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TRANSCRIPT
Introduction to Plasma Etching
姜克 2013年2月3日
contents
Intro to plasma? What is plasma?
Examples of plasma.
Plasma in IC.
What is plasma etching?
Plasma Etching Principles.
Summary
Section 1:Intro to Plasma
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)
Examples of plasma
Temperature measurement in the early days
Examples of plasma
Small plasma ball Big plasma ball
Plasma in daily life and IC
Plasma Etching
Plasma-Immersion Ion Implantation (PIII)
Plasma Deposition
Plasma Stripping (Ashing)
Plasma in IC manufacturing
Stress Relief
Section 2:What is Plasma etching
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)
Plasma etcher (刻蚀机)
Section 3:Plasma etching Principle
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
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
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
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.
- 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
Section 4:Summary
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
Thank you