Voss a, I. Bragin a, E. Bergmann a, N. Niemöller a, T. Nagy a, U. Rebhan a, K. Vogler a, I. Klaft a, S. Govorkov b, G. Hua b a Lambda Physik AG, Hans-Böckler-Straße 12, D Göttingen, Germany b Lambda Physik USA, Inc., 3201 West Commercial Blvd, Fort Lauderdale, FL Tel: Fax: RanD@lambdaphysik.com Slide 1

2 High power, High Repetition Rate F 2 -Laser Outline: Standard 2 khz F 2 - Laser System Key specifications Long-term operation & reliability data Prototype 4 khz F 2 - Laser System single line operation spectral properties beam parameters Slide 2

3 NovaLine F2020 Standard 2 khz F 2 Laser ield-application of the NL F2020 ser for more than 2 years Specifications: Power 20 2 khz Pulse energy 10 mj ( single line ) Wavelength (nom.) nm Bandwidth < 1.2 pm, FWHM Spectral purity > 95% of nm in 4 pm (red/ infrared < 1%) Beam profile (23 ± 5) mm / (5.5 ± 2) mm, 1/e Beam divergence (6 ± 2) mrad / (1.5 ± 1) mrad, 1/ Dose stability < ± 0.5% MAV(50) Peak power < 1 MW related to TIS Polarization > 95 % Gas life > 50 Mio pulses Slide 3

4 NovaLine F2020 Long-Term Operation F2020 long term site: 6.7 Bio shots Laser performance over Laser Discharge Unit Lifetime Max. pulse energy E 13m Pulse stability 0.7 %, sig Slide 4

5 NovaLine F2020 Long-Term Operation Module Demonstrated best life time at customer site [billion pulses] LDU > 5 FOM > 20 ROM > 20 Window > 2 Operating conditions: Operation at customer site 2 khz repetition rate W output power (depending on test conditions) Extended life times have been 2 khz Good basis for 4 khz operation Slide 5

6 High power, High Repetition Rate F 2 -Laser Outline: Standard Commercial 2 khz F 2 - Laser System Key specifications Long-term operation & reliability data Prototype 4 khz F 2 - Laser System single line operation spectral properties beam parameters Slide 6

7 4 khz F 2 Laser System - Broad Band Operation - Output Power and Energy Stability vs. Repetition Rate Results: (multi-line operation) Power 40 4kHz Pulse energy 10 mj (independent on reprate) Energy stability < 1%, sig Slide 7

8 4 khz F 2 Laser System - Single Line Operation - Output Power and Energy Stability vs. Repetition Rate Results (single line operation 4kHz, 20 W is achievable with good margin! P = 20W 4k Pulse energy E = 5mJ constant over rep. rate Pulse stability (sigma < 1 Slide 8

9 4 khz F 2 Laser System - Long-Term Tests - Burst 4kHz rep.rate Monitoring of: laser power, high voltage P/Watt HV/kV Time/h POWER [W] HV [kv] Slide 9

10 Spatial 157 nm F2020 Spatial Coherence (distribution within the beam): Dependence on alignment of laser resonator well adjusted : higher coherence - Distribution of regions of high and low coherence within the beam profile - not homogeneously distribut [mm] de-adjusted : lower coherence Slide 10

11 Compact High Resolution VUV 157 nm Spectrometer Individual laser check: dependence of spectral properties on repetition rate 1kHz...4 khz operation & gas conditions Features: very compact, moveable vacuum tight, N 2 purged slit function: FWHM < 0.09 pm E (95) < 0.35 pm adequate SW background subtraction inspection range = 15 pm dispersion = 13.8 fm / px Slide 11

12 4 khz F 2 Laser System - Measurements of Spectral Line - First 4kHz Results: Asymmetry = EGY EGY blue red Line Shape comparable to 2kHz operation same pressure dependenc same ratio of asymmetry r = 1.5 % FWHM ~ 1.0 pm E(95%) ~ 2.9 pm (λ - λ cent grav ) ~ 0.19 pm improve line selection second line suppression ratio: R= I(λ 2 )/ I(λ 1 ) ~ 0.35%! Slide 12

13 4 khz F 2 Laser System - Bandwidth & 2 nd Line Suppression - Bandwidth (FWHM) [pm] Measurements of Bandwidth and 2nd Line suppression Instruments: high resolution 157nm-VUV-spectrometer dependence on: reprate, HV, pulse energy, discharge circuit electrode configuration, resonator design Repetition rate [Hz] HV = 2.2 kv Line ratio [%] Rep. rate [Hz] Slide 13 Result: - Stable bandwidth versus reprate - FWHM 1.1pm(convoluted) - Second line ratio: R < 0.5%! Bandwith (FWHM) [pm] Line ratio [%]

14 4 khz F 2 Laser System - Beam Dimensions - Result of F4020: similar beam dimensions to F2020 beam width (1/e 2 ) ~ 4.5 mm x 20 mm stable over gas life and repetition rate Slide 14

15 4 khz F 2 Laser System - Divergence and Pointing Stability - First Measurements of 4kHz Beam Profiles: investigation: 157nm VUV beam profiler & new SW: Mr. Beam dependence on: reprate, HV, pulse energy, discharge circuit electrode configuration, resonator design divergence (1/e 2 ) ~ 2 mrad x 7 mrad Pointing: Over gas life: < ± 150 µrad Short term: < ± 20 µrad Slide 15

16 Summary High power, High Repetition Rate F 2 -Laser Reliable, mature 2kHz F 2 - lasers installed in the field excellent durability data achieved New metrology for true 4kHz in place 157nm, single line, 4kHz, 20W laser product (NovaLine F4020) ready for shipment Slide 16

17 High-Power High-Repetition Rate F 2 -Lasers for 157nm Lithography Acknowledgement Lambda Physik AG likes to acknowledge: Our cooperation partners for joint work within the German 157nm BMBF project (BMBF=German Ministry for Education and Research) The project was partially supported by the BMBF, project FKZ 13N8195 The authors appreciate the good cooperative work with the project partners: Carl Zeiss, Schott lithotec, Jenoptik, Infineon, Heraeus, Korth Slide 17