Performance analysis of an integrated piezoelectric ZnO sensor for detection of head–disk contact

Integrated capability for detection of head–disk contact is desired for magnetic sliders with near-contact flying height. At the same time, fabrication of added features should be compatible with the existing slider micromachining process which is highly specialized and cost sensitive. Aimed at meeting the two requirements, a novel sensor configuration is explored in the present study. The new sensor configuration consists of a piezoelectric zinc oxide (ZnO) thin-film sensor sandwiched in the magnetic slider on its trailing side. Coupled structural and piezoelectric finite-element analysis for a sensor–slider–suspension assembly was performed to investigate the dynamic sensing performance. Output voltages on the millivolt level were obtained under typical head–disk interactions. The second in-plane bending mode of the slider was found to be the major contributor to the output voltage. Parametric study further showed that a thicker ZnO layer generally generated a larger output, while the thickness of the slider overcoat had only minimal effect. Simulation results from harmonic and transient analyses demonstrated that the piezoelectric thin-film ZnO sensor was sufficiently sensitive for detection of head–disk contact.

[1]  H. Morkoç,et al.  Zinc Oxide: Fundamentals, Materials and Device Technology , 2009 .

[2]  S. Pearton,et al.  Zinc oxide bulk, thin films and nanostructures : processing, properties and applications , 2006 .

[3]  T. Olson,et al.  Magnetic Spacing Trends: From LMR to PMR and Beyond , 2009, IEEE Transactions on Magnetics.

[4]  D. Bogy,et al.  Optimal Slider-Disk Surface Topography for Head-Disk Interface Stability in Hard Disk Drives , 2008, IEEE Transactions on Magnetics.

[5]  Frank E. Talke,et al.  Contact force measurement using acoustic emission analysis and system identification methods , 2000 .

[6]  Jan H. J. Fluitman,et al.  A thin-film piezoelectric impact sensor array fabricated on a Si slider for measuring head-disk interaction , 1995 .

[7]  Zine Eddine Boutaghou,et al.  Ultra sensitive in-situ acoustic characterization system for HDD head disc interface defectoscopy , 2007 .

[8]  C. E. Yeack-Scranton.  Novel piezoelectric transducers to monitor head-disk interactions , 1986 .

[9]  T. Hughes,et al.  Finite element method for piezoelectric vibration , 1970 .

[10]  Y. Mitsuya,et al.  New method of detecting contact between floating-head and disk , 1980 .

[11]  Jan H. J. Fluitman,et al.  Fundamental study on a thin-film AE sensor for measurement of behavior of a multi-pad contact slider , 1996 .

[12]  Frank E. Talke,et al.  Investigation of Slider Vibrations Due to Contact With a Smooth Disk Surface , 2001 .

[13]  K. Viswanathan,et al.  Acoustic Emission of Laser Textured Disks Influenced by Bump Excitation , 1998, 7th Joint MMM-Intermag Conference. Abstracts (Cat. No.98CH36275).

[14]  Shigeo Nakamura,et al.  Active head slider with piezoelectric actuator using shear mode deformation , 2008 .

[15]  Hejun Du,et al.  Simulation of thermal flying height control slider with built-in contact sensor , 2012 .