JP2003338555A - Electronic switch device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device for temperature detection which is capable of dealing with a low voltage power supply, and variations of the detected temperature are suppressed without increasing a process cost. <P>SOLUTION: An electronic device for temperature detection comprises an electronic control means for outputting a control signal when a threshold voltage changes corresponding to a change in temperature, and the threshold voltage and a reference voltage corresponding to the detected reference temperature are coincident with each other, and a voltage supply means for changing the reference voltage in a positive direction with respect to the temperature change and outputting it to the electronic control means. The electronic control means is adapted such that the threshold voltage changes in a negative direction with respect to the temperature change. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device, an electronic switch device having the electronic device, and a method for manufacturing the electronic device, and more specifically, it is constructed by using an electronic component whose output voltage changes according to temperature change. The present invention relates to an electronic device for temperature detection, an electronic switch device having a built-in overheat protection function, which is configured using such an electronic device, and a manufacturing method thereof. In particular, the present invention relates to a temperature detecting electronic device including a MOS transistor (hereinafter referred to as “MOSFET”), an electronic switch device having the temperature detecting electronic device, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 7 is an equivalent circuit diagram of a conventional electronic switch device having a built-in overheat protection function. Reference numeral 1 is a diode group in which six diodes are connected in series, and 2 is a power supply line. . In the diode group 1, the anode electrode of the uppermost diode is connected to the power supply line 2.

Generally, the temperature coefficient of the power supply line 2 is very small for connecting an external power supply. Moreover, even when the voltage source is internally formed, the temperature coefficient is designed to be small.

The electronic device 4 for temperature detection is composed of a diode group 1 and a resistor 3. One electrode of the resistor 3 is connected to the cathode electrode of the lowermost diode of the diode group 1, and the other electrode is connected to the GND line. The voltage at the connection point between the lowermost cathode electrode of the diode group 1 and the resistor 3 is output as an output signal to the next stage (here, the detected temperature is designed to be 150 ° C.).

Reference numeral 5 is a power switch composed of a MOSFET, and 6 is a gate cutoff MOSFET. The voltage at the gate terminal 7 of the power switch 5 is cut off by the gate cutoff MOSFET 6 that receives the output signal from the electronic device 4. As a result, in the configuration of FIG. 7, when the temperature of the element immediately before thermal destruction is reached (that is, when a predetermined detection temperature is reached), an output signal is generated from the electronic device 4 to shut off the power switch 5. It realizes the overheat protection function.

The conventional electronic device 4 configured as described above, and the power switch 5 using the electronic device 4
The operation of the overheat protection function of will be described in more detail below.

It is generally known that the forward voltage of a diode drops at about -2.5 mV / ° C as the temperature rises. Utilizing such characteristics, the diode has been conventionally used for temperature detection. In the electronic device 4, since the diode group 1 is composed of six diodes connected in series, the total forward voltage is 25 ° C. corresponding to room temperature to the overheat detection temperature.
Approximately 1.9V (more specifically,
0.0025V / ° C x 6x (150 ° C-25 ° C) = 1.
875V). Due to this decrease, the power supply line 2 required to turn on the gate cutoff MOSFET 6
Of voltage, that is, gate cutoff M via diode group 1
Threshold voltage V to be applied to the gate of OSFET 6
2T drops from 4.6V to 2.7V by 1.9V.

Therefore, the voltage V2 of the power supply line 2 is set to 2.7.
If set to V, when the temperature reaches 150 ℃,
When the threshold voltage V2T and the voltage V2 match, the gate cutoff MOSFET 6 is turned on to cut off the power switch 5.

[0009]

However, the configuration of FIG. 7 according to the above-mentioned conventional technique has the following problems.

FIG. 8 is a graph showing the temperature characteristics of the conventional electronic device 4 for temperature detection shown in FIG.

As shown in the figure, the threshold voltage V2T and the voltage V2 of the power supply line 2 are 150 ° C. which is the detection temperature.
Have an intersection at. However, when the forward voltage of the diode group 1 changes, the position of this intersection shifts. The broken line in the figure shows the temperature characteristic of the threshold voltage V2T when the forward voltage of the diode group 1 fluctuates by ± 0.3 V (± 0.05 V per diode). In the vicinity of 150 ° C., the detected temperature (the intersection of the characteristic lines) fluctuates ± 22 ° C. This is because in the temperature range from 25 ° C., which corresponds to room temperature, to 150 ° C., which is the overheat detection temperature, the difference between the threshold voltage V2T and the voltage V2 of the power supply line 2 due to temperature change is small. This is because the variation in the forward voltage of the diode group 1 accounts for 16% of the difference.

