Active solid-state devices (e.g. – transistors – solid-state diode – Regenerative type switching device – Bidirectional rectifier with control electrode
Reexamination Certificate
2002-09-19
2003-06-17
Ngô, Ngân V. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Regenerative type switching device
Bidirectional rectifier with control electrode
C257S125000, C257S126000, C257S128000, C257S133000, C257S153000, C257S335000, C257S337000, C257S341000
Reexamination Certificate
active
06580100
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to voltage-controlled bidirectional vertical components and more specifically to voltage-controlled bidirectional vertical switches for medium-power applications enabling, for example, switching of loads connected to the mains, such as electro-domestic appliances.
2. Discussion of the Related Art
FIG. 1
is a very simplified cross-section view of a voltage-controlled vertical bidirectional switch formed from two vertical transistors of IGBT type (isolated gate bipolar transistor). It should be clear, as usual in the representation of semiconductor components, that the drawing is not to scale.
Switch
10
includes two vertical IGBT transistors
11
A,
11
B. Each transistor is comprised of a lightly-doped N-type substrate
13
A,
13
B delimited by a P-type isolating wall
14
A,
14
B. The lower surface of substrate
13
A,
13
B is uniformly coated with a P-type layer
15
A,
15
B.
On the upper surface side of substrate
13
A,
13
B is arranged a cell network
16
A,
16
B. For clarity, only two cells
16
A,
16
B are shown for each transistor
11
A,
11
B. Each cell
16
A,
16
B is comprised of a well
17
A,
17
B including a heavily-doped P-type central region
18
A,
18
B and a more lightly doped P-type peripheral region. A heavily-doped N-type ring
19
A,
19
B is formed in well
17
A,
17
B. The portion of well
17
A,
17
B outside of ring
19
A,
19
B is covered with an isolated gate
20
A,
20
B. Each transistor
11
A,
11
B also includes a P-type ring
21
A,
21
B, which surrounds cell network
16
A,
16
B. A peripheral heavily-doped N-type channel stop ring
22
A,
22
B is located at the periphery of transistor
11
A,
11
B.
A cathode metallization M
1
A, M
1
B contacts central region
18
A,
18
B of well
17
A,
17
B and N-type ring
19
A,
19
B of each cell
16
A,
16
B, as well as P-type ring
21
A,
21
B. An anode metallization M
2
A, M
2
B covers P-type layer
15
A,
15
B. A metal ring M
3
A, M
3
B is connected to peripheral channel stop ring
22
A,
22
B to make it equipotential. Similarly, a metal ring M
4
A, M
4
B is connected to isolating wall
14
A,
14
B to make it equipotential.
The terminals associated with isolated gates
20
A,
20
B of each transistor
11
A,
11
B are respectively designated with references G
1
, G
2
.
The lower surface of transistor
11
A, located on the left-hand side of
FIG. 1
, directly rests on a radiator
23
. The lower surface of transistor
11
B, located to the right of
FIG. 1
, rests on radiator
23
with an interposed insulator
24
.
The vertical bidirectional switch is obtained by connecting the two vertical IGBT transistors
11
A,
11
B as follows. Metallization M
1
A of transistor
11
A, located to the left of
FIG. 1
, is connected by an electric connector
28
to the anode, formed by metallization M
2
B, of transistor
11
B located to the right of FIG.
1
. The cathode formed by metallization M
1
B of this latter transistor
11
B is connected by an electric connector
29
to radiator
23
. The two IGBT transistors
11
A,
11
B are thus connected in antiparallel. The main terminals of bidirectional switch
10
correspond to radiator
23
and to metallization M
1
A. According to the voltages on gates G
1
, G
2
, one or the other of the two transistors, or none of them, can be turned on. A voltage-controlled bidirectional switch is thus obtained.
The above voltage-controlled bidirectional switch has the disadvantage of not being monolithic. Conversely, it includes two transistors formed on separate chips. It thus has a relatively significant bulk and requires use of wirings to connect the two transistors. Further, one of the transistors is laid on the radiator via an insulator. It is often difficult to obtain an insulator both ensuring a good electric insulation between the transistor and the radiator and a satisfactory heat exchange between the two elements.
SUMMARY OF THE INVENTION
The present invention aims at monolithically forming a voltage-controlled bidirectional switch.
To achieve this and other objects, the present invention provides a vertical voltage-controlled bidirectional monolithic switch formed between the upper and lower surfaces of a semiconductor substrate surrounded with a peripheral wall, including a first multiple-cell vertical IGBT transistor extending between a cathode formed on the upper surface side and an anode formed on the lower surface side; and a second multiple-cell vertical IGBT transistor extending between a cathode formed on the lower surface side and an anode formed on the upper surface side, in which the cells of each transistor are arranged so that portions of the cells of a transistor are active upon operation of the other transistor.
The present invention also provides a vertical voltage-controlled bidirectional monolithic switch formed in a substrate of a first conductivity type surrounded with a peripheral wall of a second conductivity type, including a network of upper cells, formed on the upper surface side of the substrate, each upper cell being formed of a ring of the first conductivity type formed in a well of a second conductivity type, the well region outside of the ring forming a channel ring covered with an upper isolated gate; an upper metallization, forming a first main electrode, connected to the central region of the well and to the ring of each upper cell; a network of lower cells similar to the upper cells, formed on the lower surface side of the substrate, opposite to the network of upper cells; and a lower metallization forming a second main electrode, connected to the central region of the well and to the ring of each lower cell.
According to an embodiment of the present invention, the lower isolated gate is connected to a sink which crosses a region of the substrate from the lower surface to the upper surface, the sink being connected to a gate contact formed on the upper surface side.
According to an embodiment of the present invention, the lower isolated gate is connected to the sink by a metallization isolated from the lower metallization.
According to an embodiment of the present invention, the lower metallization covers the entire lower surface.
According to an embodiment of the present invention, the lower metallization is connected to the peripheral wall.
According to an embodiment of the present invention, the substrate region crossed by the sink is isolated from the substrate regions where the networks of upper and lower cells are formed by the peripheral wall which extends in an auxiliary wall of the second conductivity type.
According to an embodiment of the present invention, the peripheral wall extends on the lower surface side in a lower ring of the second conductivity type surrounding the network of lower cells.
According to an embodiment of the present invention, on the upper surface side, an upper ring of the second conductivity type surrounds the network of upper cells and is connected to the upper metallization.
According to an embodiment of the present invention, on the upper surface side, a heavily-doped channel stop ring of the first conductivity type surrounds the upper ring of the second conductivity type.
The foregoing objects, features and advantages of the present invention, will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings.
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patent: 4816892 (1989-03-01), Temple
patent: 5040042 (1991-08-01), Bauer et al.
patent: 5144401 (1992-09-01), Ogura et al.
patent: 5608235 (1997-03-01), Pezzani
patent: 5608237 (1997-03-01), Aizawa et al.
patent: 6031254 (2000-02-01), Quoirin
patent: 0 111 804 (1984-06-01), None
patent: 2 787 637 (2000-06-01), None
French Preliminary Search Report from French patent application No. 0112197, filed Sep. 21, 2001.
Morris James H.
Ngo Ngan V.
STMicroelectronics S.A.
Wolf Greenfield & Sacks P.C.
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