Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2001-03-23
2003-09-09
Prenty, Mark V. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S403000, C257S408000
Reexamination Certificate
active
06617640
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a semiconductor configuration having a semiconductor body with connection zones, a channel zone and a control electrode surrounded by an insulating layer.
Such semiconductor configurations with first and second connection zones and a channel zone of the same conductivity type are, for example, “ACCUFETs” (Accumulation-Mode Field-Effect Transistors), as are described in the article “The Accumulation-Mode-Field-Effect-Transistor; A new ultralow on-resistance MOSFET” by B. Jayant Baliga, IEEE ELECTRON DEVICE LETTERS, Vol. 13, No. 8, August 1992.
U.S. Pat. No. 5,844,273 describes such an ACCUFET having an n-doped drain zone as a first connection zone, the drain zone being provided in the region of a rear side of a semiconductor body, an n-doped source zone as a second connection zone, the source zone being provided in the region of a front side of the semiconductioe body, and a weakly n-doped channel zone formed between the source zone and the drain zone. A gate electrode as a control electrode of the ACCUFET extends in the vertical direction of the semiconductor body adjacently to opposite sides of the weakly n-doped channel zone between the source zone and the drain zone. When a voltage is applied between the drain zone and the source zone, a current flows in the vertical direction of the semiconductor body in the channel zone. When a negative drive potential is applied to the gate electrode, a conducting channel in the channel zone between the drain and source zones is pinched off and the ACCUFET turns off. What is crucial for the dielectric strength of such an ACCUFET is, inter alia, the thickness of an insulation layer surrounding the gate electrode. In the ACCUFET in accordance with the above-mentioned U.S. Pat. No. 5,844,273, the drain zone has, beside a heavily n-doped region, a more weakly n-doped region adjoining the channel zone and the gate electrode. The distance—determined by the more weakly doped region of the drain zone—between the channel zone, or the gate electrode, and the more heavily doped region of the drain zone determines, inter alia, the dielectric strength of the device.
As a result, with regard to the dielectric strength, in the known ACCUFET the minimum height thereof in the vertical direction of the semiconductor body is determined by the dimensions of the gate electrode in the vertical direction of the semiconductor body, and if appropriate the dimensions of the more weakly doped region of the drain zone in the vertical direction. In the known ACCUFET, the heavily doped region of the drain zone, which reaches from a rear side of the semiconductor body up to the channel zone, or the more weakly doped region of the drain zone, takes up a considerable space of the semiconductor body. Its dimensions in the vertical direction are thus determined by the dimensions of the semiconductor body in the vertical direction minus the dimensions of the gate electrode and the dimensions—prescribed by the desired dielectric strength—in the vertical direction of the more weakly doped region of the drain zone. A significantly smaller “height” of the drain zone, or of the heavily doped region thereof, would suffice in many cases for a reliable functioning of the ACCUFET. In the known components, the drain zone thus takes up a considerable bulk proportion of the available semiconductor body which remains substantially unutilized.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a semiconductor configuration which overcomes the above-mentioned disadvantages of the heretofore-known configurations of this general type and which achieves a higher packing density, that is to say more field-effect-controllable components with first and second connection zones and channel zones of the same conductivity type and control electrodes for driving can be accommodated in the semiconductor body. In this context, “more components” also means more identically constructed cells of a component whose respective connection zones and channel zones are jointly interconnected.
With the foregoing and other objects in view there is provided, in accordance with the invention, a semiconductor configuration, including:
a semiconductor body including a first connection zone of a first conductivity type, a second connection zone of the first conductivity type, a channel zone of the first conductivity type, at least one control electrode, and an insulation layer;
the channel zone of the first conductivity type being formed between the first connection zone and the second connection zone;
the insulation layer surrounding the at least one control electrode;
the at least one control electrode extending, adjacent to the channel zone, from the first connection zone to the second connection zone;
the semiconductor body defining a vertical direction and a lateral direction; and
the first connection zone, the second connection zone and the at least one control electrode extending in the vertical direction such that, when a voltage is applied between the first and second connection zones, a current path along the lateral direction is formed in the channel zone.
In other words, the object of the invention is achieved when the first connection zone, the second connection zone and the control electrode extend in the vertical direction of the semiconductor body in such a way that when a voltage is applied between the first and second connection zones, a current path is formed in the lateral direction of the semiconductor body in the channel zone.
The properties of the semiconductor configuration according to the invention, in particular with regard to its dielectric strength, are determined, inter alia, by the thickness of the insulation layer of the control electrode, the length of the channel zone in the lateral direction of the semiconductor body and, if appropriate, the dimensions of a more weakly doped region of the first connection zone between the channel zone and a more heavily doped region of the first connection zone.
The dimensions of the cross section of the channel zone transversely with respect to the current direction influence the conductivity of the component formed in the semiconductor configuration according to the invention. In the configuration according to the invention, the first and second connection zones, the channel zone and the control electrode can extend into the semiconductor body virtually as far as desired—only limited by the height of the semiconductor body—in the vertical direction of the semiconductor body. This makes it possible to enlarge the cross section of the channel zone without influencing the dielectric strength of the component formed in the semiconductor configuration according to the invention, the dielectric strength being influenced by the dimensions of the component in the local direction. A larger part of the semiconductor body can be utilized as channel zone in the semiconductor configuration according to the invention than according to the prior art.
The control electrode is preferably in the form of a plate, its longitudinal extent in a first lateral direction of the semiconductor body and in the vertical direction of the semiconductor body being significantly greater than in a second lateral direction of the semiconductor body transversely with respect to the first lateral direction. The control electrode configured in the form of a plate along the channel zone, or on both sides of the channel zone, requires less space in the semiconductor body and so the packing density that can be achieved is additionally increased, that is to say that the number of field-effect-controllable components that can be realized in a predetermined semiconductor body increases.
Preferably, the first connection zone, the second connection zone, the channel zone and the control electrode extend from a front side of the semiconductor body in the vertical direction thereof approximately up to the rear side thereof in order that the semiconductor body is virtually completely utiliz
Greenberg Laurence A.
Infineon - Technologies AG
Mayback Gregory L.
Prenty Mark V.
Stemer Werner H.
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