This client is a global industrial manufacturing company that designs and builds equipment for silicon wafer fabrication. Silicon wafers are thin semiconductor substrates, and the client’s tools support a wide range of wafer processing capabilities used to create transistors, interconnects, advanced memory, and packaging structures.

Second Order Effects was engaged to develop a “calibration wafer” capable of traveling through the fabrication machine, measuring its distance from critical components, and reporting those measurements in real time. This enabled precise calibration of the production line and helped ensure high manufacturing yield.

The calibration wafer was required to:

• Match the exact size and weight of production silicon wafers

• Withstand extreme manufacturing environments, including temperatures up to 150 °C and vacuum levels as low as 1 mTorr

• Measure distances from 100 µm to 10 mm with 5 µm resolution

To meet these requirements, SOE selected a capacitive sensor driver that satisfied performance needs and closely met accuracy requirements across temperature. To mitigate remaining thermal risk, SOE designed a prototype test setup capable of generating a precisely known, variable gap. This allowed the team to characterize measurement accuracy across temperature exposure and develop a repeatable compensation methodology for sensor drift over the full 0–150 °C operating range.

Results

SOE designed, built, and validated the calibration wafer, fully characterizing its temperature-dependent drift before delivering the system to the client. While the wafer itself was not ultimately productized, the capacitive sensing techniques developed during this effort are being carried forward into the client’s next-generation robot proximity sensors.