Particle Counter KS41 for photoresist measurement 1 Problems

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 Reflection Diffraction Incident Light (wave length=λ, Intensity=I 0 ) Absorption Refraction φ Refractive index of media=m 0 Particle (diameter=D, refractive index=m 1) 1 -1 Scattering (Intensity=Iφ )

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

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

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

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

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 detector

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

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

Noise increase due to photoresist measurement Scattered light pulses of particles 0. 15μm 0. 1μm 0. 15μm Noise Voltage Scattered light pulses of particles Time Scattered light of photo-resist and wall of flow-cell (DC voltage) Signal output of photo-detector

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-40 A), 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 method Light source: Laser diode (wave length 830 nm, rated output 200 m. W) Light detector: PIN type photodiodes Materials of component parts exposed to sample fluid Fused silica, PFA

KS-41 Specifications Measurement size ranges: Counting efficiency: ³ 0. 15µm, ³ 0. 2µm, ³ 0. 3µm, ³ 0. 5µm 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: 10 m. L/min Maximum particle concentration: 12, 000 particles/m. L (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 k. Pa or less (gauge pressure)

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

L Shape Flow Cell 10 ch Photo Diode

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

Standard PSL particles in DI-water Adjustment： Calibration： Standard PSL particles in photoresist Using a solution of glycerin (refractive index of 1. 4) and PSL particles. With PSL particles (refractive index 1. 6) in pure water

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

Noise increase when measuring photoresist Noise 64. 5 mv KL-24 DI-water Noise 113. 5 mv KS-41 DI-water Noise 538. 6 mv Noise increase rate 8. 4 times KL-24 Photoresist Noise 197 mv KS-41 Photoresist Noise increase rate 1. 7 times

Example of particle counts in photoresist ( I ) Noise (m. V) I-line positive 582 Excimer A 243 235 Excimer B 339 Excimer C 415 Excimer D 494 Excimer E 0. 15< 1052 740 620 236 256 584 0. 2< 97 368 295 91 116 289 0. 22< 74 278 195 65 79 213 0. 25< 41 173 83 33 45 118 0. 3< 28 107 54 21 35 77 (Number /10 m. L)

Example of particle counts in photoresist ( II ) KL-20 A C. E. 0. 15 ≦ 0. 20 ≦ 0. 3 ≦ 0. 5 ≦ 1. 0 ≦ KS-41 875 512 150 72 22 1128 483 112 12 45% 31% 64% Resist A 0. 15 ≦ 0. 20 ≦ 0. 3 ≦ 0. 5 ≦ 1. 0 ≦ KS-41 1209 67 10 4 1 KL-20 A C. E. 116 34 8 1 58% 29% 50% Solvent Resist B 0. 15 ≦ 0. 20 ≦ 0. 3 ≦ 0. 5 ≦ 1. 0 ≦ KS-41 574 76 22 9 4 KL-20 A C. E. 142 56 16 3 54% 39% 56% Resist C 0. 15 ≦ 0. 20 ≦ 0. 3 ≦ 0. 5 ≦ 1. 0 ≦ KS-41 845 322 102 42 12 KL-20 A C. E. 814 243 50 6 40% 42% 84% (Number /10 m. L)

Particle measurement in DI water Unit: particle/10 m. L 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)

Viscous resistance of Particle counters Flow Rate(ml/min) 1000 KS-28(1× 1 mm) KL-22(0. 5 mmφ) KL-26(0. 3× 0. 7 mm) KL-20 A(0. 5× 0. 5 mm) 100 10 100 Viscosity(cp) 1000 • When sample input pressure is 3 kg/cm 2, 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.

Measurement of babble and solid particles 1. 0 E+06 KL-26 Relative Intensity 1. 0 E+04 1. 0 E+02 Bubble PSL 1. 0 E+00 Media: H 2 O 1. 0 E-02 0. 1 1 10 Diameter(μm） Light scattering intensity is almost the same with PSL particles and bubbles in water.

Particle measurement example in APM cleaning tank 80 75 100 70 65 10 60 0. 2μm 0. 5μm temp Temperature (℃) Particle Numbers(N/10 m. L) 1000 55 1 50 0 10 20 30 TIME 40 50 • 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.