DESIGN AND TECHNOLOGY OF SENSOR-LAST THIN-FILM MAGNETIC HEADS

The first thin film heads produced commercially by Philips were of the so-called sensor-first type, the sensor being processed on the substr ate 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 high er power consumption (low head efficiency) and limitations of use of h igh-temperature processes/materials. However, initially, topographic s tructures, step coverage and problems with wet chemical etching were o bstacles in realizing the sensor-last design. The introduction of plan arization in wafer processing technology opened the way to the sensor- last design. The design was introduced in heads for the DIGAMAX(TM) sy stem and showed all the expected advantages in comparison with the sen sor-first design. It also offers the possibility of applying new mater ials in the head, an option which is necessary for realizing new gener ations of recording systems.