EP1048074A1 - Power mosfet - Google Patents

Power mosfet

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Publication number
EP1048074A1
EP1048074A1 EP98966510A EP98966510A EP1048074A1 EP 1048074 A1 EP1048074 A1 EP 1048074A1 EP 98966510 A EP98966510 A EP 98966510A EP 98966510 A EP98966510 A EP 98966510A EP 1048074 A1 EP1048074 A1 EP 1048074A1
Authority
EP
European Patent Office
Prior art keywords
power mosfet
mosfet according
conductivity type
zone
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98966510A
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German (de)
French (fr)
Inventor
Jenö Tihanyi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Infineon Technologies AG
Original Assignee
Infineon Technologies AG
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Filing date
Publication date
Application filed by Infineon Technologies AG filed Critical Infineon Technologies AG
Publication of EP1048074A1 publication Critical patent/EP1048074A1/en
Withdrawn legal-status Critical Current

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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
    • H01L29/66—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
    • H01L29/7816—Lateral DMOS transistors, i.e. LDMOS transistors
    • 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
    • H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
    • H01L29/41725—Source or drain electrodes for field effect devices
    • H01L29/4175—Source or drain electrodes for field effect devices for lateral devices where the connection to the source or drain region is done through at least one part of the semiconductor substrate thickness, e.g. with connecting sink or with via-hole
    • 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
    • H01L29/7833—Field effect transistors with field effect produced by an insulated gate with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's
    • H01L29/7834—Field effect transistors with field effect produced by an insulated gate with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's with a non-planar structure, e.g. the gate or the source or the drain being non-planar
    • 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
    • H01L29/7833—Field effect transistors with field effect produced by an insulated gate with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's
    • H01L29/7835—Field effect transistors with field effect produced by an insulated gate with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's with asymmetrical source and drain regions, e.g. lateral high-voltage MISFETs with drain offset region, extended drain MISFETs
    • 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
    • H01L29/0684—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 the shape, relative sizes or dispositions of the semiconductor regions or junctions between the regions
    • H01L29/0692—Surface layout
    • H01L29/0696—Surface layout of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
    • 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
    • H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • 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
    • H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
    • H01L29/41725—Source or drain electrodes for field effect devices
    • H01L29/41766—Source or drain electrodes for field effect devices with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor
    • 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
    • H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • H01L29/423—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions not carrying the current to be rectified, amplified or switched
    • H01L29/42312—Gate electrodes for field effect devices
    • H01L29/42316—Gate electrodes for field effect devices for field-effect transistors
    • H01L29/4232—Gate electrodes for field effect devices for field-effect transistors with insulated gate
    • H01L29/42356—Disposition, e.g. buried gate electrode
    • H01L29/4236—Disposition, e.g. buried gate electrode within a trench, e.g. trench gate electrode, groove gate electrode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

  • the present invention relates to a power MOSFET with a semiconductor layer of the other conductivity type arranged on a highly doped semiconductor substrate of one conductivity type, in which a highly doped source zone of the other conductivity type and a highly doped drain zone of the other conductivity type are formed, and with one over a semiconductor zone of the a gate type provided conductivity type.
  • This object is achieved according to the invention in a power MOSFET of the type mentioned at the outset by a highly conductive connection between the source zone and the semiconductor substrate.
  • This highly conductive connection can in particular be a metallic conductive connection.
  • a metallically conductive connection is created between the source zone provided on one surface side of the power MOSFET to the opposite surface of the semiconductor substrate, so that the semiconductor substrate and with it the source zone, for example, by means of a cooling vane on a support, such as a car body , can be screwed on, the semiconductor substrate and thus the source zone being at 0 volts.
  • the source zone is guided “downwards" with the semiconductor substrate, which is why it is referred to as a "source-down" FET.
  • the actual MOSFET in the semiconductor layer can be of conventional construction, in which the gate electrode is embedded in an insulator layer provided on the semiconductor layer.
  • the gate electrode in a trench in the semiconductor layer, for example such a trench being lined at its edge with an insulating layer made of silicon dioxide or silicon nitride and filled inside with doped polycrystalline silicon.
  • the conductive connection between the source zone and the semiconductor substrate can be formed from a highly doped semiconductor zone of the one conductivity type.
  • a trench for this conductive connection from which dopant of one conductivity type is then diffused and which is filled with polycrystalline or monocrystalline silicon.
  • Another possibility for designing the conductive connection consists of a trench which is at least partially filled with metal or a highly conductive layer. Titanium nitride can preferably be used for such a layer. Otherwise, the interior of the trench can be covered with polycrystalline silicon. be filled, which is doped with dopant of the other conductivity type.
  • the semiconductor substrate itself can be provided directly with a cooling device, such as a cooling lug, which can be screwed onto a base. A particularly effective heat dissipation is thus achieved.
  • the semiconductor layer between the drain zone and the gate electrode is preferably less doped than in the drain zone. This enables the MOSFET to operate at higher voltages. Such an operation is also favored if the distance between the drain zone and the edge of the gate electrode is at least 0.1 ⁇ m to about 5 ⁇ m.
  • the thickness of the insulator layer should preferably increase too steadily or in steps in the direction of the drain zone.
  • the contact between the highly doped source zone and the conductive connection can take place by means of a buried metal, such as, for example, a suicide or another conductive layer made of, for example, titanium nitride.
  • a buried metal such as, for example, a suicide or another conductive layer made of, for example, titanium nitride.
  • the silicon dioxide insulator layer is deposited over the short circuit between the heavily doped source zone and the conductive connection. It is also possible to interrupt the metallization there for the drain zone, for example an aluminum layer.
  • the gate electrodes can be arranged in a grid-like manner and a “network” is formed from polycrystalline silicon of the other conductivity type, which is embedded in the insulator layer made of silicon dioxide or another material, such as silicon nitride.
  • the highly doped drain zones of the other conductivity type are preferably contacted with an all-over metal layer made of, for example, aluminum, which can be designed in a lattice shape if the individual source zones have an aluminum short circuit extending to their surface.
