Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Reexamination Certificate
2000-11-06
2001-09-18
Riley, Shawn (Department: 2838)
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
C250S338400, C323S907000
Reexamination Certificate
active
06291826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor element for electric power and a semiconductor device for electric power, and more particularly to a technique for reducing the high-frequency noise of a semiconductor device for electric power having a temperature-sensing function.
2. Description of the Background Art
A control system utilizing a semiconductor element for electric power with a temperature-sensing diode is used in order to avoid deterioration or the like of element properties caused by an abnormal junction temperature rise at the time of operation of a semiconductor element for electric power such as represented by an IGBT or a longitudinal type power MOSFET. In other words, a temperature-sensing diode part which is made of a polycrystal silicon diode and which is electrically separated completely from a semiconductor element part for electric power with the use of an insulating oxide film is formed within the semiconductor substrate in which the semiconductor element part for electric power is formed. A sensing signal indicating the amount of junction temperature rise of the semiconductor element part for electric power, which has been sensed by the temperature-sensing diode part, is transmitted to a controlling circuit part disposed outside of the semiconductor element for electric power, and the controlling circuit part performs a comparing operation of the received sensing signal with a predetermined level and, on the basis of the operation result, controls the semiconductor element part for electric power appropriately, thereby avoiding the deterioration or the like of the properties of the semiconductor element part for electric power caused by junction temperature rise.
In this case, input terminals of the temperature-sensing diode part made of a polycrystal silicon diode and input terminals of the controlling circuit part are connected, for example, with the use of a lead part made of a pair of bonding wire parts and a pair of relay lead parts; and the semiconductor element for electric power and the controlling circuit part are accommodated in a resin case.
Here, the resin case is joined onto an upper surface of a heat-dissipating plate along an outer peripheral part. The semiconductor element for electric power including the temperature-sensing diode part is stuck onto an electrically insulating substrate formed on the heat-dissipating plate.
Further, Japanese Patent Application Laid-open No. 07-202129(1995) discloses a semiconductor element for electric power equipped with a temperature-sensing diode part and an electrostatic absorbing diode part. Namely, referring to
FIG. 9
, a temperature-sensing diode part made of a plurality of diodes connected sequentially in series in the forward direction is formed on a semiconductor substrate on which a longitudinal type MOSFET is formed, and an electrostatic discharge resistance improving diode part made of one diode connected in parallel in the backward direction is formed between an anode electrode at one end of the temperature-sensing diode part and a cathode electrode at the other end. The latter one diode has a function of being capable of preventing erroneous operations of the temperature-sensing diode part caused by static electricity generated between the two terminals of the former temperature-sensing diode part. For example, a resistance voltage of 200V can be ensured by using the latter static electricity absorbing diode part. Thus, by constructing the semiconductor element for electric power in the manner shown in
FIG. 9
, the ESD (electrostatic discharge) immunity can be improved while sensing the junction temperature rise of the semiconductor element part for electric power.
In the semiconductor element for electric power disclosed by the aforementioned Patent Application, if the number of diodes connected in series in the temperature-sensing diode part is increased as much as possible within the range of the power source voltage of a later-mentioned forward direction voltage fall (VF) comparing circuit of the controlling circuit part, the sensitivity of the temperature-sensing diode part to temperature change increases to improve the sensing precision. Conversely, if the temperature-sensing diode part is constructed with only one diode, the sensitivity decreases to comparatively lower the precision, so that it is hardly conceivable to construct the temperature-sensing diode part with a single diode.
Next,
FIG. 10
shows a circuit block diagram of a semiconductor device incorporating a semiconductor element
1
P for electric power shown in FIG.
9
. As described previously, each part of the semiconductor device of
FIG. 10
is accommodated in the resin case joined on the upper surface of the heat-dissipating plate along the outer peripheries. As shown in
FIG. 10
, a controlling circuit part
8
P formed on a substrate for controlling circuits (not illustrated) is constructed with a semiconductor element controlling circuit part
2
P for controlling the semiconductor element for electric power, a circuit part
3
P for generating a controlling current IF supplied to a temperature-sensing diode part
5
AP, and a VF operating amplifying circuit part
4
P for sensing an abnormal junction temperature rise by comparing a forward direction voltage fall (VF), which is a sensing signal of the temperature-sensing diode part
5
AP, with a predetermined level. Here, the symbol
1
PP denotes an IGBT element part, and the symbol
5
BP denotes one diode that constitutes a static electricity absorbing diode part.
The conventional semiconductor device for electric power incorporating the semiconductor element
1
P for electric power shown in
FIG. 10
involves the following problems although it contributes to an improvement of the ESD (electrostatic discharge) immunity. Namely, if a high-frequency electromagnetic interference wave penetrating from the outside is generated in the inside of the semiconductor device for electric power, particularly in the neighborhood of the semiconductor element
1
P for electric power, or if a higher-mode electromagnetic interference wave generated by the aforesaid semiconductor element
1
P for electric power itself is generated in the neighborhood of the semiconductor element
1
P for electric power, an electromotive force is generated as a result of electrostatic coupling and electromagnetic coupling generated between the heat-dissipating plate and the paths (including the forward path and the backward path) of the controlling current IF of the temperature-sensing diode part constructed with a bonding wire part
10
P and a relay lead part
9
P, or between the aforementioned paths and the earth ground of the semiconductor device for electric power, or between the aforementioned paths and the electrode (gate electrode, control electrode, or the like) for large electric current that is input to and output from the semiconductor element for electric power. This electromotive force is generated in the same manner in each of the forward path and the return path of the above-mentioned controlling current IF and, as a result, an electromotive force difference is generated between the forward path and the return path.
Here, the high-frequency electromagnetic interference wave penetrating from the outside of the semiconductor device for electric power into the semiconductor device may be, for example, a radio wave noise, a wireless noise generated from a wireless apparatus, a wireless noise generated by a portable phone, or the like. Generation of such a high-frequency electromagnetic interference wave in the neighborhood of the semiconductor element for electric power occurs often, for example, if the semiconductor device for electric power is used as an electronic part in a mobile body such as an automobile. The frequency band for such a high-frequency electromagnetic interference wave extends, as an example, to the range of about 1 MHz to 10 GHz. Needless to say, electromagnetic interference waves below or above that range may
Kub{overscore (o)} Mitsunori
Majumdar Gourab
Ohmaru Takeshi
Shirasawa Takaaki
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Riley Shawn
LandOfFree
Semiconductor element for electric power with a diode for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor element for electric power with a diode for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor element for electric power with a diode for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441948