GB2354879A - A high voltage semiconductor device termination structure - Google Patents

A high voltage semiconductor device termination structure Download PDF

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Publication number
GB2354879A
GB2354879A GB9918980A GB9918980A GB2354879A GB 2354879 A GB2354879 A GB 2354879A GB 9918980 A GB9918980 A GB 9918980A GB 9918980 A GB9918980 A GB 9918980A GB 2354879 A GB2354879 A GB 2354879A
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layer
semiconductor device
substrate
voltage termination
semiconductor
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GB9918980A
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GB9918980D0 (en
GB2354879B (en
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Tatjana Traijkovic
Florin Udrea
Gehan Anil Joseph Amaratunga
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Microsemi Semiconductor Ltd
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Mitel Semiconductor Ltd
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Priority to GB9918980A priority Critical patent/GB2354879B/en
Publication of GB9918980D0 publication Critical patent/GB9918980D0/en
Priority to EP00306256A priority patent/EP1076364A3/en
Priority to US09/636,111 priority patent/US6426520B1/en
Publication of GB2354879A publication Critical patent/GB2354879A/en
Application granted granted Critical
Publication of GB2354879B publication Critical patent/GB2354879B/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
    • H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
    • H01L29/0619—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
    • H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
    • H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
    • H01L29/0619—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
    • H01L29/0623—Buried supplementary region, e.g. buried guard ring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/70—Bipolar devices
    • H01L29/74—Thyristor-type devices, e.g. having four-zone regenerative action
    • H01L29/744—Gate-turn-off devices
    • H01L29/745—Gate-turn-off devices with turn-off by field effect
    • H01L29/7455—Gate-turn-off devices with turn-off by field effect produced by an insulated gate structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/70—Bipolar devices
    • H01L29/74—Thyristor-type devices, e.g. having four-zone regenerative action
    • H01L29/749—Thyristor-type devices, e.g. having four-zone regenerative action with turn-on by field effect
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/402—Field plates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/7801—DMOS transistors, i.e. MISFETs with a channel accommodating body or base region adjoining a drain drift region
    • H01L29/7802—Vertical DMOS transistors, i.e. VDMOS transistors
    • H01L29/7811—Vertical DMOS transistors, i.e. VDMOS transistors with an edge termination structure

Abstract

An integrated circuit comprises an active area containing a high voltage semiconductor device, preferably an acummulation layer emitted thyristor (structure disclosed), and a voltage termination structure located adjacent the active area. The termination area comprises a layered substrate region; bulk layer 23 and epitaxially grown layer 24. Epitaxial layer 24 has a higher doping than bulk layer 23. The voltage termination structure comprises first 21 and second 22 layers of guard rings. The second layer 22 of guard rings is formed at the junction between the bulk substrate and the epitaxial substrate. Doping levels are disclosed.

