Abstract: The manufacture of a vertical power transistor trench-gate semiconductor device in which the source regions (13) are self-aligned to the trench-gate structures (20,17,11) including the steps of forming a mask (61) on a surface (10a) of a semiconductor body (10), using the mask (61) to form the trench-gate structures (20,17,11), then using the mask (61) to form U-shaped section layers (62A, 62B) of insulating material whose base portion (62B) provides a gate insulating layer on the gate material (11), then removing the mask (61) and forming spacers (64) against well-defined steps provided by the upright portions (62A) of the U-shaped section layers, then using the spacers (64) to form the source regions (13).

Abstract: Inner trenches (11) of a trenched Schottky rectifier (1a; 1b; 1c; 1d) bound a plurality of rectifier areas (43a) where the Schottky electrode (3) forms a Schottky barrier 43 with a drift region (4). A perimeter trench (18) extends around the outer perimeter of the plurality of rectifier areas (43a). These trenches (11, 18) accommodate respective inner field-electrodes (31) and a perimeter field-electrode (38) that are connected to the Schottky electrode (3). The inner field-electrodes (11) are capacitively coupled to the drift region (4) via dielectric material (21) that lines the inner trenches (11). The perimeter field-electrode (38) is capacitively coupled across dielectric material (28) on the inside wall (18a) of the perimeter trench 18, without acting on any outside wall (18b). Furthermore, the inner and perimeter trenches (11, 18) are closely spaced and the intermediate areas (4a, 4b) of the drift region (4) are lowly doped.

Abstract: 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 (13) of the device is formed by introducing dopant (63) into an area of the body region (15) via a mask window (51a), diffusing the dopant to form a surface region (13b) that extends laterally below the mask (51) at a distance (d) beyond the masking edge (51b) of the window (51a), and then etching the body (10) at the window (51a) to form a trench (20) for the trench-gate (11) with a lateral extent (y) that is determined by the etching of the body (10) at the masking edge (51b) of the window (51a). A portion of the surface region (13b) is left to provide the source region (13) adjacent to the trench (20).

Abstract: A cellular trench-gate field-effect transistor comprises a field plate (38) on dielectric material (28) in a perimeter trench (18). The dielectric material (28) forms a thicker dielectric layer than the gate dielectric layer (21) in the array trenches (11). The field plate (38) is connected to the source (3) or trench-gate (31) of the transistor and acts inwardly towards the cellular array rather than outwardly towards the body perimeter (15) because of its presence on the inside wall 18a of the trench (18) without acting on any outside wall (18b). The array and perimeter trenches (11,18) are sufficiently closely spaced, and the intermediate areas (4a, 4b) of the drain drift region (4) are sufficiently lowly doped, that the depletion layer (40) formed in the drain drift region (4) 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.

Abstract: The manufacture of a trench-gate semiconductor device, for example a power transistor or a memory device includes the steps of forming at a surface (10a) of a semiconductor body (10) a first mask (51) having a first window (51a), providing a thin layer of a second material (52) in the first window (51a), forming an intermediate mask (53A, 53B) of a third material having curved sidewalls and using the intermediate mask (53A, 53B) to form two L-shaped parts (52A, 52D and 52B, 52E) of the second material with a second window (52a) which is used to etch a trench-gate trench (20). The rectangular base portion (52D, 52E) of each L-shaped part ensures that the trench (20) is maintained narrow during etching. Narrow trenches are advantageous for low specific on-resistance and low RC delay in low voltage cellular trench-gate power transistors.

Abstract: A semiconductor body has source and drain regions(4 and 5) spaced apart by a body region (6) and both meeting a surface (3a) of the semiconductor body. A gate structure (7) is provided within a trench (8) for controlling a conduction channel in a conduction channel accommodation portion (60) of the body region (6) extending along at least side walls (8a) of the trench (8) and between the source and drain regions (4 and 5). A voltage-sustaining zone (600) consisting of first regions (6) of the same conductivity type as the source and drain regions interposed with second regions (62) of the opposite conductivity type is provided such that the first regions (61) provide a path for majority charge carriers to the drain region (5) when the device is conducting.

Abstract: A semiconductor body has source and drain regions (4 and 5; 4′ and 5′) spaced apart by a body region (6; 6′) and a drain drift region (50; 50′) and both meeting the same surface (3a) of the semiconductor body. An insulated gate structure (7; 70′; 700) is provided within a trench (80; 80′; 80″) extending in the semiconductor body. The gate structure has a gate conductive region (70b; 70′b; 70″b) separated from the trench by a dielectric layer (70a; 70′a) such that a conduction channel accommodation portion (60; 60′) of the body region extends along at least side walls (80a; 80′a; 80a) of the trench and between the source (4; 4′) and drain drift (50; 50′) regions.

Abstract: A field-effect semiconductor device, for example a MOSFET of the trench-gate type, comprises side-by-side device cells at a surface (10a) of a semiconductor body (10), and at least one drain connection (41) that extends in a drain trench (40) from the body surface (10a) to an underlying drain region (14a). A channel-accommodating region (15) of the device extends laterally to the drain trench (40). The drain trench (40) extends through the thickness of the channel-accommodating region (15) to the underlying drain region (14a), and the drain connection (41) is separated from the channel-accommodating region (15) by an intermediate insulating layer (24) on side-walls of the drain trench (40). A compact cellular layout can be achieved, with a significant proportion of the total cellular layout area accommodating conduction channels (12). The configuration in a discrete device avoids a need to use a substrate conduction path and so advantageously reduces the ON resistance of the device.

Abstract: Inner trenches (11) of a trenched Schottky rectifier (1a; 1b; 1c; 1d) bound a plurality of rectifier areas (43a) where the Schottky electrode (3) forms a Schottky barrier 43 with a drift region (4). A perimeter trench (18) extends around the outer perimeter of the plurality of rectifier areas (43a). These trenches (11, 18) accommodate respective inner field-electrodes (31) and a perimeter field-electrode (38) that are connected to the Schottky electrode (3). The inner field-electrodes (11) are capacitively coupled to the drift region (4) via dielectric material (21) that lines the inner trenches (11). The perimeter field-electrode (38) is capacitively coupled across dielectric material (28) on the inside wall (18a) of the perimeter trench 18, without acting on any outside wall (18b). Furthermore, the inner and perimeter trenches (11, 18) are closely spaced and the intermediate areas (4a, 4b) of the drift region (4) are lowly doped.

Abstract: In the manufacture of a trench-gate semiconductor device, for example a MOSFET or an IGBT, a starting semiconductor body (10) has two top layers (13, 15) provided for forming the source and body regions. Gate material (11′) is provided in a trench (20) with a trench etchant mask (51, FIG. 2) still present so that the gate material (11′) forms a protruding step (30) from the adjacent surface (10a) of the semiconductor body, and a side wall spacer (32) is then formed in the step (30) to replace the mask (51). The source region (13) is formed self-aligned with the protruding trench-gate structure with a lateral extent determined by the spacer (32, FIG. 5), and the gate (11) is then provided with an insulating overlayer (18, FIG. 6).

Abstract: 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-mission efficiency are indicated.

Abstract: 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.

Abstract: 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.