Laser Etching of Ceramics for Defining Slider Air-Bearing Surfaces for Magnetic Recording Heads
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LASER ETCHING OF CERAMICS FOR DEFINING SLIDER AIR-BEARING SURFACES FOR MAGNETIC RECORDING HEADS JAMAL KHAN* Digital Equipment Corporation, * Present Address:
Shrewsbury,
3 Boston Drive,
Massachusetts 01545.
Shrewsbury,
MA 01545.
ABSTRACT A laser etching process was used to etch air-bearing surface patterns (cavities) on sliders for magnetic recording heads. Results on projection through mask as well as maskless etching of patterns on the TiC-A1 2 0 3 ceramic substrate and encapsulant alumina film on the surface are described. Pattern dimensions and location, along with laser operating parameters, are defined via a computer software program in the maskless etching process, and no external hard masks were used. A combination of maskless etching processes, using a Q-switched Nd:YAG laser for most of the ceramic substrate material in the back of the cavity and an excimer laser system for the alumina coating and nearby areas in the front, was found to give the best results.
INTRODUCTION Thin film heads are key components in high density magnetic data storage drives. Making of thin film heads comprises of wafer processing coupled with mechanical slider fabrication operations [1]. Thin film patterns are deposited on relatively thick ceramic substrates by conventional processes and structures are finally encapsulated with thick alumina films. The substrate is then mechanically cut-up in bars, which have rows of devices on them. Bars are further separated into individual units, substrate material acting as a slider for the thin film devices. Airbearing surface (ABS) patterns are defined (usually done at the bar level) by a combination of grinding and lapping operations on each slider to enable it to attain the desired flying characteristics on a rotating disk in the drive. The mechanical processes were found to be unsuitable for defining complex ABS patterns, such as negative pressure slider cavity [2], which may be more desirable for the future low flying high density heads. Ion milling through contact masks has been investigated as an alternative cavity etch process [2,3]. Laser induced chemical etching of TiC-A1 2 0 3 ceramic [4-6] and Mn-Zn ferrite [7] substrate materials has also been tried. These laser and ion milling processes have the disadvantage of requiring contact masks and/or chemical agents which are undesirable in a high throughput manufacturing operation. We have recently reported a simple direct laser etching process for pattern generation in alumina films and ceramic substrates [8). No mask or chemical etchants were needed. This process was extended to investigate applications in thin film head slider fabrication. Laser etching through projection masks was also tried. Results on etching of patterns in the slider airbearing surface using these processes are discussed in this paper. Mat. Res. Soc. Symp. Proc. Vol. 236. c)1992 Materials Research Society
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MASKLESS EXCIMER LASER ETCHING PROCESS Samples were prepared by depositing thin film patterns on TiC-A1 2 0 3 ceramic substrates by the conventio
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