the contact mask is patterned on the top of the passivation layer 66 as shown in fig3 n the passivation oxide layer 66 is then etched through the patterned mask miii using an etchant which significantly attacks the passivation oxide layer 66 but not the patterned photoresist mask miii either the method of dry etch or wet etch can be employed if the dry etch method is used the etchant is plasma if the wet etch method is adopted the etchant can be hf thereafter the mask miii is removed the resultant structure up to this step is shown in fig3 using the patterned passivation layer 66 as a shielding mask boron is then implanted into the body layer 62 for the formation of the contact layer 68 which is of the p type conductivity the implant potential can be positioned between 30 to 80 kev and the implant dosage can be set at approximately 1 u00d7 10 15 cm 2 after a proper drive in cycle the contact layer 68 is formed as shown in fig3 p a metal layer 70 is thereafter deposited on the top of the planar surface 9 covering the passivation layer 66 by the sputtering method in the preferred method the material for the metal layer 70 is aluminum al which is deposited to a thickness of approximately 4 u03bc a fourth mask miv called the metal mask is then laid atop the metal layer 70 after proper patterning the resultant structure up to this step is shown in fig3 r the metal layer 70 is then selectively etched via the metal mask miv finally a.