Pressure regimes
Chip Processes Run Across 13 Decades of Pressure
Each process step runs at the pressure its physics needs: plasma etch where a plasma can be sustained, CVD where films grow at the right rate and conformality, PVD where sputtered atoms reach the wafer without collisions.
| Regime | Pressure | Process steps | Pumps |
|---|---|---|---|
| Rough | 1,000 to 1 mbar | Load locks; transfer chambers; LPCVD pump-down; gas line purge | Dry claw and multistage roots; roots boosters |
| Medium | 1 to 10-3 mbar | Plasma etch (RIE, ICP); PECVD; ALD; most CVD; implant beamline | Dry multistage roots; turbo on cleaner processes |
| High | 10-3 to 10-7 mbar | PVD sputtering; e-beam evaporation; CD-SEM and inspection chambers | Turbo backed by a dry pump |
| Ultra-high | Below 10-7 mbar | MBE for III-V growth; XPS and other surface analysis | Ion, titanium sublimation and cryopumps; baked stainless chambers with metal seals |
Dry pumps
Every Pump That Touches the Process Is Oil-Free
Oil-sealed rotary vane and liquid ring pumps backstream hydrocarbons into the chamber, and ppb-level hydrocarbon contamination causes gate dielectric and resist adhesion defects. Every pump in contact with the process at a leading-edge fab is a dry pump.
| Type | How it works | Range | Fab use | Limits |
|---|---|---|---|---|
| Multistage roots | Figure-8 lobed rotors on several stages that never touch; no oil in the gas path | Atmosphere to 10-2 mbar | Primary pump for etch, CVD and ALD; load locks | Hot gas narrows rotor clearances; corrosive service needs coated internals |
| Claw | Claw rotors trap and compress gas | Atmosphere to about 50 mbar | Final compression stage inside dry pump packages | Weak at low pressure; paired with roots stages |
| Scroll | One fixed and one orbiting spiral, sealed by tip seals | Atmosphere to about 10-2 mbar | Load locks; turbo backing; metrology; R&D lines | Tip seals wear and shed; too slow for plasma etch loads |
| Roots booster | High-speed roots stage ahead of a primary pump | Best at 1 to 100 mbar | LPCVD furnaces; high-throughput ALD | Cannot start against atmosphere; adds a failure point |
Turbomolecular pumps
Turbos Make High Vacuum, and Always Need a Dry Pump Behind Them
A turbomolecular pump drives gas molecules from the chamber toward its outlet with angled rotor blades spinning near the thermal speed of the molecules. It is clean and oil-free and reaches below 10-10 mbar in UHV setups, but it cannot exhaust to atmosphere.
| Parameter | Typical value | What it means in the fab |
|---|---|---|
| Rotor speed | 20,000 to 90,000 RPM; larger pumps spin slower | Bearing failure is the main failure mode; magnetic bearings remove the oil |
| Pumping speed | 50 to 5,000 L/s for nitrogen | Hydrogen pumps three to four times faster than nitrogen, which matters for SiH4 and H2 processes |
| Backing | Needs a dry pump holding its outlet at about 1 to 10 mbar | Every turbo is half of a two-pump set; losing the backing pump can damage the turbo |
| Vibration | Active magnetic bearing turbos below 0.1 µm/s | Required on lithography and metrology tools; see Seismic and Vibration |
| Corrosive service | Nickel-plated or coated rotors | Kept off direct corrosive exhaust; condensates unbalance the rotor |
| Spin-down | 30 to 60 minutes for large pumps | Holds vacuum briefly after power loss; controllers carry UPS for a controlled stop |
Tool-level or central
Leading-Edge Fabs Give Every Chamber Its Own Pump Set
Tool-dedicated pumping keeps one chamber's chemistry out of another's vacuum and confines a failure to one chamber, at the cost of thousands of pumps per fab.
| Architecture | Layout | Isolation | Where used |
|---|---|---|---|
| Tool-dedicated | One dry pump, plus a turbo where needed, per chamber, in the sub-fab | Complete; one failure stops one chamber | All leading-edge etch, CVD, ALD and PVD; lithography; implant |
| Central roughing | Shared dry pump manifold for load locks | Moderate; manifold failure hits a bay | Mature-node load locks; non-process vacuum |
| Central process vacuum | Large central pump stations on shared headers | Poor; per-gas abatement impractical | Older fabs; house vacuum for chucks and wands |
The sub-fab
Pumps Live One Floor Down, as Close Under the Tool as the Structure Allows
Process tools sit on the cleanroom floor; pumps, abatement, chemical delivery and exhaust sit in the sub-fab below. Foreline length sets conductance: a long foreline lowers pumping speed at the chamber and gives etch polymers, CVD silicon compounds and metal halides more cold wall to condense on, so pumps go directly beneath their tools.
