Film Thickness Measurement System - Principle and Applications -

Transcription

1 Film Thickness Measurement System - Principle and Applications CONTENTS - 1. Thin Films for Application 2. Film Thickness Measurement Requirements 3. Film Thickness Measurement Methods 4. Comparison with Other Methods 5. Repeatability of SiO2 on Si wafer 6. Spectroscopic Reflectometer Principle 7. ST Series Applications 8. ST Series System Description 9. ST Series program Outline 10. Other KMAC products 2

2 1 Thin Films for Application Semiconductor Technology - Si, SiGe based Semiconductor : DRAM, SRAM, μ-processor, - GaAs, InGaAs, InSb, HgCdTe based Compound Semiconductor Display Technology - CRT, LCD, TFT-LCD, LED, PDP, ELD, OELD, FED. Optical Coating Technology - Filter, Anti-Refraction Coating, Hard Coating,. Other Technologies - Plating, Battery, Printing. Thin Film Process - Thermal Oxidation (Dry, Wet): SiO 2, ONO - LPCVD: SiO 2, Si 3 N 4, NO, Poly-Si, TEOS, BPSG, a-si, W, WSi, Ti, TiN - PECVD: SiO x, SiN x, a-si - VPE, MOCVD, LPE, MBE: Si, GaAs, AlGaAs, InGaAs, SiGe, GaN - PVD(Sputtering, Evaporation): Al, Cu, Si, SiO x, WSi, Au, Ti - Spin Coating: Photoresist, p-imide, SOG, Low-D. - Others: Plating, Painting, Dip coating 3 2 Film Thickness Measurement Requirements Semiconductor Technology -SiO 2, Si 3 N 4, poly-si, and photo resist with wide spec. limit. - Ellipsometer, Spectrophotometer with simple algorithm Current and Future Stage of Thin Film Technology - Various materials: Doped p-si, a-si, TiN, compound semiconductors - Very thin and/or very thick film: ~10A SiO 2, ~100μm P.R. for bumping - In-situ measurement: direct measurement on patterned wafer - Necessary to control n, k, and reflectivity - Metal films with no contact, no damage, no particle generation Ability to measure very thin films or very thick films with high accuracy Simultaneous measurement of some optical constant (n, k and reflectivity) Ability to measure on front side of sample (reflection mode) Small beam spot size Automation (auto loading and mapping) Fast and reliable result Simultaneous measurement of Multi layer Easy to operation and easy to maintenance 4

3 3 Film Thickness Measurement Methods Microscopy - Optical microscope, SEM, TEM - Cross sectional image of sample with high magnification - Destructive, special sample preparation, micro structure - Any kinds of films, multi structure Surface Profiler - Use a sharp tip - Mechanical step difference according to surface profile - Contact, Destructive, Sample preparation -Any kinds of films X-ray Fluorescence -Use an X-ray hν hν - Characterized X-ray Fluorescence intensity of film composition - n contact, n destructive -Metal films 5 3 Film Thickness Measurement Methods Optical Reflectance - Use Visible, Ultra Violet, Infrared lights - Interference of lights reflected from surface and film interfaces - n contact, n destructive, Able to focus on small spot - Dielectrics, Transparent films Ellipsometer - Use a polarized light - Optical polarity rotation during transition into the film matrix - n contact, n destructive - Dielectrics, Transparent films Other Methods -Phonon emission from crystal lattice: Metal films - RS(Sheet Resistance) Measurement: Metal films - C-V Plotter: Dielectric films -FTIR: Epitaxiallayer - Photo acoustic Metrology: Metal and Transparent films 6

4 4 Comparison with Other Methods Property Method Optical Reflectance Ellipsometer Surface Profiler X-ray Fluorescent n-destructive Yes Yes Yes Micro Area Yes Pattern Wafer Possible(4μm) Impossible Impossible Impossible Thickness Range Thick(μm) Thin(A ) Possible Possible Periodic Ambiguity Possible Possible Possible Possible Impossible Measuring Speed > 0.5 sec > ~ min > ~10min > ~20min Throughput High Low Very low Very low Metal Film Yes Spec. Metal N, K Measurement Yes Yes Sample Preparation Easy (In-situ) Easy Difficult Difficult Convenience Good Bad Bad Bad Price Medium High Medium High 7 4 Comparison with Other Methods ( by Visual Thick) 26.13um MgO on Glass um 8

5 4 Comparison with Other Methods Organic matter on Glass 9 4 Comparison with Other Methods SiN x SRM (KRISS) SE(KRISS) SR(KM AC) Diffe ren ce TH K n TH K n TH K n ΔTH K Δn (u n it: A ) Thickness Refractive index SE & SR correlation value R 2 =99.9% (THK) 10