As described above, the conventional temperature detecting device using only the temperature characteristic of the forward voltage of the diode is configured because the gain with respect to temperature (the change rate of the output voltage with respect to the temperature change, that is, the sensitivity) is small. There is a problem that variations in element characteristics have a large influence on changes in voltage due to temperature, and as a result, variations in detected temperature increase.

In order to suppress the variation in the detected temperature, a method of increasing the number of diodes to increase the gain with respect to the temperature change, or a method of using a highly accurate comparator to reduce the variation factor is used.

However, with regard to the former, there is a limit to the number of diodes that can be connected in series between the power supply line and the GND line as the driving of low voltage progresses. For the latter, it is necessary to use a process that can completely separate the devices, such as a costly PN separation process.
Therefore, either method, as a solution to the above problems,
Not necessarily preferred.

The present invention has been made to solve the above-mentioned problems, and its purpose is (1) it can be applied to a low-voltage power supply without increasing the process cost, and the detected temperature varies. To provide an electronic device for temperature detection that is suppressed, and (2) an electronic device that incorporates an overheat protection function that uses such an electronic device for temperature detection at low cost and has little variation in operating functions. A switch device and a manufacturing method thereof are provided.

[0016]

An electronic device provided by the present invention is an electronic device for temperature detection, wherein a threshold voltage changes in response to a temperature change and a reference voltage corresponding to a detected reference temperature. An electronic control unit that outputs a control signal when the voltage and the threshold voltage match, and a voltage supply unit that changes the reference voltage in a positive direction with respect to a temperature change and outputs the reference voltage to the electronic control unit. And the electronic control means is configured such that the threshold voltage changes in a negative direction with respect to the temperature change, whereby the above object is achieved.

With this configuration, as the temperature rises, the reference voltage supplied as the output voltage of the voltage supply means and the threshold voltage of the electronic control means change oppositely to each other.
Due to the synergistic effect, the change amount (gain) of the voltage with respect to the temperature change increases. As a result, the influence of the variation in the operation of the constituent elements due to the temperature change of the detected temperature is relatively reduced, and as a result, the variation in the detected temperature is reduced.

Preferably, the voltage supply means changes the voltage between the terminals in the negative direction with respect to the temperature change, and the first element having a negative temperature coefficient and the voltage between the terminals, A second element having a positive temperature coefficient that changes in a positive direction with respect to the temperature change;
And the second element are connected in series with each other and are configured so that the output voltage from the terminal between the first and the second element is input to the electronic control means.

In one embodiment, in the voltage supply means, the first element includes a resistor formed of polysilicon, and the second element is a MOS type in which a drain electrode and a gate electrode are connected. Including transistor.

By doing so, the reference voltage increased as the temperature rises is output to the electronic control means.

[0021] In another embodiment, in the voltage supply means, the first element includes a resistor formed of polysilicon, and the second element has a drain electrode and a gate electrode connected to each other. Including 1 MOS type transistor,
The electronic control means includes a resistor and a second MOS transistor, and the second MOS included in the electronic control means.
The threshold voltage of the MOS transistor is higher than the threshold voltage of the first MOS transistor included in the voltage supply means.

In such a structure, the voltage supply means and the electronic control means are both constituted by a combination of elements such as a polysilicon resistor and a MOS type transistor which can be formed by a self-isolation structure, so that the PN isolation process and the dielectric material are formed. An electronic device for temperature detection having high sensitivity and less variation in detected temperature can be realized without using a costly process such as a separation process.

More preferably, the threshold voltage of the first MOS type transistor included in the voltage supply means and the threshold voltage of the second MOS type transistor included in the electronic control means are: It has the same temperature coefficient with respect to temperature change.

As a result, even if the threshold voltage of the MOS type transistor fluctuates due to variations in parameters in the manufacturing process, the output voltage of the voltage supply means and the input threshold voltage of the electronic control means are offset in the same direction. However, variations in the detected temperature can be suppressed.

The second M included in the electronic control means.
The impurity concentration of the substrate surface around the source region of the OS-type transistor is determined by the first M concentration included in the voltage supply means.
It can be set higher than the impurity concentration of the substrate surface around the source region of the OS type transistor.

Thus, the MO included in the electronic control means
The threshold voltage of the S-type transistor is set higher than the threshold voltage of the MOS-type transistor included in the voltage supply means.

An electronic switch device provided by another aspect of the present invention controls a temperature detecting electronic device, a power switch, and an on / off operation of the power switch based on an output of the temperature detecting electronic device. An electronic switch device including a control unit for overheat protection, wherein the electronic device for temperature detection is an electronic device having the characteristics described above, and thereby the above-described object is achieved.

As a result, it is possible to realize an electronic switch device having a built-in overheat protection function with high accuracy of on / off control.

In one embodiment, the power switch includes a MOS transistor, and the temperature detecting electronic device includes a MOS transistor connected in series with each other and a resistor formed of polysilicon. The switch and the temperature detecting electronic device are formed on the same semiconductor substrate.