  • a distance of a few tenths to 5 .mu.m should exist in the insulator layer between the highly doped drain zone of the other conductivity type and the edge of the gate electrode made of polycrystalline silicon in order to achieve a high dielectric strength. This is also promoted if the thickness of the insulating layer in the region of the gate electrode increases too gradually or continuously in the direction of the drain zone.
  • the drain zone can also be located higher or lower than the source zone with respect to the semiconductor surface.
  • a highly doped zone of the one conductivity type is used for the conductive connection, then this zone can be produced in a manner similar to that used for insulation diffusion or for integrated circuits insulated with a pn junction.
  • the conductive connection can also be made via a trench, from which dopant of one conductivity type has diffused out, and which is then filled with polycrystalline or single-crystal silicon or with an insulator, such as silicon dioxide.
  • the arrangement of the drain connections and the source zones can be strip-shaped or cell-like.
  • this is implanted in a trench which surrounds the drain zone.
  • the source zone which is connected to the conductive connection, which preferably consists of a deep Trench with a conductive wall consists of titanium nitride, for example, to which the semiconductor substrate is electrically connected.
  • the conductive connections can be arranged in any way; they can be provided, for example, in the form of cells between strip-shaped drain zones or even in strip form.
  • FIG. 1 is a sectional view through a first embodiment of the MOSFET according to the invention
  • FIG. 2 shows a sectional view through a second exemplary embodiment of the MOSFET according to the invention
  • FIG. 3 shows a plan view to illustrate the position of source zones and drain zones in a cell arrangement with a plurality of power MOSFETs
  • Fig. 4 is a sectional view through a third embodiment of the present invention.
  • FIG. 1 shows a sectional view of a silicon semiconductor substrate 1 which is p ++ -conducting, that is to say has a high boron doping, for example.
  • An n-type semiconductor layer 2 is epitaxially applied to this semiconductor substrate 1, in which n + -conductive drain zones 3 and n + -conductive source zones 4 are provided.
  • a p-conducting channel zone 5 is located between the source zones 4 and the drain zones 3.
  • Zones 3, 4 and 5 can each have an annular shape.
  • An insulator layer 6 made of silicon dioxide is provided on the surface of the semiconductor layer 2, in which gate electrodes 7 made of polycrystalline silicon are embedded.
  • the drain zones 3 are contacted with a metallization 8 made of aluminum.
  • this zone 9 with the source zone 4 via a metal
  • An electrode 11 made of, for example, aluminum is applied to the semiconductor substrate 1 on the “underside”, and is connected to a cooling vane 12 made of a relatively thick metal layer, with which the MOSFET can be screwed onto, for example, a car body.
  • the metal 10 causes a short circuit between the source zone 4 and the p + -conducting zone 9.
  • a silicide or, for example, titanium nitride can be used for this metal 10.
  • the insulator layer 6 is deposited over this short-circuit point. Another possibility is to interrupt the metallization 8 via the short-circuit point.
  • the metal 10 extends to the outer surface of the semiconductor layer 2.
  • the gate electrodes 7 are arranged in a grid-like manner and preferably consist of n + -conducting polycrystalline silicon which is embedded in the insulator layer 6 made of silicon dioxide or another suitable insulating material.
  • the n + -conducting drain zones 3 are contacted with the metal metallization 8 made of aluminum.
  • the distance between the zones 3 and the edge of the gate electrode 7 should range from a few 0.1 ⁇ m to about 5 ⁇ m in order to achieve a high dielectric strength. For the same reason, it is also possible to allow the thickness of the insulator layer 6 to grow gradually or continuously below the gate electrode in the direction of the drain zone 3, although this is not shown in FIG. 1.
  • the drain zone 3 can also be located higher or lower than the source zone 4.
  • FIG. 2 shows a further exemplary embodiment of the power MOSFET according to the invention, which differs from the exemplary embodiment in FIG. 1 in that the conductive connection consists of a trench 13 into which p + -conducting polycrystalline or monocrystalline silicon 14 is filled , from which a p + -conducting zone 15 has diffused into the semiconductor layer 2.
  • a dashed line 22 indicates how the thickness of the insulator layer 6 below the gate electrode 7, the underside of which is given by this dashed line 22, can continuously increase in the direction of the drain zone 3.
  • FIG. 3 shows a plan view of a large number of power MOSFETs, it being indicated here how the respective source zones 4 or drain zones 3 can be arranged, and the edge of this arrangement being designed as a source strip.
  • FIGS. 1 and 2 show a power MOSFET in which the gate electrodes are used in "traditional" Are arranged.
  • FIG. 4 shows a sectional view of a power MOSFET in which the gate electrodes 7 are accommodated in trenches 16 which are filled with insulating material 17, for example silicon dioxide, in which n + -doped polycrystalline silicon is contained. These grooves 16 extend up to a p ⁇ -lei- Tenden layer 18, the p + -type between the silicon substrate 1 and the n "-type silicon layer 2 is arranged.
  • the conductive connection between the source zones 4 and the semiconductor substrate 1 takes place here via trenches 19 which are filled with highly conductive material, such as, for example, titanium nitride 20 at their edge and in their interior with n + -conducting polycrystalline silicon 21.
  • highly conductive material such as, for example, titanium nitride 20 at their edge and in their interior with n + -conducting polycrystalline silicon 21.
  • an insulator for example silicon dioxide or silicon nitride, which can have a cavity, can also be used.
  • a metal such as tungsten, can also be introduced into the trench for the conductive connection.
  • the layer thicknesses are for example, 0.2 mm for the semiconductor substrate 1, 2 micron layer 18 for the p ⁇ -type, 3 microns for the "height" of the gate electrodes 7 and 4 microns for the n ⁇ - type semiconductor layer 2 having a resistivity of, for example, 0.5 ohm / cm.
  • the distance between the trenches 16 can be approximately 4 ⁇ m, each trench 16 having a width of approximately 1 ⁇ m.
  • the trenches 19 can also have a width of approximately 1 ⁇ m.
