AVS 47th International Symposium
    MEMS Thursday Sessions
       Session MM-ThA

Paper MM-ThA4
MOCVD PZT as a Pathway to Integrated Piezoelectric MEMS

Thursday, October 5, 2000, 3:00 pm, Room 309

Session: Material Science of MEMS
Presenter: I.-S. Chen, ATMI
Authors: I.-S. Chen, ATMI
J.F. Roeder, ATMI
D.-J. Kim, North Carolina State University
J.-P. Maria, North Carolina State University
A.I. Kingon, North Carolina State University
Correspondent: Click to Email
Development of reliable actuation methods is one of many challenges in thin film MEMS devices. Piezoelectric actuation using bulk ceramic materials is well known, but widespread use in MEMS requires suitable deposition and integration methods that are compatible with large-scale manufacturing. One primary factor limiting the development of piezoelectric MEMS has been the lack of a suitable thin film piezoelectric material. PZT and its derivatives have excellent piezoelectric properties and therefore are a logical choice for MEMS applications. Metalorganic Chemical Vapor Deposition (MOCVD) offers a unique combination of precise composition control, uniformity over large areas, and relatively low process temperatures that are compatible with integrated Si processing. We have developed MOCVD processes to prepare PZT films on advanced electrodes with longitudinal piezoelectric coefficients (d@sub 33@) up to 50pm/V. Robust electrode stacks were developed to suppress diffusion of reactive / mobile species into the silicon substrate during PZT deposition. The electrode stacks are fully compatible with substrates typically used in bulk micromachining, namely silicon wafers coated with either silicon nitride or boron-doped epitaxial silicon as an etch stop. For temperature-critical surface-micromachined structures, process temperatures as low as 450 °C have been successfully demonstrated.