Design and technology of sensor-last thin film magnetic heads

Abstract

The first thin film heads produced commercially by Philips were of the socalled sensor-first type, the sensor being processed on the substrate and the remaining parts of the head being processed on top of the sensor. This design has various drawbacks in comparison with a design where the sensor is processed at the end (sensor-last), such as a higher power consumption (low head efficiency) and limitations of use of high-temperature processes/materials. However, initially, topographic structures, step coverage and problems with wet chemical etching were obstacles in realizing the sensor-last design. The introduction of planarization in wafer processing technology opened the way to the sensor-last design. The design was introduced in heads for the DIGAMAX^TM system and showed all the expected advantages in comparison with the sensor-first design. It also offers the possibility of applying new materials in the head, an option which is necessary for realizing new generations of recording systems.