With this configuration, by inputting the output of the temperature detecting electronic device to the control circuit of the power switch, an electronic switching device having a small variation in operating functions can be realized at low cost.

According to another aspect of the present invention, an electronic device for temperature detection, a power switch, and an overheat protection control for controlling on / off operation of the power switch based on an output of the electronic device for temperature detection. And a power switch and the temperature detection electronic device are formed on the same semiconductor substrate.
In the manufacturing method, the impurity concentration of the substrate surface around the source region of the MOS type transistor of the electronic control unit included in the temperature detecting electronic device is determined by the MOS type transistor of the voltage supplying unit included in the temperature detecting electronic device. And a well forming step of forming a well of the power switch, the concentration adjusting step and the well forming step being performed at the same time. Be seen. With such a feature, the above-mentioned object is achieved.

As a result, variations in the detected temperature due to variations in parameters in the manufacturing process are greatly reduced.

According to still another aspect of the present invention, a low breakdown voltage region and a high breakdown voltage region provided on the same semiconductor substrate,
A shallow well region provided under the low breakdown voltage region and a region that substantially surrounds the periphery of the shallow well region and is continuous with the shallow well region and reaches a position deeper than the shallow well region. Also provided is an electronic device having a deep well region having the same conductivity type as the shallow well region but having a higher impurity concentration, thereby achieving the above-mentioned object.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
2 is an equivalent circuit diagram of the electronic device 100 according to the embodiment, specifically, the electronic switch device 100 including the temperature detecting electronic device, and FIG. 2 is an element structure when the temperature detecting electronic device is configured as a semiconductor device. FIG.

In FIG. 1, 10 is a voltage supply device, and 11 is a control device capable of outputting a signal when the temperature is detected to an element in a subsequent stage (hereinafter, also simply referred to as "control device").
Is. Reference numeral 12 denotes an electronic device for temperature detection (hereinafter, also simply referred to as “electronic device”). The electronic device 12 is composed of a voltage supply device 10 and a control device 11. Reference numeral 13 is a power switch, and the power switch 13 is composed of a MOSFET. 14
Is a control unit of the power switch 13. Electronic device 1
2, the power switch 13, and the control unit 14 form an electronic switch device 100 with a built-in overheat protection function.

The voltage supply device 10 includes a resistor 15 and a MOSF.
Connect the drain and gate terminals of ET16,
It is configured. On the other hand, the control device 11 is configured by further connecting a polysilicon resistor 18 in series to a polysilicon diode group 17 in which a plurality of diodes are connected in series.

FIG. 2 is a sectional view showing the structure of the semiconductor substrate on which the voltage control device and its electronic control device are formed. Specifically, 20 is an N-type epitaxial region, 2
1 is a P-type well, 22 is a source N-type region, 23 is a drain N-type region, 24 is an insulating film, 25 is an interlayer insulating film, 26 is a gate polysilicon layer, 27 is a polysilicon layer, 28 is an anode region, 29 Is a cathode region, 30 is an aluminum electrode, 31 is a source electrode, 32 is a gate electrode, and 33 is a drain electrode.

First, the structure of the MOSFET and the method of manufacturing the same will be described below.

First, the insulative film 24 is selectively formed on the N-type epitaxial region 20, and the P-type well 21 is formed in the opening.
To form. A gate polysilicon layer 26 is formed on the P-type well 21, and the gate polysilicon layer 26 is further formed.
Is used as a mask to form a source N-type region 22 and a drain N-type region 23 on the P-type well 21. Subsequently, the source N-type region 22, the drain N-type region 23, and the gate polysilicon layer 26 are covered with the interlayer insulating film 25. Next, in the interlayer insulating film 25, the source N-type region 22
Then, the portion above the drain N-type region 23 is removed, and the aluminum electrode 30 is formed on that portion instead. As a result, the aluminum electrode 30 is connected to the source N-type region 22 and the drain N-type region 23.

Next, the structure of the polysilicon resistor and the diode and the manufacturing method thereof will be described.

First, the insulative film 24 is selectively formed on the N-type epitaxial region 20. A polysilicon layer 27 is formed on the insulating film 24, and an anode region 28 and a cathode region 29 are formed on the same polysilicon layer 2.
7 are formed so as to be in contact with each other. continue,
The polysilicon layer 27, the anode region 28, and the cathode region 29 are covered with the interlayer insulating film 25. further,
Of the interlayer insulating film 25, the portions of the polysilicon layer 27, the anode region 28, and the cathode region 29 that are located above the portions that will become terminals are removed, and instead, the aluminum electrodes 30 are formed in those portions. As a result, the aluminum electrode 30 is connected to the polysilicon layer 27, the anode region 28, and the predetermined region of the cathode region 29.

