introduction to plasma etching - semi-sace.org€¦ · plasma etching recipe. - etched thickness x...
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Introduction to Plasma Etching
姜克 2013年2月3日
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contents
Intro to plasma? What is plasma?
Examples of plasma.
Plasma in IC.
What is plasma etching?
Plasma Etching Principles.
Summary
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Section 1:Intro to Plasma
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What is plasma?
plasma is a the forth state of matter. Heating a gas
may ionize its molecules or atoms thus turning it into a
plasma, which contains charged particles: positive ions and
negative electrons. (99.9% of matters in the space)
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Examples of plasma
Temperature measurement in the early days
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Examples of plasma
Small plasma ball Big plasma ball
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Plasma in daily life and IC
Plasma Etching
Plasma-Immersion Ion Implantation (PIII)
Plasma Deposition
Plasma Stripping (Ashing)
Plasma in IC manufacturing
Stress Relief
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Section 2:What is Plasma etching
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Plasma process that removes material from surface
Selective etch transfers IC design image on the
photoresist to the surface layer on wafer
Other applications: Mask making, 3D integration
What is plasma etching?
Trench etch (0.2 μm wide by 4 μm deep)
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Plasma etcher (刻蚀机)
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Section 3:Plasma etching Principle
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Chemical
Neutral Radical Volatile by-Product
Chemical Reaction
Thermalized neutral radicals chemically combine with
substrate material forming volatile products
- Isotropic
- Purely Chemical Reaction
- High Pressure
- Batch Wafer Type
- Less Electrical Damage
Plasma etching principles
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Sputtering
Ion
Sputtered Atom (Molecule)
Physical bombardment
The ion energy mechanically ejects substrate material
- Anisotropic
- Purely Physical Process
- High Directionality
- Low Pressure
- Single Wafer Type
- Low Etch rate
Plasma etching principles
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Energetic Ion Enhanced (Chemical + Sputtering)
Neutral Radical
Volatile by-Product
Chemical Reaction
Ion bombardment enhances or promotes the reaction
between an active species and the substrate material
- Physically Enhanced
Chemical Reactivity
- Damage Enhanced
Chemical Reactivity
- Chemically Enhanced
Physical Sputtering
- Ion Reaction
Ion
Plasma etching principles
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Etchant Additives Inert Gas
Purpose Primary Etchant Selectivity
Control
Stablize Plasma, Dilute Etchant
Examples See below table O2, N2, H2, etc He, Ar, Xe, etc
Solid Etchant By-Products (Tb) Applications
Si
NF3, SF6, CF4, ..
Cl2, CCl4,
HBr
SiF4 (-86℃)
SiCl4 (58℃)
SiBr4 (154℃)
STI, Gate
SiO2
(Si3N4, SiON)
CF4, C4F8, C4F6, …
CHF3, CH2F2, CH3F, …
SiF4 &
CO(-191℃), CO2 (-57℃),
HCN (26℃)
Contact
Al Cl2, BCl3 AlCl3 (180℃, subl.)
Interconnectio
n Ti, TiN Cl2, CCl4 TiCl3 (136℃)
W NF3, SF6, CF4, Cl2 … WF6 (19℃), WCl6 (337℃)
PR (a-Carbon) O2, N2, … CO, CO2, HCN Mask
Cu, Fe, Ni, Co, Pt, … Difficult to Etch Cu2Cl2 (1490℃), Cu2F2 (1100℃) Metal
Plasma etching recipe.
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- Etched thickness x divided by etching time t - ~10um/min (Si) PSX800 from Panasonic
t
xER Etch Rate (ER)
Selectivity
- The ratio of the etch rates of two materials etched simultaneously such as etched layer and PR mask
B
ABA
ER
ERS /
In the same plasma condition = Etch rate of layer A = Etch rate of layer B
AER
BER
Uniformity
-how uniform the etching rate for die to die, wafer to wafer, lot to lot
100/2
][ minmax
NE
EEUniformity
i
ERi : Etch rate at several points ERmax : Maximum etch rate ERmin : Minimum etch rate
x
Plasma etching principles
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Section 4:Summary
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18
Plasma- 4th state of matter.
Plasma etching + litho are used to do pattern
transfer in nano/micro-electronics
manufacturing.
Energy and Vacuum is needed to maintain
plasma (gas discharge).
poly, oxide and metal (some) can be etched.
Home Taking Message
Q: Wanna homebrew plasma trick?
A: Vaccum+Energy
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Thank you