PZT (lead zirconate titanate) remains the benchmark material for high-performance PiezoMEMS. Its strong piezoelectric response – characterised by a high transverse piezoelectric coefficient (e31f) and reliable dielectric breakdown strength – makes it the material of choice for demanding actuation and sensing applications. Silex is the first pure-play MEMS foundry to have brought PZT into volume production. Built over more than 15 years through a sustained collaboration with ULVAC, the Silex PZT platform operates on a 200 mm wafer format with multi-chamber sputtering capacity, dedicated in-line characterisation, and a holistic process control framework covering deposition, etch, measurement, and reliability testing. As the first pure-play MEMS foundry to offer PZT production, Silex Microsystems has spent over 15 years building the process infrastructure, characterisation capability, and integration knowledge that industrialising PiezoMEMS demands. Silex develops and tailors piezo films to match customer requirements, recognising that different applications demand different film characteristics – from uniformity and stress control to specific piezoelectric coefficients and lifetime targets. Recent process improvements at Silex have delivered measurable gains: the optimised PZT film achieves 10-15 percent higher e31f at high electric fields compared to the previous baseline. At the same time, improved processing has produced sharper polarisation reversal as well as enhanced wafer-level uniformity and more stable, symmetric behaviour under bias. These improvements are not incidental. They reflect an approach in which PZT film development is treated as an ongoing engineering discipline, not a fixed specification. For PiezoMEMS devices to be manufacturable at volume, the thin film must behave consistently not just from device to device, but across the entire wafer surface. At Silex, sputtered PZT achieves thickness uniformity of approximately 0.5% within a 200 mm wafer – a level of consistency that is essential for devices where small variations in film properties translate directly into performance differences. This uniformity is maintained through a structured process control framework that spans the full manufacturing flow. Statistical Process Control (SPC) monitors key parameters at each stage, while tool and target qualification procedures ensure that deposition conditions remain within defined windows. Time Dependent Dielectric Breakdown (TDDB) testing provides additional data on long-term electrical stability, enabling early detection of degradation mechanisms before they affect production yield. Multi-chamber sputtering capacity at Silex also supports the production throughput needed for volume applications, with the process control infrastructure scaling alongside capacity.