A dry pump draws 2 to 5 kW, so a fab running several thousand pumps spends on the order of 10 MW on vacuum alone. Variable-speed drives, idle modes and magnetic-bearing turbos are among the energy levers covered on Power for Fabs.
Pumps and abatement
Pump and Abatement Are Engineered as One Unit
Pump exhaust carries unreacted process gas, byproducts and particles at near-atmospheric pressure, so the abatement unit sits between the pump outlet and the house exhaust and handles the same chemistry. Abatement chemistry is on Emissions and Abatement.
| Exhaust stream | Source | Treatment | Design consequence |
|---|---|---|---|
| Fluorinated gases (NF3, CF4, C2F6, CHF3) | Unreacted etch and chamber-clean gas; 10% to 50% passes through the plasma | Burn-wet or plasma abatement; wet scrub for the HF it makes | Sized for peak recipe flow; a large share of tool operating cost |
| Pyrophorics (SiH4, Si2H6, B2H6, PH3) | Unreacted CVD and dopant gas | N2 dilution below the lower flammable limit; pyrophoric-rated burn box | Fail-safe N2 purge interlocks; classified electrical zones |
| Acid gases (HCl, HBr, HF, Cl2) | Halogen etch byproducts; HF from fluorinated gas abatement | Caustic wet scrubber with pH control | Acidic wastewater; PTFE, PVC and FRP throughout |
| Solids and condensables | Deposition byproducts; AlF3; metal halides | Foreline traps; heated forelines; coated pump internals | The most frequent vacuum maintenance; mean time between maintenance drives vendor choice |
Suppliers
Four Companies Supply Most Fab Vacuum
Edwards and Ebara hold most process pump placements at leading-edge logic and memory fabs, with Pfeiffer and Leybold strong in Europe and in turbos. Tool makers (Applied Materials, Lam Research, Tokyo Electron, ASML) increasingly qualify a pump-plus-abatement package from one supplier, which favors Edwards and Ebara, the two with both product lines. A quality event or export restriction at either would slow tool installs at new fabs.
| Supplier | Parent and base | Product lines | Position |
|---|---|---|---|
| Edwards | Atlas Copco; Burgess Hill, UK | iXH and iXL dry pumps; nEXT and STP turbos; integrated abatement | Largest semiconductor vacuum supplier; pump-plus-abatement packages at TSMC, Samsung and Intel |
| Ebara | Tokyo, Japan | EV-series dry pumps; turbos; abatement | Strongest at Japanese fabs and Korean memory; qualified at TSMC |
| Pfeiffer Vacuum | Busch Group since 2023; Asslar, Germany | HiPace turbos; ACP dry pumps; leak detectors | Strong in turbos and metrology tool vacuum |
| Leybold | Atlas Copco; Cologne, Germany | DRYVAC dry pumps; TURBOVAC turbos | Strong in European fabs; sister brand to Edwards |
| Agilent Vacuum | Agilent Technologies; Santa Clara, California | TwisTorr turbos; ion and titanium sublimation pumps | UHV, research and analytical; minor in production primary pumps |
| Kashiyama Industries | Saku, Japan | Dry pumps for process tools | Mainly Japanese fabs |
| Chinese suppliers | Shanghai Hanbell Precise Machinery; KYKY Technology (Beijing) | Dry pumps; turbos | Growing at Chinese fabs as China localizes fab equipment |
Operating KPIs
Pump Health Is Tracked Like a Production Metric
| KPI | Target | If it slips |
|---|---|---|
| Pump uptime | Above 99.5% per pump; leading fabs above 99.9% | Aborted recipes, scrapped lots, two to eight hours of tool recovery |
| Mean time between maintenance | 12 to 24 months in corrosive service; 24 to 36 months clean; turbo bearings three to five years | Rebuild cost and downtime rise |
| Foreline pressure | Within 5% of the recipe baseline | Chamber pressure drifts; lots go on hold |
| Motor current | Within 10% of baseline at equal gas load | Earliest sign of deposits or bearing wear |
| Abatement destruction efficiency | Above 95% for NF3 and PFCs; above 99% for HCl and HF | Excess greenhouse and toxic release |
Record
Page Record
- Covers
- Vacuum regimes, dry and turbomolecular pumps, pump architecture, the sub-fab, pump-abatement integration, suppliers and KPIs
- Sources
- Edwards, Ebara, Pfeiffer Vacuum, Leybold and Agilent product literature; Busch Group; ASML and SPIE papers on EUV hydrogen environments; SEMI
- Last verified
- October 2026