Maxpower Semiconductor Inc.

Volterra Semiconductor Corporation

Alpha Omega Semiconductor Inc.

Power Integrations, Inc.

Semiconductor Components Industries, LLC

Amit Paul

Mohamed N Darwish

Marco A Zuniga

Badredin Fatemizadeh

Yang Lu

Jun Ruan

Jayasimha Prasad

Shekar Mallikarjunaswamy

Donald Ray Disney

Chiteh Chiang

Craig Cassella

Jun Zeng

Mark Griswold

John Xia

Arash Elhami Khorasani

Mohammed N Darwish

In an embodiment, a semiconductor device includes a resistor that overlies a doped region of the semiconductor device. The resistor is formed as an elongated element that is formed into a pattern of a spiral. An embodiment of the pattern of the resistor includes a plurality of revolutions from the starting point to an ending point. The resistor material has one of a separation distance between adjacent revolutions that increases with distance along a periphery of the resistor material or a width of the resistor material that increases with distance along the periphery of the resistor material.

Method of forming a semiconductor device and structure therefor

A voltage regulator includes a high-side device, a low-side device, and a controller. The high-side device includes first and second transistors each coupled between an input terminal and an intermediate terminal, where the first transistor has a higher breakdown voltage than the second transistor. The low-side device is coupled between the intermediate terminal and a ground terminal. The controller is configured to drive the high-side and low-side devices to (a) alternately couple the intermediate terminal to the input terminal and the ground terminal and (b) cause the first transistor to control a voltage across the second transistor during switching transitions of the second transistor.

Voltage regulators with multiple transistors

The present application features a transistor that includes an n-well region implanted into a surface of a substrate, a gate region, and a source region, and a drain region. The source region is on a first side of the gate region and includes a p-body region in the n-well region. An n+ region and a p+ region are implanted in the p-body region such that the p+ region is below the n+ region. The drain region is on a second side of the gate region and includes an n+ region.

Transistor with buried P+ and source contact

A lateral SOI device may include a semiconductor channel region connected to a drain region by a drift region. An insulation region on the drift layer is positioned between the channel region and the drain region. Permanent charges may be embedded in the insulation region sufficient to cause inversion in the insulation region. The semiconductor layer also overlies a global insulation layer, and permanent charges are preferably embedded in at least selected areas of this insulation layer too.

Semiconductor on insulator devices containing permanent charge

A voltage regulator has an input terminal and a ground terminal. The voltage regulator includes a high-side device, a low side device, and a controller. The high-side device is coupled between the input terminal and an intermediate terminal. The high-side device includes first and second transistors each coupled between the input terminal and the intermediate terminal, such that the first transistor controls a drain-source switching voltage of the second transistor. The low-side device is coupled between the intermediate terminal and the ground terminal. The controller drives the high-side and low-side devices to alternately couple the intermediate terminal to the input terminal and the ground terminal.

A lateral device includes a gate region connected to a drain region by a drift layer. An insulation region adjoins the drift layer between the gate region and the drain region. Permanent charges are embedded in the insulation region, sufficient to cause inversion in the insulation region.

Lateral devices containing permanent charge

Described here are transistors and fabrication methods thereof. In one implementation, a transistor includes an n-well region implanted into a surface of a substrate, and a trench in the n-well region. The trench extends from the surface to a first depth. The trench includes a gate of conductive material in the trench, and dielectric material filling a volume of the trench not filled by the conductive material. The transistor also includes a p-type material in a first region extending from a second depth to a third depth, the second depth and the third depth being greater than the first depth. The transistor further includes a source region and a drain region.

Vertical gate LDMOS device

A method of fabricating a vertical gate region in LDMOS transistor includes depositing a first masking layer on an n-well region implanted on a substrate, patterning the first masking layer to define an area, depositing a second masking layer over the area, etching through the second masking layer in a first portion of the area to expose the n-well region, and etching the exposed n-well region to form a first trench. The first trench, extending from a surface of the n-well region to a first depth, is filled with an oxide. The second masking layer is etched through in a second portion of the area to expose the n-well region. A second trench is formed in the n-well, the second trench extending from the surface to a second depth, less than the first depth. An asymmetric vertical gate is formed by filling the second trench with a conductive material.

The present application features methods of fabricating a gate region in a vertical laterally diffused metal oxide semiconductor (LDMOS) transistor. In one aspect, a method includes depositing a masking layer on an n-well region implanted on a substrate, patterning the masking layer to define an area, and forming a first trench in the area such that a length of the first trench extends from a surface of the n-well region to a first depth in the n-well region. The method also includes filling the first trench by a conductive material and depositing a layer of oxide over the area. The method further includes etching out at least a portion of the oxide layer to expose a portion of the conductive material, removing the conductive material from the exposed portion to form a second trench, and filling the second trench with an oxide to form an asymmetric gate of the transistor.

The present inventors have realized that manufacturability plays into optimization of power semiconductor devices in some surprising new ways. If the process window is too narrow, the maximum breakdown voltage will not be achieved due to doping variations and the like normally seen in device fabrication. Thus, among other teachings, the present application describes some ways to improve the process margin, for a given breakdown voltage specification, by actually reducing the maximum breakdown voltage. In one class of embodiments, this is done by introducing a vertical gradation in the density of fixed electrostatic charge, or in the background doping of the drift region, or both. Several techniques are disclosed for achieving this.

Growing community of inventors

Sunnyvale, CA, United States of America

Amit Paul