Overview

Customer Specifications 

Our customer, a leading manufacturer of excimer lasers used in semiconductor manufacturing, was looking for a high-speed fan blower motor that is able to operate in excimer gases - a corrosive gas composed of Fluorine mixed with Argon or Krypton. Multiple configurations of the product based upon customer’s specifications were developed over the years.

Solution

An electric discharge gas laser with a laser cavity, containing laser gas and a fan for circulating the gas was developed. The blower fan was driven by a Magnaforce™ permanent magnet motor with the entire rotating assembly supported by Calnetix’s Powerflux™ active magnetic bearing system. The variable speed motor was comprised of a stator and a rotor that provided rotation to the fan. The permanent magnet rotor of the motor operated inside the gas environment of the laser cavity. The motor’s stator and magnetic bearing actuators were located outside the gas environment. Active magnetic bearings were used to substantially increase bearing reliability as well as laser system performance when compared to conventional bearings by eliminating mechanical contact and bearing lubrication.

Challenges

It was critical to isolate the stator winding of the motor as well as the actuator coils of the magnetic bearings from the corrosive gas environment, and incorporating a bore seal in the design was the most robust solution. The second challenge for Calnetix engineers was to optimize the blower fan’s motor design and the magnetic bearing design to accommodate the bore seal while taking into account the bore seal’s material, which was selected by the customer for compatibility with the laser gas.

Results 

The high-speed permanent magnet motors helped increase the speed of the fan, thereby providing better mixing of chamber gas. Calnetix delivered a unique design for their fans, and the customer has been successfully shipping thousands of machines since early 2000.