  • the course of the current I is indicated in FIG. 4 by a broken line: it leads from the electrode 11 through the semiconductor substrate 1, the p " -type layer 18 into the n " -line layer 2 and from there around the gate electrode 7 around to the drain zone 3.
  • the trenches 19 with the short circuit between the semiconductor substrate 1 and the source zones 4 can be arranged as desired. They can be provided, for example, in a cell-like manner between strip-shaped drain zones 3 and, if appropriate, can also be designed in the form of strips.

Abstract

The invention relates to a power MOSFET comprising a first conductive type highly doped semiconductor substrate (1) upon which a second conductive type semiconductor layer (2) is arranged and wherein a second conductive type highly doped source zone (4) and a second conductive type highly doped drain zone (3) are formed, in addition to a gate electrode (7). A metal conducting connection (9) runs between the source zone (4) and the semiconductor substrate (1). The MOSFET is thus embodied as a source down MOSFET and heat is dissipated by means of the semiconductor substrate or a cooling device (12) installed thereon.

Description

Leistungs-MOSFETPower MOSFET
Die vorliegende Erfindung bezieht sich auf einen Leistungs- MOSFET mit einer auf einem hochdotierten Halbleitersubstrat des einen Leitfähigkeitstyps angeordneten Halbleiterschicht des anderen Leitfähigkeitstyps, in der eine hochdotierte Sourcezone des anderen Leitfähigkeitstyps und eine hochdotierte Drainzone des anderen Leitfähigkeitstyps ausgebildet sind, und mit einer über einer Halbleiterzone des einen Leitfähigkeitstyps vorgesehenen Gateelektrode.The present invention relates to a power MOSFET with a semiconductor layer of the other conductivity type arranged on a highly doped semiconductor substrate of one conductivity type, in which a highly doped source zone of the other conductivity type and a highly doped drain zone of the other conductivity type are formed, and with one over a semiconductor zone of the a gate type provided conductivity type.
Bei Leistungs-MOSFETs spielt deren Kühlung bzw. die Wärmeabführung aus dem Halbleiterkörper eine herausragende Rolle. Diese wäre sehr einfach, wenn beispielsweise bei einem n- Kanal-MOSFET dessen Halbleitersubstrat, das gegebenenfalls mit einer Kühlfahne ausgestattet ist, direkt auf einen die Wärme aufnehmenden Körper, wie beispielsweise eine Autokarosserie, aufgeschraubt werden könnte. Voraussetzung hierfür ist, daß das Halbleitersubstrat und mit diesem die Sourcezone auf 0 Volt liegen können und der MOSFET in seinen sonstigen Eigenschaften nicht beeinträchtigt ist, also beispielsweise keinen zu hohen Einschaltwiderstand aufweist.In power MOSFETs, their cooling or heat dissipation from the semiconductor body play an outstanding role. This would be very simple if, for example, in the case of an n-channel MOSFET, its semiconductor substrate, which may be equipped with a cooling vane, could be screwed directly onto a heat-absorbing body, such as a car body. The prerequisite for this is that the semiconductor substrate and with it the source zone can be at 0 volts and the other properties of the MOSFET are not impaired, that is to say, for example, they do not have an on-resistance which is too high.
Es ist daher Aufgabe der vorliegenden Erfindung, einen Leistungs-MOSFET zu schaffen, dessen Halbleitersubstrat auf 0 Volt Spannung kühlbar ist, und der keinen zu hohen Einschaltwiderstand zeigt.It is therefore an object of the present invention to provide a power MOSFET whose semiconductor substrate can be cooled to 0 volt and which does not show an on-resistance which is too high.
Diese Aufgabe wird bei einem Leistungs-MOSFET der eingangs genannten Art erfindungsgemäß gelöst durch eine gut leitende Verbindung zwischen Sourcezone und Halbleitersubstrat. Diese gut leitende Verbindung kann insbesondere eine metallisch leitende Verbindung sein. Bei der vorliegenden Erfindung wird also eine metallisch leitende Verbindung zwischen der an der einen Oberflächenseite des Leistungs-MOSFETs vorgesehenen Sourcezone zu der gegenüberliegenden Oberfläche des Halbleitersubstrates geschaffen, so daß das Halbleitersubstrat und mit diesem die Sourcezone beispielsweise mittels einer Kühlfahne auf eine Unterlage, wie eine Autokarosserie, aufgeschraubt werden kann, wobei das Halbleitersubstrat und damit die Sourcezone auf 0 Volt liegen. Mit dem Halbleitersubstrat ist bei einer solchen Struktur die Sourcezone "nach unten" geführt, weshalb von einem "Source-Down"-FET gesprochen wird.This object is achieved according to the invention in a power MOSFET of the type mentioned at the outset by a highly conductive connection between the source zone and the semiconductor substrate. This highly conductive connection can in particular be a metallic conductive connection. In the present invention, therefore, a metallically conductive connection is created between the source zone provided on one surface side of the power MOSFET to the opposite surface of the semiconductor substrate, so that the semiconductor substrate and with it the source zone, for example, by means of a cooling vane on a support, such as a car body , can be screwed on, the semiconductor substrate and thus the source zone being at 0 volts. With such a structure, the source zone is guided "downwards" with the semiconductor substrate, which is why it is referred to as a "source-down" FET.
Der eigentliche MOSFET in der Halbleiterschicht kann von üblichem Aufbau sein, bei dem die Gateelektrode in eine auf der Halbleiterschicht vorgesehene Isolatorschicht eingebettet ist. Es ist aber auch möglich, die Gateelektrode in einem Graben in der Halbleiterschicht unterzubringen, wobei beispielsweise ein solcher Graben an seinem Rand mit einer Isolierschicht aus Siliziumdioxid oder Siliziumnitrid ausgekleidet und in seinem Innern mit dotiertem polykristallinem Silizium gefüllt wird.The actual MOSFET in the semiconductor layer can be of conventional construction, in which the gate electrode is embedded in an insulator layer provided on the semiconductor layer. However, it is also possible to accommodate the gate electrode in a trench in the semiconductor layer, for example such a trench being lined at its edge with an insulating layer made of silicon dioxide or silicon nitride and filled inside with doped polycrystalline silicon.
