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.

Abstract: An improved trench MOS-gated device comprises a monocrystalline semiconductor substrate on which is disposed a doped upper layer. The upper layer includes at an upper surface a plurality of heavily doped body regions having a first polarity and overlying a drain region. The upper layer further includes at its upper surface a plurality of heavily doped source regions having a second polarity opposite that of the body regions. A gate trench extends from the upper surface of the upper layer to the drain region and separates one source region from another. The trench has a floor and sidewalls comprising a layer of dielectric material and contains a conductive gate material filled to a selected level and an isolation layer of dielectric material that overlies the gate material and substantially fills the trench. The upper surface of the overlying layer of dielectric material in the trench is thus substantially coplanar with the upper surface of the upper layer.

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, source regions having the first conductivity type formed in the well region adjacent the active trench, and a first termination trench extending below the well region and disposed at an outer edge of an active region of the device. The sidewalls and bottom of the active trench are lined with dielectric material, and substantially filled with a first conductive layer forming an upper electrode and a second conductive layer forming a lower electrode, the upper electrode being disposed above the lower electrode and separated therefrom by inter-electrode dielectric material.

Abstract: A method for forming thick oxide at the bottom of a trench formed in a semiconductor substrate includes forming a conformal oxide film that fills the trench and covers a top surface of the substrate. and 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. The oxide film can be deposited by sub-atmospheric chemical vapor deposition processes, directional Tetraethoxysilate (TEOS) processes, or high density plasma deposition processes that form a thicker oxide at the bottom of the trench than on the sidewalls of the trench.

Abstract: An improved trench MOS-gated device comprises a monocrystalline semiconductor substrate on which is disposed a doped upper layer. The upper layer includes at an upper surface a plurality of heavily doped body regions having a first polarity and overlying a drain region. The upper layer further includes at its upper surface a plurality of heavily doped source regions having a second polarity opposite that of the body regions. A gate trench extends from the upper surface of the upper layer to the drain region and separates one source region from another. The trench has a floor and sidewalls comprising a layer of dielectric material and contains a conductive gate material filled to a selected level and an isolation layer of dielectric material that overlies the gate material and substantially fills the trench. The upper surface of the overlying layer of dielectric material in the trench is thus substantially coplanar with the upper surface of the upper layer.

Abstract: An improved trench MOS-gated device comprises a monocrystalline semiconductor substrate on which is disposed a doped upper layer. The upper layer includes at an upper surface a plurality of heavily doped body regions having a first polarity and overlying a drain region. The upper layer further includes at its upper surface a plurality of heavily doped source regions having a second polarity opposite that of the body regions. A gate trench extends from the upper surface of the upper layer to the drain region and separates one source region from another. The trench has a floor and sidewalls comprising a layer of dielectric material and contains a conductive gate material filled to a selected level and an isolation layer of dielectric material that overlies the gate material and substantially fills the trench. The upper surface of the overlying layer of dielectric material in the trench is thus substantially coplanar with the upper surface of the upper layer.

Abstract: Various embodiments for improved power devices as well as their methods of manufacture, packaging and circuitry incorporating the same for use in a wide variety of power electronic applications are disclosed. One aspect of the invention combines a number of charge balancing techniques and other techniques for reducing parasitic capacitance to arrive at different embodiments for power devices with improved voltage performance, higher switching speed, and lower on-resistance. Another aspect of the invention provides improved termination structures for low, medium and high voltage devices. Improved methods of fabrication for power devices are provided according to other aspects of the invention. Improvements to specific processing steps, such as formation of trenches, formation of dielectric layers inside trenches, formation of mesa structures and processes for reducing substrate thickness, among others, are presented.

Abstract: A method for reducing miller capacitance and switching losses in an integrated circuit includes providing a switching gate electrode having respective portions that are coplanar with the source and well regions of the integrated circuit. The switching gate electrode is configured for switching the integrated circuit on and off in response to a relatively small change in applied voltage. A shielding gate electrode is formed with respective portions coplanar with the switching electrode and the well region. The shielding electrode is configured for charging the gate-to-drain overlap region of the integrated circuit.

