Piezoelectric materials have resonant frequencies in the megahertz range and when integrated within MEMS have high the potential to produce high accuracy RF resonant structures, large amplitude actuators as well as accurate low-power sensors of various types. The typical piezoelectric material used to date is the ferroelectric lead zirconate titanate PZT.
ST did not announce what material or materials its piezoelectric MEMS process is based although PZT was one of the topics of the European LAB4MEMS program that was used to help develop the process. The process is customizable and ST plans to work with customers to co-develop specific process variants optimized for customer applications.
One of the first customers for ST’s TFP process is PoLight AS (Horten, Norway) a vendor of optical MEMS actuated autofocus lenses for cameras. The TLens (Tuneable Lens) uses a piezoelectric actuator to change the shape of a transparent polymer film, imitating the focussing function of the human eye. The company claims that its autofocus has a response time that is 10 times faster than voice-coil motor (VCM) operated autofocus systems while consuming 1/20 of the power.
The technology potential applications for actuators such as inkjet printheads in 2D and 3D printing and can be used for piezoelectric based sensors and in fields such as energy harvesting. ST is targeting volume production from a 200mm wafer fab in Agrate for its initial customers in mid-2015.
"Piezoelectric actuators and sensors can now be manufactured in our Agrate 8-inch fab that has produced billions of motion sensors, taking full advantage of ST’s long-standing position as the world’s leading manufacturer of MEMS devices," said Anton Hofmeister, general manager of ST’s custom MEMS division, in a statement. "Our TFP MEMS technology rewrites the script, opening up new cost/benefit scenarios that will, in turn, enable many new applications."
"PoLight will use STMicroelectronics TFP MEMS technology to manufacture its TLens autofocus lens, a product that brings new camera autofocus performance to smartphones," said Christian Dupont, poLight chief marketing officer, in the same statement. "This breakthrough combines poLight’s innovative technology and ST’s ability to optimize their TFP process to provide the required strong piezo actuator through a high-volume manufacturing process that is key for our smartphone customers,"
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