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1. Problems of counting particles in photoresist 2. KS-41 Specifications

Particle Counter KS-41 for photoresist measurement. 1. Problems of counting particles in photoresist 2. KS-41 Specifications 3. Adjustment and calibration method 4. Actual measurement example. Principle of the Light scattering particle counter. Interaction between Light and Particle.

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1. Problems of counting particles in photoresist 2. KS-41 Specifications

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  1. Particle Counter KS-41 for photoresist measurement 1. Problems of counting particles in photoresist 2. KS-41 Specifications 3. Adjustment and calibration method 4. Actual measurement example

  2. Principle of the Light scattering particle counter Interaction between Light and Particle Reflection Diffraction Incident Light (wave length=λ, Intensity=I0 ) Refraction Absorption φ Particle (diameter=D, refractive index=m1) Refractive index of media=m0 Scattering (Intensity=Iφ ) 1-1

  3. Reyleigh scattering pattern Direction of electrolytic vibration Irradiating light Light scattering intensity pattern Direction of magnetic vibration 1-2

  4. The structure of sensor for Airborne particle counter Inlet Scattering light collection lenses Scattering light reflection mirror Photodiode Beam forming lenses Outlet Light source 1-4

  5. Pulse signal from PSL particle Pulse height Pulse height Pulse number (frequency) Time 1-5

  6. Cumulative distribution Frequency distribution Particle Count (standardization) Calibration voltage Pulse voltage 1-6

  7. Problems of measuring particles in photoresist ・Scattering of irradiating light in resist becomes noise. ・Refractive index of the resist (approx. 1.4 to 1.6) affects the precision of particle diameter determination. ・Sample flow rate changes according to its viscosity. polymer molecule, polymer, etc 1.6 1.5 1.33 Sample Flow cell Irradiating light Photo detector Particle Particle Particle detector

  8. Scattering by polymer in photoresist (Top view) Photo Diode Flow cell Sample Lens Aperture Laser beam

  9. Collection light spot diameter depending on refractive index (Top View) Photo Diode Laser beam Flow cell Aperture Sample Lens Laser Spot diameter in resist Spot diameter in DI-water

  10. Noise increase due to photoresist measurement Scattered light pulses of particles 0.15μm 0.1μm Scattered light pulses of particles 0.1μm 0.15μm Noise Noise Voltage Voltage Time Time Scattered light of photo-resist and wall of flow-cell (DC voltage) Signal output of photo-detector Signal output of photo-detector

  11. KS-41　Specifications • Outline • KS-41 is a sensor for measuring particles in photoresist. • By connecting the unit to the controller (KE-40 or KE-40A), power supply, measurement control and data output are carried out. • As the unit does not incorporate flow control circuit, the additional flow rate controller should be prepared. Specifications Optional system: 90°sideway light scattering methodLight source: Laser diode (wave length 830nm, rated output 200 mW)Light detector: PIN type photodiodesMaterials of component parts exposed to sample fluid Fused silica, PFA

  12. KS-41　Specifications Measurement size ranges: ³0.15µm, ³0.2µm, ³0.3µm, ³0. 5µm Counting efficiency: 50±10%(measuring PSL particles in the range of 0.3µm, using count of 0.2µm and above for comparison with reference unit) Sample fluid rate: 10mL/min Maximum particle concentration: 12,000 particles/mL (coincidence loss 5% for 0.15 µm particles) Ambient conditions for operation: 15 to 30ºC, 0 to 85% RH (no condensation) Allowable sample fluid pressure 300 kPa or less (gauge pressure)

  13. Particle detector system for photoresist measurement (Side View) Scattered light ( from fringe of the flow cell) Photo Diode Aperture Scattered light (from center of flow cell) ×1 Lenses Flow Cell KL-26 Optical System Laser Beam (Vertical to paper) Scattered light ( from fringe of the flow cell) 10ch Photo Diode L Shape Flow Cell ×8 Lenses Scattered light (from center of flow cell) KS-41 Optical System

