Processing

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Substrate Cleaning

Simple Clean

Removes organic contaminants.

  1. Cover the surface of the wafer with acetone.
  2. Thoroughly scrub the surface of the wafer with a swab.
  3. Rinse the wafer with IPA.
  4. Blow dry the wafer with N2 gun.

Photoresist Stripping

Wet Resist Stripping

AMI Strip

  1. Acetone soak 10 min
  2. Methanol soak 5 min
  3. Isopropyl soak 5 min
  4. DI Water Rinse

Ultrasonic strip

  1. Acetone filled covered glass beaker inserted in an Ultrasonic cleaner filled with water.

Piranha Strip

  • Sulfuric Acid, Hydrogen Peroxide solution, 5:1.

Dry Resist Stripping

Ashing
O2 Plasma
Temperature: 25 - 40 °C
Gases: CH4 - 10 sccm
CH4 - 10 sccm
Pressure: 30 mTorr
Power: 200 W
DC-bias: 440 V
Etch Rate: 400 Å/min

RCA Clean

Removes organic, oxide, and metallic contaminants

  1. Organic Clean: Removal of insoluble organic contaminants with a 5:1:1 H2O:H2O2:NH4OH solution.
  2. Oxide Strip: Removal of thin silicon dioxide layer where metallic contaminants may have accumulated as a result of step 1, using a dilute 20:1 H2O:HF solution.
  3. Ionic clean: Removal of ionic and heavy metal contaminants using a solution of 6:1:1 H2O:H2O2:HCl.

Piranha Clean

Removes organic materials (photoresist, oil, etc.)
Do not use on aluminum.

  1. Mix 98% H2SO4 and 30% H2O2 in volume ratios of 2-4:1
  2. Heat to 100 °C

Deposition

Thermal Growth

Poly-Silicon

Temp (°C) 580 - 650 (Lower T, Lower Stress)
Pressure (mT) 200 - 400
Gas (sccm) SiH4: 50 - 100
Refractive Index 4.0
Rate (Å/min) 50 - 100 (Lower T/P, Lower Dep. Rate)

Semi Insulating Polycrystalline Silicon

Temp (°C) 700-850
Pressure (mT) 200 - 400
Gas1 (sccm) N2O - 100
Gas2 (sccm) SiH4: 10-25
Refractive Index 1.45
Rate (Å/min) 50 - 100

Thermal Oxide

Low Temp
Temp (°C) 400-450
Pressure (mT) 200 - 400
Gas1 (sccm) SiH4 - 85
Gas2 (sccm) O2: 120
Refractive Index 1.45
Rate (Å/min) 100-120
High Temp
Temp (°C) 700-850
Pressure (mT) 200 - 400
Gas1 (sccm) N2O - 100
Gas2 (sccm) SiH4: 10-25
Refractive Index 1.45
Rate (Å/min) 50 - 100

Oxidation

Wet Oxidations
Tystar Furnace
Equipment Tystar Furnace
Temp (°C) 800-1150
Pressure (mT) atm
Gas1 (sccm) O2 - 3000
Rate (Å/min) --

Thermal Nitride

Standard Nitride
Equipment Tystar Furnace
Temp (°C) 780-800 (Higher T, Lower Stress)
Pressure (mT) 200-400
Gas1 (sccm) SiH2Cl2 - 33
Gas2 (sccm) NH3 - 100
Refractive Index 2.0
Deposition Rate (Å/min) --
Low Stress Nitride
Recipe Low Stress Nitride
Temp (°C) 780-800 (Higher T, Lower Stress)
Pressure (mT) 200-400
Gas1 (sccm) SiH2Cl2 - 100
Gas2 (sccm) NH3 - 25
Refractive Index 2.1
Deposition Rate (Å/min) 30-60
Recipe Low Stress
Temp (°C) 780-880 (Higher T, Lower Stress)
Pressure (mT) 200-400
Gas1 (sccm) SiH2Cl2 - 100
Gas2 (sccm) NH3 - 20
Refractive Index 2.2
Deposition Rate (Å/min) 30-60
Recipe Zero Stress or Compressive
Temp (°C) 780-800 (Higher T, Lower Stress)
Pressure (mT) 200-400
Gas1 (sccm) SiH2Cl2 - 100
Gas2 (sccm) NH3 - 16
Refractive Index 2.3
Deposition Rate (Å/min) 30-60

