Active solid-state devices (e.g. – transistors – solid-state diode – With means to control surface effects – With inversion-preventing shield electrode
Reexamination Certificate
2000-08-16
2001-11-27
Meier, Stephen D. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
With means to control surface effects
With inversion-preventing shield electrode
C257S648000, C257S354000
Reexamination Certificate
active
06323539
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a high voltage integrated circuit used for controlling and driving a power device, and in particular to a high voltage integrated circuit formed on a semiconductor substrate independent of the power device, or on the same semiconductor substrate on which the power device is provided.
BACKGROUND OF THE INVENTION
Numerals denoting footnotes to various references including patents and other documents are provided in the following description of the related prior art. The references cited in the footnotes are listed in the Bibliography section of the specification immediately following Background of the Invention section.
Power devices have been widely used in many applications including inverters or converters for controlling motors, inverters for illumination, various power sources, and switches for driving solenoids and relays
1-4
. The power devices were conventionally driven and controlled by electronic circuits constructed as a combination of individual semiconductor devices and electronic components
5,6
. These functions have been more recently performed by low-voltage integrated circuits of several dozens of volts class
7,8
or high voltage integrated circuits of several hundreds of volts
9,10
, which utilize recent LSI (large scale integration) technology. Power integrated circuits in which drive and control circuits and power devices are integrated on the same semiconductor substrate are also used to reduce the size of conversion devices, such as inverters or converters, and achieve high operating reliability thereof
11,12
.
FIG. 33
is a circuit diagram mainly showing a power-related portion of an inverter for controlling a motor. Power devices (Q
1
-Q
6
as IGBTs—insulated gate bipolor transistor—and D
1
-D
6
as diodes in this example) used for driving a three-phase motor form a bridge circuit, and are all stored in the same package to provide a power module
13
. The main power source V
CC
usually provides a high voltage of dc 100 to 400 volts. V
CCH
represents the high-potential side of the main power source V
CC
, and V
CCL
represents the low-potential side of the main power source V
CC
. To drive IGBTs Q
1
-Q
3
connected to the V
CCH
, the potential of gate electrodes of the IGBTs Q
1
-Q
3
needs to be higher than the V
CCH
. Accordingly, the drive circuit is provided with a photo coupler (PC) or a high voltage integrated circuit (HVIC). The input and output terminals (I/O) of the drive circuit are usually connected to a microcomputer adapted for controlling the inverter as a whole.
FIG. 34
is a block diagram showing constituent units of the high voltage integrated circuit (HVIC) used in the circuit of FIG.
33
. This circuit includes a control unit CU, gate drive units GDU and a level shift unit LSU. The control unit sends and receives signals to and from a microcomputer, through input and output terminals I/O, to generate control signals for turning on and off selected one(s) of the IGBTS. The gate drive units GDU
4
-
6
receive signals from the control circuit CU through input lines SIN
4
-
6
and generate signals to output lines OUT
4
-
6
for driving gates of the corresponding IGBTs. Each of the gate drive units GDU
4
-
6
also detects excessive current and heat of the IGBT with a current detecting terminal
14
OC
4
-
6
and a temperature terminal
15
OT
4
-
6
, and generates abnormal signals through a corresponding output line SOUT
4
-
6
. In this manner, the gate drive units GDU
4
-
6
drive corresponding IGBT Q
4
-Q
6
connected to the low-potential side V
CCL
of the main power source V
CC
of FIG.
33
. The gate drive units GDU
1
-GDU
3
performs the same functions as the gate drive units GDU
4
-GDU
6
, to drive corresponding IGBT Q
1
to Q
3
that are connected to the high-potential side V
CCH
of the main power source V
CC
. The level shift unit LSU functions as an interface between the V
CC
-level signals of the control circuit CU, and the signals (SIN
1
-
3
, SOUT
1
-
3
) of GDU
1
-
3
which fluctuate between the V
CCH
level and the V
CCL
level. Drive power sources (shown in
FIG. 35
) V
DD1
-V
DD3
for the GDU
1
-
3
have respective high-potential sides V
DDH1
-V
DDH3
and low-potential sides V
DDL1
-V
DDL3
. The GDU
4
-
6
are connected to a common drive power source V
DDC
(not shown in FIG.