Die leitende Verbindung zwischen der Sourcezone und dem Halbleitersubstrat kann aus einer hochdotierten Halbleiterzone des einen Leitfähigkeitstyps gebildet werden. Es ist aber auch möglich, für diese leitende Verbindung einen Graben vorzusehen, aus welchem dann Dotierstoff des einen Leitfähigkeitstyps aufdiffundiert wird und der mit poly- oder monokristallinem Silizium aufgefüllt wird. Eine andere Möglichkeit zur Gestaltung der leitenden Verbindung besteht aus einem Graben, der wenigstens teilweise mit Metall oder einer gut leitenden Schicht gefüllt ist. Für eine solche Schicht kann vorzugsweise Titannitrid eingesetzt werden. Im übrigen kann das Innere des Grabens mit polykristallinem Silizium aufge- füllt werden, das mit Dotierstoff des anderen Leitfähigkeitstyps dotiert ist.The conductive connection between the source zone and the semiconductor substrate can be formed from a highly doped semiconductor zone of the one conductivity type. However, it is also possible to provide a trench for this conductive connection, from which dopant of one conductivity type is then diffused and which is filled with polycrystalline or monocrystalline silicon. Another possibility for designing the conductive connection consists of a trench which is at least partially filled with metal or a highly conductive layer. Titanium nitride can preferably be used for such a layer. Otherwise, the interior of the trench can be covered with polycrystalline silicon. be filled, which is doped with dopant of the other conductivity type.
Das Halbleitersubstrat selbst kann direkt mit einer Kühleinrichtung, wie beispielsweise einer Kühlfahne, die auf eine Unterlage aufschraubbar ist, versehen werden. Damit wird eine besonders wirksame Wärmeabführung erreicht.The semiconductor substrate itself can be provided directly with a cooling device, such as a cooling lug, which can be screwed onto a base. A particularly effective heat dissipation is thus achieved.
Die Halbleiterschicht ist zwischen der Drainzone und der Gateelektrode vorzugsweise schwächer dotiert als in der Drainzone. Dadurch ist ein Betrieb des MOSFETs mit höheren Spannungen möglich. Ein solcher Betrieb wird auch dadurch begünstigt, wenn der Abstand zwischen der Drainzone und der Kante der Gateelektrode wenigstens 0,1 um bis etwa 5 um beträgt. Auch sollte die Dicke der Isolatorschicht vorzugsweise in Richtung auf die Drainzone zu stetig oder stufenartig anwachsen.The semiconductor layer between the drain zone and the gate electrode is preferably less doped than in the drain zone. This enables the MOSFET to operate at higher voltages. Such an operation is also favored if the distance between the drain zone and the edge of the gate electrode is at least 0.1 µm to about 5 µm. The thickness of the insulator layer should preferably increase too steadily or in steps in the direction of the drain zone.
Die Kontaktgabe zwischen der hochdotierten Sourcezone und der leitenden Verbindung kann mittels eines vergrabenen Metalles, wie beispielsweise eines Suizides oder einer anderen leitenden Schicht aus beispielsweise Titannitrid erfolgen.The contact between the highly doped source zone and the conductive connection can take place by means of a buried metal, such as, for example, a suicide or another conductive layer made of, for example, titanium nitride.
Über der Kurzschlußstelle zwischen der hochdotierten Sourcezone und der leitenden Verbindung ist die Isolatorschicht aus Siliziumdioxid abgeschieden. Es ist auch möglich, dort die Metallisierung für die Drainzone, also beispielsweise eine Aluminiumschicht, zu unterbrechen.The silicon dioxide insulator layer is deposited over the short circuit between the heavily doped source zone and the conductive connection. It is also possible to interrupt the metallization there for the drain zone, for example an aluminum layer.
Die Gateelektroden können gitterartig angeordnet sein und ein "Netz" aus polykristallinem Silizium des anderen Leitfähigkeitstyps gebildet ist, welches in die Isolatorschicht aus Siliziumdioxid oder einem anderen Material, wie beispielsweise Siliziumnitrid eingebettet ist. Die hochdotierten Drainzonen des anderen Leitfähigkeitstyps sind vorzugsweise mit einer ganzflächigen Metallschicht aus beispielsweise Aluminium kontaktiert, die gitterförmig gestaltet sein kann, wenn die einzelnen Sourcezonen einen bis zu ihrer Oberfläche reichenden Aluminium-Kurzschluß haben.The gate electrodes can be arranged in a grid-like manner and a “network” is formed from polycrystalline silicon of the other conductivity type, which is embedded in the insulator layer made of silicon dioxide or another material, such as silicon nitride. The highly doped drain zones of the other conductivity type are preferably contacted with an all-over metal layer made of, for example, aluminum, which can be designed in a lattice shape if the individual source zones have an aluminum short circuit extending to their surface.
Zwischen der hochdotierten Drainzone des anderen Leitfähigkeitstyps und der Kante der aus polykristallinem Silizium bestehenden Gateelektrode sollte in der Isolatorschicht ein Abstand von einigen Zehntel um bis 5 um bestehen, um eine hohe Spannungsfestigkeit zu erreichen. Diese wird auch dadurch gefördert, wenn die Dicke der Isolierschicht im Bereich der Gateelektrode in Richtung auf die Drainzone zu stufenartig oder stetig anwächst. Auch kann die Drainzone in bezug auf die Halbleiteroberfläche höher oder tiefer gelegen sein als die Sourcezone.A distance of a few tenths to 5 .mu.m should exist in the insulator layer between the highly doped drain zone of the other conductivity type and the edge of the gate electrode made of polycrystalline silicon in order to achieve a high dielectric strength. This is also promoted if the thickness of the insulating layer in the region of the gate electrode increases too gradually or continuously in the direction of the drain zone. The drain zone can also be located higher or lower than the source zone with respect to the semiconductor surface.
