U.S. Philips Corporation

Koninklijke Philips Corporation N.V.

Koninklijke Phillips Electronics N.v.

Erwin A Hijzen

Tom Van Zutphen

Ron Kroon

Raymond J E Hueting

Cornelis Eustatius Timmering

Frederik C Gehring

Mark A De Samber

Henricus G R Maas

John R Cutter

Raymond J E Heuting

Michael A A Zandt In't

Cornelius E Timmering

Raymond Je Hueting

Godefridus Adrianus Maria Hurkx

Punch-through diode having an inverted structure

The manufacture of a vertical power transistor trench-gate semiconductor device in which the source regions ( ) are self-aligned to the trench-gate structures ( ) including the steps of forming a mask ( ) on a surface ( ) of a semiconductor body ( ), using the mask ( ) to form the trench-gate structures ( ), then using the mask ( ) to form U-shaped section layers ( A, B) of insulating material whose base portion ( B) provides a gate insulating layer on the gate material ( ), then removing the mask ( ) and forming spacers ( ) against well-defined steps provided by the upright portions ( A) of the U-shaped section layers, then using the spacers ( ) to form the source regions ( ).

Manufacture or trench-gate semiconductor devices

In the manufacture of a trench-gate semiconductor device, for example a MOSFET or an IGBT, a starting semiconductor body ( ) has two top layers ( ) provided for forming the source and body regions. Gate material ( &prime;) is provided in a trench ( ) with a trench etchant mask ( , FIG. ) still present so that the gate material ( &prime;) forms a protruding step ( ) from the adjacent surface ( ) of the semiconductor body, and a side wall spacer ( ) is then formed in the step ( ) to replace the mask ( ). The source region ( ) is formed self-aligned with the protruding trench-gate structure with a lateral extent determined by the spacer ( , FIG. ), and the gate ( ) is then provided with an insulating overlayer ( , FIG. ). Forming the sidewall spacer ( ) when the protruding trench-gate structure has a well-defined edge provided by the gate material ( &prime;) allows better definition of the source region ( ) compared with a prior-art process in which the gate insulating overlayer is provided in the trench before causing the trench-gate structure to have the protruding step for the sidewall spacer.

Manufacture of trench-gate semiconductor devices

Inner trenches ( ) of a trenched Schottky rectifier ( ) bound a plurality of rectifier areas ( ) where the Schottky electrode ( ) forms a Schottky barrier with a drift region ( ). A perimeter trench ( ) extends around the outer perimeter of the plurality of rectifier areas ( ). These trenches ( ) accommodate respective inner field-electrodes ( ) and a perimeter field-electrode ( ) that are connected to the Schottky electrode ( ). The inner field-electrodes ( ) are capacitively coupled to the drift region ( ) via dielectric material ( ) that lines the inner trenches ( ). The perimeter field-electrode ( ) is capacitively coupled across dielectric material ( ) on the inside wall ( ) of the perimeter trench , without acting on any outside wall ( ). Furthermore, the inner and perimeter trenches ( ) are closely spaced and the intermediate areas ( ) of the drift region ( ) are lowly doped. The spacing is so close and the doping is so low that the depletion layer ( ) formed in the drift region ( ), from the Schottky barrier ( ) and from the field-relief regions ( ) in the blocking state of the rectifier, may deplete the whole of the intermediate areas ( ) between the trenches ( ) at a blocking voltage just below the breakdown voltage. This arrangement reduces the risk of premature breakdown that can occur at high field points in the depletion layer ( ), especially at the perimeter of the array of rectifier areas ( ).

Trenched Schottky rectifiers

A trench-gate semiconductor device, for example a MOSFET or IGBT, of compact geometry is manufactured with self-aligned masking techniques in a simple process with good reproducibility. The source region ( ) of the device is formed by introducing dopant ( ) into an area of the body region ( ) via a mask window ( ), diffusing the dopant to form a surface region ( ) that extends laterally below the mask ( ) at a distance (d) beyond the masking edge ( ) of the window ( ), and then etching the body ( ) at the window ( ) to form a trench ( ) for the trench-gate ( ) with a lateral extent (y) that is determined by the etching of the body ( ) at the masking edge ( ) of the window ( ). A portion of the surface region ( ) is left to provide the source region ( ) adjacent to the trench ( ). The invention permits the etch edge definition for the trench ( ) to be better controlled by using the masking edge ( ) of a well-defined mask ( ), as compared with the less well defined edges that tend to result from the use of a side-wall extension in prior-art processes.

A cellular trench-gate field-effect transistor comprises a field plate ( ) on dielectric material ( ) in a perimeter trench ( ). The dielectric material ( ) forms a thicker dielectric layer than the gate dielectric layer ( ) in the array trenches ( ). The field plate ( ) is connected to the source ( ) or trench-gate ( ) of the transistor and acts inwardly towards the cellular array rather than outwardly towards the body perimeter ( ) because of its presence on the inside wall of the trench ( ) without acting on any outside wall ( ). The array and perimeter trenches ( ) are sufficiently closely spaced, and the intermediate areas ( ) of the drain drift region ( ) are sufficiently lowly doped, that the depletion layer ( ) formed in the drain drift region ( ) in the blocking state of the transistor depletes the whole of these intermediate areas between neighbouring trenches at a voltage less than the breakdown voltage. This arrangement reduces the risk of premature breakdown that can occur at high field points in the depletion layer ( ), especially at the perimeter of the cellular array.

Cellular trench-gate field-effect transistors

A semiconductor cathode (,) in a semiconductor structure, in which the sturdiness of the cathode is increased by covering the emitting surface (,) with a layer of a semiconductor material (,) having a larger bandgap than the semiconductor material of the semiconductor cathode. Various measures for increasing the electron-mission efficiency are indicated.

Electron tube having a semiconductor cathode with lower and higher bandgap layers

Semiconductor device with a semiconductor cathode having an emissive part (pn junction) separated from a contact part which has locations at which a controlled breakdown occurs on a contact part metallization at excessive voltages, so that, during manufacture and operation, the emissive part in an election tube is protected from damage.

Semiconductor cathode and electron tube comprising a semiconductor

A semiconductor cathode (11) in a semiconductor structure, in which the sturdiness of the cathode is increased by covering the emitting surface (4) with a layer of a semiconductor material (7) having a larger bandgap than the semiconductor material of the semiconductor cathode. Various measures for increasing the electron-emission efficiency are indicated.

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Breda, Netherlands

Erwin A Hijzen