Description

1 2354879 A SEMICONDUCTOR DEVICE This invention relates to a semiconductor
device, and in particular to a power semiconductor device such as an accumulation layer emitted thyristor (ALET) and to a large class of high to ultra-high voltage devices such as diodes, DMOSFETs, DMOS 5 IGBTs, trench MOSFETs and trench IGBTs.
In order to prevent voltage breakdown at the edges of a power semiconductor device such as an ALET, the device (which is typically built in a relatively large silicon wafer) is provided with a termination structure. A standard termination structure utilises a floating ring termination technique having, say, p-type regions (rings) in a surface layer surrounding the active region (of n-type material) of the device.
The success of a controllable semiconductor device at high or ultra-high voltages is almost entirely determined by a successful implementation of the edge termination.
There are three main reasons which make the termination problem more difficult as the voltage ratings increase. Firstly, the number of floating rings increases significantly, and thus the wasted area and the ratio between the wasted area and the active area increases. This results in a poorer yield and a higher on-state voltage. Secondly, as the voltage increases, and accordingly the doping concentration of the base decreases, the device is more prone to parasitic field charge or passivation charge effects, which may cause premature breakdown. Thirdly, as the number of rings increases, the control of the depth and spacing between the rings becomes even tighter than that for a relatively-lower voltage termination, and therefore the termination effectiveness is very susceptible to process variations.
The present inventio n provides a semiconductor device comprising an active area with a voltage termination structure located adjacent to the active area at an edge portion of the device, the edge portion comprising a substrate region of a first semiconductor type, wherein the voltage termination structure comprises first and second layers formed 2 within the substrate region, the first and second layers defining regions each of a second semiconductor type.
Preferably, the first and second layers of the voltage termination structure each 5 comprises a plurality of semiconductor regions.
In a preferred embodiment, the edge portion surrounds the active area, the first and second layers of the voltage termination structure extending around the edge portion. Conveniently, the first and second layers of the voltage termination structure are formed as rings.
Advantageously, the first layer of the voltage termination structure is formed in the region of an upper surface of the substrate region, the second voltage termination layer being formed beneath the first layer.
Preferably, the first substrate region is formed of n-type semiconductor material, and the first and second layers of the voltage termination are formed of p-type semiconductor material, and the substrate region comprises first and second substrate layers. In the latter case, the second voltage termination layer is located at the junction between the first and second substrate layers, the first substrate layer is an epitaxial layer, and the second substrate layer is a drift layer.
Advantageously, the active area comprises a gate portion in the form of a trench which extends from an upper edge of the substrate region into an active area substrate region.
Conveniently, the plurality of semiconductor regions comprising the second voltage termination layer are formed so as to be equidistant to each other.
Preferably, the plurality of semiconductor regions comprising the second voltage termination layer are formed so as to provide an optimised potential distribution.
3 The semiconductor regions may be formed as separate rings, or as a mesh arrangement. It will be appreciated that the separate rings are not necessarily circular, but should substantially surround the active area of the device.
In a preferred embodiment, the plurality of semiconductor regions comprising the first voltage termination layer are formed so that their upper edges are in alignment with an upper edge of the active area of the device.
Advantageously, the semiconductor regions comprising the first voltage termination layer are arranged adjacent to one another. Preferably, the doping concentration of the semiconductor regions comprising the first voltage termination layer decreases as the distance from the active area of the device increases.
In a preferred embodiment, the semiconductor regions of the first voltage termination layer are floating p+ rings in the upper part of the substrate region.
A power semiconductor device constructed in accordance with the invention will now be described in greater detail, by way of example, with reference to the drawings, in which:
Figure I is a sectional view of the edge termination structure of the device; Figure 2 is a sectional view of part of the active area of the device; Figure 3 shows the potential distribution for a similar edge termination structure to that of Figure 1; Figure 4 shows the breakdown characteristics for the device of Figure 1; and Figure 5 is a sectional view of a modified form of the edge termination structure of Figure 1.
Referring to the drawings, Figure 1 shows the edge termination structure of an ALET, and Figure 2 shows the adjacent portion of the active area of the device. This device has a gate I in the form of a trench which extends through a region 2 of p-type silicon into an underlying n-type region 3 of low conductivity. Buried p regions 4 below the bottom of the trench form part of a thyristor which, in operation, is triggered into conduction by conduction of a PIN diode, which is produced when an accumulation layer 5 is formed in the n-type region 3 adjacent to the trench, under the action of a gate signal. The device has a high on-state conductivity, and is protected against high voltage breakdown in its off-stage by the presence of the buried layer. A cathode 6 is attached to the upper surface of the region 2 of p-type silicon, and an anode 7 is provided at the lower surface of the device. The device is described in greater detail in our British patent specification 2327295.