Dielectrics Deposition (non-thermal)

Oxide & Nitride Films

Silicon Oxide
Standard
PlasmaTherm PECVD - Standard Oxide
Temp (°C) 100-350
Pressure (mT) 900
Gases (sccm) SiH4 (2% in N2) - 400
N2O - 900
Power (W) 25
Deposition Rate (Å/min) 400
Unaxis PECVD - Standard Oxide
Temp (°C) 100-350
Pressure (mT) 900
Gases (sccm) SiH4 (5% in He) - 400
N2O - 900
Power (W) 30
Deposition Rate (Å/min) 600
High Frequency - STS PECVD
High Frequency
Temperature: 300 °C
Gases: SiH4 (2% in N2) - 400 sccm
N2O - 1420 sccm
Pressure: 800 mTorr
Power: 20 W @ 13.56 MHz
Recipe: hfsio.set
N2O 1420 sccm
(2%) SiH4 400 sccm
Process Pressure 800 mT
Process Temp. 300°C
Aux Temp. 250 °C
RF Forward Power (13.56 MHz) 20 W
Load Position 51.0 %
Tune Position 61.6 %

Fit Parm: Oxide Thickness Å Index N@633nm Index N@1550 MSE
Average: 4874.2 1.4791 1.4707 4.0460
Minimum: 4861.3 1.4783 1.4690 2.5700
Maximum: 4883.4 1.4806 1.4725 6.6600
Std Dev: 8.5020 9.8336E-4 0.0013502 1.6836
% Range: 0.22609 0.077750 0.11899 50.544
 
1:(0.00,1.50) 4883.4 1.4783 1.4698 2.5700
2:(-1.50,0.00) 4880.3 1.4796 1.4713 2.6500
3:(0.00,0.00) 4873.1 1.4788 1.4707 3.7600
4:(1.50,0.00) 4861.3 1.4806 1.4725 4.5900
5:(0.00,-1.50) 4873.0 1.4783 1.4690 6.6600
Low Frequency - STS PECVD
Low Frequency
Temperature: 300 °C
Gases: SiH4 (2% in N2) - 400 sccm
N2O - 1420 sccm
Pressure: 550 mTorr
Power: 60 W @ 380 KHz
Recipe: lfsio.set
N2O 1420 sccm
(2%) SiH4 400 sccm
Process Pressure 550 mT
APC Angle 67.8°C
Process Temp. 300°C
Aux Temp. 250 °C
RF Forward Power (380 kHz) 60 W
Load Position 10.0 %
Tune Position 62 %

Fit Parm: Oxide Thickness Å Index N@633nm Index N@1550 MSE
Average: 7060.1 1.4677 1.4600 6.0880
Minimum: 7003.9 1.4495 1.4422 4.5900
Maximum: 7199.8 1.4737 1.4659 7.6000
Std Dev: 79.323 0.010272 0.010062 1.2212
% Range: 1.3874 0.82443 0.81164 24.721
 
1:(0.00,1.50) 7199.8 1.4495 1.4422 7.6000
2:(-1.50,0.00) 7003.9 1.4737 1.4659 5.5500
3:(0.00,0.00) 7042.6 1.4711 1.4635 5.6400
4:(1.50,0.00) 7030.2 1.4704 1.4625 7.0600
5:(0.00,-1.50) 7024.1 1.4737 1.4659 4.5900
Silicon Nitride
Standard
PlasmaTherm PECVD - Standard Nitride
Temperature: 200-350 °C
Gases: SiH4 (2% in N2) - 200 sccm
N2 - 900 sccm
NH3 - 5 sccm
Pressure: 900 mTorr
Power: 25 W
Deposition Rate (Å/min) 100
Unaxis PECVD - Standard Nitride
Temperature: 200-350 °C
Gases: SiH4 - 4 sccm
N2 - 1100 sccm
NH3 - 5 sccm
Pressure: 900 mTorr
Power: 25 W
Deposition Rate (Å/min) 100
High Frequency - STS PECVD
High Frequency
Temperature: 300 °C
Gases: SiH4 (2% in N2) - 2000 sccm
N2 - 40 sccm
Pressure: 900 mTorr
Power: 20 W @ 13.56 MHz
Recipe: hfsin.set
NH3 40 sccm
(2%) SiH4 2000
Process Pressure 800 mT
Process Temp. 300°C
Aux Temp. 250°C
RF Forward Power (13.56 MHz) 20 W
Load Position 57.4%
Tune Position 60.8%

