Advanced Motion Controls Boost Wafer Handling Efficiency

One of the greatest challenges in developing this wafer handling systems was testing and implementing a motion control system that could meet demanding requirements for expandability, resolution, stiffness, and reliability at a competitive price. The company opted for the Danaher Motion XMP series motion controllers. “We discovered that we could add up to 32 axes of motion simply by plugging them in. The XMP motion controller bolsters quality and helps us remain competitive. It meets our demanding repeatability and speed requirements with ease,” says Chris Kiley, BlueShift vice-president of engineering.

Wafer handling
Conventional cluster tools are arranged in a radial pattern with processing stations and load locks for inserting and removing wafers located around their circumference. As wafers have grown larger and semiconductor processing operations become more complex, the size of these cluster tools has continued to grow.

QuickLink versus cluster tools.

Today, the transfer chamber at the heart of the cluster tool can easily be 10 ft long by six ft wide, even before adding process chambers where the wafers are turned into valuable integrated circuits. Designed to maintain high levels of vacuum, transfer chambers are machined from large, expensive pieces of aluminum.

The QuickLink linkable vacuum wafer handler delivers significant technical benefits over current cluster tool offerings. It offers better particle performance, reduced organic and metal contamination, better process isolation, and automatic software configuration.

BlueShift’s linear geometry allows wafers to pass along a line of process modules. The linear transfer chambers are much smaller than radial chambers which reduce raw materials and machining costs, and makes the new approach between 30% and 40% less expensive. The linkable design permits processing modules to be added as needed in a compact configuration, resulting in footprint reductions up to 40% compared to radial footprints and allowing the fabricator to optimize throughput by balancing the flow while eliminating bottleneck processing chambers. The use of building blocks makes it easy to configure wafer handling systems for high capacity and long process time, high throughput and short process time or increased vacuum isolation and contamination control.

Kiley adds, “When we were designing QuickLink, it was apparent that off-the-shelf components had improved to the point where they could handle this application. With current manufacturing practices, their reliability is higher and cost is lower than custom components. We started with motion control cards and amplifiers based on the Firewire A standard. Firewire A is fast but susceptible to noise and it could not run more than one robot axis at a time. Each of our robots has three axes; alpha and beta rotational axes, and A/Z axis for vertical motion. Our
design specifies that one card will control an entire wafer handling system which might easily utilize six robots.”

BlueShift called in Target Electronic Supply, Inc., a system integrator involved in motion control applications. BlueShift needed to add axes as needed to support the QuickLink modular architecture. The Danaher XMP series motion controllers provide up to 32 axes and support servo update rates up to 16 kHz, which helps provide high levels of speed and accuracy. The XMP delivers a synchronous real-time connection between the motion controller, servo drives, I/O modules, and custom nodes.

BlueShift offers a world-class 3D remote diagnostic monitoring interface.

“Target got us up and running with the XMP motion controller quickly,” says Kiley. “The controller worked well out of the box and can scale well beyond our requirements in this application. Our systems can be expanded simply by snapping the robot transfer links together and connecting the cables to link the new robot to the controller. We have had no problems with the capabilities and robustness of the Danaher Motion control components. They can easily meet our requirements to position the wafers within about 100 microns.”

BlueShift is also using Kollmorgen S200 servo amplifiers from Danaher Motion. The company’s robot drives have only 10 components and are designed for 24 million mean cycles between failures. The modular design makes it possible to service the system in place rather then replacing entire robots in the case of a failure.