Joel Galliher
Semiconductor Industry Manager,
Bosch Rexroth Corp.
These are the disciplines that have led to perfecting manufacturing processes that, in turn, have brought remarkable advances in microelectronic technology. In semiconductor manufacturing, the focus has mainly been on the process — essentially in the deposition and etching chambers. What happened outside was far less important.
With this sort of emphasis, the industry has long existed with low levels of automation outside its core processes: Wafers were manually transported between tools. But that has changed in recent years as wafers became larger and feature widths smaller. Chipmakers were forced to give issues like productivity, throughput, reliability, and automation a much larger share of mind.
Fast forward to today. The methods by which wafers move into and out of fabrication tools, and get positioned and repositioned within the tool, all have a significant influence on overall productivity. As tools process wafers faster and more accurately, the productivity bottleneck of material handling has become more apparent. Efficient wafer handling between tools becomes increasingly critical to improving productivity.
Consequently, the days of seeing people hauling wafer caddies from one station to another are over. Semiconductor fabs are boosting their levels of automation significantly and turning more attention to the flow of materials throughout the fab. This trend has also brought a need for more-sophisticated process integration, such as enabling in-line metrology to detect errors faster and earlier to increase yields.
As fabs have become more automated, there has been more interest in the quality, reliability, and performance of automation components. For example, it is unacceptable to simply increase the speed of motion in transferring wafers. The mechatronic handling systems must be optimized to meet cycle time requirements, yet still protect delicate, high-value wafers.
This is one reason toolmakers in the semiconductor industry are outsourcing more of their fab-automation engineering needs to outside experts. This is a mark of a maturing industry where vertical design is replaced by collaborative design. Beyond getting a great product, such outsourcing also helps moderate risk in the cyclical semiconductor market.
Of course, downtime anywhere in the flow is disastrously expensive. Toolmakers and fab designers evaluate not only basic performance, but also maintainability, durability, mean time to failure, cycle life, and similar metrics that will give some measure of reliability.
Also important is the ease with which various components are integrated. It’s not unthinkable to find multiple motion-control devices — servocontrols, pneumatics, and linear motion — within just a few feet of each other in the fabrication process. So those devices must work well together.
As they focus more on efficient material handling, fabs are learning that investments in superior tools can save in the long run through faster assembly, higher reliability, easier maintenance, and even higher end-user satisfaction. All in all, the mechatronic approach to fab automation has brought throughput, reliability, and cost improvement, and can help bring surprising levels of profitability as well.
Edited by Kenneth Korane