TRANSISTOR, VHF SILICON POWER (5W)
Quarterly progress rept. no. 2, 1 Oct-31 Dec 1962
RADIO CORP OF AMERICA SOMERVILLE NJ
Pagination or Media Count:
A review of the overlay concept and a comparison of this structure with the comb type geometry is presented. The resistivities and diffusion parameters of this device were determined and successfully employed in the diffusion cycles. Photoresist techniques were developed which allow excellent definition and registration of the required photoresist patterns in the silicon dioxide however, improvement is still required in the defining and etching of the aluminum. In the fabrication of the insulating layer, the main difficulty is one of opening the emitter oxide area after anodizing or silicon monoxide evaporation. The difficulty is inadequate ad herence of the defined photoresist to the sub strate resulting in lifting during immersion of the wafer in oxide etch. Devices with only a few percent of the emitter areas opened were fabricated and display excellent diode charac teristics. These results indicate the feasibil ity of the anodized aluminum approach to the fabrication of an overlay structure. Alternate approaches for producing the insulating layer are being considered. These include metal mask evaporation of a dielectric material only over the base metalling and the use of a second thin metal film over the anodized film, which can be defined, and will act as a mask for defining the silicon oxide.
- Electrical and Electronic Equipment