PZT
Fabrication of piezoelectric thick-film bimorph micro-actuators from bulk ceramics using batch-scale methods
R.P.Jourdain and S.A.Wilson
Materials Department, School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL, United Kingdom
Abstract
Piezoelectric ceramic films in the 20-60 micron thickness range are rarely employed today in commercial micro-mechanical devices, even though their expected force capability suggests that they are well suited to many micro-fluidic and micro-pneumatic applications. Some examples would be micro-scale fuel cells and micro-combustors. Head sliders, radio-frequency (RF) micro-switches and powered micro-optics are further potential application areas. These are only a few and the barriers in bringing them into reality are those of processing compatibility rather than commercial desirability. Such issues are being addressed in the EU Framework 6 Project ‘Q2M’, which focuses on batch-scale fabrication issues for high quality new micromechanical devices that are cost-effective and which have extended capabilities.
This paper discusses a potential batch-scale production route for piezoelectric thick-film bimorph microactuators that combines ultra-precision grinding of ceramics and femto-second laser machining, along with standard micro-fabrication techniques such as wafer bonding. This new method has the key advantage that many different shapes and thicknesses of actuator can be made with only minor process changes, meaning that actuators can be designed to suit their intended application. It contrasts with current practice whereby micro-actuators are often designed around a limited range of standard components, with consequent reduction in their achievable performance. The examples used are a 6mm diameter plane-spiral bimorph actuator for integration into a polymeric micro-valve and 2-5mm long bimorph cantilevers intended for use in
a new type of silicon ‘house’ micro-valve, with pneumatic applications.
categories
actuators | Bimorph | ceramic based | femto-second | Mechanical machining | MEMS | micro-actuator | PZT | ultra-precision grinding | wafer bonding
| 189 reads | Material aspects for batch integration of PZT thin films using transfer bonding technologies – Q2M development
D. Bhattacharyya (a), R. V. Wright (a), Q. Zhang (a), P.B. Kirby (a), R. Guerre (b), U. Drechsler (b), M. Despont (b),
F. Saharil (c), J.Oberhammer (c)
(a) Materials Department, Cranfield University, Bedford MK43 0AL, UK
(b) IBM Research Gmbh, Zurich Research Laboratory, Rueschlikon, Switzerland
(c) Microsystem Technology Lab, KTH – Royal Institute of Technology, Stockholm, Sweden
Abstract
Transfer bonding is a reliable cost-efficient and low-temperature CMOS compatible technique which allows batch integration of materials whose incompatibility with Si makes them unsuitable for monolithic integration. In this heterogeneous device integration method the material and process incompatibilities inherent in Si IC technology are overcome by fabricating devices on separate substrates and then transferring them onto target (e.g. CMOS) wafers. Transfer bonding has great potential for integrating RF-MEMS devices incorporating, for example, high thermal budget materials such as PZT and PST or non-ferroelectric piezoelectrics such as AlN and ZnO into microwave ICs for enhanced systems performance. This paper presents an overview of technology developments within the EU sponsored project Q2M for the realization of transfer bonded piezoelectrically actuated RF MEMS switches and other components focusing in particular on material factors relating to growth of the piezoelectric films, in this case sol-gel deposited PZT, that restricts the choice of device layers and impact on PZT properties such as microstructure, film orientation and piezoelectric coefficients. New process developments such as hard masking of PZT pattern during RIE etching and its compatibility with polymer transfer bonding are discussed.
categories
Adhesive bonding | Assembly & packaging | PZT | RF MEMS switches | sol-gel | switches | transfer bonding
Copyright© 4M Network of Excellence.