  14. 10ch Photo Diode L Shape Flow Cell

  15. Scattered light ( from fringe of the flow cell) L Shape Flow Cell 10ch Photo Diode ×8 Lenses Scattered light (from center of flow cell). Laser Beam (Vertical to paper) Proto-KS-41 Optical System Scattered light ( from fringe of the flow cell) 10ch Photo Diode L Shape Flow Cell ×8 Lenses Scattered light (from center of flow cell) KS-41 Optical System Photoresist measurement using sensor calibrated with PSL particles and DI-water

  16. Standard PSL particlesin DI-water Standard PSL particlesin photoresist Adjustment：　　Using a solution of glycerin (refractive index of 1.4) and PSL particles. Calibration：　　With PSL particles (refractive index 1.6) in pure water

  17. KS-41　　Sensor construction drawing Collection lenses Photodiode Scattering light collection lens Laser diode Beam forming lenses

  18. Noise 113.5mv KS-41 DI-water Noise increase when measuring photoresist Noise increase rate 8.4 times Noise 64.5mv Noise 538.6mv KL-24 Photoresist KL-24 DI-water Noise increase rate 1.7 times Noise　 197mv KS-41 Photoresist

  19. Example of particle counts in photoresist ( I ) (mV) 0.15< 0.2< 0.22< 0.25< 0.3< Noise I-line positive 582 1052 97 74 41 28 Excimer A 243 740 368 278 173 107 235 620 295 195 83 54 Excimer B 339 236 91 65 33 21 Excimer C 415 256 116 79 45 35 Excimer D 494 584 289 213 118 77 Excimer E (Number /10mL)

  20. KS-41 KL-20A KS-41 KL-20A Resist B C.E. Solvent C. E. 0.15 574 0.15 875 ≦ ≦ 0.20 76 142 54% 0.20 512 1128 45% ≦ ≦ 0.3 22 56 39% 0.3 150 483 31% ≦ ≦ 0.5 9 16 56% 0.5 72 112 64% ≦ ≦ 4 3 1.0 22 12 1.0 ≦ ≦ KS-41 KL-20A KS-41 KL-20A Resist C C.E. Resist A C.E. 0.15 845 0.15 1209 ≦ ≦ 0.20 322 814 40% 0.20 67 116 58% ≦ ≦ 0.3 102 243 42% 0.3 10 34 29% ≦ ≦ 0.5 42 50 84% 0.5 4 8 50% ≦ ≦ 12 6 1.0 1 1 1.0 ≦ ≦ Example of particle counts in photoresist ( II ) (Number /10mL)

  21. Particle measurement in DI water Unit: particle/10mL PSL particle measurement in Ethyllactate (particle size: 0.321 µm) Reference: KS-41 (Counting efficiency 58%, measuring in the range of 0.2 µm, using count of 0.309 µm for comparison with reference unit)

  22. 1000 KS-28(1×1mm) KL-22(0.5mmφ) KL-26(0.3×0.7mm) KL-20A(0.5×0.5mm) 100 Flow Rate(ml/min) 10 1 1000 10 100 Viscosity(cp) Viscous resistance of Particle counters • When sample input pressure is 3 kg/cm2, flow rate limitations which depend on viscosity of sample are measured. • Absolute values depend on measurement error of sample viscosity and surface exposed to sample fluid. • The difference of the flow path shape varies the maximum flow rate widely.

  23. Measurement of babble and solid particles 1.0E+06 KL-26 1.0E+04 Relative Intensity 1.0E+02 Bubble PSL 1.0E+00 Media:H2O 1.0E-02 0.1 1 10 Diameter(μm） Light scattering intensity is almost the same with PSL particles and bubbles in water.

  24. 1000 80 75 100 70 Temperature (℃) Particle Numbers(N/10mL) 65 10 60 0.2μm 0.5μm 55 temp 1 50 0 10 20 30 40 50 TIME Particle measurement example in APM cleaning tank • Particle counts which vary depending on the APM temperature are regarded as bubble counts. • Particle counts are not affected by the temperature 60℃ and below.

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