Structures and methods with reduced sensitivity to surface charge

摘要

The present application provides (in addition to more broadly applicable inventions) improvements which are particularly applicable to two-sided power semiconductor devices which use bipolar conduction. In this class of devices, the inventor has realized that two or three of the four (or more) semiconductor doping components which form the carrier-emission structures and control structures in the active device (array) portion of a two-sided power device can also be used, with surprising advantages, to form field-limiting rings around the active arrays on both surfaces. Most preferably, in some but not necessarily all embodiments, a shallow implant of one conductivity type is used to counterdope the surface of a well having the other conductivity type. This shallow implant, singly or in combination with another shallow implant of the same conductivity type, works to shield the well from the effects of excess charge at or above the surface of the semiconductor material.

主权项

1. A semiconductor device comprising:
first and second charge-carrier emission structures on first and second opposed faces of a semiconductor die; first and second semiconductor control regions which are located on said first and second faces respectively, and are each positioned to control emission of first-polarity charge-carriers from said first and said second emission structures respectively; a first field-limiting ring structure, on said first face, which laterally surrounds said first emission structure; a second field-limiting ring structure, on said second face, which laterally surrounds said second emission structure; wherein said first emission structure and said first control region collectively include at least three doping components, including shallow p-type and n-type components, which each have the same profile as a corresponding respective doping component of said second field-limiting ring structure, and also includes at least one other doping component which does not have the same profile as any component of said second field-limiting ring structure; and wherein said second emission structure and said second control region collectively include at least three doping components, including shallow p-type and n-type components, which each have the same profile as a corresponding respective doping component of said first field-limiting ring structure, and also includes at least one other doping component which does not have the same profile as any component of said first field-limiting ring structure; whereby said field-limiting ring structures, in combination, smooth lateral voltage profiles between said emission structures and an edge of the die.