Toshiyuki Numazawa

Effects of Aspect Ratio of Lead Zirconate Titanate on 1-3 Piezoelectric Composite Properties

An array of lead zirconate titanate (PZT) rods whose cross section is 25 µ m square was fabricated using synchrotron radiation (SR) lithography, and the effects of the aspect ratio (height/width) of the PZT rod on 1-3 piezoelectric composite properties were studied. The aspect ratio was between 3 and 9. Mechanical quality factor and acoustic impedance were found to depend weakly on the aspect ratio. However, electromechanical coupling coefficients were found to increase as the aspect ratio increased. Based on the result of deformation simulation by the finite element method (FEM), this dependence was found to be caused by the increase in piezoelectric coefficients as the aspect ratio increased.

Development of LIGA process using a superconducting compact synchrotron light source

This paper describes the LIGA process using a 600-MeV superconducting compact synchrotron light source. Deep-etch X-ray lithography is conducted using a new resist and mask. The resist is composed of a copolymer of methyl methacrylate (MMA) and methacrylic acid (MAA). Its main benefit is its high sensitivity, which is one order of magnitude greater than that of polymethyl methacrylate (PMMA) conventionally used in the LIGA process. The mask is composed of a 2-μm-thick silicon nitride membrane with high transparency, supporting a 5-μm-thick tungsten absorber. Experimental results for deep-etch X-ray lithography, electroplating, and molding techniques are presented. A micro-ultrasonic transmitter obtained using these techniques is also described. The purpose of this study is the realization of low-cost microcomponents for a variety of industrial applications.

The copolymer of methyl methacrylate and methacrylic acid as a sensitive resist for deep-etch X-ray lithography

The copolymer of methyl methacrylate and methacrylic acid was developed as a new sensitive resist for the LIGA (Lithographie, Galvanoformung, Abformtechnik) process. The resist exposures were carried out at the LIGA beamline of a superconducting compact light source NIJI-III. The absorbed energy density required to remove the entire exposed resist and produce a defect-free microstructure was between 0.4 and 7 kJ/cm3 (4 and 20 kJ/cm3 for PMMA). The sensitivity and patterning depth of the copolymer were 10 times and 3.5 times, respectively, those of poly methyl methacrylate (PMMA) assuming that both resists were exposed to synchrotron radiation (SR) of the same wavelength. Moreover, the copolymer showed high contrast and process stability.