Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2002-06-19
2003-11-18
Abraham, Fetsum (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S357000, C257S346000, C257S371000, C257S335000, C257S328000
Reexamination Certificate
active
06649974
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a field-effect controlled semiconductor component and to a method for manufacturing such a semiconductor component.
Such a component is for example a vertically configured field-effect transistor which is described, for example, by Stengl, Tihanyi in the book “Leistungs-MOSFET-Praxis” (Power MOSFET in practice), Pflaum Publishers, Munich, 1992, page 37. The field-effect transistor has a drain zone, as first connection zone, with which a contact can be provided on a rear side of the semiconductor body, and a second connection zone, as a source zone, with which a contact can be provided on a front side opposite the rear side. The source zone is formed in what is referred to as a body zone which is in turn formed in a drift zone above the drain zone. The drain zone, the source zone and the drift zone are of the same conductivity type, while the body zone is of a complementary conductivity type. The drift zone is weakly doped when compared to the drain zone and the source zone and, when a voltage is applied between the drain and source, it absorbs a large part of this voltage. Above the body zone, a control electrode is formed as a gate electrode which, when a suitable drive potential is applied, brings about a conductive channel in the body zone between the source zone and the drift zone. The gate electrode forms, with the region of the semiconductor body lying below it, a capacitor which has to be charged to switch through the transistor and discharged to switch off the transistor, and which thus influences the switching behavior of the transistor.
Such components are suitable, depending on their specific embodiments, for switching currents up to several tens of amperes with a dielectric strength of up to several hundred volts.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a semiconductor component which overcomes the above-mentioned disadvantages of the heretofore-known semiconductor components of this general type and which in particular for applications in which voltages of less than 100 volts are to be switched or blocked, provides a low value for the gate capacitance.
With the foregoing and other objects in view there is provided, in accordance with the invention, a semiconductor component, including:
a semiconductor body having a first side and a second side opposite the first side, the semiconductor body defining a vertical direction and a lateral direction transverse to the vertical direction, the vertical direction extending from the first side to the second side;
the semiconductor body including a first connection zone of a first conductivity type for providing a contact at the first side of the semiconductor body;
the semiconductor body including a second connection zone of the first conductivity type for providing a contact at the second side of the semiconductor body;
the semiconductor body including a drift zone adjoining the first connection zone and extending in the vertical direction as far as the second side of the semiconductor body;
the semiconductor body including a body zone of a second conductivity type disposed between the second connection zone and the first connection zone or the drift zone; and
a control electrode insulated from the semiconductor body, the control electrode being disposed above the body zone such that the control electrode substantially does not overlap with the drift zone and the second connection zone in the lateral direction.
According to another feature of the invention, the drift zone and the body zone have respective regions adjoining one another; and the respective regions are doped such that, when a reverse voltage is applied between the first connection zone and the second connection zone, at least the drift zone is completely emptied of charge carriers.
According to another feature of the invention, the body zone has a first zone with a first doping concentration of the second conductivity type and a second zone with a second doping concentration of the second conductivity type, the first doping concentration is higher than the second doping concentration; and the first zone adjoins the second connection zone and the second zone.
According to yet another feature of the invention, the body zone has a given zone of the second conductivity type, the given zone is disposed underneath the control electrode and at a given distance from the second side, the given zone of the second conductivity type is more heavily doped than a remainder of the body zone.
According to another feature of the invention, the drift zone has at least two adjacent zones, a first one of the at least two adjacent zones is of the first conductivity type and a second one of the at least two adjacent zones is of the second conductivity type; and the at least two adjacent zones extend from the first connection zone in the vertical direction of the semiconductor body toward the second side of the semiconductor body.
According to a further feature of the invention, the drift zone has a plurality of respectively alternating zones of the first and second conductivity types; and the plurality of respectively alternating zones extend from the first connection zone in the vertical direction of the semiconductor body toward the second side of the semiconductor body.
According to another feature of the invention, the at least two adjacent zones of the drift zone extend as elongated zones in the lateral direction of the semiconductor body.
According to another feature of the invention, the body zone, the second connection zone and the control electrode extend as elongated zones in a further lateral direction of the semiconductor body transverse to the lateral direction.
According to yet another feature of the invention, the drift zone has a given zone of the first conductivity type, the given zone is more heavily doped than a remainder of the drift zone, the given zone adjoins the body zone and is disposed at the second side of the semiconductor body.
The component according to the invention has a first connection zone of a first conductivity type, with which contact can be made on a first side of a semiconductor body, a second connection zone of the first conductivity type, with which contact can be made on a second side of the semiconductor body lying opposite the first side, a drift zone which adjoins the first connection zone and extends in the vertical direction of the semiconductor body as far as the second side of the semiconductor body, a body zone of a second conductivity type which is formed between the second connection zone and the drift zone, and a control electrode which is formed over the body zone and which is insulated from the semiconductor body. According to the invention, the control electrode is formed at least approximately without overlap with the drift zone and the second connection zone in the lateral direction of the semiconductor body. This results in a capacitance between the control electrode and the drift zone which is less than that of similar conventional components, that is to say a smaller gate/drain capacitance or Miller capacitance, as a result of which faster switching operations of the semiconductor component are possible.
Ideally, such semiconductor components have a small value for the product of the gate/drain capacitance and switch-on resistance, the switch-on resistance being the effective electrical resistance between the first and second connection zones when the control electrode is driven to the conductive state.
According to one embodiment of the invention, there is therefore provision that the regions of the body zone and of the drift zone which adjoin one another are doped in such a way that, when a voltage is applied between the first and second connection zones and the control electrode is not driven—that is to say when there is no conductive channel present in the body zone—at least the drift zone is completely emptied, i.e. completely drained of charge carriers. “Completely emptied” means that there are only
Hirler Franz
Werner Wolfgang
Abraham Fetsum
Infineon - Technologies AG
Locher Ralph E.
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