Microglide™ Air Bearing Positioning Systems

Microglide™ N 250

300mm Wafer Positioning Solutions

Anorad's Microglide N320 nested XY air bearing platforms were created for 300mm wafer positioning. Its open frame-in-frame design uses balanced magnetic preload on the lift and guide bearings to maintain extraordinary flatness and straightness. Both axes are actuated by a pair of Anorad zero-cogging linear motors mounted in parallel at opposite sides of each frame. The resultant motive force acts along the centerline of each axis, thereby preventing angular pitch and roll errors due to unwanted torque on the individual axes. Additionally, the outer frame is stabilized horizontally by a pair of magnetically preloaded air bearings which glide on a granite reference surface at the platform's center.

The coplanar nested XY design enables all lift bearings to float atop the same ultra-flat lapped granite reference surface. This minimizes stack up and Abbe errors typically associated with stacked multi-axis positioning systems, providing maximum accuracy while giving the system a very compact profile. The N320 also has a high performance "air brake" for nanometer-level position stability at rest during critical inspection processes.

The N320 owes its extremely smooth motion to a completely non-contacting system design. The magnetically preloaded air bearings and linear optical encoders have virtually no resistance to motion. When actuated by Anorad's sinusoidally commutated zero-cogging linear motors in conjunction with high resolution feedback, the N320 can move with minimal velocity ripple. Combining this feature with the vibration damping characteristics of the air bearings makes this platform ideal for wafer scanning and many other sensitive precision positioning applications.

Options include: additional rotary, vertical, tip, and tilt axes; zero-jitter air brake; fixed overhead granite bridge; support frames; vibration isolation systems; servo controllers, and custom travels.

Specifications

Performance Specification Units Model N320E Model N320L
Travel 1 mm 320 x 320 320 x 320
Feedback System - Optical Linear
Encoder 		Plane-Mirror
Interferometer
Resolution 2 nm 0.5 - 500 0.31 - 10
Repeatability µm ± 0.3 ± 0.15
Positioning Accuracy 3 µm ± 0.5 ± 0.2
Flatness of Travel µm ± 1.0 ± 1.0
Straightness of Travel µm ± 1.0 ± 0.25
Orthogonality arc sec ± 2.0 ± 0.5
Pitch, Roll and Yaw arc sec ± 1.0 ± 1.0
Mazimum Load Capacity 4 kg 35 35
Maximum Velocity 5 mm/s 500 500
Maximum Acceleration 4 m/s 2 10 10
Scanning Velocity 5 mm/s 350 350
Average Velocity Ripple 6 % < 1.0 < 1.0
Position Stability 6 counts ± 1 ± 1
25 mm Step-&-Settle Time 6 ms < 400 < 400

Notes: Specifications are based on overall travel of each axis (significantly better positioning accuracy is possible over shorter travels) and operation in a controlled environment with Anorad approved vibration isolation system. Additional performance, travel, and configuration options are available. Contact Anorad for details.

  1. Additional 3 mm overtravel at each end before hard-stops.
  2. Resolutions available to 0.5 nm (encoder with 8192 x multiplier) or 0.31 nm (laser with l/2048 interpolation).
  3. After error mapping axes.
  4. Load based on lift bearing capacity. Applied load may determine maximum acceleration.
  5. Dependent upon system resolution and data rate.
  6. Typical dynamics for configured load, acceleration, velocity, resolution and data rate.

Outline Drawings

Carriage mounting holes are made to meet specific end user requirements. 430 x 430 mm opening in center frame. Dimensions (mm)