Introduction to Wafer fabrication Process Presented by Asst.Prof. Dr. Rardchawadee Silapunt.
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Transcript of Introduction to Wafer fabrication Process Presented by Asst.Prof. Dr. Rardchawadee Silapunt.
Introduction to Wafer fabricationProcess
Presented byAsst.Prof. Dr. Rardchawadee Silapunt
Outlines
Clean room 1
Wafer Fab Process
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Outlines
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Clean room 1
Clean Room @ TMEC
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It took time to install cleanroom
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PLAY MOVIE
Outlines
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Wafer Fab Process
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Processing line @ TMEC
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Furnace
Plasma CVD
PhotolithographyCleaning Process
Implanter
Dry EtchingSputtering
Metrology
Down to 0.5μm Technology
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”
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Overview to Lithography process
9 Steps of Lithography process.
1. Wafer preparation
2. Coat with Photoresist
3. Prebake, Softbake
4. Align and Exposure
5. Post-Exposure Bake (PEB)
8. Etch or Implant
6. Development
7. Postbake, Hardbake
9. Photoresist strip
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Photolithography Problem
Light Diffraction is occur during photolithography process.
OPC patterns are used to reduce the error in photolithography process.
(a) (b)
(c) (d)
Without OPC With OPC
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How to patterning circuit
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Wafer
Processing - Film Deposition - Photolithography- Etching- Implantation
Integrated Circuit (IC)
Processing line
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p-type wafer
p-type
Silicon Wafer
Processing line
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Film Deposition
Initial oxidation: O2/H2 (Thickness: 420 nm)
p-type
SiO2
Processing line
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p-type
Photoresist (PR)
Coater Stepper Developer
Photolithography
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 parametersB = Non-bleachable absorption coefficients of Dill parameters
Other non-bleachable components of the PR such as dye are added to B
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Photoresist Characteristic
Processing line
T(0)
T(∞)
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:
is the initial slope of the transmittance vs dose curve
is transmittance at theair-resist interface
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
T(0) is the transmittance of the unexposed resist, and
T(∞) is the transmittance of the completely exposed resist
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Processing lineDill Paramaters of Photoresist
Simulation of Plasma Etching
Processing line
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Etching
p-type
Dry etch oxidePhotoresist (PR)
Processing line
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Etching
Isotropic Etch Directional Etch Vertical Etch
Directionality of Etcing Process
Processing line
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Etching
Wet Etching
Two Kinds of Etching Method
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
Processing line
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Implantation
p-type
Photoresist (PR)
n-well implantation : Phosphorus
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 withthe "mechanical" effect provided by polishing with an abrasive material.
Processing line
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Chemical Mechanical Planarization (CMP)
Processing line
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How to patterning a CMOS !!!