Control Systems Improve Semiconductor Manufacturing

Even the most basic CMOS process has dozens of manufacturing steps requiring precise systems and subsystems. Motion control is fundamental to almost every step. In addition, heat and chemicals play a critical role in process consistency. Six new products demonstrate suppliers' efforts to improve semiconductor processing.

SINGLE-AXIS DIGITAL DRIVE

The ION Digital Drive from Performance Motion Devices Inc. (PMD) simplifies the control of dc brush, brushless dc and microstepping motors in semiconductor and other general automation applications. Each single-axis module combines network connectivity, positioning motion control and power amplification to eliminate wiring complexity and the cost of a motion control card connecting to a separate amplifier. In addition to including profile generation, servo compensation, stall detection and field-oriented control, the unit provides an output capability of up to 15A peak and 500W at 56V. With the connectivity from either an asynchronous serial network (RS485) or a CANbus network version, up to 127 ION modules can connect on a single distributed control network. A Windows-based exerciser program, called Pro-Motion, provides the graphical user interface to C-Motion, a C source code library and VB-Motion software libraries that simplify the development of user-specific applications.

AIR-BEARING ROTARY STAGE

Aerotech's ABRS (for Air-Bearing Rotary Stage) Series targets the critical requirements of wafer inspection, high precision metrology, X-ray diffraction systems, optical inspection and fabrication and MEMS/nanotechnology device fabrication. The low profile, 80-, 90-, 100- or 110-mm height, units use a direct-drive slotless, brushless servomotor that produces a continuous torque of 0.28 to 7.4 Nm, depending on the series. Calibrated accuracy of the units is ±2 arc sec and repeatability is ±1 arc sec. Large air-bearing surfaces provide high stiffness and load capacity to achieve synchronous axial error of less than 100 nm, synchronous radial error of less than 250 nm and asynchronous axial and radial error less than 20 nm. With its standard direct-coupled optical encoder, the ABRS mated to Aerotech's feedback multipliers and controls achieves resolutions of less than 0.036 arc sec. Units operate at 80 psig (5.5 bar) +0 psig (0.0 bar) / -10 psig (0.7 bar).

INTEGRATED ROTARY ACTUATOR

WITTENSTEIN motion control's TPM+ rotary actuator is a clean-room tested solution for wafer handling and CMP processes, providing a clean, efficient control for less complicated machine designs. The unit integrates a high-precision gearhead, a high-pole motor and feedback into a single package. The actuator design eliminates the additional rotating parts, such as bearings, couplings and larger shafts, required for a traditional solution that reduces the actuator's inertia. Moving the magnets closer to the load improves the stiffness and provides higher dynamics. The TPM+ sizes range from 004 to 110 with ratios of 16 to 91, maximum output torque of 40 to 1600 Nm and maximum output speed of 431 to 325 rpm. By merging the planetary gearhead and ac servo motor into a single unit, the sun wheel and the rotor shaft are connected without a coupling and the size and mass have been reduced by 50 percent compared to a standard motor and gearbox combination.

INTEGRATED CONTROL LOOP

Watlow's EZ-ZONE ST integrates temperature control, power control, safety shutdown and a power disconnect in a single package. Besides semiconductor processing, these units target temperature-controlling applications in plastics processing, packaging, environmental chambers, analytical instrumentation and general equipment use. In addition to a proportional-integral-derivative (PID) temperature controller connected to a high amperage solid state relay (SSR), users have the option of adding a properly sized heat sink, current measurement, an over/under temperature limit, a definite-purpose mechanical contactor and digital communications into the package. Other user options include the addition of one or more remote user interface (RUI) displays, where the RUI is a 1/16 DIN that can be mounted at the front of the equipment for easy access. An EZ key in the RUI allows user customization capabilities to perform repeatable functions. The modular and scalable design can be stacked into multiple configurations providing the user flexibility and cost-effective implementation, as well as a platform to solve a wide range of application needs.

INTEGRATED SERVO MOTOR SYSTEM

WITTENSTEIN motion control's Ternary BLM (brushless motor) actuator combines a servo drive and precision mechanics with a ball screw spindle and a stainless steel connecting rod in a single package. With semiconductor chip production and positioning and format changes in industrial engineering in mind, the maximum force of the linear actuator and the torque of the rotary actuator have been tripled and the maximum linear velocity and speed are as much as 11 percent higher, depending on the model. The units offer higher drive performance and lower noise level and the achievable clock pulse rates can be more than doubled in practical duty based on the integrated servo's dynamics. In addition to the serial and parallel interfaces, Profibus, CANopen or DeviceNet can be supplied. With the unit's standard serial interface, compatible with all fieldbus variants, the data-setting software is easier to use and does not require additional PC interface cards.

CMP PAD CONDITIONING ARM

Entrepix' SteadySweep pad conditioning arm retrofits to virtually any rotational polishing platform in a Chemical Mechanical Planarization (CMP) system. With a down force of 0.5 to 20.0 lb achieved through pneumatic applied pressure, the conditioner requires less force and usage to achieve a stable removal rate and wafer uniformity. Testing of a standard unit operating at 8 lb conditioning down force compared to a SteadySweep operating at 2 lb conditioning down force resulted in near-zero removal rate decay and improved uniformity through a four-hour run. Lower pad cut rates and properly applied forces mean increased polish pad lifetime. The unit's stable triple diaphragm regulator results in no delay or lag in applied force control over rotational speeds from 0 to 200 rpm. Features such as program timed delays during a polish process and pad profiling provide optimized process uniformity and polish pad lifetime.