The resistor 15 shown in FIG. 1 is specifically a polysilicon layer 27 on the insulating film 24, as shown in FIG.
And has a negative temperature coefficient. On the other hand, the MOSFET 16 has a lateral structure like the MOSFET shown in FIG. 2, and the gate electrode 32 and the drain electrode 33 are short-circuited and connected to the resistor 15. The gate-source voltage of the MOSFET 16 may have both a positive temperature coefficient and a negative temperature coefficient depending on the value of the drain current, but here, the resistance of the resistor 15 is set so as to have a positive temperature coefficient. The value is being adjusted.

The input terminal 39 of the voltage supply device 10 is one terminal of the resistor 15 (high potential side of the resistor 15), and
The output terminal 40 is a connection point between the resistor 15 and the drain terminal and the gate terminal of the MOSFET 16 at point A (MOSF).
It is taken from the high potential side of ET16).

When the temperature rises while a constant voltage is applied to the input terminal 41 of the controller 11, the resistance value of the resistor 15 made of polysilicon decreases. That is, the voltage across the terminals of the resistor 15 has a negative temperature coefficient. On the other hand, a MOS having a positive temperature coefficient as the temperature rises
The gate-source voltage of the FET 16 rises, so that
The voltage VOA at point A also rises. That is, the output voltage VOA of the voltage supply device 10 rises as the temperature rises.

The control device 11 uses the anode terminal of the uppermost diode of the diode group 17 as its input terminal 41, and the output terminal 42 from the connection point B between the polysilicon resistor 18 and the cathode terminal of the lowermost diode. ing. A low signal is output from the output terminal 42 when no current flows through the diode group 17, and a high signal is output when a current flows.

When the voltage of the input terminal 41 is increased at a certain temperature, a current starts to flow when the voltage exceeds the total forward voltage of the polysilicon diode group 17, and the voltage VOA of the output terminal 42 rapidly increases. Rise to. When the output voltage VOA rises sharply, the state of the element in the subsequent stage is reversed. The input voltage (input threshold voltage) VIB required for reversing the state of the element in the subsequent stage becomes low as the temperature rises because the temperature coefficient of the forward voltage of the polysilicon diode group 17 is negative. That is, the input threshold voltage VIB of the control device 11 changes based on the negative temperature coefficient.

As described above, the electronic device 12 outputs the output voltage V
The output terminal 40 of the voltage supply device 10 having a positive temperature coefficient of OA and the input terminal 41 of the control device 11 having a negative temperature coefficient of the input threshold voltage VIB are connected to each other.

Further, the control section 14 of the power switch 13
Is composed of a gate cutoff MOSFET 43 for controlling the gate voltage of the power switch 13 and a resistor 44 for pulldown, and the output of the electronic device 12 is input to the gate of the gate cutoff MOSFET 43.

Here, the electronic device 1 for temperature detection is used.
2, the power switch 13, and the control unit 14 are formed on the same semiconductor substrate to realize a semiconductor device having a built-in overheat protection function.

The specific operation of the electronic device 100 according to the first embodiment of the present invention will be described below.

In the voltage supply device 10, the resistance value of the resistor 15 is 25 kΩ, the threshold voltage of the MOSFET 16 is 1 V (drain-source voltage VDS = 5 V, and drain-source current IDS = 1 μA). In the control device 11, the forward voltage of each polysilicon diode included in the diode group 17 is set to 0.6 V, and the number of diodes forming the diode group 17 is 6V.
The resistance value of the polysilicon resistor 18 is 200 kΩ.

Also, as the gate cutoff MOSFET 43, an N channel MOSFE having a threshold voltage of 1V is used.
Use T. The drain terminal of the gate cutoff MOSFET 43 is connected to the wiring connected to the gate of the power switch 13, and the gate terminal is the output terminal 4 of the control device 11.
2, i.e. connected to the output of the electronic device 12 for temperature detection.

With such a structure, it is possible to realize the electronic switch device 100 having the overheat protection function of the MOSFET whose detected temperature is 150 ° C.

When a voltage of 5 V is applied to the input terminal 39 of the voltage supply device 10 at a temperature of 25 ° C., the voltage VO at the point A
A is a voltage divided by the resistor 15 and the MOSFET 16, specifically 2.1V. On the other hand, since the input threshold voltage VIB of the control device 11 is 4.6 V, a Low signal is output from the electronic device 12 at this temperature,
The gate cutoff MOSFET 43 is off.

Here, when the temperature reaches 150 ° C., the resistance 1
As the resistance value of 5 decreases and the flowing current increases,
Since the gate-source voltage of the MOSFET 16 rises, the voltage VOA at the point A rises to 2.7V. On the other hand, the input threshold voltage VIB of the control device 11 drops to 2.7 V because the forward voltage of the polysilicon diode drops at -2.5 mV / ° C. Therefore, the gate cutoff MOSFET 43 is turned on, and the gate voltage of the power switch 13 is lowered by the voltage drop of the pull-down resistor 44. Along with this, the power switch 13 is turned off.

