Creating Motion Control and Drive Electronics With an FPGA-based System
- Wednesday, 01 August 2007
Complex machines in semiconductor manufacturing often have tough performance requirements for motion control. When traditional PLCor PC-based motion controllers fail to meet these requirements, machine builders turn to custom board development — a time-consuming and expensive process. Recent advances in embedded technologies have made it possible to use FPGA-based COTS platforms to not only meet those requirements, but also to get to market faster by using graphical system design.
When it comes to semiconductor wafer processing requiring high-speed servo update rates for piezo actuators, machine builders turn to designing their own motion controllers on a custom PCB. Not only is the development expensive in terms of time and cost, but the fixed personality of the motion controller makes the system inflexible for future redesigns or for accommodating variations in the motion control algorithms at run-time.
National Instruments reconfigurable I/O technology, coupled with LabVIEW SoftMotion technology, was used to design a machine for manufacturing semiconductors that consists of four chambers with different temperature and pressure settings for wafer manufacture. A system must be implemented to monitor and control the temperature and pressure in each chamber according to defined set points or according to a profile. An embedded control unit could be controlling the temperature and logging the average temperature once a minute to local storage while sending the current temperature data up to the host system for data logging. An operator may need to log into the system to view previous values up to a previous day’s worth of data. A process engineer who needs to load a new temperature profile for the chambers could do this by logging in at a higher access level than the operator.
National Instruments CompactRIO is a small, rugged industrial control and acquisition system powered by reconfigurable I/O FPGA technology. It incorporates a real-time processor and reconfigurable FPGA for standalone embedded or distributed applications, and hot-swappable industrial I/O modules with built-in signal conditioning for direct connection to sensors and actuators. CompactRIO embedded systems are developed using LabVIEW graphical programming tools.
CompactRIO combines a low-power-consumption real-time embedded processor with a high-performance FPGA chipset. The FPGA core has builtin data transfer mechanisms to pass data to the embedded processor for real-time analysis, post-processing, data logging, or communication to a networked host computer. The LabVIEW graphical system design platform combines off-theshelf hardware and LabVIEW real-time execution with algorithm design tools for simple to advanced control applications. The NI SoftMotion Development Module for LabVIEW provides virtual instruments (VIs) and functions to help build custom motion controllers that run using LabVIEW in combination with hardware such as CompactRIO. The module provides all of the functions that typically reside on a motion controller.
Wafer Measurement & Testing
Automation Works, Inc. was looking to automatically sort semiconductor wafers into categories based on physical and electrical characteristics such as thickness, bow, warp, total thickness variation (TTV), and type (N-type or P-type) in addition to matching the precision and repeatability of industry-standard equipment with greater throughput, flexibility, and user friendliness at much lower cost. They were able to achieve this by taking maximum advantage of National Instruments LabVIEW software, toolkits, and advanced analysis capabilities with tightly synchronized motion, vision, and data acquisition (DAQ) hardware products to create a PC-based system that sets a new standard for semiconductor wafer sorting.
To accommodate tight process step tolerances, wafers must be pre-sorted into narrow categories based on electrical and mechanical parametric values such as thickness, bow, warp, TTV, and type after semiconductor wafers are sawn from an ingot and before processing. Gigamat Technologies of Milpitas, CA — a manufacturer of sorting, polishing, and edge grinding equipment — undertook the task of developing the Model 200TRT, a new generation of automated, high-accuracy, high-throughput, full-scan wafer sorting machines with the help of AutomationWorks.