The device has a p+ silicon substrate 8 having the anode 7 on its lower surface. The n-type region 3 is an n-type epitaxial layer formed above an intermediate n+ epitaxial layer 9. The trench electrode 1 is of conductive polysilicon, and is provided with a thin insulating oxide layer I a at its outer surface. Small cathode diffusion regions 10 of n+ silicon are formed at the upper surface 11 of the device when it abuts the oxide layer Ia.
The pn junction between the regions 2 and 10 is electrically shorted at the surface 11 by the cathode 6.
The region 2 is formed by diffusion into the n-type region 3, and the buried p regions 4 are also formed by diffusion into the region 3 during a pause in its epitaxial growth.
As shown in Figure 1, the edge termination structure has a double layer configuration, having a first layer of shallow p+ rings 21 and a second layer of buried p+ rings 22.
The rings 21 are formed at the same level as the upper region 2 of p-type silicon (only the extreme edge of which can be seen in Figure 1) of the ALET. The rings 22 are formed at the junction of an n- drift layer 23 and an n- epitaxial layer 24 which are formed at the same time as the n-type region 3 of the active area of the device.
In the case of a 6.5 kV device, for example, the doping concentration of the n-drift layer 23 is I X 1012 CM-3. The p+ buried rings 22 are equidistant with a 5pm/5pLm width/spacing aspect ratio. The top concentration of the p+ buried rings 22 is I x 10111cm-3. The n-layer 24 grown above the buried rings 22 has a doping concentration of 5 x 1011cm-1. and a thickness of 7pm. The p+ surface rings 21 have a depth of 2gm, and a typical concentration of IX I011Cm-3.
The p+ shallow rings 21 are preferably formed at the same time as the ptype region 2, and more preferably using the same mask. Similarly, the p+ buried rings 22 are preferably formed at the same time as the buried regions 4, and more preferably using the same mask.
The p+ buried rings 22 act as a first potential lines filter, thus helping the spreading of the depletion region laterally, and realising a first step towards distributing the potential lines uniformly at the surface. The p+ shallow surface rings 21 constitute a second filter, which helps ftirther the redistribution of the potential lines evenly across the surface 11.
Figure 3 shows the distribution of the potential lines for a 1.2kV device, and illustrates the even distribution which results from the double layer termination of the invention. A 1.2kV device is used for this illustration, as the distribution for a 6.5 kV device would show many more potential lines, and this would make it difficult to see the even distribution.
The p+ buried rings 22 may be equidistant to each other, or they may be laid out in such way as to give an optimised potential distribution. In the first case, there is no need for aligning the p+ buried rings 22 to the surface 11, and they can be simply used in conjunction with the ALET. In the second case, the p+ rings 22 need to be aligned to the main surface 11, and the termination can be used for a more general purpose.
In comparison with a conventional termination technique, the use of the p+ buried rings 22 helps the distribution of the potential lines more uniformly at the surface, without sacrificing the surface area. Thus, in the conventional techniques, the use of several large and deep p+ buried rings results in a large wasted area, since the depletion region can only spread between those rings. In the termination of the invention, the p+ surface rings 21 are very shallow and narrow, and their number is limited -(the p+ surface rings are mainly needed in the proximity of the active area). For a 6.5 kV termination, the use of this termination technique may result in the termination region being as little as a half of that conventionally needed.
6 At the same time, the use of the buried layer implant 4, and the subsequent epitaxial growth, allows the n-layer 24 above the buried rings 22 to have a higher doping concentration than the bulk concentration of the n-layer 23, and therefore results in a device less susceptible to parasitic charges in the oxide or passivation layers.
Finally, the careful use of the p+ buried rings 22 may result in a higher breakdown voltage than that offered by a conventional termination, since the actual breakdown spot may be forced to take place in the bulk between two buried rings and not at the surface 11.
The graph of Figure 4 shows the numerical simulations of the breakdown voltage for the 6.5 kV ALET of Figure I with (a) no termination, (b) p+ surface rings only, (c) equidistant p+ buried layer rings only, and (d) the double layer termination of the invention, namely the p+ buried rings 21 and the p+ surface rings 21. Clearly, the double layer termination technique of the invention leads to much superior breakdown characteristics than either of the known techniques.
Figure 5 shows a modified form of the structure of Figure 1, wherein the first voltage termination layer is made of several (at least two) conductive regions (25, 26, 27) such that the region 25 closest to the active area is highly doped; and, as the distance from the active area increases, the doping of these regions 26, 27 decreases. The purpose of the second voltage termination layer is to act as a first filter for the potential lines, whilst the first voltage termination layer, comprising the above- mentioned regions 25,26, 27, provides even distribution of the potential lines at the device surface.
Preferably, at least one of the p type regions 25, 26, 27 is formed at the same time, and/or uses the same mask, as that used to form the p-base region 2.
7