In this way, the overheat protection function of the MOSFET whose detected temperature is 150 ° C. is realized.

FIG. 3 shows the output voltage VO of the voltage supply device 10.
6 is a graph showing the relationship between A and the input threshold voltage VIB of the control device.

As shown in the figure, at 25 ° C., the difference between the output voltage VOA of the voltage supply device 10 and the input threshold voltage VIB of the control device 11 is 2.5V. However, at the detected temperature of 150 ° C., the output voltage VOA of the voltage supply device 10 and the input threshold voltage VIB of the control device 11 match. That is, from 25 ° C to 15
During the temperature change to 0 ° C, the above voltage difference changes by 2.5V.

Here, the total forward voltage of the diode group 17 is ± 0.3 V (± 0.
(05V) The characteristic when it fluctuates is shown by the broken line in FIG. As a result, the variation range of the detected temperature is suppressed to ± 14 ° C in the vicinity of the original detected temperature of 150 ° C. This is because the device configuration shown in FIG. 1 has a larger gain with respect to temperature than the conventional configuration.

As described above, according to the first embodiment of the present invention, by adding the voltage supply device 10 to the conventional configuration, the gain of the temperature detecting electronic device 12 with respect to the temperature can be increased. As a result, even if the number of diodes constituting the polysilicon diode group 17 is not increased, the variation in the detected temperature can be significantly reduced as compared with the conventional case. Therefore, even when only a low power supply voltage can be used, it is possible to realize the temperature detection electronic device 12 in which variations in detected temperature are small.

As described above, in the present embodiment, by combining one polysilicon resistor 15 and one MOSFET 16, the voltage supply device 10 whose output voltage has a positive temperature coefficient can be easily realized. . Further, by adding the voltage supply device 10, the temperature detection electronic device 1 capable of coping with a low power supply voltage and having a small variation in detected temperature.
0 is realized. Further, the temperature detecting electronic device 10
By inputting the output of 1 to the control unit 14 of the power switch 13, the electronic switch device 100 having a built-in overheat protection function with less variation in operation function is realized.

Furthermore, by constructing the voltage supply device 10 only with the elements that can be formed by the self-isolation structure of the polysilicon resistor 15 and the N-channel MOSFET 16, the costly PN isolation process and the dielectric isolation process are not used. In addition, the electronic device 10 for temperature detection of the present embodiment is realized.

In the above-described first embodiment, the resistor 15 made of polysilicon is used as the voltage supply device 10.
However, it is needless to say that the same action and effect can be obtained even if another combination having a positive temperature coefficient or a single element is used. In addition, a MOSFET is used as the power switch 13.
However, it goes without saying that a similar electronic device can be realized in the case of another switching element such as an IGBT or a bipolar transistor.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 3 is an equivalent circuit diagram of the electronic device 200 in the embodiment, specifically, the electronic device for temperature detection and the electronic switch device 200 including the electronic device for temperature detection.

In the configuration of FIG. 4, 50 is a voltage supply device, and 51 is a control device (hereinafter, also simply referred to as "control device") capable of outputting a signal when the temperature is detected to an element in the subsequent stage. Reference numeral 52 denotes an electronic device for temperature detection (hereinafter, also simply referred to as “electronic device”), which includes a voltage supply device 50 and a control device 51. Reference numeral 53 is a power switch, and a MOSFET is used here. 54
Is a control unit of the power switch 53. Electronic device 52
The power switch 53 and the control section 54 constitute an electronic switch device 200 having a built-in overheat protection function.

Voltage supply device 50 included in electronic device 52
1 has the same configuration as the voltage supply device 10 described in the first embodiment with reference to FIG. 1, and is configured by connecting the resistor 55 formed of polysilicon and the drain terminal and gate terminal of the MOSFET 56. There is. When a constant voltage is applied to the input terminal 57, the voltage of the output terminal 58 has a positive temperature coefficient.

On the other hand, the control device 51 includes a resistor 59 and a MOS.
It has a configuration of a resistance type inverter in which the drain terminal of the FET 60 is connected in series, and the input terminal 61 is taken from the gate terminal of the MOSFET 60, while the MOSFET is
The output terminal 62 is taken from the connection point between the resistor 60 and the resistor 59. Here, the threshold voltage of MOSFET 60 is set higher than the threshold voltage of MOSFET 56 in voltage supply device 50. The value of the resistor 59 is such that the input threshold voltage of the controller 51 has a negative temperature coefficient,
Has been adjusted.

