Passivation method of a high-speed power diode by means of an amorphous carbon passivation layer

摘要

The passivation layer (5) of the potential ring structure (3) consists of a structured undoped oxygen-free stable hydrogenated carbon layer tempered at temperatures above 350-440o C. Power diode comprises a semiconductor body with layered zones consisting of a high ohmic middle zone (1) of first conductivity type and a second outer zone (2) of second conductivity type including a pn-junction. The two zones have a support shelf-life adjusted by irradiating with high energetic particles in two phases, and a metallic contact solderable on the cathode side. An Independent claim is also included for a process for passivating the power diode comprising: (a) producing a hydrogenated carbon layer on an oxide-free semiconductor surface by plasma deposition, where the self-bias voltage is adjusted between 700 and 1000 V and the temperature of the wafer is 140-180o C; (b) applying a photolacquer of 2-8 microns thickness to the hydrogenated carbon layer and structuring; (c) etching the hydrogenated carbon layer in an oxygen-containing plasma at a self-bias voltage of 120-500 V; (d) metallizing the thickness between 4-8 microns and structuring; and (e) tempering the wafer at 360-440o C to achieve good adhesion to the metallization.