A short pulsed laser cleaning system for EUVL tool

Transcription

1 A short pulsed laser cleaning system for EUVL tool Masami Yonekawa, Hisashi Namba and Tatsuya Hayashi Nanotechnology & Advanced System Research Laboratories, Canon inc , Kiyohara-Kogyodanchi, Utsunomiya-shi, Tochigi , Japan Tel.: , Fax.:

2 Introduction and background Reticle particle adhesion? Illumination light Projection optics particle generation: 1. high speed reticle stage 2. reticle handling 3. debris from light source 4. gas to particle conversion, etc To prevent a defect due to particles: Wafer 1. Using particle free materials and mechanics 2. Developing reticle protection method in vacuum In-situ laser cleaning method International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 2

3 Introduction and background (Cont.) 1. Conventional laser cleaning method In atmosphere Excimer laser Wafer Assist gas 2. Unknown factor Not clear about removal effect in vacuum and probability of substrate damage 3. Improvement in this study Verification of the removal on organic particles in vacuum(p~10-3 Pa) and then damage of Mo/Si multilayer International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 3

4 Application of laser cleaning system to EUVL tool sheet beam width: W [mm] controller reticle stage optics reticle DUV laser velocity: Vs [mm/s] In atmosphere (10 5 Pa) In vacuum (10-5 Pa) repetition rate: F [Hz] required numbers of pulse: N [#] System requirements : W F Vs > N energy density [mj/cm 2 ] wavelength [nm] pulse duration [ns] International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 4

5 A schematic diagram of experimental system Sample-making equipment Atomizer, Powder disperser 1064 nm 532 nm Experimental setup 355 nm 266 nm Attenuator Shutter Measurement facilities KLA SurfScan6420 diffusive adhesion aerosol DMA Neutralizer Chamber (P<10-3 Pa) Stage CNTRL PC YAG Laser Olympus Fluorescent Microscope Veeco AFM TORAY FE-SEM,TEM International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 5

6 Photographs of experimental system DMA Sample-making equipment neutralizer CPC Experimental setup Q-switched YAG laser FFU vacuum chamber slit lens, homogenizer sample chamber buffer chamber atomizer shutter attenuator test sample powder disperser Inside of the chamber beam irradiated area sample substrate International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 6

7 Examples of images of PSL particle removal KLA Surfscan image Olympus Fluorescent-microscope image 0.5 um PSL particle non-irradiated area irradiated area irradiated area 0.1 um PSL particle 338 um (mm) (mm) sub.: bare-si wafer sub.: Ru-capped Mo/Si multilayer International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 7

8 Removal experiments in atmosphere =266 nm =355 nm Ru-capped Mo/Si multilayer 0.1 um PSL =532 nm =1064 nm Dependence of removal rates on laser wavelength in atmosphere The removal using DUV laser is the most effective. International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 8

9 Removal experiments in atmosphere (Cont.) Si-capped Mo/Si multilayer 0.1 um PSL =266 nm International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 9 =355 nm =532 nm =1064 nm Dependence of removal rates on laser wavelength in atmosphere The removal using DUV laser is the most effective.

10 Removal experiments in vacuum Ru-capped Mo/Si multilayer 0.1 um PSL Si-capped Mo/Si multilayer 0.1 um PSL Removal rates at the laser wavelength of 266 nm in vacuum(p~10-3 Pa) Organic particles on Mo/Si multilayer can be removed in vacuum. International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 10

11 Cross-section of irradiated multilayer in vacuum Ru-capped Mo/Si multilayer Si-capped Mo/Si multilayer SEM image Mo/Si multilayer Mo/Si multilayer irradiated condition: 266 nm, 20 mj/cm^2, 400 pulse removal rate: ~100 % TEM image 300 nm No particular damage Ru-cap (2 nm) Mo/Si multilayer (280 nm) 300 nm Si-cap (11 nm) Mo/Si multilayer (280 nm) SiO2 sub. SiO2 sub. International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 11

12 Roughness of irradiated capping layer in vacuum Ru-capped Mo/Si multilayer Energy density 10 mj/cm 2 30 mj/cm 2 50 mj/cm 2 90 mj/cm 2 Numbers of pulse nm(rq) 0.30 nm(rq) 0.30 nm(rq) 0.39 nm(rq) 1m Numbers of pulse Energy density 20 mj/cm nm(rq) 0.28 nm(rq) 0.29 nm(rq) 0.29 nm(rq) 1m International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 12

13 Roughness of irradiated capping layer in vacuum (Cont.) Ru-capped Mo/Si multilayer Numbers of pulse:100 reference Energy density:20 mj/cm 2 reference Numbers of pulse:100 Energy density:20 mj/cm 2 Si-capped Mo/Si multilayer reference International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 13 reference Roughness of capping layer depends on laser energy density per pulse.

14 Comparison of the removal rates between in atmosphere and in vacuum 0.5 um PSL bare-si In atmosphere (P=10 5 Pa) In vacuum (P~10-3 Pa) irradiated condition: 266 nm, 20 mj/cm 2, 100 pulse removal rate: 47 % removal rate: 86 % [mj/cm 2 ] : <0.4 um : >0.4 um A short pulsed laser cleaning has an advantage in vacuum. International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 14

15 Particle trajectory model dv m = f f f dt p p D VDW G 3 πµ dp( vp vgas) idrag force: fd = Cc 1.1 Cc = 1+ Kn exp Kn Ad p ivan der walls force: fvdw = i 2 12z0 igravity force: f = m g j G x = z0 initial condition : x vpx =, vpy = 0 t p 0 substrate z0 = 0.5nm f d f vdw particle f g m (, ) p x y V p where, mp: particle mass[kg], vp: particle velocity[m/s], v : gas velocity[m/s], µ : gas viscosity[kg/m s], d z gas p : particle diameter[m], A: Hamaker constant[j], : atomic seperation length[m], 2 g: gravity acceleration[m/s ], Kn: particle Knudsen number[-] International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 15

16 Consideration of the difference of removal rates In atmosphere (10 5 Pa) In vacuum (~10-3 Pa) assumption of calculation 0.5m PSL / Bare-Si particle displacement z=2 nm at t= 7 ns substrate roughness:1 nm reattach remove In atmosphere => Predominant forces acting on the particle are drag force and van der Walls force. In vacuum => Particle Knudsen number, Kn~10 8, indicates free molecule regime, so that the drag force is negligible. International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 16

17 Summary 1. Using DUV short pulsed laser, organic particles on the EUV multilayer can be removed at the pressure around 10-3 Pa. 2. It is not found that there is any particular damage of the EUV multilayer at the above condition. 3. The removal of organic particles on the EUV multilayer strongly depends on the laser wavelength. 4. It is more effective to remove particles in vacuum than in atmosphere by using a short pulsed laser cleaning method. International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 17

18 Future plan 1. Verifying the removal effects of inorganic particles in vacuum 2. Conducting experiments on using smaller particles than 100 nm in diameter 3. Removal of particles on substrate with pattern, and investigation of its surface damage International EUVL Symposium, October 15-18, 2006 Barcelona, Spain Slide 18