Claims (1)

  1. Claims
    1. A semiconductor device comprising an active area with a voltage termination structure located adjacent to the active area at an edge portion of the device, the edge portion comprising a substrate region of a first semiconductor type, wherein the voltage termination structure comprises first and second layers formed within the substrate region, the first and second layers defining regions each of a second semiconductor type.
    2. A semiconductor device according to claim 1, wherein the first and second layers of the voltage termination structure each comprises a plurality of semiconductor regions.
    3. A semiconductor device according to claim I or claim 2, wherein the edge portion surrounds the active area, the first and second layers of the voltage termination structure extending around the edge portion.
    4. A semiconductor device according to claim 3, wherein the first and second layers of the voltage termination structure are formed as rings.
    5. A semiconductor device according to any preceding claim, wherein the first layer of the voltage termination structure is formed in the region of an upper surface of the substrate region, the second voltage termination layer being formed beneath the first layer.
    6. A semiconductor device according to any preceding claim, wherein the first substrate region is formed of n-type semiconductor material, and the first and second layers of the voltage termination structure are formed of p-type semiconductor material.
    7. A semiconductor device according to any preceding claim, wherein the substrate region comprises first and second substrate layers.
    8 8. A semiconductor device according to claim 7, wherein the second voltage termination layer is located at the junction between the first and second substrate layers.
    9. A semiconductor device according to claim 7 or claim 8, wherein the first substrate layer is an epitaxial layer, and the second substrate layer is a drift layer. 10. A semiconductor device according to any one of claims 7 and 9, wherein the active area extends into the first substrate layer from the upper surface of the substrate 10 region. 11. A semiconductor device according to any preceding claim, wherein the active area comprises a gate portion in the form of a trench which extends from an upper edge of the substrate region into an active area substrate region. 15 12. A semiconductor device according to any one of claims 7 to 11, wherein the doping concentration of the first substrate layer is higher than that of the second substrate layer. 20 13. A semiconductor device according to any one of claims 2 to 12, wherein the plurality of semiconductor regions comprising the second voltage termination layer are formed so as to be equidistant to each other. 14. A semiconductor device according to any one of claims 2 to 12, wherein the 25 plurality of semiconductor regions comprising the second voltage termination layer are formed so as to provide an optimised potential distribution. 15. A semiconductor device according to claim 14, wherein the plurality of semiconductor regions comprising the first voltage termination layer are formed so that 30 their upper edges are in alignment with an upper edge of the active area of the device.
    9 16. A semiconductor device according to claim 2, or to any one of claims 3 to 15 when appendant to claim 2, wherein the semiconductor regions comprising the first voltage termination layer are arranged adjacent to one another.
    17. A semiconductor device according to claim 2, or to any one of claims 3 to 16 when appendant to claim 2, wherein the doping concentration of the semiconductor regions comprising the first voltage termination layer decreases as the distance from the active area of the device increases. 10 18. A semiconductor device as claimed in claim 2, or in any one of claims 3 to 17 when appendant to claim 2, wherein the semiconductor regions of the first voltage termination layer are floating p+ rings in the upper part of the substrate region. 19. A semiconductor device according to any preceding claim, wherein the device 15 performs as an accumulation layer emitter thyristor (ALET), a diode, a DMOSFET, DMOS/GBT, a trench MOSFET, or a trench IGBT.
GB9918980A 1999-08-11 1999-08-11 A semiconductor device Expired - Fee Related GB2354879B (en)

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Application Number Priority Date Filing Date Title
GB9918980A GB2354879B (en) 1999-08-11 1999-08-11 A semiconductor device
EP00306256A EP1076364A3 (en) 1999-08-11 2000-07-24 Power semiconductor device
US09/636,111 US6426520B1 (en) 1999-08-11 2000-08-10 Semiconductor device

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JP6139356B2 (en) * 2013-09-24 2017-05-31 トヨタ自動車株式会社 Semiconductor device
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EP1076364A3 (en) 2003-07-30

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