Abstract: A semiconductor device includes a semiconductor region having a pn junction and a field shaping region located adjacent the pn junction to increase the reverse breakdown voltage of the device. The field shaping region is coupled via capacitive voltage coupling regions to substantially the same voltages as are applied to the pn junction. When a reverse voltage is applied across the pn junction and the device is non-conducting, a capacitive electric field is present in a part of the field shaping region which extends beyond a limit of the pn junction depletion region which would exist in the absence of the field shaping region. The electric field in the field shaping region inducing a stretched electric field limited to a correspondingly stretched pn junction depletion region in the semiconductor region.

Abstract: A trench MOSFET with drain (8), drift region (10) body (12) and source (14). In order to improve the figure of merit for use of the MOSFET as control and sync FETs, the trench (20) is partially filled with dielectric (24) adjacent to the drift region (10) and a graded doping profile is used in the drift region (10).

Abstract: A field-effect transistor having cells (18) each having a source region (22), source body region (26), drift region (20), drain body region (28) and drain region (24) arranged longitudinally, laterally alternating with structures to achieve a reduced surface field. In embodiments, the structures can include longitudinally spaced insulated gate trenches (35) defining a gate region (31) adjacent the source or drain region (22, 24) and a longitudinally extending potential plate region (33) adjacent the drift region (20). Alternatively, a separate potential plate region (33) or a longitudinally extending semi-insulating field plate (50) may be provided adjacent the drift region (20). The transistor is suitable for bi-directional switching.

Abstract: A semiconductor device includes a semiconductor region having a pn junction and a field shaping region located adjacent the pn junction to increase the reverse breakdown voltage of the device. The field shaping region is coupled via capacitive voltage coupling regions to substantially the same voltages as are applied to the pn junction. When a reverse voltage is applied across the pn junction and the device is non-conducting, a capacitive electric field is present in a part of the field shaping region which extends beyond a limit of the pn junction depletion region which would exist in the absence of the field shaping region. The electric field in the field shaping region inducing a stretched electric field limited to a correspondingly stretched pn junction depletion region in the semiconductor region.

Abstract: A semiconductor device has a trench (42) adjacent to a cell (18). The cell includes source and drain contact regions (26, 28), and a central body (40) of opposite conductivity type. The device is bidirectional and controls current in either direction with a relatively low on-resistance. Preferred embodiments include potential plates (60) that act together with source and drain drift regions (30, 32) to create a RESURF effect.

Abstract: Semiconductor devices may be fabricated using nanowires. In an example embodiment, a conductive gate may be used to control conduction along the nanowires, in which case one of the contacts is a drain and the other a source. The nanowires may be grown in a trench or through-hole in a substrate or in particular in an epitaxial layer on substrate. In another example embodiment, the gate may be provided only at one end of the nanowires. The nanowires can be of the same material along their length; alternatively different materials can be used, especially different materials adjacent to the gate and between the gate and the base of the trench.

Abstract: A semiconductor device, for example a diode (200), having a pn junction (101) has an insulating material field shaping region (201) adjacent, and possibly bridging, the pn junction. The field shaping region (201) preferably has a high dielectric constant and is coupled via capacitive voltage coupling regions (204,205) to substantially the same voltages as are applied to the pn junction. When a reverse voltage is applied across the pn junction (101) and the device is non-conducting, a capacitive electric field, is present in a part of the field shaping region which extends beyond a limit of the pn junction depletion region which would exist in the absence of the field shaping region (201), the electric field in the field shaping region inducing a stretched electric field limited to a correspondingly stretched pn junction depletion region (208,209) and an increased reverse breakdown voltage of the device.

Abstract: A field-effect transistor having cells (18) each having a source region (22), source body region (26), drift region (20), drain body region (28) and drain region (24) arranged longitudinally, laterally alternating with structures to achieve a reduced surface field. In embodiments, the structures can include longitudinally spaced insulated gate trenches (35) defining a gate region (31) adjacent the source or drain region (22, 24) and a longitudinally extending potential plate region (33) adjacent the drift region (20). Alternatively, a separate potential plate region (33) or a longitudinally extending semi-insulating field plate (50) may be provided adjacent the drift region (20). The transistor is suitable for bi-directional switching.

Abstract: The invention relates to a trench MOSFET with drain (8), sub-channel region (10) body (12) and source (14). The sub-channel region is doped to be the same conductivity type as the body (12), but of lower doping density. A field plate electrode (34) is provided adjacent to the sub-channel region (10) 10 and a gate electrode (32) next to the body (12).

Abstract: A vertical insulated gate transistor is manufactured by providing a trench (26) extending through a source layer (8) and a channel layer (6) towards a drain layer (2). A spacer etch is used to form gate portions (20) along the trench side walls, a dielectric material (30) is filled into the trench between the sidewalls gate portions (20), and a gate electrical connection layer (30) is formed at the top of the trench electrically connecting the gate portions (20) across the trench.

