Abstract: A method can include forming a drift region, forming a well region above the drift region, and forming an active trench extending through the well region and into the drift region. The method can include forming a first source region in contact with a first sidewall of the active trench and a second source region in contact with a second sidewall of the active trench. The method also includes forming a charge control trench where the charge control trench is aligned parallel to the active trench and laterally separated from the active trench by a mesa region, and where the portion of the well region is in contact with the charge control trench and excludes any source region. The method also includes forming an oxide along a bottom of the active trench having a thickness greater than a thickness of an oxide along the first sidewall of the active trench.

Abstract: A field effect transistor (FET) includes a body region of a first conductivity type disposed within a semiconductor region of a second conductivity type and a gate trench extending through the body region and terminating within the semiconductor region. The FET also includes a flared shield dielectric layer disposed in a lower portion of the gate trench, the flared shield dielectric layer including a flared portion that extends under the body region. The FET further includes a conductive shield electrode disposed in the trench and disposed, at least partially, within the flared shield dielectric.

Abstract: In one general aspect, an apparatus can include a semiconductor region, and a trench defined within the semiconductor region. The trench can have a depth aligned along a vertical axis and have a length aligned along a longitudinal axis orthogonal to the vertical axis. The trench can have a first portion of the length included in a termination region of the semiconductor region and can have a second portion of the length included in an active region of the semiconductor region.

Abstract: A field effect transistor (FET) includes a body region of a first conductivity type disposed within a semiconductor region of a second conductivity type and a gate trench extending through the body region and terminating within the semiconductor region. The FET also includes a flared shield dielectric layer disposed in a lower portion of the gate trench, the flared shield dielectric layer including a flared portion that extends under the body region. The FET further includes a conductive shield electrode disposed in the trench and disposed, at least partially, within the flared shield dielectric.

Abstract: A field effect transistor includes a gate trench extending into a semiconductor region. The gate trench has a recessed gate electrode disposed therein. A source region in the semiconductor region flanks each side of the gate trench. A conductive material fills an upper portion of the gate trench so as to make electrical contact with the source regions along upper sidewalls of the gate trench. The conductive material is insulated from the recessed gate electrode.

Abstract: A method for forming thick oxide at the bottom of a trench formed in a semiconductor substrate includes forming a conformal oxide film by a sub-atmospheric chemical vapor deposition process that fills the trench and covers a top surface of the substrate. The method also includes etching the oxide film off the top surface of the substrate and inside the trench to leave a substantially flat layer of oxide having a target thickness at the bottom of the trench.

Abstract: A field effect transistor includes a body region of a first conductivity type over a semiconductor region of a second conductivity type. A gate trench extends through the body region and terminates within the semiconductor region. At least one conductive shield electrode is disposed in the gate trench. A gate electrode is disposed in the gate trench over but insulated from the at least one conductive shield electrode. A shield dielectric layer insulates the at lease one conductive shield electrode from the semiconductor region. A gate dielectric layer insulates the gate electrode from the body region. The shield dielectric layer is formed such that it flares out and extends directly under the body region.

Abstract: A method of manufacturing a semiconductor device having a charge control trench and an active control trench with a thick oxide bottom includes forming a drift region, a well region extending above the drift region, an active trench extending through the well region and into the drift region, a charge control trench extending deeper into the drift region than the active trench, an oxide film that fills the active trench, the charge control trench and covers a top surface of the substrate, an electrode in the active trench, and source regions. The method also includes etching the oxide film off the top surface of the substrate and inside the active trench to leave a substantially flat layer of thick oxide having a target thickness at the bottom of the active trench.

Abstract: A method for forming power semiconductor devices having an inter-electrode dielectric (IPD) layer inside a trench includes providing a semiconductor substrate with a trench, lining the sidewalls and bottom of the trench with a first layer of dielectric material, filling the trench with a first layer of conductive material to form a first electrode, recessing the first layer of dielectric material and the first layer of conductive material to a first depth inside the trench, forming a layer of polysilicon material on a top surface of the dielectric material and conductive material inside the trench, oxidizing the layer of polysilicon material, and forming a second electrode inside the trench atop the oxidized layer and isolated from trench sidewalls by a second dielectric layer. The oxidation step can be enhanced by either chemically or physically altering the top portion polysilicon such as by implanting impurities.

Abstract: A method of forming a field effect transistor includes: forming a trench in a semiconductor region; forming a shield electrode in the trench; performing an angled sidewall implant of impurities of the first conductivity type to form a channel enhancement region adjacent the trench; forming a body region of a second conductivity type in the semiconductor region; and forming a source region of the first conductivity type in the body region, the source region and an interface between the body region and the semiconductor region defining a channel region therebetween, the channel region extending along the trench sidewall. The channel enhancement region partially extends into a lower portion of the channel region to thereby reduce a resistance of the channel region.

Abstract: A method of forming a field effect transistor includes: forming a trench in a semiconductor region; forming a shield electrode in the trench; performing an angled sidewall implant of impurities of the first conductivity type to form a channel enhancement region adjacent the trench; forming a body region of a second conductivity type in the semiconductor region; and forming a source region of the first conductivity type in the body region, the source region and an interface between the body region and the semiconductor region defining a channel region therebetween, the channel region extending along the trench sidewall. The channel enhancement region partially extends into a lower portion of the channel region to thereby reduce a resistance of the channel region.

