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Polysilicon as a Diffusion Source for Subcollector Formation

IP.com Disclosure Number: IPCOM000052173D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11

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Abbas, SA Magdo, IE Riseman, J [+details]


The subcollector of a bipolar transistor can be formed by using a consumable polycrystalline silicon layer acting as the diffusion source. This method allows the subsequent growth of high quality epitaxial silicon. The fact that the dopant is totally ion-implanted in the polycrystalline silicon layer limits the damage to that subcollector region. This means that the surface of the silicon in the subcollector region is essentially defect-free, and the silicon epitaxy grown has better quality.