Piezoelectric Motors & Actuators for Semiconductor | Piezo LEGS®
Engineered for vacuum, non-magnetic environments and nanometer-class motion control.
Vacuum-ready, non-magnetic piezoelectric motors/actuators with sub-nm resolution for semiconductor tools.
Why Piezo LEGS® in the fab
- Vacuum & bake-out ready. Dedicated Piezo LEGS® variants are prepared for vacuum with minimized outgassing and bake-out up to 125 °C—ideal for vacuum chambers and load-locks.
- Non-magnetic by design. Piezoceramic elements and non-magnetic alloys keep magnetic flux below sensor noise (~<1 nT at 10 mm)—safe around e-beam columns and high-field tools.
- True direct drive. No gears or screws → zero backlash, smooth motion, compact footprint, and fewer particles from moving transmissions.
- Sub-nanometer resolution & fast settle. Micro-stepping of the drive waveform enables nanometer to sub-nanometer positioning with excellent dynamic control.
- Power-off holding. The friction-walk mechanism is inherently self-locking—hold position with zero power draw, a major thermal and energy advantage in vacuum.
- Force in a small package. Standard Piezo LEGS® linear actuators cover 6.5–40 N (with strokes to ~75 mm); platform extensions reach 300–450 N for heavy optics and wafer-level subsystems.
Where they excel in semiconductor equipment
- Optics & metrology: focus/zoom, filter/aperture selection, interferometer alignment, mask/reticle fine-positioning. (Piezo motors are widely used for UHV/non-magnetic positioning in semiconductor metrology.)
- Probe & test: sub-micron approach, contact force tuning, drift-free hold during long measurements.
- Wafer handling modules: end-effector Z-trim, chuck leveling, alignment pins, miniature shutters.
- E-beam / ion tools: non-magnetic actuators for stage accessories and calibration mechanisms.
Performance at a glance (typical)
- Resolution: < 1 nm with controller micro-stepping (up to 8192 micro-steps per waveform step) and encoder feedback.
Speed: from nanometers/s to ~15–24 mm/s depending on model/drive.
Stroke: defined by drive-rod length; standard options up to ~74.5 mm on compact models.
Force: 6.5 N, 20 N, 40 N standard; 300–450 N in covered/heavy-duty variants.
Vacuum rating: to ~10⁻⁷ torr (LL10D class) with non-magnetic build; prepared for 125 °C bake-out.
Example: LL10D non-magnetic/vacuum motor — 6.5 N stall, 7 N hold, 0–15 mm/s, up to 74.5 mm stroke; magnetic flux < 1 nT at 10 mm.
How Piezo LEGS® works (engineer’s cut)
A non-resonant walking sequence drives four piezo “legs” in a controlled cycle. Each waveform cycle (a wfm-step) advances the rod a few micrometers; the controller subdivides this into thousands of micro-steps for nanometer positioning. The mechanism’s frictional pre-load yields high stiffness and power-off holding, without cogging or magnetic fields.
Integration & control
- Controllers: PMD301 (module) and PMD401 (board-level) over RS-485/USB, supporting micro-stepping to sub-nm resolution and multi-axis chaining.
- Feedback: works with external encoders for closed-loop motion; direct-drive architecture simplifies control loops (no screw/gear compliance).
- Form factors: compact actuators with swappable drive-rod lengths, vacuum and non-magnetic builds for fab integration.
Piezoelectric motor vs. stepper/BLDC in vacuum
| Criterion | Piezoelectric motor / actuator (Piezo LEGS®) | Stepper/BLDC with screw |
|---|---|---|
| Magnetics | Non-magnetic; no stray fields | Requires magnetic mitigation; can disturb e-beam/ion paths |
| Backlash | None (direct friction-walk) | Depends on screw/gear and preload |
| Holding | Self-locking at rest; zero power | Hold torque → heat in vacuum |
| Heat load | Very low at hold; efficient small moves | Higher, especially under hold/constant current |
| Vacuum readiness | Vacuum-prepared variants; bake-out to 125 °C | Special greases, outgassing control needed |
| Resolution | Sub-nm with micro-stepping & encoder | Limited by screw pitch, compliance, encoder |
Specifying a Piezo LEGS® actuator for your tool
- Environment: target pressure (HV/UHV), bake-out profile, magnetic constraints
- Axis mechanics: required stroke, external guiding (if any), and stiffness budget
- Throughput: speed and settle time; specify move profile (step-settle vs. scan)
- Load case: continuous vs. peak force, orientation, and duty cycle
Frequently asked questions
Are Piezo LEGS® motors piezoelectric motors or piezoelectric actuators?
Both. The motor is a piezoelectric actuator assembly that performs useful mechanical work as a piezoelectric motor via a controlled walking sequence.
Do they work in UHV and strong magnetic fields?
Non-magnetic/vacuum versions are specified to vacuum levels around 10⁻⁷ torr with non-magnetic construction; piezo mechanisms are widely used in UHV and strong-field environments across semiconductor metrology and positioning. For UHV beyond that, consult us for materials/finish options.
How much force and travel can I get?
Standard linear Piezo LEGS® motors cover 6.5–40 N with strokes up to ~75 mm; covered/heavy-duty variants extend to 300–450 N. Travel is set by the drive-rod length.
What’s the real-world resolution?
With an encoder and PMD-series controller, sub-nanometer command increments are achievable; application-level resolution depends on mechanics and noise.