Will MEMS drive future growth of thin film PZT?

Claire Troadec, Market & Technology Analyst, Semiconductor Manufacturing, at Yole Développement, comments: “Thin film piezoelectric materials are gaining increasingly more importance within the MEMS industry. Although semiconductor manufacturing companies are historically reluctant to introduce such exotic materials into their production lines, every major MEMS foundry nowadays is working on the implementation and qualification of piezoelectric thin film in their MEMS manufacturing processes.”

EPSON introduced the first MEMS inkjet heads manufactured with thin film PZT technology in September 2013. This highly publicised announcement tells us that thin film PZT MEMS applications are now on the market, proving the reliability and maturity of this technology.

A very interesting ferroelectric material, PZT (Pb[Zr_xTi_1-x]O3 with 0≤x≤1) is also known as lead zirconium titanate. It combines the advantages of three different material properties: high dielectric constant, pyroelectric effect and piezoelectric effect. However, this is composition dependant.

The 2 leading applications for thin film PZT have for many years been the integration of thin film PZT in Integrated Passives Devices and to a lesser extent in Ferroelectric memories. Taking advantage of its high dielectric constant property, this IPD market is dominated by STMicroelectronics and NXP Semiconductors. Despite remaining quite marginal in this field, Pyreos is utilising the pyroelectric effect of PZT to produce thin film PZT based uncooled Infrared detector. Companies such as Wavelens and PoLight are developing autofocus based products using thin film PZT technology.

One of the key challenges facing thin film PZT technology is the integration of this exotic material into a robust and reproducible process flow. There are also complex technological difficulties which arise when integrating thin film PZT into a product, including deposition, etching, process monitoring, testing and reliability. Despite extensive R&D efforts made by labs, equipment and material suppliers, and device manufacturers, these complex challenges require more work to achieve robust products for high volume production.

There are two competing technologies in deposition: Sol-Gel and Sputtering. Featuring good uniformity and higher breakdown voltages, Sol-Gel gives better intrinsic film properties as deposited thin film PZT but it shows some limitations in throughput for high volume production. Therefore, many equipment manufacturers within the semiconductor industry are working on a more classical solution: Sputtering.

Possessing the more reliable PVD technology today, ULVAC was among the first companies to develop thin film PZT deposition based on a PVD process. Preparing to compete in this market for 18 months, big semiconductor players like Applied Materials are rapidly ramping up their activities on thin film PZT. Other players like Oerlikon and SolMateS are continuing to improve their deposition technology, be it PVD or Pulsed Laser Deposition. With their recent PLD technology and smaller company size, SolMateS is an interesting case. They end up competing with large PVD equipment manufacturers in this thin film PZT manufacturing area.

In the "Thin Film PZT for Semiconductor Application Trends & Technology Update" report, Yole Développement evaluates and compares each thin film PZT deposition technology and present a roadmap for each key player with their expected year for market entry. The analysts’ team describes all key thin film PZT based applications, while Yole present their thin film PZT production forecasts for the 2013-2018 period.

The thin film PZT manufacturing battle has only just started: the next 5 years will be very interesting!