JP7087374B2 - Semiconductor devices, image pickup devices and optical sensors - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Application of Article 30, Paragraph 2 of the Patent Act, announced at IMFEDK 2017 held at Ryukoku University Symphony Hall on June 29, 2017.

The present invention relates to a semiconductor device, an image pickup device and an optical sensor.

In general, many photoelectric conversion elements have a linear characteristic in the output signal with respect to the amount of received light. When a photoelectric conversion element is used as an image sensor, it is required to reproduce what the human eye sees as it is, and it is known that the information of light captured by the human eye needs to be handled in the form of logarithmic compression of the signal amount. There is. Therefore, a technique for logarithmically compressing the output signal of the photoelectric conversion element has been discussed, and there is a technique for expanding the dynamic range of the amount of light to be handled.

For example, in Patent Document 1, an image pickup device in which a MOSFET is connected in series to a photoelectric conversion element for the purpose of logarithmic compression of the dynamic range of photoelectric conversion characteristics, improvement of image quality (color tone), reduction of thermal noise, and reduction of processing time. Is described.

However, in the conventional image pickup apparatus, the range in which logarithmic compression is possible is not sufficient, and it is difficult to appropriately control the output current. There is also known a technique of obtaining multiple pixel outputs with different exposure times and synthesizing them by signal processing to obtain an image with a wide dynamic range. However, in this technique, multiple pixel outputs are obtained. Processing is complicated.

An object of the present invention is to provide a semiconductor device, an image pickup device, and an optical sensor capable of compressing and outputting a signal corresponding to incident light having a wide dynamic range to an appropriate dynamic range.

One aspect of the semiconductor device includes an electric field effect transistor and a photoelectric conversion unit connected to a channel of the electric field effect transistor to change the threshold voltage of the electric field effect transistor, and the photoelectric conversion unit is bipolar. It has a phototransistor of structure, the base of the phototransistor and the channel are at the same potential, the emitter of the phototransistor and the source of the electric field effect transistor are at the same potential, and the collector of the phototransistor and the collector of the phototransistor. The drains of the electric field effect transistors are at the same potential as each other, and the first semiconductor region of the first conductive type including the emitter and the source and the second semiconductor region of the second conductive type including the base and the channel. And a first conductive type third semiconductor region including the collector and the drain, the second semiconductor region is below the first semiconductor region, and the third semiconductor region is. A groove is formed below the second semiconductor region and reaches the third semiconductor region, the gate insulating film and the gate electrode are provided in the groove, and the voltage applied to the gate electrode is 0.5. In the range of [V] to 1.2 [V], the amount of change in the photocurrent becomes smaller as the voltage is increased, and the dynamic range of the change in the photocurrent with respect to the change in the amount of light irradiated to the phototransistor. Is characterized by being compressed .

According to the present invention, a signal corresponding to incident light having a wide dynamic range can be compressed to an appropriate dynamic range and output.

It is a circuit diagram which shows the semiconductor device which concerns on 1st Embodiment. It is a circuit diagram which shows the semiconductor device which concerns on 2nd Embodiment. It is sectional drawing which shows the semiconductor device which concerns on 2nd Embodiment. It is a circuit diagram which shows the semiconductor device which concerns on 3rd Embodiment. It is a top view which shows the semiconductor device which concerns on 3rd Embodiment. It is sectional drawing which shows the semiconductor device which concerns on 3rd Embodiment. It is a band diagram which shows the operation of the semiconductor device which concerns on 3rd Embodiment. It is sectional drawing which shows the modification of 3rd Embodiment. It is a top view which shows the semiconductor device which concerns on 4th Embodiment. It is sectional drawing which shows the semiconductor device which concerns on 4th Embodiment. It is a graph which shows the relationship between the gate bias and the photocurrent in the semiconductor device which concerns on 4th Embodiment. It is a graph which shows the relationship between the light intensity and the photocurrent in the semiconductor device which concerns on 4th Embodiment. It is a graph which shows the output characteristic of the semiconductor device which concerns on 4th Embodiment. It is sectional drawing which shows the modification of 4th Embodiment. It is a circuit diagram which shows the semiconductor device which concerns on 5th Embodiment. It is sectional drawing which shows the semiconductor device which concerns on 5th Embodiment. It is a figure which shows the optical sensor which concerns on 6th Embodiment. It is a circuit diagram which shows the specific structure of the optical sensor which concerns on 6th Embodiment. It is a figure which shows the image pickup apparatus which concerns on 7th Embodiment. It is a figure which shows the pixel array. It is a figure which shows the stereo camera which concerns on 8th Embodiment. It is a figure which shows the blower device which concerns on 9th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
First, the semiconductor device according to the first embodiment will be described. FIG. 1 is a circuit diagram showing a semiconductor device according to the first embodiment.