The control section 54 of the power switch 53 includes a gate cutoff MOSFET 63 for controlling the gate voltage of the power switch 53, an inverter 64, and a resistor 65 for pulling down, and an output terminal of the electronic device 52. The output from 62 is input to the gate of the gate cutoff MOSFET 63 while being inverted by the inverter 64.

In the configuration of this embodiment, the MOSFET 56
Is set to 1V and the threshold voltage of the MOSFET 60 is set to about 2.5V. Also, the resistance 5
Reference numeral 9 is made of polysilicon and has a resistance value of 200 kΩ so that the input threshold voltage of the control device 51 has a negative temperature coefficient.

FIGS. 5 and 6 show MOSFETs 56 and 6 having a small signal logic function in the configuration of FIG. 4, respectively.
0 and DMOSFET functioning as power switch 53
53A and 53B are a cross-sectional view and a plan view of a configuration 90 obtained when integrated with 53 (vertical double diffusion MOSFET). Note that FIG.
2, the same components as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted here.

The surface impurity concentration of the P well region 21 formed around the source N type region 22 of the MOSFET 56 is about 3 × 10 ¹⁶ cm ^-3 , while the MOSFET 6
The surface impurity concentration of the P well region 21a formed around the source N-type region 22 in the 0 P well region 21 is about 2 × 10 ¹⁷ cm ⁻³ . In this way, MOSF
In the periphery of the source N type region 22 of the ET60, the MOSFE
A P-well region 21a having a slightly higher impurity concentration than the P-well region 21 around the source type region 22 of T56 is formed, thereby raising the threshold voltage of the control device 51. A gate cutoff MOS not shown in FIG.
The FET 63 is formed by the same manufacturing method as the MOSFET 56.

Further, as the power switch 53, an N-channel vertical DMOSFET 53 having a withstand voltage of about 80 V is used. The P well region 21a formed around the source N-type region 22 of the DMOSFET 53 is a MOSFET.
60 has the same impurity concentration as the surface impurity concentration of the P well region 21a formed around the source N-type region 22.

In the present embodiment, the electronic device 52 for detecting the temperature, the power switch 53, and the control unit 54 for controlling the on / off operation of the power switch 53 based on the output of the electronic device 52 are provided. When manufacturing the electronic switch device 200 in which the switch 53 and the electronic device 52 are formed on the same semiconductor substrate, the impurity concentration of the substrate surface around the source region of the MOSFET 60 of the control device 51 included in the electronic device 52 is set as follows. The step of increasing the impurity concentration on the substrate surface around the source region of the MOSFET 56 of the voltage supply device 50 included in the electronic device 52 and the step of forming the well of the power switch 53 are simultaneously performed.

By the way, as in the configuration of this embodiment, the low voltage MOSFETs 56 and 60 and the high voltage DMOSF are used.
When the ET53 and the ET53 are integrated on the same substrate, it is a problem to prevent the low-voltage MOSFETs 56 and 60 from being affected by voltage fluctuations and surges accompanying the operation of the high-voltage DMOSFET 53. In particular, low voltage MOSFETs 56 and 6
When 0 and the high-voltage DMOSFET 53 are integrated on one semiconductor substrate, the above-mentioned influence is remarkable when a current flows in the vertical direction of the high-voltage DMOSFET 53 and the potential of the semiconductor substrate largely changes. Can occur.

To solve the above problem, according to the prior art,
A shallow diffusion region is provided in the low voltage region. However, in such a countermeasure, in the case of the vertical DMOSFET, the potential on the back surface of the substrate largely changes at each switching and surge noise is easily applied. If the diffusion region breaks down due to these potential fluctuations and high voltage surges, a voltage drop occurs until the current flows into the surface electrode portion, and malfunction due to the action of the parasitic transistor is likely to occur.

Therefore, in the configuration 90 of this embodiment, as shown in FIG.
And, as shown in FIG. 6, a MOSF having a small signal logic function.
ETs 56 and 60, an insulating film 24 for insulatingly arranging them, a lower portion of the insulating film 24, and a MOSFET
A low breakdown voltage region including at least a shallow well region 70 commonly connected to the P well regions 21 and 21a of 56 and 60, and a DMOSF functioning as a power switch 53.
And a high breakdown voltage region 80 including ET53. The low breakdown voltage region and the high breakdown voltage region 80 are deep P regions provided at least around the shallow P well region 70 below the low breakdown voltage region.
The well region 71 is electrically isolated. The deep P well region 71 has a higher impurity concentration than the shallow P well region 70 and is provided so as to reach a deep position. In this electrical isolation, it is more preferable to surround not only the periphery of the shallow P well region 70 below the low voltage region but also the periphery of the DMOSFET 53.