6 4 Comparison with Other Methods Ite m E llip so m e try R e fle cto m e try C o m m e n ts input Δ,Ψ R(% ) Polarization & Reflection output n,k,t n,k,t sam e Reference - Si w afer incident light Theory 2 π E(z, t) = E 0 sin( (z vt) + ξ) λ Electrom agnetic w ave O ptical D ata A nalysis Regression analysis m ethods 1. SE(Spectroscopic Ellipsometry) & SR(Spectroscopic Reflectometry) 의 RI 차이 Δn < 0.05 정도의차이를갖고있음. 2. SE 는 delta(δ) 와 psi(ψ) 두개의측정데이터를이용하여 n&k, THK 를분석하므로 SR 보다는다소정확한면이있음. 3. SR 은시료의절대반사도 ( 두께와굴절률의정보를포함 ) 를측정하여 n&k, THK 를분석함. 4. 일반적으로 SR 의사용이 SE 보다쉬운것으로알려져있어공정모니터링용으로많이사용함 Repeatability of SiO2 on Si wafer 5000 Repeatability 4000 Thickness (A ) A 1000A 2000A 5000A Times Repeatability of 30 times 250A 1000A 2000A 5000A Range (Max-Min)

7 6 Spectroscopic Reflectometer Principle Interference phenomenon Incident Light Reflected Light 1 Reflected Light 2 Indirect Measurement using Light Light & Signal path Visible light => Thin Layers => Reflection from Surface & interfaces => Fiber Probe => Spectrophotometer => Wavelength Decomposition => CCD => A/D Conversion => PC => Software Thickness by Spectrum Fitting Measured Spectrum shows sine shapes or valleys in Wavelength Domain depending on Film Thickenss and N & K Optimize Film Thickness and N & K by fitting Computed Spectrum to Measured one as varying Film Characteristics 13 Transparent Layer (Multi-Layer) Substrate 7 ST Series Applications 1. Semiconductor 2. LCD 3. PDP 4. Optical Coating 5. OSP 6. Thin Metal Film 7. Color Measurement 8. 3D surface profiller 9. CD(Critical Dimension) Measurement 10. Material Science 14

8 7 ST Series Applications 1. Semiconductor 1 번 2 번 3 번 A 사 A 사 A 사 15 7 ST Series Applications 2. LCD Sample ID Substrate Layer 예상두께 #1(30s) Glass ITO #2(40s) Glass ITO #3(50s) Glass ITO #4(60s) Glass ITO - #5(70s) Glass ITO #6(80s) Glass ITO #7(90s) Glass ITO #8(t-Etch) Glass ITO 1500Å -Etching 후시간에따른 ITO 그래프 s 40s 50s 60s 70s 80s 90s Uniformity Area #1(30s) #2(40s) #3(50s) #4(60s) M ax M in Range Average Uniformity Area #5(70s) #6(80s) #7(90s) #8(t_Etch) M ax M in Range Average Uniformity Unit[Å] 16

9 7 ST Series Applications 3. PDP MgO 두께측정결과 ( 단위 : um) Random 한위치 MgO(X5 Lens) (X5) MgO / 유전체 / Bus, Black strip/glass MAX 0.74 MIN 0.70 AVR 0.72 RANGE 0.04 STD ST Series Applications 4. Optical Coating Uniformity Areas Area1 Area2 Area3 Area4 Area5 AVG MIN MAX Range Polymer Polmyer Polymer Polymer Polymer Polymer Film Film Film Area1 Area2 Area3 Area4 Area5 18

10 7 ST Series Applications 5. OSP 1) SEM 측정 Image SEM OSP 두께분포 : 1560Å, 1870 Å, 1950 Å, 2000 Å, 2180 Å, 2470 Å, 2690 Å, 3080 Å, 3300 Å, 4780 Å KMAC ST4080-OSP 측정결과 : OSP 두께분포 : 1030Å ~ 4948Å Mean = 2174Å, Stdev = 822Å 19 7 ST Series Applications 5. OSP

11 7 ST Series Applications 6. Thin Metal Film Au film 측정결과 21 7 ST Series Applications 7. Color Measurement O.C의두께측정영역및각영역별측정결과 #2 #1 #6 #5 #4 #3 #3 CS #2 #1 O.C Glass ITO #6 CS CF 영역 측정영역 O.C CS 참고 # OC만측정 Red # OC만측정 Cell영역 # O.C&CS동시 # OC만측정 Blue # OC만측정 # O.C&CS동시 Edge영역 # O.C&CS동시단위 :A #5 CF Sample #4 22

12 7 ST Series Applications 8. 3D surface profile 23 7 ST Series Applications 9. CD(critical dimension) measurement A B 24

13 8 ST Series System Description R&D 및실험용박막두께측정기 Thin Film Measurement System Reflectometry In-situ measurement It is possible that n,k Data 2D,3D Mapping data Display (point by point) Semi-automatic mechanism stage control Use to easy CCD Camera + Auto Focusing 25 9 ST Series program Outline 26

14 9 ST Series program Outline Other KMAC products 공정용 Color 측정기 CD 측정장비 UV-Vis Spectrometer Hybrid 3D 측정기 OSP 막두께측정장비 공정용박막두께측정기 r 28

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