The semiconductor device 100 according to the first embodiment includes a field effect transistor (FET) 110 and a photoelectric conversion unit 120 connected to a channel 114 of the FET 110. The FET 110 is a MOS (Metal-Oxide-Semiconductor) transistor including, for example, a gate 111, a source 112, a drain 113, and a channel 114.

In the semiconductor device 100, when the photoelectric conversion unit 120 is irradiated with light, the photoelectric conversion unit 120 generates an electric charge or a potential according to the amount of light received. Therefore, the potential of the channel 114 to which the photoelectric conversion unit 120 is connected, for example, the substrate potential of the FET 110 changes according to the amount of light received by the photoelectric conversion unit 120. If the FET 110 is an N-channel MOS transistor and holes move to the channel 114, the potential of the channel 114 rises in the positive direction, so that the threshold voltage of the FET 110 drops due to the substrate bias effect. Therefore, if the gate voltage is constant, the output current becomes large. Further, if the operating region of the FET 110 is a subthreshold region, the output current changes logarithmically with respect to a change in the threshold voltage, so that the output current changes significantly. Further, by changing the gate voltage, it is possible to control the amount of change in the output current according to the amount of received light.

As described above, according to the first embodiment, the electric charge or potential difference generated by the photoelectric conversion unit 120 receiving photons is used to control the potential of the channel 114 of the FET 110, thereby making the electrical characteristics of the FET 110 logarithmic. Can be changed to. Therefore, the signal corresponding to the incident light having a wide dynamic range can be compressed to an appropriate dynamic range and output.

(Second embodiment)
Next, the semiconductor device according to the second embodiment will be described. FIG. 2 is a circuit diagram showing a semiconductor device according to the second embodiment. FIG. 3 is a cross-sectional view showing a semiconductor device according to the second embodiment.

As shown in FIG. 2, the semiconductor device 200 according to the second embodiment includes an FET 210 and a photodiode 220 in which the anode 222 is connected to the channel 214 of the FET 210. The FET 210 is an N-channel MOS transistor including a gate 211, a source 212, a drain 213 and a channel 214. For example, a power supply voltage is supplied to the cathode 221 of the photodiode 220.

As shown in FIG. 3, the semiconductor device 200 includes an element separation film 253a formed on the surface of the P-type silicon substrate 251, an element separation film 253b in a region surrounded by the element separation film 253a, and an element separation film 253a. Includes a gate insulating film 254 and a gate electrode 255 between the element separation film 253b. A P-well 252 is formed on the surface of the P-type silicon substrate 251 in the region surrounded by the element separation membrane 253a, and N-type impurities for the cathode are diffused on the surface of the P-well 252 in the region surrounded by the element separation membrane 253b. Layer 256c is formed. Between the element separation film 253a and the element separation film 253b, an N-type impurity diffusion layer 256s for a source is formed on the element separation film 253a side of the gate electrode 255, and an N-type impurity diffusion for drain is formed on the element separation film 253b side. Layer 256d is formed. The P-well 252 includes a portion that functions as a channel 214 and a portion that functions as an anode 222.