Abstract: A semiconductor power device includes a drift region of a first conductivity type, a well region extending above the drift region and having a second conductivity type opposite the first conductivity type, an active trench extending through the well region and into the drift region. The active trench, which includes sidewalls and bottom lined with dielectric material, is substantially filled with a first conductive layer and a second conductive layer. The second conductive layer forms a gate electrode and is disposed above the first conductive layer and is separated from the first conductive layer by an inter-electrode dielectric material. The device also includes source regions having the first conductivity type formed inside the well region and adjacent the active trench and a charge control trench that extends deeper into the drift region than the active trench and is substantially filled with material to allow for vertical charge control in the drift region.

Abstract: A field effect transistor includes a body region of a first conductivity type in a semiconductor region of a second conductivity type. A gate trench extends through the body region and terminating within the semiconductor region. A source region of the second conductivity type extends in the body region adjacent the gate trench. The source region and an interface between the body region and the semiconductor region define a channel region therebetween which extends along the gate trench sidewall. A channel enhancement region of the second conductivity type is formed adjacent the gate trench. The channel enhancement region partially extends into a lower portion of the channel region to thereby reduce a resistance of the channel region.

Abstract: A field effect transistor includes a body region of a first conductivity type in a semiconductor region of a second conductivity type. A gate trench extends through the body region and terminating within the semiconductor region. A source region of the second conductivity type extends in the body region adjacent the gate trench. The source region and an interface between the body region and the semiconductor region define a channel region therebetween which extends along the gate trench sidewall. A channel enhancement region of the second conductivity type is formed adjacent the gate trench. The channel enhancement region partially extends into a lower portion of the channel region to thereby reduce a resistance of the channel region.

Abstract: A field effect transistor includes a body region of a first conductivity type over a semiconductor region of a second conductivity type. A gate trench extends through the body region and terminates within the semiconductor region. At least one conductive shield electrode is disposed in the gate trench. A gate electrode is disposed in the gate trench over but insulated from the at least one conductive shield electrode. A shield dielectric layer insulates the at lease one conductive shield electrode from the semiconductor region. A gate dielectric layer insulates the gate electrode from the body region. The shield dielectric layer is formed such that it flares out and extends directly under the body region.

Abstract: A method for forming a shielded gate field effect transistor includes the following steps. Trenches extending into a silicon region are formed using a mask that includes a protective layer. A shield dielectric layer lining sidewalls and bottom of each trench is formed. A shield electrode is formed in a bottom portion of each trench. Protective spacers are formed along upper sidewalls of each trench. An inter-electrode dielectric is formed over the shield electrode. The protective spacers and the protective layer of the mask prevent formation of inter-electrode dielectric along the upper sidewalls of each trench and over mesa surfaces adjacent each trench. A gate electrode is formed in each trench over the inter-electrode dielectric.

Abstract: A field effect transistor is formed as follows. Trenches are formed in a semiconductor region of a first conductivity type. Each trench is partially filled with one or more materials. A dual-pass angled implant is carried out to implant dopants of a second conductivity type into the semiconductor region through an upper surface of the semiconductor region and through upper trench sidewalls not covered by the one or more material. A high temperature process is carried out to drive the implanted dopants deeper into the mesa region thereby forming body regions of the second conductivity type between adjacent trenches. Source regions of the first conductivity type are then formed in each body region.

Abstract: A method for controlling the thickness of an expitaxially grown semiconductor material includes providing a semiconductor substrate that is doped by dopants of a first type; forming a buffer layer atop the semiconductor substrate, the buffer layer being doped with dopants of a second type that has much less diffusivity relative to that of dopants of the first type and forming the expitaxially grown layer atop the buffer layer to a desired thickness. The buffer layer, which acts to counter an up-diffusion of the dopants of the first type from the substrate into the epitaxially grown layer, can be doped with arsenic or carbon or both arsenic and carbon. A semiconductor device includes the buffer layer to counter an up-diffusion of the dopants of the first type from the substrate into the epitaxially grown layer.

Abstract: A method for forming power semiconductor devices having an inter-electrode dielectric (IPD) layer inside a trench includes providing a semiconductor substrate with a trench, lining the sidewalls and bottom of the trench with a first layer of dielectric material, filling the trench with a first layer of conductive material to form a first electrode, recessing the first layer of dielectric material and the first layer of conductive material to a first depth inside the trench, forming a layer of polysilicon material on a top surface of the dielectric material and conductive material inside the trench, oxidizing the layer of polysilicon material, and forming a second electrode inside the trench atop the oxidized layer and isolated from trench sidewalls by a second dielectric layer. The oxidation step can be enhanced by either chemically or physically altering the top portion polysilicon such as by implanting impurities.

Abstract: A semiconductor power device includes a drift region of a first conductivity type, a well region extending above the drift region and having a second conductivity type opposite the first conductivity type, an active trench extending through the well region and into the drift region. The active trench, which includes sidewalls and bottom lined with dielectric material, is substantially filled with a first conductive layer and a second conductive layer. The second conductive layer forms a gate electrode and is disposed above the first conductive layer and is separated from the first conductive layer by an inter-electrode dielectric material. The device also includes source regions having the first conductivity type formed inside the well region and adjacent the active trench and a charge control trench that extends deeper into the drift region than the active trench and is substantially filled with material to allow for vertical charge control in the drift region.