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NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing. Semiconductor Manufacturing Technology: Semiconductor Manufacturing Processes. Conrad T. Sorenson Praxair, Inc. 1999 Arizona Board of Regents for The University of Arizona. Wafer Preparation.
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NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing Semiconductor Manufacturing Technology: Semiconductor Manufacturing Processes Conrad T. Sorenson Praxair, Inc. 1999 Arizona Board of Regents for The University of Arizona
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Semiconductor Manufacturing Processes • Design • Wafer Preparation • Front-end Processes • Photolithography • Etch • Cleaning • Thin Films • Ion Implantation • Planarization • Test and Assembly
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Design • Establish Design Rules • Circuit Element Design • Interconnect Routing • Device Simulation • Pattern Preparation
Chrome Pattern Pellicle Quartz Substrate Pattern Preparation Reticle
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Wafer Preparation • Polysilicon Refining • Crystal Pulling • Wafer Slicing & Polishing • Epitaxial Silicon Deposition
Polysilicon Refining Chemical Reactions Silicon Refining: SiO2 + 2 C Si + 2 CO Silicon Purification: Si + 3 HCl HSiCl3 + H2 Silicon Deposition: HSiCl3 + H2 Si + 3 HCl Reactants H2 Silicon Intermediates H2SiCl2 HSiCl3
Quartz Tube Rotating Chuck Seed Crystal Growing Crystal (boule) RF or Resistance Heating Coils Molten Silicon (Melt) Crucible Crystal Pulling Process Conditions Flow Rate: 20 to 50 liters/min Time: 18 to 24 hours Temperature: >1,300 degrees C Pressure: 20 Torr Materials Polysilicon Nodules * Ar * H2 * High proportion of the total product use
silicon wafer p+ silicon substrate Wafer Slicing & Polishing The silicon ingot is sliced into individual wafers, polished, and cleaned. 3/15/98 PRAX01C.PPT Rev. 1.0
silicon wafer p- silicon epi layer p+ silicon substrate Silicon Sources SiH4 H2SiCl2 HSiCl3* SiCl4* Dopants AsH3 B2H6 PH3 Etchant HCl Carriers Ar H2* N2 Epitaxial Silicon Deposition Gas Input Lamp Module Susceptor Chemical Reactions Silicon Deposition: HSiCl3 + H2 Si + 3 HCl Process Conditions Flow Rates: 5 to 50 liters/min Temperature: 900 to 1,100 degrees C. Pressure: 100 Torr to Atmospheric Quartz Lamps Wafers Exhaust * High proportion of the total product use
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Front-End Processes • Thermal Oxidation • Silicon Nitride Deposition • Low Pressure Chemical Vapor Deposition (LPCVD) • Polysilicon Deposition • Low Pressure Chemical Vapor Deposition (LPCVD) • Annealing
Vertical LPCVD Furnace Exhaust Via Vacuum Pumps and Scrubber Quartz Tube 3 Zone Temperature Control Gas Inlet Front-End Processes Chemical Reactions Thermal Oxidation: Si + O2 SiO2 Nitride Deposition: 3 SiH4 + 4 NH3 Si3N4 + 12 H2 Polysilicon Deposition: SiH4 Si + 2 H2 Process Conditions (Silicon Nitride LPCVD) Flow Rates: 10 - 300 sccm Temperature: 600 degrees C. Pressure: 100 mTorr Oxidation Ar N2 H2O Cl2 H2 HCl * O2 * Dichloroethene * Polysilicon H2 N2 SiH4* AsH3 B2H6 PH3 Nitride NH3 * H2SiCl2 * N2 SiH4 * SiCl4 Annealing Ar He H2 N2 * High proportion of the total product use
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Photolithography • Photoresist Coating Processes • Exposure Processes
