Method of making a hyperabrupt varactor diode utilizing molecular beam epitaxy
AssigneeBell Telephone Laboratories, Incorporated
InventorsCharles A. Goodwin, Yusuke Ota
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Abstract
A semiconductor varactor diode of the hyperabrupt junction type, typically having a PNN+ configuration, is disclosed. The impurity concentration in the intermediate N-type portion is grown in by the molecular beam epitaxy process to provide the hyperabrupt profile. Also, the N-type background doping in the P-type zone is minimized by the same epitaxial process to reduce the level of impurity compensation needed.
Claims4
A method of fabricating a silicon semiconductor varactor diode of the hyperabrupt junction type in which an epitaxial layer having a PN junction therein is formed on a starting portion of high conductivity and of one conductivity type
- characterized by the steps of:
- (1) growing by molecular beam epitaxy on said starting portion a layer of one conductivity type and during said growing adding an impurity of said one conductivity type in an increasing amount so that the concentration of said impurity increases to a peak value, and
- (2) terminating the addition of said impurity to the growing process at the preselected peak value while continuing to grow said epitaxial layer thereby to form a surface-adjoining layer.
Dependencies are inferred from the claim text.