Abstract: A gallium nitride based semiconductor diode includes a substrate, a GaN layer formed on the substrate, an AlGaN layer formed on the GaN layer where the GaN layer and the AlGaN layer forms a cathode region of the diode, a metal layer formed on the AlGaN layer forming a Schottky junction therewith where the metal layer forms an anode electrode of the diode, and a high barrier region formed in the top surface of the AlGaN layer and positioned under an edge of the metal layer. The high barrier region has a higher bandgap energy than the AlGaN layer or being more resistive than the AlGaN layer.
Abstract: A semiconductor package is disclosed for packaging two adjacent semiconductor dies atop a circuit substrate. The dies are separated from each other along their longitudinal edges with an inter-die distance. An elevation-adaptive electrical connection connects a top metalized contact of die two to the bottom surface of die one while accommodating for elevation difference between the surfaces. The elevation-adaptive electrical connection includes: a) An L-shaped circuit route that is part of the circuit substrate, extending transversely from a die one longitudinal edge and placing an intermediate contact area next to a die two transverse edge. b) An interconnection plate connecting the top metalized contact area of die two with the intermediate contact area while being formed to accommodate for elevation difference between the contact areas.
Abstract: Trench gate MOSFET devices may be formed using a single mask to define gate trenches and body contact trenches. A hard mask is formed on a surface of a semiconductor substrate. A trench mask is applied on the hard mask to predefine a body contact trench and a gate trench. These predefined trenches are simultaneously etched into the substrate to a first predetermined depth. A gate trench mask is next applied on top of the hard mask. The gate trench mask covers the body contact trenches and has openings at the gate trenches that are wider than those trenches. The gate trench, but not the body contact trench, is etched to a second predetermined depth. Conductive material of a first kind may fill the gate trench to form a gate. Conductive material of a second kind may fill the body contact trench to form a body contact.
Type:
Application
Filed:
January 29, 2009
Publication date:
July 29, 2010
Applicant:
ALPHA & OMEGA SEMICONDUCTOR, INC
Inventors:
Yeeheng Lee, Hong Chang, Tiesheng Li, John Chen, Anup Bhalla
Abstract: A current limiting load switch for bridging supply Vss and load with a reference voltage VRdt dynamically generated by a VRdt-generator is proposed. It includes: A pair of power FET and sense FET interconnected in split-current configuration. The FET pair develops a load voltage while limiting load current Iload to a preset maximum Imax. The FET pair is sized to draw device currents Ipower and Is with RATIOI=Is/Ipower<<1. The sense FET high-side terminal is coupled to Vss through a sense resistor Rsense developing a sense voltage Vs=Is×Rsense. A current limiting amplifier with inputs connected to VRdt and Vs and output controlling FET pair closing a current limiting feedback loop. The VRdt-generator dynamically adjusts VRdt concurrent and compensatory with an undesirable effect of changing RATIOI caused by the sense FET operational transition thus eliminating a transitional overshoot of Iload beyond Imax.
Type:
Grant
Filed:
October 10, 2008
Date of Patent:
June 1, 2010
Assignee:
Alpha & Omega Semiconductor, Inc.
Inventors:
Kevin Ng, Zhinan Wei, Wai-Keung Peter Cheng, Allen Chang
Abstract: A structure is disclosed for measuring body pinch resistance Rp of trench MOSFET arrays on a wafer. The trench MOSFET array has a common drain layer of first conductivity type and a 2D-trench MOSFET array atop the common drain layer. The 2D-trench MOSFET array has an interdigitated array of source-body columns and gate trench columns. Each source-body column has a bottom body region of second conductivity type with up-extending finger structures. Each source-body column has top source regions of first conductivity type bridging the finger structures. The structure includes: a) A source-body column wherein each finger structure of the bottom body region has a formed top contact electrode. b) Two gate trench columns flank the source-body column and both have a formed top common gate contact electrode. Upon connection of the structure to external voltage/current measurement devices, Rp can be measured while mimicking the parasitic effect of neighboring trench MOSFETs.
Abstract: This invention discloses a semiconductor wafer for manufacturing electronic circuit thereon. The semiconductor substrate further includes an etch-back indicator that includes trenches of different sizes having polysilicon filled in the trenches and then completely removed from some of the trenches of greater planar trench dimensions and the polysilicon still remaining in a bottom portion in some of the trenches having smaller planar trench dimensions.
Type:
Grant
Filed:
April 29, 2006
Date of Patent:
December 15, 2009
Assignee:
Alpha & Omega Semiconductor, Inc.
Inventors:
Yu Wang, Tiesheng Li, Sung-Shan Tai, Hong Chang
Abstract: A method and device structure are disclosed for preventing gate oxide damage of a trench MOSFET during wafer processing while adding an ESD protection module atop the trench MOSFET. The ESD protection module has a low temperature oxide (LTO) bottom layer whose patterning process is found to cause the gate oxide damage. The method includes: a) Fabricate numerous trench MOSFETs on a wafer. b) Add a Si3N4 isolation layer, capable of preventing the LTO patterning process from damaging the gate oxide, atop the wafer. c) Add numerous ESD protection modules atop the Si3N4 isolation layer. d) Remove those portions of the Si3N4 isolation layer that are not beneath the ESD protection modules. In one embodiment, hydrofluoric acid is used as a first etchant for patterning the LTO while hot phosphoric acid is used as a second etchant for removing portions of the Si3N4 isolation layer.
Abstract: A circuit for limiting di/dt caused by a main switching FET during its turn-off against an inductive switching circuit is proposed. The circuit for limiting di/dt includes: An auxiliary inductor in series with the main switching FET for inducing an auxiliary inductive voltage proportional to di/dt. An auxiliary FET in parallel with the main switching FET. The auxiliary FET gate is connected to produce a gate voltage equal to the auxiliary inductive voltage. When the di/dt tends to exceed a pre-determined maximum rate of decrease, the auxiliary FET produces an auxiliary current component counteracting further decrease of the di/dt. The main switching FET and the auxiliary FET can be formed from a single die with shared source and drain. The auxiliary inductor can be implemented as a parasitic inductance of an inherently required bonding wire connecting the main switching FET to its device terminal to simplify packaging with reduced cost.
Abstract: A semiconductor device comprises a drain, a body disposed over the drain, having a body top surface, a source embedded in the body, extending downward from the body top surface into the body, a gate trench extending through the source and the body into the drain, a gate disposed in the gate trench, a source body contact trench having a trench wall and an anti-punch through implant that is disposed along the trench wall. A method of fabricating a semiconductor device comprises forming a hard mask on a substrate having a top substrate surface, forming a gate trench in the substrate, through the hard mask, depositing gate material in the gate trench, removing the hard mask to leave a gate structure, forming a source body contact trench having a trench wall and forming an anti-punch through implant.