Abstract: An improved trench MOS-gated device comprises a monocrystalline semiconductor substrate on which is disposed a doped upper layer. The upper layer includes at an upper surface a plurality of heavily doped body regions having a first polarity and overlying a drain region. The upper layer further includes at its upper surface a plurality of heavily doped source regions having a second polarity opposite that of the body regions A gate trench extends from the upper surface of the upper layer to the drain region and separates one source region from another. The trench has a floor and sidewalls comprising a layer of dielectric material and contains a conductive gate material filled to a selected level and an isolation layer of dielectric material that overlies the gate material and substantially fills the trench. The upper surface of the overlying layer of dielectric material in the trench is thus substantially coplanar with the upper surface of the upper layer.

Abstract: A gate structure for a semiconductor device includes a shielding electrode and a switching electrode. Respective portions of the shielding electrode are disposed above said drain region and said well region. A first dielectric layer is disposed between the shielding electrode and the drain and well regions. The switching electrode includes respective portions that are disposed above said well region and said source region. A second dielectric layer is disposed between the switching electrode and the well and source regions. A third dielectric layer is disposed between the shielding electrode and the switching electrode.

Abstract: In a power semiconductor device 10, a continuous trench has an outer circumferential portion 58 that includes a field plate and inner portions 28 that carry include one or more gate runners 34 to that the gate runners and the field plate are integral with each other. The trench structure 58, 28 is simpler to form and takes up less surface space that the separate structures of the prior art. The trench is lined with an insulator and further filled with conductive polysilicon and a top insulator.

Abstract: A gate structure for a semiconductor device includes a shielding electrode and a switching electrode. Respective portions of the shielding electrode are disposed above said drain region and said well region. A first dielectric layer is disposed between the shielding electrode and the drain and well regions. The switching electrode includes respective portions that are disposed above said well region and said source region. A second dielectric layer is disposed between the switching electrode and the well and source regions. A third dielectric layer is disposed between the shielding electrode and the switching electrode.

Abstract: An LDMOS device is made on a semiconductor substrate 112. It has an N+ source and drain regions 120, 132 are formed within a P well region 122. An interlevel dielectric layer 140 encapsulates biased charge control electrodes 142a and they control the electric field within the area of the drift region 14 between P-base 122 and the N drain region 132 to increase the reverse breakdown voltage of the device. This permits the user to more heavily dope the drift region and achieve a lower on resistance.

Abstract: In a power semiconductor device 10, a continuous trench has an outer circumferential portion 58 that includes a field plate and inner portions 28 that carry include one or more gate runners 34 to that the gate runners and the field plate are integral with each other. The trench structure 58, 28 is simpler to form and takes up less surface space that the separate structures of the prior art. The trench is lined with an insulator and further filled with conductive polysilicon and a top insulator.

Abstract: A process for constructing a trench MOS-gated device includes: forming in a semiconductor substrate an extended trench that comprises an upper segment and a bottom segment, wherein the bottom segment has a lesser width relative to a greater width of the trench upper segment and extends to a depth corresponding to the total depth of the extended trench. The bottom segment of the trench is substantially filled with dielectric material. The trench upper segment has a floor and sidewalls comprising dielectric material and is substantially filled with a conductive material to form a gate region. A heavily doped source region of the first conduction type and a heavily doped body region of the second conduction type are formed in a surface well region on the side of the extended trench opposite an extended doped zone.

Abstract: An MOS power device a substrate comprises an upper layer having an upper surface and an underlying drain region, a well region of a first conductance type disposed in the upper layer over the drain region, and a plurality of spaced apart buried gates, each of which comprises a trench that extends from the upper surface of the upper layer through the well region into the drain region. Each trench comprises an insulating material lining its surface, a conductive material filling its lower portion to a selected level substantially below the upper surface of the upper layer, and an insulating material substantially filling the remainder of the trench. A plurality of highly doped source regions of a second conductance type are disposed in the upper layer adjacent the upper portion of each trench, each source region extending from the upper surface to a depth in the upper layer selected to provide overlap between the source regions and the conductive material in the trenches.

Abstract: An improved MOS-gated power device 300 with a substrate 101 having an upper layer 101a of doped monocrystalline silicon of a first conduction type that includes a doped well region 107 of a second conduction type. The substrate further includes at least one heavily doped source region 111 of the first conduction type disposed in a well region 107 at an upper surface of the upper layer, a gate region 106 having a conductive material 105 electrically insulated from the source region by a dielectric material, a patterned interlevel dielectric layer 112 on the upper surface overlying the gate and source regions 114, and a heavily doped drain region of the first conduction type 115. The improvement includes body regions 301 containing heavily doped polysilicon of the second conduction type disposed in a well region 107 at the upper surface of the monocrystalline substrate.