Fit Parm: Nitride Thickness Å Index N@633nm Index N@350nm K@350nm MSE
Average: 2456.7 2.0474 2.3388 0.068900 24.234
Minimum: 2446.1 2.0386 2.3250 0.063300 15.500
Maximum: 2469.3 2.0605 2.3514 0.075700 32.190
Std Dev: 10.727 0.0088248 0.012343 0.0057650 7.0441
% Range: 0.47157 0.53483 0.56438 8.9986 34.435
 
1:(0.00,1.50) 2448.9 2.0517 2.3473 0.063300 23.440
2:(-1.50,0.00) 2446.1 2.0605 2.3442 0.063900 32.190
3:(0.00,0.00) 2451.9 2.0413 2.3514 0.067400 30.360
4:(1.50,0.00) 2469.3 2.0386 2.3262 0.075700 19.680
5:(0.00,-1.50) 2467.0 2.0448 2.3250 0.074200 15.500
Low Frequency - STS PECVD
Low Frequency
Temperature: 300 °C
Gases: SiH4 (2% in N2) - 2000 sccm
N2 - 10 sccm
Pressure: 550 mTorr
Power: 60 W @ 380KHz
Recipe: lfsin.set
NH3 10 sccm
(2So) SiH4 2000
Process Pressure 550 mT
Process Temp. 300°C
Aux Temp. 250°C
RF Forward Power (13.56 MHz) 60 W
Load Position 0.0%
Tune Position 57.0%

Fit Parm: Nitride Thickness Å Index N@633nm Index N@350nm K@350nm MSE
Average: 8755.4 2.0317 1.9319 0.025300 22.692
Minimum: 8646.4 2.0133 1.6970 0.021800 16.000
Maximum: 8874.2 2.0513 2.0541 0.028800 31.830
Std Dev: 84.524 0.013671 0.15640 0.0026954 6.6062
% Range: 1.3008 0.93520 9.2423 13.834 34.880
 
1:(0.00,1.50) 8874.2 2.0133 2.0225 0.026900 19.120
2:(-1.50,0.00) 8646.4 2.0513 1.6970 0.025100 19.200
3:(0.00,0.00) 8781.7 2.0287 2.0411 0.021800 27.310
4:(1.50,0.00) 8762.1 2.0298 1.8447 0.023900 31.830
5:(0.00,-1.50) 8712.4 2.0352 2.0541 0.028800 16.000
Low Stress
STS PECVD - Low Stress
Temperature: 300 °C
Gases: SiH4 (2% in N2) - 2000 sccm
N2 - 30 sccm
Pressure: 750 mTorr
Power: 20 W @ 13.56 MHz / 6 sec 20 W @ 380 KHz/1.5 sec
Unaxis PECVD - Low Stress (He Based)
Temperature: 250 °C
Gases: SiH4 (5% in He) - 200 sccm
NH3 - 8 sccm
He - 560 sccm
N2 - 150 sccm
Pressure: 900 mTorr
Power: 30 W
Deposition Rate (Å/min) 100
Silicon Oxynitride
Unaxis PECVD
Temperature: 200-350 °C
Gases: SiH4 (100%) - 6 sccm
N2 - 1200 sccm NH3 - 30 sccm
N2O - 30 sccm
Pressure: 900 mTorr
Power: 35 W
Deposition Rate (Å/min) 100-250

Silicon Carbide

Unaxis PECVD
Temperature: 300 °C
Gases: SiH4 (5% in He) - 300 sccm
He - 700 sccm CH4 - 100 sccm
Pressure: 900 mTorr
Power: 50 W
Deposition Rate (Å/min) 50

Diamond-Like Carbon

Astex ECR
Temperature: 25 °C
Gases: CH4 - 75 sccm
Pressure: 200 mTorr
Power: 40 W
DC-bias: 110 V