Wenn für die leitende Verbindung eine hochdotierte Zone des einen Leitfähigkeitstyps verwendet wird, dann kann diese Zone auf ähnliche Weise hergestellt werden, wie dies bei Isolierdiffusionen oder bei mit einem pn-Übergang isolierten integrierten Schaltungen geschieht. Die leitende Verbindung kann aber auch über einen Graben erfolgen, aus welchem Dotierstoff des einen Leitfähigkeitstyps ausdiffundiert ist, und der dann mit polykristallinem oder einkristallinem Silizium oder mit einem Isolator, wie beispielsweise Siliziumdioxid aufgefüllt wird.If a highly doped zone of the one conductivity type is used for the conductive connection, then this zone can be produced in a manner similar to that used for insulation diffusion or for integrated circuits insulated with a pn junction. However, the conductive connection can also be made via a trench, from which dopant of one conductivity type has diffused out, and which is then filled with polycrystalline or single-crystal silicon or with an insulator, such as silicon dioxide.
Die Anordnung der Drainanschlüsse und der Sourcezonen kann streifenförmig oder zellenartig sein. Bei einer in der Halbleiterschicht vorgesehenen Gateelektrode ist diese in einen Graben eingepflanzt, der die Drainzone umringt. Außerhalb des Grabens ist die Sourcezone angeordnet, welche mit der leitenden Verbindung, die in bevorzugter Weise aus einem tiefen Graben mit leitfähiger Wand aus beispielsweise Titannitrid besteht, mit dem Halbleitersubstrat elektrisch verbunden ist.The arrangement of the drain connections and the source zones can be strip-shaped or cell-like. In the case of a gate electrode provided in the semiconductor layer, this is implanted in a trench which surrounds the drain zone. Outside the trench is the source zone, which is connected to the conductive connection, which preferably consists of a deep Trench with a conductive wall consists of titanium nitride, for example, to which the semiconductor substrate is electrically connected.
Die leitenden Verbindungen können beliebig angeordnet sein; sie können beispielsweise zellenförmig zwischen streifenför- migen Drainzonen oder selbst streifenförmig vorgesehen werden.The conductive connections can be arranged in any way; they can be provided, for example, in the form of cells between strip-shaped drain zones or even in strip form.
Nachfolgend wird die Erfindung anhand der Zeichnungen näher erläutert. Es zeigen:The invention is explained in more detail below with reference to the drawings. Show it:
Fig. 1 ein Schnittbild durch ein erstes Ausführungsbeispiel des erfindungsgemäßen MOSFETs,1 is a sectional view through a first embodiment of the MOSFET according to the invention,
Fig. 2 ein Schnittbild durch ein zweites Ausführungsbeispiel des erfindungsgemäßen MOSFETs,2 shows a sectional view through a second exemplary embodiment of the MOSFET according to the invention,
Fig. 3 eine Draufsicht zur Veranschaulichung der Lage von Sourcezonen und Drainzonen bei einer Zellenanordnung mit mehreren Leistungs- MOSFETs, und3 shows a plan view to illustrate the position of source zones and drain zones in a cell arrangement with a plurality of power MOSFETs, and
Fig. 4 ein Schnittbild durch ein drittes Ausführungsbeispiel der vorliegenden Erfindung.Fig. 4 is a sectional view through a third embodiment of the present invention.
Fig. 1 zeigt in einem Schnittbild ein Silizium-Halbleitersubstrat 1, das p++-leitend ist, also beispielsweise eine hohe Bordotierung aufweist. Auf dieses Halbleitersubstrat 1 ist epitaktisch eine n-leitende Halbleiterschicht 2 aufgetragen, in welcher n+-leitende Drainzonen 3 sowie n+-leitende Sourcezonen 4 vorgesehen sind. Zwischen den Sourcezonen 4 und den Drainzonen 3 befindet sich eine p-leitende Kanalzone 5.1 shows a sectional view of a silicon semiconductor substrate 1 which is p ++ -conducting, that is to say has a high boron doping, for example. An n-type semiconductor layer 2 is epitaxially applied to this semiconductor substrate 1, in which n + -conductive drain zones 3 and n + -conductive source zones 4 are provided. A p-conducting channel zone 5 is located between the source zones 4 and the drain zones 3.
Die Zonen 3, 4 und 5 können jeweils ringförmig gestaltet sein. Auf der Oberfläche der Halbleiterschicht 2 ist eine Isolatorschicht 6 aus Siliziumdioxid vorgesehen, in die Gateelektroden 7 aus polykristallinem Silizium eingebettet sind. Die Drainzonen 3 sind mit einer Metallisierung 8 aus Aluminium kontaktiert.Zones 3, 4 and 5 can each have an annular shape. An insulator layer 6 made of silicon dioxide is provided on the surface of the semiconductor layer 2, in which gate electrodes 7 made of polycrystalline silicon are embedded. The drain zones 3 are contacted with a metallization 8 made of aluminum.
Zwischen dem Halbleitersubstrat 1 und der Sourcezone 4 befindet sich eine leitende Verbindung aus einer p+-leitenden ZoneBetween the semiconductor substrate 1 and the source zone 4 there is a conductive connection from a p + -conducting zone
9, wobei diese Zone 9 mit der Sourcezone 4 über ein Metall9, this zone 9 with the source zone 4 via a metal
10, wie beispielsweise ein Silizid oder Titannitrid verbunden ist.10, such as a silicide or titanium nitride.
Auf das Halbleitersubstrat 1 ist an der "Unterseite" eine Elektrode 11 aus beispielsweise Aluminium aufgetragen, die mit einer Kühlfahne 12 aus einer relativ dicken Metallschicht verbunden ist, mit welcher der MOSFET an beispielsweise einer Autokarosserie angeschraubt werden kann.An electrode 11 made of, for example, aluminum is applied to the semiconductor substrate 1 on the “underside”, and is connected to a cooling vane 12 made of a relatively thick metal layer, with which the MOSFET can be screwed onto, for example, a car body.
