Unitrode Corporation

Scott C Blackstone

Philip Leland Hower

Elizabeth M Roughan

Christopher H Doucette

Carolyn Q Cotnam

Roy Lee

A semiconductor device is disclosed having improved vertical gain symmetry, and which includes thick, lightly-doped regions which are dielectrically isolated and provided by at least two separately processed semiconductor wafers which are bonded together and further processed to provide the finished device. Alternate embodiments include buried layers exhibiting very low resistance. Further alternate embodiments provide high voltage and/or high current devices which are fabricated together with low-power circuitry as an integrated circuit.

Inverted epitaxial process semiconductor devices

A new diode structure is provided by bonding two semiconductor materials together having a low capacitance, a large contact area and mechanical ruggedness. The cross-sectional area of at least one of the semiconductor materials is reduced in the region of the bond resulting in a structure with either an hourglass or truncated hourglass-like cross-section. A diode PN junction is contained in the neighborhood of the area of reduced cross section. The diode so constructed provides a sufficient spacing between the unbonded semiconductor regions to reduce total packaged diode capacitance without introducing a spacer layer. The diode is processed to limit the area of the PN junction formed therein to the region of the bonding between the semiconductor materials, without limiting the metallized contact area, further controlling the diode capacitance as well as other electrical characteristics. The outer ends of the diode parallel to the bond, comprising typically P and N type semiconductor regions, are typically connected to metal leads which comprise the diode leads and the diode is packaged to form a mechanically and electrically stable low capacitance diode. This diode can be encapsulated such that no void or cavity exists within the interior of the structure without changing the diode construction process.

New diode structure

A method for processing at least two semiconductor wafers for producing a partially processed semiconductor substrate which can be subsequently further processed utilizing conventional planar semiconductor processing techniques to achieve a complementary semiconductor structure in which a plurality of matched semiconductor elements can be formed. An embedded silicide layer in the bonded semiconductor substrate acts as a conduit for horizontally dispersing dopant during the diffusion process. The dopant subsequently up-diffuses into an adjacent silicon region forming generally uniform and shallow, buried layer regions.

Method of processing a semiconductor substrate including silicide bonding

A process for fabricating a semiconductor device by forming a diffusion region in a first semiconductor wafer and bonding the surface of the first semiconductor wafer having the diffused region to a second semiconductor wafer to form a low resistance buried layer. The process includes further diffusion to provide an external electrical contact with the buried layer. Further enhancements are provided by selectively forming voids and/or selectively applying materials of greater and lesser conductivity on at least one of the semiconductor wafers before bonding, forming complex internal semiconductor structures in the bonded wafer structures.

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Needham, MA, United States of America

Scott C Blackstone