Introduction to Wafer fabrication Process Presented by Asst.Prof. Dr. Rardchawadee Silapunt

Outlines Clean room 1 Wafer Fab Process 2

Outlines Clean room 1

Clean Room @ TMEC

It took time to install cleanroom PLAY MOVIE

Outlines Wafer Fab Process 2 6

Processing line @ TMEC Down to 0.5μm Technology Furnace Cleaning Process Photolithography Down to 0.5μm Technology Implanter Metrology Plasma CVD Sputtering Dry Etching

Overview to Lithography process What is Lithography Process? The word come from the Greek “Lithos” and “Graphia” Lithos = Stones , Graphia = to write It means “ Writing on stones”. In Semiconductor, stones are Silicon wafers and our patterns are written with a light-sensitive polymer called “Photoresist”

Overview to Lithography process 9 Steps of Lithography process. 1. Wafer preparation 5. Post-Exposure Bake (PEB) 6. Development 2. Coat with Photoresist 7. Postbake, Hardbake 3. Prebake, Softbake 8. Etch or Implant 4. Align and Exposure 9. Photoresist strip

Photolithography Problem Without OPC With OPC Light Diffraction is occur during photolithography process. (a) (b) (c) (d) OPC patterns are used to reduce the error in photolithography process.

How to patterning circuit Processing - Film Deposition - Photolithography - Etching - Implantation Wafer Integrated Circuit (IC)

Processing line Silicon Wafer p-type wafer p-type

Initial oxidation: O2/H2 (Thickness: 420 nm) Processing line Film Deposition Initial oxidation: O2/H2 (Thickness: 420 nm) SiO2 p-type

Processing line Photolithography Coater Stepper Developer Photoresist (PR) p-type

Processing line Photoresist Characteristic PR is made up of a resin R, the photoactive compound M, the solvent S, and component appears during exposure which are exposure products P. The exposure products generated by the reaction of M with UV light.!! Applying Beer’s Law, the absorption coefficient  is then, M0 = initial PAC concentration (non-exposed) A = bleachable absorption coefficients of Dill parameters B = Non-bleachable absorption coefficients of Other non-bleachable components of the PR such as dye are added to B

Processing line Dill Paramaters of Photoresist Where several assumptions are made in solving this differential equation and I x t is the optical dose. If D is the resist thickness, the Dill parameters can be measured by: T(0) T(∞) is transmittance at the air-resist interface T(0) is the transmittance of the unexposed resist, and T(∞) is the transmittance of the completely exposed resist is the initial slope of the transmittance vs dose curve Two transmittance curves for Kodak 820 resist 365 nm. The curves are for a convection oven post-apply bake of 30 minutes at the temperatures shown

Processing line Etching Simulation of Plasma Etching Photoresist (PR) Dry etch oxide p-type

Directionality of Etcing Process Processing line Etching Directionality of Etcing Process Isotropic Etch Directional Etch Vertical Etch

Processing line Etching Wet Etching Dry Etching Two Kinds of Etching Method Wet Etching Dry Etching by Wet chemical solution Isotropic etching by Plasma Anisotropic etching Vertical E/R ~ Horizontal E/R Pure Chemical Reaction High Selectivity CD Loss or Gain Vertical E/R >> Horizontal E/R Ion assisted Relatively low Selectivity No CD bias

n-well implantation : Phosphorus Processing line Implantation n-well implantation : Phosphorus Photoresist (PR) p-type

Processing line Chemical Mechanical Planarization (CMP) CMP removes material from uneven topography on a wafer surface until a flat (planarized) surface is created. CMP combines the chemical removal effect of an acidic or basic fluid solution with the "mechanical" effect provided by polishing with an abrasive material.

How to patterning a CMOS !!! Processing line How to patterning a CMOS !!!

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