Wesentlich an der vorliegenden Erfindung ist, daß von der Sourcezone 4 über das Metall 10 und die hochdotierte Zone 9 eine leitende Verbindung zu dem Halbleitersubstrat 1 besteht, so daß die Sourcezone "unten" über die Elektrode 11 kontaktiert ist ("Source-Down-MOSFET") .It is essential to the present invention that there is a conductive connection from the source zone 4 via the metal 10 and the heavily doped zone 9 to the semiconductor substrate 1, so that the source zone is contacted “below” via the electrode 11 (“source-down MOSFET ").
Das Metall 10 bewirkt einen Kurzschluß zwischen der Sourcezone 4 und der p+-leitenden Zone 9. Für dieses Metall 10 kann, wie bereits oben erläutert wurde, ein Silizid oder auch beispielsweise Titannitrid verwendet werden. Über dieser Kurzschlußstelle ist die Isolatorschicht 6 abgeschieden. Eine andere Möglichkeit besteht darin, über der Kurzschlußstelle die Metallisierung 8 zu unterbrechen. Jedenfalls reicht das Metall 10 bis zur äußeren Oberfläche der Halbleiterschicht 2. Die Gateelektroden 7 sind gitterartig angeordnet und bestehen vorzugsweise aus n+-leitendem polykristallinem Silizium, das in die Isolatorschicht 6 aus Siliziumdioxid oder einem anderen geeigneten Isoliermaterial eingebettet ist.The metal 10 causes a short circuit between the source zone 4 and the p + -conducting zone 9. As already explained above, a silicide or, for example, titanium nitride can be used for this metal 10. The insulator layer 6 is deposited over this short-circuit point. Another possibility is to interrupt the metallization 8 via the short-circuit point. In any case, the metal 10 extends to the outer surface of the semiconductor layer 2. The gate electrodes 7 are arranged in a grid-like manner and preferably consist of n + -conducting polycrystalline silicon which is embedded in the insulator layer 6 made of silicon dioxide or another suitable insulating material.
Die n+-leitenden Drainzonen 3 sind mit der ganzflächigen Metallisierung 8 aus Aluminium kontaktiert. Der Abstand zwischen den Zonen 3 und der Kante der Gateelektrode 7 sollte von einigen 0,1 μm bis etwa 5 μm reichen, um eine hohe Spannungsfestigkeit zu erzielen. Aus dem gleichen Grund ist es auch möglich, die Dicke der Isolatorschicht 6 unterhalb der Gateelektrode in Richtung auf die Drainzone 3 stufenweise oder stetig anwachsen zu lassen, obwohl dies in Fig. 1 nicht dargestellt ist. Auch kann die Drainzone 3 höher oder tiefer gelegen sein als die Sourcezone 4.The n + -conducting drain zones 3 are contacted with the metal metallization 8 made of aluminum. The distance between the zones 3 and the edge of the gate electrode 7 should range from a few 0.1 μm to about 5 μm in order to achieve a high dielectric strength. For the same reason, it is also possible to allow the thickness of the insulator layer 6 to grow gradually or continuously below the gate electrode in the direction of the drain zone 3, although this is not shown in FIG. 1. The drain zone 3 can also be located higher or lower than the source zone 4.
Fig. 2 zeigt ein weiteres Ausführungsbeispiel des erfindungsgemäßen Leistungs-MOSFETs, das sich von dem Ausführungsbei- spiel der Fig. 1 dadurch unterscheidet, daß die leitende Verbindung aus einem Graben 13 besteht, in den p+-leitendes polykristallines oder monokristallines Silizium 14 gefüllt ist, aus welchem eine p+-leitende Zone 15 in die Halbleiterschicht 2 ausdiffundiert ist. Mit einer Strichlinie 22 ist angedeutet, wie die Dicke der Isolatorschicht 6 unterhalb der Gateelektrode 7, deren Unterseite durch diese Strichlinie 22 gegeben ist, in Richtung auf die Drainzone 3 kontinuierlich anwachsen kann.FIG. 2 shows a further exemplary embodiment of the power MOSFET according to the invention, which differs from the exemplary embodiment in FIG. 1 in that the conductive connection consists of a trench 13 into which p + -conducting polycrystalline or monocrystalline silicon 14 is filled , from which a p + -conducting zone 15 has diffused into the semiconductor layer 2. A dashed line 22 indicates how the thickness of the insulator layer 6 below the gate electrode 7, the underside of which is given by this dashed line 22, can continuously increase in the direction of the drain zone 3.
Fig. 3 zeigt eine Draufsicht auf eine Vielzahl von Leistungs- MOSFETs, wobei hier angegeben ist, wie die jeweiligen Sourcezonen 4 bzw. Drainzonen 3 angeordnet werden können, und wobei der Rand dieser Anordnung als Source-Streifen ausgeführt ist.3 shows a plan view of a large number of power MOSFETs, it being indicated here how the respective source zones 4 or drain zones 3 can be arranged, and the edge of this arrangement being designed as a source strip.
Die Ausführungsbeispiele der Fig. 1 und 2 zeigen einen Leistungs-MOSFET, bei dem die Gateelektroden in "traditioneller" Weise angeordnet sind. Im Gegensatz hierzu ist in Fig. 4 ein Schnittbild eines Leistungs-MOSFETs dargestellt, bei dem die Gateelektroden 7 in Gräben 16 untergebracht sind, die mit Isoliermaterial 17, wie beispielsweise Siliziumdioxid, gefüllt sind, in welchem n+-dotiertes polykristallines Silizium enthalten ist. Diese Gräben 16 reichen bis zu einer p~-lei- tenden Schicht 18, die zwischen dem p+-leitenden Siliziumsubstrat 1 und der n"-leitenden Siliziumschicht 2 angeordnet ist.The exemplary embodiments in FIGS. 1 and 2 show a power MOSFET in which the gate electrodes are used in "traditional" Are arranged. In contrast to this, FIG. 4 shows a sectional view of a power MOSFET in which the gate electrodes 7 are accommodated in trenches 16 which are filled with insulating material 17, for example silicon dioxide, in which n + -doped polycrystalline silicon is contained. These grooves 16 extend up to a p ~ -lei- Tenden layer 18, the p + -type between the silicon substrate 1 and the n "-type silicon layer 2 is arranged.