Photoresist Coating Processes photoresist field oxide p- epi p+ substrate Photoresists Negative Photoresist * Positive Photoresist * Other Ancillary Materials (Liquids) Edge Bead Removers * Anti-Reflective Coatings * Adhesion Promoters/Primers (HMDS) * Rinsers/Thinners/Corrosion Inhibitors * Contrast Enhancement Materials * Developers TMAH * Specialty Developers * Inert Gases Ar N2
photoresist field oxide p- epi p+ substrate Exposure Processes Expose Kr + F2 (gas) * Inert Gases N2
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Ion Implantation • Well Implants • Channel Implants • Source/Drain Implants
Focus Beam trap and gate plate Neutral beam and beam path gated Neutral beam trap and beam gate Y - axis scanner X - axis scanner Wafer in wafer process chamber Equipment Ground Resolving Aperture 180 kV Gases Ar AsH3 B11F3* He N2 PH3 SiH4 SiF4 GeH4 Solids Ga In Sb Liquids Al(CH3)3 Acceleration Tube 90° Analyzing Magnet Terminal Ground Ion Source 20 kV Ion Implantation junction depth Process Conditions Flow Rate: 5 sccm Pressure: 10-5 Torr Accelerating Voltage: 5 to 200 keV * High proportion of the total product use
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Etch • Conductor Etch • Poly Etch and Silicon Trench Etch • Metal Etch • Dielectric Etch
Cluster Tool Configuration Etch Chambers Wafers Transfer Chamber Loadlock Gas Inlet RIE Chamber Wafer Transfer Chamber Polysilicon Etches HBr * C2F6 SF6* NF3* O2 Aluminum Etches BCl3 * Cl2 Diluents Ar He N2 RF Power Exhaust Conductor Etch Chemical Reactions Silicon Etch: Si + 4 HBr SiBr4 + 2 H2 Aluminum Etch: Al + 2 Cl2 AlCl4 Process Conditions Flow Rates: 100 to 300 sccm Pressure: 10 to 500 mTorr RF Power: 50 to 100 Watts * High proportion of the total product use
Contact locations Cluster Tool Configuration Etch Chambers Wafers Transfer Chamber Loadlock Gas Inlet RIE Chamber Wafer Transfer Chamber Plasma Dielectric Etches CHF3* CF4 C2F6 C3F8 CO * Diluents Ar He N2 CO2 O2 SF6 SiF4 RF Power Exhaust Dielectric Etch Chemical Reactions Oxide Etch: SiO2 + C2F6 SiF4 + CO2 + CF4 + 2 CO Process Conditions Flow Rates: 10 to 300 sccm Pressure: 5 to 10 mTorr RF Power: 100 to 200 Watts * High proportion of the total product use
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Cleaning • Critical Cleaning • Photoresist Strips • Pre-Deposition Cleans
Contact locations Critical Cleaning Process Conditions Temperature: Piranha Strip is 180 degrees C. RCA Clean SC1 Clean (H2O + NH4OH + H2O2) * * SC2 Clean (H2O + HCl + H2O2) * Piranha Strip * H2SO4 + H2O2* Nitride Strip H3PO4 * Oxide Strip HF + H2O * Dry Strip N2O O2 CF4 + O2 O3 Solvent Cleans NMP Proprietary Amines (liquid) Dry Cleans HF O2 Plasma Alcohol + O3
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Thin Films • Chemical Vapor Deposition (CVD) Dielectric • CVD Tungsten • Physical Vapor Deposition (PVD) • Chamber Cleaning
Metering Pump Inert Mixing Gas Vaporizer Direct Liquid Injection Process Gas LPCVD Chamber Gas Inlet CVD Dielectric O2 O3 TEOS * TMP * Wafer Transfer Chamber RF Power Exhaust Chemical Vapor Deposition (CVD) Dielectric TEOS Source Chemical Reactions Si(OC2H5)4 + 9 O3 SiO2 + 5 CO + 3 CO2 + 10 H2O Process Conditions (ILD) Flow Rate: 100 to 300 sccm Pressure: 50 Torr to Atmospheric * High proportion of the total product use
