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Abstract

A process for providing a thin encapsulation layer for thin film heads includes controlling the bias voltage of the substrate and head during the encapsulation layer deposition process. The bias voltage is first maintained at approximately 60 volts while the standard encapsulation overcoat portion of the layer is deposited. This may take approximately one hour. Over the next thirty minutes, the bias voltage is ramped from approximately 60 volts to approximately 200 volts in a gradual, linear manner to reduce the stress on the wafer and heads. The bias voltage is then maintained at approximately 200 volts for the next three hours while the remainder of the encapsulation layer is deposited. Because of the higher bias voltage, the layer is deposited in a substantially planar manner so that there is no need for a lapping back process. Stress to the head is minimized by ramping the bias voltage. In addition, relatively short studs can be used for routing signals to and from the read/write elements of the head. The encapsulation layer is etched back in the vicinity of the studs with an NaOH/EDTA solution which produces via sidewalls with shallow angles, in the range of 20 degrees from horizontal.

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First Claim