The deep P well region 71 is a DMOSFET.
It is formed in the same process as the P well region 21a of 53.
Therefore, the insulating layer 24 made of LOCOS above the deep P well region 71 is removed to form the deep well 71 by diffusion. In addition, the deep P well region 7
1 diffusion depth and P-well region 21 of DMOSFET 53
The diffusion depth of a is almost the same, and the
Since the cross-sectional shapes of 1 and 21a are also similar, the local breakdown voltage does not decrease.

Further, the insulating layer 24 is formed around the low breakdown voltage region.
Is formed, and the deep P well region 71 is located so as to extend beyond the region where the insulating layer 24 is located and to the high breakdown voltage region 80 side. As a result, the low withstand voltage region and the high withstand voltage region are better electrically isolated.

As described above, in the present invention, the impurity concentration on the surface of the peripheral portion of the shallow diffusion region (shallow well region) 70 is increased (that is, the deep well region 71 is formed) before connection with the electrode. By diffusion area (well)
The potential of is fixed. In particular, the potential in the well can be fixed to a deeper position by expanding the region 71 having a high impurity concentration to a deeper region.

By providing the deep P well region 71 so as to surround the low breakdown voltage region, the breakdown voltage with the substrate is determined by the radius of curvature of the junction surface between the deep P well region 71 and the substrate. Become so. Even if a breakdown occurs, the current flows through the well having a high concentration to the electrode portion, so that a malfunction hardly occurs.

The deep well region 71 and the high breakdown voltage region 8
The distance to 0 is fixed. The deep well region 71 preferably has the same structure as the low breakdown voltage region and the high breakdown voltage region 80.

On the other hand, regarding the thickness of the gate oxide film that most affects the threshold voltage, MOSFETs 56 and 6
By using the oxide film of the same thickness formed by the same process in both 0, the threshold voltage of each MOSFET 56 and 60 has the temperature coefficient of the same sign with respect to temperature change, and the same direction. Change (increase or decrease). Further, except for the step of forming the P well region 21a around the source N type region 22 of the MOSFET 60, both M
By forming the OSFETs 56 and 60 in exactly the same process, the threshold voltages of the MOSFETs 56 and 60 have the same temperature coefficient even if other structural parameters change in the manufacturing process.

The specific operation of the electronic device 200 according to the second embodiment of the present invention will be described below.

In the voltage supply device 50, assuming that the resistance value of the resistor 55 is 60 kΩ, the voltage of the output terminal 58 is 1.5 V when the voltage of 5 V is applied to the input terminal 57. At this time, the voltage of the output terminal 58 has a positive temperature coefficient. On the other hand, the input threshold voltage of the control device 51 is the threshold voltage of the MOSFET 60 and is about 2.5.
It becomes V. This input threshold voltage has a negative temperature coefficient.

When the temperature is 25 ° C., the controller 5
The voltage applied to the input terminal 61 of 1 is 1.5V,
This is below the input threshold voltage. Therefore, the potential of the output terminal 62 becomes 0 V, the electronic device 52 outputs the High signal, and the High signal is input to the control unit 54. As a result, the gate cutoff M is generated via the inverter 64.
The Low signal is input to the gate of the OSFET 63, and the gate cutoff MOSFET 63 is in the off state.

Here, when the temperature rises, the output voltage of the voltage supply device 50 rises because it has a positive temperature coefficient,
On the other hand, the input threshold voltage of control device 51 decreases because it has a negative temperature coefficient. When the temperature reaches 150 ° C,
The output voltage of the voltage supply device 50 and the input threshold voltage of the control device 51 become the same value (2.1 V), and the electronic device 52
Outputs a Low signal, which is input to the control unit 54. In the controller 54, the High signal (5 V) is applied to the gate of the gate cutoff MOSFET 63 via the inverter 64, and the gate cutoff MOSFET 63 is turned on, so that the power switch 53 is turned off. In this way, the overheat protection function of the MOSFET whose detected temperature is 150 ° C. is realized.

Even if the threshold voltage of the MOSFET fluctuates due to variations in parameters in the manufacturing process, M
Since the OSFETs 56 and 60 have the threshold voltages having the temperature coefficient of the same sign and are configured to change (increase or decrease) in the same direction, the voltage supply device 50.
And the input threshold voltage of the control device 51 are offset in the same direction. Therefore, variations in the detected temperature can be suppressed.

As described above, the resistance type inverter is used as the control device 51, and the M is used for the voltage supply device 50.
By setting the threshold voltage of the MOSFET 60 used in the resistance-type inverter higher than the threshold voltage of the OSFET 56, variation in detected temperature due to parameter variation in the manufacturing process of the electronic device 52 for temperature detection is reduced. .

Further, in the electronic device having the N-channel vertical DMOSFET 53 built therein as the power switch 53, the P well forming process of the DMOSFET 53 is used to perform 2 steps.
By forming the MOSFETs 56 and 60 having three different threshold voltages, it is possible to realize the electronic switch device 200 having a built-in overheat protection function with less variation in operation function without adding the number of steps.

