ECE_5360_Lec_12_14_lithography

ECE_5360_Lec_12_14_lithography - Photo-Lithography ES174...

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Photo-Lithography ES174 Photonic and Electronic Device Laboratory Lecture # 7 Text Book: Jaeger, Chap. 2 Other Sources: Plummer Chap. 5
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Harvard_Fabrication_ES174Si4.ppt – 2006 2 Tropical Cyclone Larry – Mar. 19, 2006 ; 180 mph
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Harvard_Fabrication_ES174Si4.ppt – 2006 3 Photolithography (A Simple Example) 8) Develop inspect 5) Post-exposure bake 6) Develop 7) Hard bake UV Light Mask λ λ 4) Alignment and Exposure Resist 2) Spin coat 3) Soft bake 1) Vapor prime HMDS
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Harvard_Fabrication_ES174Si4.ppt – 2006 4 Photolithography (Production) Prime Coat Pre-Bake Expose Post-Bake Hard Bake Develop
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Harvard_Fabrication_ES174Si4.ppt – 2006 5 Positive Resist Photolithography photoresist Light Island Areas exposed to light are dissolved. Resulting pattern after the resist is developed. Shadow on photoresist Exposed area of photoresist Chrome island on glass mask Window Silicon substrate Photoresist Oxide Photoresist Oxide Silicon substrate Development of latent image
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Harvard_Fabrication_ES174Si4.ppt – 2006 6 Negative Resist Photolithography Light Island Areas exposed to light are cross-linked and resist the developer chemical. Resulting pattern after the resist is developed. Window Exposed area of photoresist Shadow on photoresist Chrome island on glass mask Silicon substrate Photoresist Oxide Photoresist Oxide Silicon substrate Development of latent image
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Harvard_Fabrication_ES174Si4.ppt – 2006 7 Photolithography Instruments Contact Proximity Projection (Steppers) Fast, simple & inexpensive Diffraction minimized by small (~0) mask-resist gap But, mask-wear, defect generation & wafer-sized mask and light scattering in resist limits resolution 2L min resist thickness = z λ s Less mask wear/contamination Fast, simple & inexpensive But, Greater diffraction & less resolution Wafer sized mask No mask contact/contamination Mask demagnified 4x and 5x usually Mask pattern at chip size with wafer stepped for exposure Expensive instrumentation R : resolution, k a constant that is a function of the design/set-up parameters
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Harvard_Fabrication_ES174Si4.ppt – 2006 8 Lithography Tools Illuminator Alignment scope (split vision) Mask Wafer Vacuum chuck Mask stage (X, Y , Z , θ) Wafer stage (X, Y, Z, θ) Mercury arc lamp Contact/Proximity Stepper/Projection
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Harvard_Fabrication_ES174Si4.ppt – 2006 9 Lithography Tools Contact Projection
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Harvard_Fabrication_ES174Si4.ppt – 2006 10 Light Sources Mercury Lamp Light Sources Source λ (nm) Max. Output (mJ/pulse) Frequency (pulses/s) Common Nomenclature Hg lamp 436 G line Hg lamp 405 H line Hg lamp 365 I line KrF (laser) 248 10 2000 DUV ArF (laser) 193 10 2000 193 DUV F 2 (laser) 157 40 500 200 300 400 500 600 Wavelength (nm) Relative Intensity (%) g-line 436 nm i-line 365 nm h-line 405 nm DUV* 248 nm
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Harvard_Fabrication_ES174Si4.ppt – 2006 11 For n=0 there is no diffraction (direct beam) For n= 1 we have the first order diffracted beams For n= 2 we have the second order diffracted beam Diffraction pattern is the Fourier Transform of the object Wave Nature
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Harvard_Fabrication_ES174Si4.ppt – 2006 12 Diffraction grating: For constructive interference, the path difference must be equal to an integer number
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This note was uploaded on 04/04/2009 for the course ECE 5360 taught by Professor Shealy during the Fall '07 term at Cornell University (Engineering School).

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ECE_5360_Lec_12_14_lithography - Photo-Lithography ES174...

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