RF Sputterer Dieletrics

Metal Deposition

Method Advantages Disadvantages
E-Beam Evaporation
  1. Handles high temp materials.
  2. Good for liftoff.
  3. Highest purity.
  1. Some CMOS processes are sensitive to radiation
  2. Alloys are difficult.
  3. Poor step coverage.
Filament Evaporation
  1. Simple to implement
  2. Good for liftoff.
  1. Unable to handle high temp materials.
  2. Alloys are difficult.
  3. Poor step coverage.
Sputtering
  1. Improved step coverage
  2. Good for alloys.
  3. Handles high temp materials.
  4. Less radiation damage.
  1. Film quality not as good (possible grainy/porous films)
  2. Plasma damage/contamination.

Thin Film Evaporation Reference

Aluminum

DC Sputterer, E-Beam Evaporator, E-Beam Evaporator 2, PVD Filament Evaporator, RF Sputterer

Chromium

DC Sputterer, E-Beam Evaporator, E-Beam Evaporator 2, PVD Filament Evaporator

Copper

DC Sputterer, E-Beam Evaporator, E-Beam Evaporator 2, PVD Filament Evaporator, RF Sputterer

Gold

DC Sputterer, E-Beam Evaporator, E-Beam Evaporator 2, PVD Filament Evaporator, RF Sputterer

Indium

PVD Filament Evaporator,

Iron

DC Sputterer, E-Beam Evaporator, PVD Filament Evaporator, RF Sputterer

Nickel

DC Sputterer, E-Beam Evaporator, PVD Filament Evaporator, RF Sputterer

Palladium

DC Sputterer, E-Beam Evaporator

Platinum

DC Sputterer, E-Beam Evaporator, E-Beam Evaporator 2, RF Sputterer

Ruthenium

DC Sputterer

Silver

DC Sputterer, E-Beam Evaporator 2, PVD Filament Evaporator

Tantalum

DC Sputterer

Tin

E-Beam Evaporator, PVD Filament Evaporator

Titanium

DC Sputterer, E-Beam Evaporator, E-Beam Evaporator 2

Tungsten

DC Sputterer

Doping

N-type Dopant
Equipment Tystar Furnace
Temp (C) 950
Pressure (mT) atm
P-type Dopant
Equipment Tystar Furnace
Temp (C) 950
Pressure (mT) atm
Gas 1 (sccm) O2 - 200
Gas 2 (sccm) N2 - 5000
Rate (Å/min) N2 - 5000

Etching

Metals

Metal and Semiconductor Wet Etching

Aluminum

Plasma-Therm RIE
Temperature: 25 °C
Gases: BCl3 - 40 sccm
Cl2 - 10 sccm
Pressure: 30 mTorr
Power: 125 W
DC-bias: 250 V
Etch Rate: 500-2000 Å/min

Chrome

Plasma-Therm ICP
Temperature: 25 °C
Gases: Step 1 Step 2
O2 10 sccm 6 sccm
Cl2 20 sccm 24 sccm
Pressure: 10 mTorr 10 mTorr
Power RF: 25 W 10 W
Power ICP: 600 W 500 W
Time: 20 sec Endpoint
Plasma-Therm RIE
Temperature: 25 °C
Gases: Cl2 - 40 sccm
O2 - 10 sccm
Pressure: 75 mTorr
Power: 55 W
DC-bias: 50 V
Etch Rate: 100-200 Å/min

Semiconductor

Metal and Semiconductor Wet Etching

III-V

Gallium Arsenide/Aluminum Gallium Arsenide
Plasma-Therm RIE - Feature Etch
Temperature: 25-40 °C
Gases: Cl2 - 20 sccm
BCl3 - 30 sccm
Pressure: 15 mTorr
Power: 150 W
DC-bias: 250 V
Etch Rate: 2000 Å/min

Plasma-Therm RIE - Via Hole Etch
Temperature: 25-40 °C
Gases: Cl2 - 10 sccm
BCl3 - 40 sccm
Pressure: 20 mTorr
Power: 75 W
DC-bias: 150 V
Etch Rate: 8000 - 10000 Å/min