[0091]

As described above, in the electronic device for temperature detection of the present invention, the temperature coefficient of the input threshold voltage is negative at the output terminal of the voltage supply means having the positive temperature coefficient of the output voltage. By adopting a configuration in which the input terminal of a certain electronic control means is connected, it is possible to realize a temperature detecting electronic device that can cope with a low power supply voltage and has a small variation in detected temperature at low cost. Further, by using the resistance type inverter using the MOSFET having the threshold voltage higher than that of the MOSFET used as the voltage supply means as the electronic control means, the variation of the detected temperature due to the variation of the parameter in the manufacturing process is significantly increased. Will be reduced.

Further, according to the electronic switch device of the present invention, by incorporating a power switch in the above-mentioned electronic device for temperature detection, a device having an overheat protection function with a small variation in operating function can be realized.

Further, according to the method for manufacturing an electronic switch device of the present invention, it is possible to manufacture an electronic switch device having a built-in overheat protection function with less variation in operating function without adding steps.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of an electronic device according to a first embodiment of the present invention, specifically, an electronic switch device including an electronic device for temperature detection.

FIG. 2 is a cross-sectional view showing an element structure when the temperature detecting electronic device of FIG. 1 is configured as a semiconductor device.

FIG. 3 is a graph showing the relationship between the output voltage of the voltage supply device and the input threshold voltage of the control device in the configuration of FIG.

FIG. 4 is an equivalent circuit diagram of an electronic device according to a second embodiment of the present invention, specifically, an electronic switch device including an electronic device for temperature detection.

5 is a DMOS functioning as a power switch and a MOSFET having a small signal logic function in the configuration of FIG.
It is sectional drawing of the structure obtained when integrating FET (vertical double diffusion MOSFET).

6 is a schematic plan view of a part of the configuration of FIG.

FIG. 7 is an equivalent circuit diagram of an example of a conventional electronic switch device having a built-in overheat protection function.

FIG. 8 is a graph showing temperature characteristics of the conventional electronic device for temperature detection in FIG.

[Explanation of symbols]

10, 50 Voltage supply device 11,51 Control device 12,52 Electronic device 13,53 power switch 14, 54 Control unit 15,44,55,59,65 Resistance 16, 56, 60 MOSFET 17 Polysilicon diode 18 Polysilicon resistor 20 N type epitaxial region 21, 21a P-type well region 22 Source N-type region 23 Drain N-type region 24 Insulating film 25 Interlayer insulation film 26 gate polysilicon layer 27 Polysilicon layer 28 Anode region 29 cathode area 30 aluminum electrode 31 source electrode 32 gate electrode 33 drain electrode 39, 41, 57, 61 Input terminals 40, 42, 58, 62 output terminals 43, 63 Gate cutoff MOSFET 64 inverter 70 Shallow P-well area 71 Deep P-well area 80 High voltage region

Front page continued (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 29/78 656 H03K 17/94 J H01L 27/04 H 27/06 102A 657 27/08 102E H03K 17/08 102F 17 / 94 F term (reference) 5F038 AR28 AV06 AZ08 BH02 BH04 BH07 BH16 DF01 EZ20 5F048 AC01 AC06 AC10 BB18 BC20 BD07 BE04 BE05 BE06 BG12 BH02 CB06 CC01 CC04 CC06 CC08 CC15 CC18 DA10 DA13 5J050 AA32 BB23DD26BB22 AA32 AA37 BB26A22 AA32 BB37DD0822. 5J055 AX34 BX44 CX27 DX22 DX52 DX55 EX07 EY01 EY12 EY21 EZ07 FX06 FX19 FX33 FX37 GX01 GX06 GX07 GX08

Claims (2)

[Claims] 1. An electronic device for temperature detection, a power switch, and an overheat protection control unit for controlling on / off operation of the power switch based on an output of the electronic device for temperature detection. A method of manufacturing an electronic switch device in which a switch and the temperature detecting electronic device are formed on the same semiconductor substrate, wherein the manufacturing method includes a MOS of an electronic control unit included in the temperature detecting electronic device.
Of adjusting the impurity concentration of the substrate surface around the source region of the MOS transistor to be higher than the impurity concentration of the substrate surface around the source region of the MOS transistor of the voltage supply means included in the temperature detecting electronic device, And a well forming step of forming a well of the power switch, wherein the concentration adjusting step and the well forming step are performed at the same time. 2. A low breakdown voltage region and a high breakdown voltage region provided on the same semiconductor substrate, a shallow well region provided below the low breakdown voltage region, and a shallow well region continuous with the shallow well region. A deep well region substantially surrounding the periphery and formed to reach a position deeper than the shallow well region, the deep well region having the same conductivity type as the shallow well region but having a higher impurity concentration. Is an electronic device.