Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2003-05-16
2004-12-14
Jackson, Jerome (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S356000, C257S341000, C257S262000, C257S266000, C257S136000, C257S173000, C361S101000
Reexamination Certificate
active
06831328
ABSTRACT:
The present invention generally relates to vertical power components. It more specifically relates to the provision of a voltage linked to the anode voltage of such a component.
Generally, in vertical power components, the rear surface is uniformly metallized and corresponds to the anode of the component, while the front surface comprises a cathode metallization and one or several control terminals. Generally, the anode is brought to a high voltage and it may be useful to have a detection voltage varying in the same way as the anode voltage.
FIGS. 1A
to
5
A show simplified cross-section views of various examples of vertical power components of cellular type.
FIGS. 1B
to
5
B show equivalent diagrams. In all cases, it is considered that the structure is formed from a lightly-doped N-type substrate
1
.
FIG. 1A
shows a cross-section view of a cell of a cellular-type thyristor. On the rear surface side of substrate
1
is formed a P-type layer
2
corresponding to the anode layer and coated with an anode metallization MA. On the front surface side is formed a P-type well
3
, in which are formed heavily-doped N-type cathode regions
4
. Preferably, the central portion of each well comprises a heavily-doped P-type region
6
. A cathode metallization MK is integral with regions
4
and
6
and a gate metallization G is integral with well
3
.
FIG. 1B
shows the conventional equivalent diagram of a thyristor formed of the association of two PNP and NPN transistors. In
FIG. 1B
as in
FIGS. 2B
to
5
B, the anode is shown at the top of the drawing, while in the cross-section views of
FIGS. 1A
to
5
A, the anode is shown at the bottom of the drawing.
FIG. 2A
shows a cross-section view of vertical MOS transistors or of an IGBT transistor. In the case of a MOS-type transistor, rear surface layer
2
is of type N
+
. In the case of an IGBT transistor, rear surface layer
2
is of type P
+
. The structure diffused on the front surface side is similar to that of a cellular thyristor and comprises a P-type well
3
, an N
+
-type region
4
, and a P
+
-type region
6
. Cathode metallization MK is similar to that of FIG.
1
A. The control electrode corresponds to a gate metallization G isolated from the periphery of well
3
and formed thereabove.
FIG. 2B
shows the equivalent diagram in the case where layer
2
is of type P
+
, that is, where the component is an IGBT transistor. This structure comprises the association of a PNP transistor and of an enrichment MOS transistor connected between the base and the collector of the PNP transistor.
FIGS. 3A and 3B
show a gate turn-on and turn-off MOS thyristor.
FIGS. 4A and 4B
show a structure of an emitter-switched thyristor, currently called an EST structure.
FIGS. 5A and 5B
show a cross-section view of a base-resistor thyristor, currently designated as a BRT.
FIGS. 3
to
5
will not be described in more detail, and it should only be noted that a P
+
-type layer
2
coated with an anode metallization MA is provided on the rear surface side. To simplify the understanding of these structures, the gates of the MOS transistors implied in
FIGS. 3A
,
4
A and
5
A have been designated as G
1
and G
2
, and these gates have been designated in the same way in the equivalent diagrams of the corresponding
FIGS. 3B
,
4
B, and
5
B. For further details, reference can be made to “Trends in Power Semiconductor Devices”, B. J. Baliga, IEEE Transactions on Electron Devices, vol. 43, October 1996, pp. 1717-1731.
FIGS. 1
to
5
have only been described to remind the structure of a few examples of vertical components to which the present invention is likely to apply.
The object of the present invention is to provide a voltage sensor likely to provide, on a front surface electrode of the component, a voltage much lower than the anode voltage, but varying in the same direction as this anode voltage. In other words, a voltage which is the image of the anode voltage is desired to be obtained.
To achieve this object, the present invention provides a sensor of an anode voltage of vertical power component selected from the group comprising the so-called thyristor, MOS, IGBT, PMCT, EST, BRT transistor, MOS thyristor, gate turn-off MOS thyristor, formed in a lightly-doped N-type substrate and having its rear surface, coated with a metallization, which corresponds to the anode of the component, comprising, on the front surface side, an area of the substrate surrounded at least partially with a P-type region at a low voltage as compared to an anode voltage, said area being coated with a metallization in ohmic contact therewith, on which is provided an image of the anode voltage.
According to an embodiment of the present invention, the metallization is formed on a heavily-doped N-type region.
According to an embodiment of the present invention, the anode metallization is formed on a P
+
-type region.
Further, the present invention aims at a specific use of such a sensor to detect whether the load connected to the power component is in short-circuit.
The present invention also provides a use of the above-mentioned anode voltage sensor to inhibit the operation of a vertical power component when the detected voltage exceeds a predetermined threshold.
The present invention also provides a circuit for controlling the turning-off of a vertical power component comprising a voltage sensor such as mentioned hereabove, the output voltage of which is applied to the control terminal of a switch connected between the cathode and the control terminal of a vertical power component that can be turned off when this control terminal is connected to the cathode, a delay circuit being interposed between the sensor voltage and the gate terminal.
According to an embodiment of the present invention, the delay circuit comprises a MOS transistor, the gate of which receives the signal from the sensor and the main circuit of which is connected between the gate of said switch and a resistor connected to the control terminal of the vertical component.
REFERENCES:
patent: 4896196 (1990-01-01), Blanchard et al.
patent: 5075751 (1991-12-01), Tomii et al.
patent: 6137124 (2000-10-01), Michel et al.
patent: 0 029 932 (1981-06-01), None
patent: 0 872 894 (1998-10-01), None
patent: 2 532 503 (1984-03-01), None
patent: 2 766 993 (1999-02-01), None
“Bipolar Static Induction Transistor (BSIT) Static Model”, Proceedings of the Mediterannean Electrotechnical Conference, US, New York, IEEE, Ionescu A M et al., vol. conf. 6, May 22, 1991, pp. 107-110, XP000255352, Figure 1.
“A Novel Pulse Delay Circuit for converter Control”, P.B. Anjaneyulu et al., Int. J. Electronics, vol. 50, No. 6, 1981, pp. 477-484, XP000946269.
“Trends in Power Semiconductor Devices”, B. Jayant Baliga, IEEE Transactions on Electron Devices, IEEE Inc., New York, US, vol. 43, No. 10, Oct. 1, 1996, pp. 1717-1731, XP000626907.
“Time Delay Circuit for S.C.R. Control”, R. Arockiasamy, Electronic Engineering, vol. 46, No. 556, Jun. 1974, pp. 14-17, XP000951463.
Austin Patrick
Breil Marie
Causse Olivier
Jalade Jean
Laur Jean-Pierre
Centre National de la Recherche Scientifique
Duane Morris LLP
Jackson Jerome
LandOfFree
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