Silicon

Plasma-Therm RIE
Trench Etch - Fluorine
Temperature: 25 °C
Gases: SF6 - 25 sccm
O2 - 25 sccm
Pressure: 100 mTorr
Power: 180 W
DC-bias: 150 V
Etch Rate: 5000-7500 Å/min

Trench Etch - Chlorine
Temperature: 40 °C
Gases: SiCl4 - 30 sccm
Cl2 - 20 sccm
Pressure: 30 mTorr
Power: 150 W
DC-bias: 200 V
Etch Rate: 1000 Å/min
STS ICP
Module 1: 2µm wide, 60µm depth bulk Si etch
  Etch Cycle Dep Cycle
Gases: SF6 - 130 sccm
O2 - 13 sccm
C4F8 - 20 sccm (ramped @ -4 sccm/min)
(11+0s)
C4F8 - 85 sccm
(8+0s)
Pressure: 24 - 22 mT
(75% Fixed APC)
10 - 12 mT
(75% Fixed APC)
Coil Power: 800 W 600 W
Platen Power: 12W, HF --
Process Time: 43:23 (min:s)
Temperature: Lid - 45°C
Platen - 20°C
He Back-cooling: 10 T

Module 1 Results
Etch Depth: 60µm
Etch Rate: 1.55µm/min
Profile Angle: 89.9°
Selectivity (Si:PR): 53:1
Uniformity across wafer: ±1.0%
Initial Mask Undercut: 364nm/edge
Sidewall roughness: 150nm
Uniformity btw wafers: ±1.0%

Module 2: 1µm wide, 10µm depth SOI etch
  Etch Cycle Dep Cycle
Gases: SF6 - 130 sccm
O2 - 13 sccm
7+0s)
C4F8 - 100 sccm
(5+0s)
Pressure: 20 mT
(Auto APC)
20 mT
(Auto APC)
Coil Power: 600 W 600 W
Platen Power: 14W, LF (5ms on) --
Process Time: 6:30 (min:s) with 10% over-etch
Temperature: Lid - 45°C
Platen - 20°C
He Back-cooling: 10 T

Module 2 Results
Etch Depth: 10µm
Etch Rate: 1.91µm/min
Profile Angle: 89.4°
Selectivity (Si:PR): 53:1
Uniformity across wafer: ±1.0%
Initial Mask Undercut: 163nm/edge
Sidewall roughness: 123nm
Notch width at oxide interface: 148nm/edge
Uniformity btw wafers: ±1.0%

Module 3: 5µm wide, 10µm depth SOI etch
  Etch Cycle Dep Cycle
Gases: SF6 - 130 sccm
O2 - 13 sccm
(7.5+0s)
C4F8 - 100 sccm
(5+0s)
Pressure: 25 mT
(Auto APC)
25 mT
(Auto APC)
Coil Power: 600 W 600 W
Platen Power: 16W, LF (5ms on) --
Process Time: 8:45 (min:s)
Temperature: Lid - 45°C
Platen - 20°C
He Back-cooling: 10 T

Module 3 Results
Etch Depth: 10µm
Etch Rate: 1.67µm/min
Profile Angle: 90.1°
Selectivity (Si:PR): 39:1
Uniformity across wafer: ±1.2%
Initial Mask Undercut: 147nm/edge
Sidewall roughness: 188nm
Notch width at oxide interface: 143nm/edge
Uniformity btw wafers: ±2.7%

Dielectics

Silicon Nitride

Plasma-Therm ICP
Temperature: 25 °C
He Backside Pressure: 7-9 Torr
Gases: CF4 - 30 sccm
Pressure: 5 mTorr
Power (RF): 50 W
Power (ICP): 400 W
Etch Rate: 2000 Å/min
Plasma-Therm RIE
High Rate
Temperature: 25 °C
Gases: CF4 - 45 sccm
O2 - 5 sccm
Pressure: 40 mTorr
Power: 200 W
DC-bias: 425 V
Etch Rate: 1000 - 2000 Å/min

Selective to Si
Temperature: 25 °C
Gases: CHF3 - 45 sccm
O2 - 5 sccm
Pressure: 40 mTorr
Power: 200 W
DC-bias: 440 V
Etch Rate: 400 - 500 Å/min

