METHOD OF MAKING A PN JUNCTION DEVICE WITH A RECRYSTALLIZATION

摘要

1395871 Semi-conductor devices MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 15 June 1972 [15 June 1971 (2) 9 Aug 1971 (2)] 28005/72 Heading H1K A metal dot is alloyed to one face of a semiconductor wafer of one conductivity type to form a recrystallization zone of opposite type, the zone extending to, or material being removed to expose it at, the opposite wafer face. Material of the opposite type is then brought into contact with an exposed area of said zone to form a PN junction. Typically the zone is formed by alloying aluminium through an N- type silicon wafer. N-type silicon is then epitaxially deposited over the P-type recrystallized zone exposed on the back face of the wafer and aluminium deposited thereon to form a contact. The junction may then be relocated by heating above the alloying temperature. As an alternative a plate of N-type silicon is placed against the back face, the assembly reheated to bond the plate to the wafer by extension of the recrystallization zone and an aluminium silicon eutectic wafer heated in contact with the plate to form an electrode. To form a hyper abrupt junction a specified tinantimony-aluminium alloy is alloyed through a P-type silicon wafer. During the epitaxial deposition of P-type silicon on the recrystallized zone aluminium diffuses out into it to form a P + region adjacent the N-type recrystallized zone. In a modification of this a P-layer epitaxially grown on a P+ base is placed against the recrystallization zone and heating effected to extend this zone into the layer and diffuse the aluminium to form the P + layer. By removing part or all of the residual aluminium or tinantimony-aluminium alloy prior to reheating the extension of the recrystallization zone may be controlled.