Die leitende Verbindung zwischen den Sourcezonen 4 und dem Halbleitersubstrat 1 erfolgt hier über Gräben 19, die mit gut leitendem Material, wie beispielsweise Titannitrid 20 an ihrem Rand und in ihrem Inneren mit n+-leitendem polykristallinem Silizium 21 gefüllt sind. Anstelle des polykristallinen Siliziums kann auch ein Isolator, beispielsweise Siliziumdioxid oder Siliziumnitrid verwendet werden, das einen Hohlraum aufweisen kann. Für die leitende Verbindung kann auch ein Metall, wie beispielsweise Wolfram, in den Graben eingebracht werden.The conductive connection between the source zones 4 and the semiconductor substrate 1 takes place here via trenches 19 which are filled with highly conductive material, such as, for example, titanium nitride 20 at their edge and in their interior with n + -conducting polycrystalline silicon 21. Instead of polycrystalline silicon, an insulator, for example silicon dioxide or silicon nitride, which can have a cavity, can also be used. A metal, such as tungsten, can also be introduced into the trench for the conductive connection.
Die Schichtdicken betragen beispielsweise 0,2 mm für das Halbleitersubstrat 1, 2 μm für die p~-leitende Schicht 18, 3 μm für die "Höhe" der Gateelektroden 7 und 4 μm für die n~- leitende Halbleiterschicht 2, die einen spezifischen Widerstand von beispielsweise 0,5 Ohm/cm haben kann. Der Abstand zwischen den Gräben 16 kann etwa 4 μm betragen, wobei jeder Graben 16 eine Breite von etwa 1 μm hat. Auch die Gräben 19 können eine Breite von etwa 1 μm aufweisen.The layer thicknesses are for example, 0.2 mm for the semiconductor substrate 1, 2 micron layer 18 for the p ~ -type, 3 microns for the "height" of the gate electrodes 7 and 4 microns for the n ~ - type semiconductor layer 2 having a resistivity of, for example, 0.5 ohm / cm. The distance between the trenches 16 can be approximately 4 μm, each trench 16 having a width of approximately 1 μm. The trenches 19 can also have a width of approximately 1 μm.
Der Verlauf des Stromes I ist in Fig. 4 durch eine Strichlinie angedeutet: er führt von der Elektrode 11 durch das Halbleitersubstrat 1, die p"-leitende Schicht 18 in die n"-lei- tende Schicht 2 und von dort um die Gateelektrode 7 herum zu der Drainzone 3. Die Gräben 19 mit dem Kurzschluß zwischen dem Halbleitersubstrat 1 und den Sourcezonen 4 können beliebig angeordnet sein. Sie können beispielsweise zellenförmig zwischen strei- fenförmigen Drainzonen 3 vorgesehen und gegebenenfalls ebenfalls streifenförmig ausgeführt werden. The course of the current I is indicated in FIG. 4 by a broken line: it leads from the electrode 11 through the semiconductor substrate 1, the p " -type layer 18 into the n " -line layer 2 and from there around the gate electrode 7 around to the drain zone 3. The trenches 19 with the short circuit between the semiconductor substrate 1 and the source zones 4 can be arranged as desired. They can be provided, for example, in a cell-like manner between strip-shaped drain zones 3 and, if appropriate, can also be designed in the form of strips.

Claims

Patentansprüche claims
1. Leistungs-MOSFET mit einer auf einem hochdotierten Halbleitersubstrat (1) des einen Leitfähigkeitstyps angeordneten Halbleiterschicht (2) des anderen Leitfähigkeitstyps, in der eine hochdotierte Sourcezone (4) des anderen Leitfähigkeitstyps und eine hochdotierte Drainzone (3) des anderen Leitfähigkeitstyps ausgebildet sind, und mit einer über einer Halbleiterzone (S) des einen Leitfähigkeitstyps vorgesehenen Gateelektrode (7), gekennzeichnet durch eine gut leitende Verbindung (9; 19, 20, 21) zwischen Sourcezone (4) und Halbleitersubstrat (1) .1. Power MOSFET with a semiconductor layer (2) of the other conductivity type arranged on a highly doped semiconductor substrate (1) of one conductivity type, in which a highly doped source zone (4) of the other conductivity type and a highly doped drain zone (3) of the other conductivity type are formed, and with a gate electrode (7) provided over a semiconductor zone (S) of the one conductivity type, characterized by a highly conductive connection (9; 19, 20, 21) between the source zone (4) and the semiconductor substrate (1).
2. Leistungs-MOSFET nach Anspruch 1, dadurch gekennzeichnet, daß die Gateelektrode (7) in einer auf der Halbleiterschicht (2) angeordneten Isolatorschicht (6) vorgesehen ist.2. Power MOSFET according to claim 1, characterized in that the gate electrode (7) in an on the semiconductor layer (2) arranged insulator layer (6) is provided.
3. Leistungs-MOSFET nach Anspruch 1, dadurch gekennzeichnet, daß die Gateelektrode (7) in einem Graben (16) in der Halbleiterschicht (2) vorgesehen ist.3. Power MOSFET according to claim 1, characterized in that the gate electrode (7) is provided in a trench (16) in the semiconductor layer (2).
4. Leistungs-MOSFET nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die leitende Verbindung (9) aus einer hochdotierten Halbleiterzone des einen Leitfähigkeitstyps gebildet ist.4. Power MOSFET according to one of claims 1 to 3, characterized in that the conductive connection (9) is formed from a highly doped semiconductor zone of one conductivity type.
5. Leistungs-MOSFET nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die leitende Verbindung aus einem Graben (13) gebildet ist, aus dem Dotierstoff des einen Leitf higkeitstyps (15) ausdiffundiert ist und der mit poly- oder monokristallinem Silizium (14) aufgefüllt ist. 5. Power MOSFET according to one of claims 1 to 3, characterized in that the conductive connection is formed from a trench (13), from the dopant of a conductivity type (15) is diffused and with poly- or monocrystalline silicon ( 14) is filled up.