Chemical Vapor Deposition (CVD) Tungsten Input Cassette Output Cassette Chemical Reactions WF6 + 3 H2 W + 6 HF Process Conditions Flow Rate: 100 to 300 sccm Pressure: 100 mTorr Temperature: 400 degrees C. Wafer Hander Wafers Multistation Sequential Deposition Chamber CVD Dielectric WF6* Ar H2 N2 Water-cooled Showerheads Resistively Heated Pedestal * High proportion of the total product use
N S N Physical Vapor Deposition (PVD) Physical Vapor Deposition Chambers Cluster Tool Configuration Wafers Transfer Chamber Loadlock Process Conditions Pressure: < 5 mTorr Temperature: 200 degrees C. RF Power: Reactive Gases PVD Chamber Cryo Pump Barrier Metals SiH4 Ar N2 N2 Ti PVD Targets * Transfer Chamber • e - + Wafer Argon & Nitrogen Backside He Cooling DC Power Supply (+) * High proportion of the total product use
Multistation Sequential Deposition Chamber Water-cooled Showerheads Resistively Heated Pedestal Aluminum Surface Coating Process Material Residue Chamber Cleaning Chemical Reactions Oxide Etch: SiO2 + C2F6 SiF4 + CO2 + CF4 + 2 CO Process Conditions Flow Rates: 10 to 300 sccm Pressure: 10 to 100 mTorr RF Power: 100 to 200 Watts Chamber Cleaning C2F6* NF3 ClF3 Chamber Wall Cross-Section * High proportion of the total product use
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Planarization • Oxide Planarization • Metal Planarization
Platen Head Sweep Slide Polishing Head Load/Unload Station Pad Conditioner Wafer Handling Robot & I/O Carousel Backing (Carrier) Film Polyurethane Pad Polyurethane Pad Conditioner Abrasive CMP (Oxide) Silica Slurry KOH * NH4OH H2O CMP (Metal) Alumina * FeNO3 Chemical Mechanical Planarization (CMP) Process Conditions (Oxide) Flow: 250 to 1000 ml/min Particle Size: 100 to 250 nm Concentration: 10 to 15%, 10.5 to 11.3 pH Process Conditions (Metal) Flow: 50 to 100 ml/min Particle Size: 180 to 280 nm Concentration: 3 to 7%, 4.1 - 4.4 pH Wafer Carrier Polishing Pad Slurry Delivery * Wafer Platen * High proportion of the total product use.
Wafer Preparation Design Front-End Processes Thin Films Photo- lithography Ion Implantation Etch Cleaning Planarization Test & Assembly Test and Assembly • Electrical Test Probe • Die Cut and Assembly • Die Attach and Wire Bonding • Final Test
bonding pad nitride Metal 2 p-well n-well n-channel transistor p-channel transistor p+ substrate Electrical Test Probe Defective IC Individual integrated circuits are tested to distinguish good die from bad ones.
Die Cut and Assembly Good chips are attached to a lead frame package.
Die Attach and Wire Bonding lead frame gold wire bonding pad connecting pin
Final Test Chips are electrically tested under varying environmental conditions.
References 1. CMOS Process Flow in Wafer Fab, Semiconductor Manufacturing Technology, DRAFT, Austin Community College, January 2, 1997. 2. Semiconductor Processing with MKS Instruments, Inc. 3. Worthington, Eric. “New CMP architecture addresses key process issues,” Solid State Technology, January 1996. 4. Leskonic, Sharon. “Overview of CMP Processing,” SEMATECH Presentation, 1996. 5. Gwozdz, Peter. “Semiconductor Processing Technology” SEMI, 1997. 6. CVD Tungsten, Novellus Sales Brochure, 7/96. 7. Fullman Company website. “Fullman Company - The Semiconductor Manufacturing Process,” http://www.fullman.com/semiconductors/index.html, 1997. 8. Barrett, Craig R. “From Sand to Silicon: Manufacturing an Integrated Circuit,” Scientific American Special Issue: The Solid State Century, January 22, 1998.