Office of Technology Transfer – University of Michigan

Linear Stage System with Low Energy Consumption and Motor Force

Technology #6253

Linear Stage System with Low Energy Consumption and Motor Force

High precision linear stages are a critical component of manufacturing and printing processes. These stages are particularly vital during optical lithography, which has been and continues to be the preeminent lithographic technique used in the fabrication of integrated circuit devices in the semiconductor industry4. In the U.S. semiconductor machinery manufacturing is sparking growth and new technology and emerging markets will benefit the industry. Semiconductor machinery manufacturing in the U.S. generates an 11.5 billion dollar revenue and 379.0 million dollar profit. Global semiconductor and electronic part demand and manufacturing are also rising. Outsourcing of semiconductor manufacturing work to Asian foundries is occurring at a rapid pace, resulting in a steep growth for the Asian semiconductor manufacturing market. Worldwide sales of semiconductors reached $26.34 billion for the month of April 2014.

Current linear stages utilize friction free bearings and high force servomotors configured in series to obtain the desired scanning speed, acceleration, and frequency. However, the high force required for scanning function can generate a large amount of heat and adversely affect machine performance and reliability. Moreover, the operational costs and equipment size can increase with the necessity of using these larger mechanical and electrical components. Therefore there is great interest within the industry to develop scanning stages that meet the existing performance demands, but minimize energy consumption, force generation, and operation cost.

Active Assist Stage for Scanning Applications

The proposed technology utilizes an additional set of permanent magnetic assistive devices that can actively adjust their assist force level to reduce the linear motor actuation effort and therefore minimize energy consumption. The scanning stage is designed such that kinetic energy is recycled when the stage reverses directions and accelerates towards a constant scanning speed. The stage utilizes active actuators that synergistically drive the stage at the required level of performance. Two pairs of permanent magnet arrays, moving masses which house a permanent magnet, are added to the ends of the stage and kinetic energy can be stored in this “magnetic spring”. The stiffness of the magnetic spring can be adjusted using simple and inexpensive actuators to further improve the system level efficiency. The moving masses are less sensitive to vibration and can move at a lower velocity and can therefore be driven by a rotary motor with a ball screw assembly for force multiplication. The use of a rotary motor can reduce energy consumption and device size. Turning knobs for operators can also be added to the system and used to meet different machine requirements. Compared to the prior art, the designed stage consumes 66.4% less energy during scanning motion, the linear motor peak force is reduced by 87.8%, and the peak stage acceleration is increased by 87.3%. The proposed technology minimizes stage energy consumption and force generation, which could reduce operation costs and improve reliability for any stage application in which fast switchback is required.

Applications

• Silicon wafer scanning • Laser cutting/scribing • Laser micromachining • Printing • Measurement and instrumentation • Automation • Image scanning

Advantages

• Less energy consumption • Reduced linear motor peak force • Increased peak stage acceleration • Reduced motor size • Reduced stage vibration