Passivation Removal
Temperature: 25 °C
Gases: SF6 - 33 sccm
O2 - 7 sccm
Pressure: 75 mTorr
Power: 85 W
Etch Rate: 1000 Å/min

Silicon Oxide

Plasma-Therm ICP
Standard
Temperature: 25 °C
He backside pressure (Torr): 7-9
Gases: PR Mask Cr Mask
CF4 30 sccm 25 sccm
Pressure: 5 mTorr 12 mTorr
Power RF: 100 W 60 W
Power ICP: 400 W 800 W
Etch Rate: 2000 Å/min 3500 Å/min

High Selectivity
Temperature: 25 °C
Gases: C4F6 - 10 sccm
O2 - 3 sccm
Ar - 15 sccm
CF4 - 10 sccm
Pressure: 5 mTorr
Power RF: 400 W
Power ICP: 100 W
Etch Rate: 1265 Å/min
Selectivity: 10:1 SiO2:Si
virtually no PR etched
Plasma-Therm RIE
Temperature: 25 °C
Gases: CHF3 - 45 sccm
O2 - 5 sccm
Pressure: 40 mTorr
Power: 200 W
DC-bias: 440 V
Etch Rate: 400 - 500 Å/min

Gallium Nitride

Plasma-Therm ICP
Temperature: 25 °C
Gases: BCl3 - 15 sccm
Cl2 - 4 sccm
Pressure: 5 mTorr
Power (RF): 300 W
Power (ICP): 300 W
DC-bias: 100 V
Etch Rate: 0.2 - 0.3 µ/min
Selectivity (Mask): 0.5 - 0.7 (PR)

Indium Phosphide

Plasma-Therm RIE
Temperature: 25 - 40 °C
Gases: CH4 - 10 sccm
H2 - 40 sccm
Pressure: 30 mTorr
Power: 200 W
DC-bias: 440 V
Etch Rate: 400 Å/min

Zinc Sulfide

Plasma-Therm RIE
Temperature: 25 °C
Gases: Ar - 25 sccm
H2 - 25 sccm
Pressure: 30 mTorr
Power: 500 W
Etch Rate: 250 Å/min

Polymer

Polyimide

Isotropic
Plasma-Therm RIE
Temperature: 25 °C
Gases: O2 - 40 sccm
CF4 - 10 sccm
Pressure: 200 mTorr
Power: 250 W
Etch Rate: 5000 Å/min
Anistropic
Plasma-Therm RIE
Temperature: 25 °C
Gases: O2 - 10 sccm
He - 10 sccm
Pressure: 10 mTorr
Power: 200 W
Etch Rate: 1000 Å/min

Photoresist

Plasma-Therm RIE
Temperature: 25 °C
Gases: O2 - 10 sccm
He - 10 sccm
Pressure: 10 mTorr
Power: 200 W
Etch Rate: 1000 Å/min

Mask Design and Production

Lithography

Resist Information

Shipley Co., Inc. Photoresists
AZ Electronic Materials Photoresists
Futurrex, Inc. Photoresists

Spin Coating

CEE Spinner (5)
RC8 Spin Coater
Solitec Spin Coater
SCS Spin Coater

Mask Alignment

MJB3 (left)
MJB3 (right)
MA6
OAI
EVG

E-Beam Nanolithography

Thermal Processing

Film Growth

Annealing/Sintering

Tystar Furnace
Equipment Tystar Furnace
Temp (°C) 250 - 700 700 - 1350
Pressure (mT) atm
Gas (sccm)
Forming Gas 3000 - 10000
N2 3000 - 10000
O2 3000 - 10000
Ar 3000 - 10000
Lindberg Furnace (Tube 1)
Rapid Thermal Processor (RTP)

Metrology

Film Thickness

Ellipsometer

Woollam, Plas-Mos

Profilometer

Contact: AS500, Dektak, KLA P15 Tencor

Non-contact: Wyko

Reflectometer

Nanospec Refractometer

Optical Properties

Plas-Mos, Woollam

Film Uniformity

Woollam, Wyko

Surface Properties

AFM, EDS, Four-Point Probe, Surface Charge Analyzer, Tribo Indenter

Imaging

AFM, KLA P15 Tencor, SEM, Wyko