Abstract: A trench-gate semiconductor device (100) has a trench network (STR1, ITR1) surrounding a plurality of closed transistor cells (TCS). The trench network comprises segment trench regions (STR1) adjacent sides of the transistor cells (TCS) and intersection trench regions (ITR1) adjacent corners of the transistor cells. As shown in FIG. 16 which is a section view along the line II-II of FIG. 11, the intersection trench regions (ITR1) each include insulating material (21D) which extends from the bottom of the intersection trench region with a thickness which is greater than the thickness of the insulating material (21B1) at the bottom of the segment trench regions (STR1). The greater thickness of the insulating material (21D) extending from the bottom of the intersection trench regions (ITR1) is effective to increase the drain-source reverse breakdown voltage of the device (100).

Abstract: A method of making a trench MOSFET includes forming a nitride liner 50 on the sidewalls 28 of a trench and a plug of doped polysilicon 26 at the bottom of a trench. The plug of polysilicon 26 may then be oxidised to form a thick oxide plug 30 at the bottom of the trench whilst the nitride liner 50 protects the sidewalls 28 from oxidation. This forms a thick oxide plug at the bottom of the trench thereby reducing capacitance between gate and drain.

Abstract: A RESURF trench gate MOSFET has a sufficiently small pitch (close spacing of neighbouring trenches) that intermediate areas of the drain drift region are depleted in the blocking condition of the MOSFET. However, premature breakdown can still occur in this known device structure at the perimeter/edge of the active device area and/or adjacent the gate bondpad. To counter premature breakdown, the invention adopts two principles: the gate bondpad is either connected to an underlying stripe trench network surrounded by active cells, or is directly on top of the active cells, and a compatible 2D edge termination scheme is provided around the RESURF active device area. These principles can be implemented in various cellular layouts e.g.

Abstract: In semiconductor devices which include an insulated trench electrode (11) in a trench (20), for example, trench-gate field effect power transistors and trenched Schottky diodes, a cavity (23) is provided between the bottom (25) of the trench electrode (11) and the bottom (27) of the trench (20) to reduce the dielectric coupling between the trench electrode (11) and the body portion at the bottom (27) of the trench in a compact manner. In power transistors, the reduction in dielectric coupling reduces switching power losses, and in Schottky diodes, it enables the trench width to be reduced.

Abstract: In semiconductor devices which include an insulated trench electrode (11) in a trench (20), for example, trench-gate field effect power transistors and trenched Schottky diodes, a cavity (23) is provided between the bottom (25) of the trench electrode (11) and the bottom (27) of the trench (20) to reduce the dielectric coupling between the trench electrode (11) and the body portion at the bottom (27) of the trench in a compact manner. In power transistors, the reduction in dielectric coupling reduces switching power losses, and in Schottky diodes, it enables the trench width to be reduced.

Abstract: A RESURF trench gate MOSFET has a sufficiently small pitch (close spacing of neighbouring trenches) that intermediate areas of the drain drift region are depleted in the blocking condition of the MOSFET. However, premature breakdown can still occur in this known device structure at the perimeter/edge of the active device area and/or adjacent the gate bondpad. To counter premature breakdown, the invention adopts two principles: the gate bondpad is either connected to an underlying stripe trench network surrounded by active cells, or is directly on top of the active cells, and a compatible 2D edge termination scheme is provided around the RESURF active device area. These principles can be implemented in various cellular layouts e.g.

Abstract: To avoid premature breakdown at the edge of the active area of RESURF trench-gate MOS device, an edge field plate (24) can be placed with a connection to the gate and a second spaced field plate (24) in the same trench (12). The gate trench network (12) could be either formed by hexagon unit cells or by square unit cells. Since the RESURF condition requires a small cell pitch, self-aligned processing could be used.

Abstract: A metal-oxide-semiconductor trench-gate semiconductor device in which a substantially intrinsic region (40) is provided below the gate trench (20), which extends from the base of the trench, substantially across the drain drift region (14) towards the drain contact region (14a), such that when the drain-source voltage falls during turn-on of the device its rate of decrease is higher. This reduces the switching losses of the device. The substantially intrinsic region (40) may, for example, be formed by implanting a region below the trench (20) with a damage implant.

Abstract: The invention relates to a trench bipolar transistor structure, having a base 7, emitter 9 and collector 4, the latter being divided into a higher doped region 3 and a lower doped drift region 5. An insulated gate 11 is provided to deplete the drift region 5 when the transistor is switched off. The gate 11 and/or doping levels in the drift region 5 are arranged to provide a substantially uniform electric field in the drift region in this state, to minimise breakdown. In particular, the gate 11 may be seminsulating and a voltage applied along the gate between connections 21,23.

Abstract: A field effect transistor semiconductor device (1) comprises a source region (33), a drain region (14) and a drain drift region (11), the device having a field shaping region (20) adjacent the drift region (11) and arranged such that, in use, when a voltage is applied between the source (33) and drain (14) regions and the device is non-conducting, a substantially constant electric field is generated in the field shaping region (20) and accordingly in the adjacent drift region (11). The field shaping region (20), which may be intrinsic semiconductor, is arranged to function as a capacitor dielectric region (20) between a first capacitor electrode region (21) and a second capacitor electrode region (22), the first and second capacitor electrode regions (21, 22) being adjacent respective ends of the dielectric region (20) and having different electron energy barriers.