PlanarHDX Two Axis, Silicon Carbide, Planar Air-Bearing Stage

Description

Design Features

• Advanced silicon-carbide structure for high-dynamics and ultra-precise motion performance
• Speeds to 1.5 m/s and accelerations to 5 g
• Proprietary reaction-mass design enables fast turnaround and move-and-settle times
• Active and passive isolation system options
• Encoder or laser interferometer feedback
• Linear motors with improved thermal management
• Advanced control solutions offer enhanced throughput

Aerotech’s long history of supplying ultra-precise positioning systems in high-technology fields such as semiconductor manufacturing has enabled ongoing development and improvement of key motion technologies. By building upon these technologies, Aerotech has developed the Planar_HDX, the most advanced commercially available planar air-bearing platform on the market.

Ultra-Precise Design

Planar_HDX structural elements have been designed using an advanced silicon carbide ceramic that has a specific stiffness (elastic modulus/density) five times higher than aluminum and a coefficient of thermal expansion approximately five times lower. The resulting material along with an FEA-optimized structure enables high-throughput motion (1.5 m/s scan speeds and 5 g peak acceleration with a payload up to 20 kg) without sacrificing dynamic tracking, geometric performance, or thermal stability.

Using nearly 50 years of experience in air bearing and precision motion system design, Aerotech has developed a new air-bearing compensation strategy that increases stiffness and load capacity for demanding high-dynamic applications. Using proven air-on-air preloading in critical bearing elements improves turnaround and settling times over vacuum-preloaded designs.

A proprietary reaction-mass design dramatically reduces stage-induced forces in the step-axis that are transferred to the isolation system or customer’s structure (optics, sensors, etc.). By minimizing these dynamic forces, move-and-settle time is reduced and process throughput is increased.

Depending on the application requirements, the Planar_HDX is available with passive or active isolation systems. Additional axes such as Z-tip-tilt or Z-theta designs as well as custom wafer load/unload mechanisms and wafer chucks are available. Machine weldments, complex granite base structures or enclosures can also be provided.

High Accuracy Feedback

As a standard offering, the Planar_HDX is available with low-expansion glass scales on each axis. The scale and readhead locations are chosen to minimize Abbe and thermally-induced errors. For applications requiring the highest-levels of accuracy, Aerotech can provide laser interferometer feedback with mirrors located at the workpoint with integrated wafer chucks or workholding devices. In both encoder and interferometer feedback systems, the materials and mounting methods are optimized to provide high dynamic operation while minimizing thermally-induced accuracy errors.

Noncontact Direct-Drive Technology

At the heart of the Planar_HDX are Aerotech’s BLM and BLMH linear motors, which employ an ironless forcer design for ultra-smooth motion. Both the step and scan axes use multiple motors driving near the center-of-mass to provide exceptional vertical/lateral straightness and minimal angular errors. The motors are thermally-isolated, and for high duty-cycle applications can be water cooled to minimize thermal errors caused by motor heating.

Advanced Mechatronic Solution

Aerotech manufactures not only the mechanical elements, but also the electronics and control elements of the positioning system. In doing so, critical drive and software control features can be tightly coupled to the mechanics, providing not only a one-stop solution, but also enabling a complete mechatronic solution with unmatched performance. Many advanced control features such as directional gain scheduling, iterative learning control, and harmonic cancellation exist as a result of development for use in specific applications with Aerotech controls and mechanics.

Aerotech’s ETM (Enhanced Throughput Module) option helps improve the positioning performance of high-dynamic motion systems like the Planar_HDX by directly measuring the unwanted motion of the machine base and communicating it back to the controller. By working in concert with the Dynamic Controls Toolbox and Aerotech controllers, the ETM significantly improves move-and-settle time and contouring performance, increases throughput of existing and new machines, and greatly reduces the effects of frame motion on the servo system.