6. Leistungs-MOSFET nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die leitende Verbindung aus einem Graben (19) besteht, der wenigstens teilweise mit einem Metall oder einer gut leitenden Schicht (20) gefüllt ist.6. Power MOSFET according to one of claims 1 to 3, characterized in that the conductive connection consists of a trench (19) which is at least partially filled with a metal or a highly conductive layer (20).
7. Leistungs-MOSFET nach Anspruch 6, dadurch gekennzeichnet, daß das Metall Wolfram ist und die gut leitende Schicht7. Power MOSFET according to claim 6, characterized in that the metal is tungsten and the highly conductive layer
(20) aus Titannitrid besteht.(20) consists of titanium nitride.
8. Leistungs-MOSFET nach Anspruch 6 oder 7, dadurch gekennzeichnet, daß das Innere des Grabens (19) mit mit Dotierstoff des einen Leitfähigkeitstyps dotiertem polykristallinem Silizium (21) oder mit einem Isolator gefüllt ist.8. Power MOSFET according to claim 6 or 7, characterized in that the interior of the trench (19) is filled with dopant of a conductivity type doped polycrystalline silicon (21) or with an insulator.
9. Leistungs-MOSFET nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß das Halbleitersubstrat (1) mit einer insbesondere aus Metall bestehenden Kühleinrichtung (12) verbunden ist.9. Power MOSFET according to one of claims 1 to 8, characterized in that the semiconductor substrate (1) is connected to a cooling device (12) consisting in particular of metal.
10. Leistungs-MOSFET nach Anspruch 3, dadurch gekennzeichnet, daß die Halbleiterschicht zwischen der Drainzone (3) und Gate (7) schwächer dotiert ist als die Drainzone (3) .10. Power MOSFET according to claim 3, characterized in that the semiconductor layer between the drain zone (3) and gate (7) is less doped than the drain zone (3).
11. Leistungs-MOSFET nach Anspruch 4 oder 5, gekennzeichnet durch einen vergrabenen Metallbereich (10) zwischen Sourcezone (4) und hochdotierter Halbleiterzone (9) bzw. poly- oder monokristallinem Silizium (14) .11. Power MOSFET according to claim 4 or 5, characterized by a buried metal region (10) between the source zone (4) and highly doped semiconductor zone (9) or poly- or monocrystalline silicon (14).
12. Leistungs-MOSFET nach Anspruch 2, dadurch gekennzeichnet, daß der Abstand zwischen Drainzone (3) und Kante der Gateelektrode (7) etwa 0,1 μm bis 5 μm beträgt.12. Power MOSFET according to claim 2, characterized in that the distance between the drain zone (3) and the edge of the gate electrode (7) is approximately 0.1 μm to 5 μm.
13. Leistungs-MOSFET nach Anspruch 2, dadurch gekennzeichnet, daß die Dicke der Isolatorschicht (6) unter der Gateelek- trode (7) in Richtung auf die Drainzone (3) stetig oder stufenartig zunimmt.13. Power MOSFET according to claim 2, characterized in that the thickness of the insulator layer (6) under the gate elec- trode (7) in the direction of the drain zone (3) increases continuously or in steps.
14. Leistungs-MOSFET nach Anspruch 3, gekennzeichnet durch eine schwach dotierte Halbleiterschicht (18) des einen Leitfähigkeitstyps zwischen dem Halbleitersubstrat (1) und der Halbleiterschicht (2) des anderen Leitfähigkeitstyps.14. Power MOSFET according to claim 3, characterized by a weakly doped semiconductor layer (18) of one conductivity type between the semiconductor substrate (1) and the semiconductor layer (2) of the other conductivity type.
15. Leistungs-MOSFET nach einem der Ansprüche 1 bis 14, dadurch gekennzeichnet, daß das Halbleitersubstrat (1) eine Schichtdicke von etwa 0,2 mm aufweist.15. Power MOSFET according to one of claims 1 to 14, characterized in that the semiconductor substrate (1) has a layer thickness of about 0.2 mm.
16. Leistungs-MOSFET nach Anspruch 14, dadurch gekennzeichnet, daß die Halbleiterschicht (18) des einen Leitfahigkeitstyps eine Schichtdicke von etwa 2 μm aufweist.16. Power MOSFET according to claim 14, characterized in that the semiconductor layer (18) of one conductivity type has a layer thickness of about 2 microns.
17. Leistungs-MOSFET nach Anspruch 3, dadurch gekennzeichnet, daß die Gateelektrode eine Schichtdicke bzw. -tiefe von etwa 3 μm aufweist.17. Power MOSFET according to claim 3, characterized in that the gate electrode has a layer thickness or depth of about 3 microns.
18. Leistungs-MOSFET nach Anspruch 17, dadurch gekennzeichnet, daß die Gateelektrode eine Breite von etwa 1 μm aufweist.18. Power MOSFET according to claim 17, characterized in that the gate electrode has a width of about 1 micron.
19. Leistungs-MOSFET nach einem der Ansprüche 1 bis 18, dadurch gekennzeichnet, daß die Halbleiterschicht (2) des anderen Leitfähigkeitstyps eine Schichtdicke von etwa19. Power MOSFET according to one of claims 1 to 18, characterized in that the semiconductor layer (2) of the other conductivity type has a layer thickness of about
4 μm aufweist.4 μm.
20. Leistungs-MOSFET nach einem der Ansprüche 1 bis 19, dadurch gekennzeichnet, daß die leitende Verbindung (9; 19, 20, 21) eine Breite von etwa 1 bis 2 μm aufweist. 20. Power MOSFET according to one of claims 1 to 19, characterized in that the conductive connection (9; 19, 20, 21) has a width of about 1 to 2 microns.
21. Leistungs-MOSFET nach Anspruch 8, dadurch gekennzeichnet, daß der Isolator einen Hohlraum beinhaltet. 21. Power MOSFET according to claim 8, characterized in that the insulator contains a cavity.
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US6459142B1 (en) 2002-10-01

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