JPS5550671A - Manufacturing of variable capacitance element - Google Patents

Abstract

PURPOSE: To enhance the dielectric strength of a variable capacitance element by forming an opening at a substrate by a self-alignment as a mask when forming hyper abrupt junction thereat to thereby increase the radius of curvature at the junction edge.

CONSTITUTION: An n-type layer 11 is epitaxially grown on an n-type silicon substrate 10, an SiO₂ film 12 is coated thereon, an opening 13 is perforated at predetermined region thereof, and an opening 14 is perforated in the layer exposed by a chemical or ion etching process. A great deal of phosphorus ion is implanted into the opening 14, and heat treated to thereby form an n⁺-type region 15. Then, a boron nitride plate is urged in contact within the region 15, and heat treated to thereby from a p-type region 16 in the region 15 to thus produce a hyper abrupt junction 17 in the boundary between the regions 16 and 15. Then, an electrode 18 is coated on the region 16, and an electrode 19 is coated on the back surface of the substrate 10 to thereby form a hyper abrupt junction type variable capacitance element. Thus, it can enhance the radius of curvature at the edge portion larger than using the conventional oxide film mask to thereby increase the dielectric strength of the element without using guard ring.

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