35
), which has a high-potential side V
DDHC
and a low-potential side V
DDLC
. The common drive power source V
DDC
for the GDU
4
-
6
and CU is about 10 to 20V, and the low-potential side V
DDLC
of this common power source V
DDC
is connected to the low-potential side V
CCL
of the main power source V
CC
of FIG.
33
.
FIG. 35
shows in more detail the connection between the GDU
1
of FIG.
34
and the IGBT Q
1
. The other GDUs and IGBTs are not shown in this figure. The drive power source V
DD1
of the GDU
1
is about 10 to 20 volts. The low-potential side V
DDL1
of this power source is connected to an emitter terminal of IGBT Q
1
, namely, a U phase of inverter output, and a collector terminal C of the IGBT Q
1
is connected to the high-potential side V
CCH
of the main power source V
CC
. In this arrangement, when the IGBT Q
1
is turned on, the potential of V
DDL1
is made substantially equal to the potential of V
CCH
. When the IGBT Q
1
is turned off, the potential of V
DDL1
is made substantially equal to the potential of V
CCL
Accordingly, the withstand voltage between the GDU
1
and other circuit units needs to be higher than the voltage of the main power source V
CC
. This also applies to GDU
2
and GDU
3
. Further, the level shift circuit LSU itself must have high withstand voltage. In
FIG. 35
, the IGBT Q
1
includes a current detecting element
16
M, a temperature detecting element &thgr;, and a temperature detecting terminal Temp. The gate drive unit GDU
1
detects abnormal states of the IGBT Q
1
, through the current detecting terminal OC
1
and the temperature detecting terminal OT
1
, and abnormal signals are generated through the output line SOUT
1
. OUT
1
indicates a gate drive terminal.
FIG. 36
is a circuit diagram showing substantially the same circuit as that of
FIG. 33
, except the use of a product called “intelligent power module”
18
. In this case, the gate drive units GDU
1
-GDU
6
consist of low voltage integrated circuits, individual electronic components and semiconductor devices, and are stored along with power devices (Q
1
-Q
6
, D
1
-D
6
) in a package containing the power devices. In this case, too, a photo coupler PC or high voltage integrated circuit HVIC is used as an exterior drive circuit.
FIG. 37
shows in detail the vicinity of IGBT Q
1
and GDU
1
of FIG.
36
. SIN
1
and SOUT
1
are connected to the PC or HVIC provided outside of the power module.
To provide other structures, power IC technology for integrating the GDU
1
and Q
1
on one chip (on the same semiconductor substrate)
19,20
, or power IC technology for integrating all the units of
FIG. 36
in one chip
11,12
can be employed.
FIG. 38
is a plan view showing a chip of the high voltage integrated circuit HVIC shown in
FIG. 34
, to clarify the arrangement of circuit units constituting the circuit. The GDU
1
is formed in an island electrically separated from the other circuit units by junction separation
21,22,10
or dielectric separation
23,11,12
to assure high withstand voltage, and the periphery of this GDU
1
is surrounded by a high voltage junction terminating structure HVJT
11,21
. The HVJT is a structure of a terminating part of the junction to which high voltage is applied to insulate the unit therein from the other units. Within the level shift circuit LSU, there is provided a high voltage n-channel MOSFET (HVN) adapted for shifting a level of signal having the potential V
CCL
on the low-potential side of the main power source V
CC
, to a level of signal (to be fed to the input line SIN
1
) having the potential V
DDL1
on the low-potential side of the drive power source V
DD1
. This high voltage n-channel MOSFET is provided with a high voltage junction termin
Fujihira Tatsuhiko
Kumagai Naoki
Obinata Shigeyuki
Yano Yukio
Fuji Electric & Co., Ltd.
Meier Stephen D.
Rossi & Associates
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