In the semiconductor device 200, when the photodiode 220 is irradiated with light, the photodiode 220 generates electron-hole pairs according to the amount of light received, electrons move toward the cathode 221 and holes are directed toward the anode 222. Moves and a drift current is generated. Then, the holes moved to the anode 222 side are accumulated in the channel 214 (back region) of the FET 210, and the potential of the channel 214 rises in the positive direction. That is, when the interface between the N-type impurity diffusion layer 256c and the P well 252 is irradiated with light, holes are accumulated in the P well 252 and the potential of the channel 214 of the FET 210 rises in the positive direction. Here, the increase in the potential of the channel 214 increases in proportion to the amount of received light. Therefore, due to the substrate bias effect, the threshold voltage of the FET 210 decreases according to the amount of received light, and if the gate voltage is constant, the output current increases. Further, if the operating region of the FET 210 is a subthreshold region, the output current changes logarithmically with respect to a change in the threshold voltage, so that the output current changes significantly. Further, by changing the gate voltage, it is possible to control the amount of change in the output current according to the amount of received light.

Thus, according to the second embodiment, the electric charge or potential difference generated by the photodiode 220 receiving photons is used to control the potential of the channel 214 of the FET 210, thereby logarithmically changing the electrical characteristics of the FET 210. Can be changed. Therefore, the signal corresponding to the incident light having a wide dynamic range can be compressed to an appropriate dynamic range and output.

(Third embodiment)
Next, the semiconductor device according to the third embodiment will be described. FIG. 4 is a circuit diagram showing a semiconductor device according to the third embodiment. FIG. 5 is a plan view showing the semiconductor device according to the third embodiment. FIG. 6 is a cross-sectional view showing the semiconductor device according to the third embodiment. FIG. 6 corresponds to a cross-sectional view taken along the line I-I in FIG.

As shown in FIG. 4, the semiconductor device 300 according to the third embodiment includes an FET 310 and a phototransistor 320 in which a base 321 is connected to a channel 314 of the FET 310. The FET 310 is an N-channel MOS transistor including a gate 311, a source 312, a drain 313 and a channel 314. The phototransistor 320 is an NPN type bipolar transistor including a base 321 and an emitter 322, the emitter 322 is connected to the source 312, and the collector 323 is connected to the drain 313.

As shown in FIGS. 5 and 6, the semiconductor device 300 includes a P-well 352 formed on the surface of the N-type silicon substrate 351 and a gate insulating film 354 and a gate formed along the contour on the P-well 352. Includes electrode 355. In the region surrounded by the gate electrode 355, an N-type impurity diffusion layer 356 is formed on the surface of the P well 352. The N-type silicon substrate 351 includes a portion that functions as a drain 313 and a portion that functions as a collector 323. The P-well 352 includes a portion that functions as a channel 314 and a portion that functions as a base 321. The N-type impurity diffusion layer 356 includes a portion that functions as a source 312 and a portion that functions as an emitter 322.

FIG. 7 is a band diagram showing the operation of the semiconductor device 300. In the semiconductor device 300, when the phototransistor 320 is irradiated with light, the phototransistor 320 generates electron-hole pairs according to the amount of light received, electrons move toward the collector 323, and holes move toward the base 321. However, a drift current is generated. Since there is a PN junction potential barrier between the base 321 and the emitter 322, holes that have moved to the base 321 side are accumulated, raising the potential of the base 321 and raising the potential of the base 321. When the amount of holes accumulated increases and the potential barrier between the base and the emitter becomes sufficiently low to enter a forward bias state, electrons on the emitter 322 side flow into the collector 323 side as carriers. As a result, the amplified current is output from the phototransistor 320. Here, the amount of increase in the potential of the base 321 when the phototransistor 320 operates increases in proportion to the amount of light received. In the semiconductor device 300, since the base 321 and the channel 314 (back region) are included in the P well 352, the potential of the channel 314 rises by the amount that the potential of the base 321 rises. Therefore, due to the substrate bias effect, the threshold voltage of the FET 310 decreases according to the amount of received light, and if the gate voltage is constant, the output current increases. Further, if the operating region of the FET 210 is a subthreshold region, the output current changes logarithmically with respect to a change in the threshold voltage, so that the output current changes significantly. Further, by changing the gate voltage, it is possible to control the amount of change in the output current according to the amount of received light.

In the semiconductor device 300, the phototransistor 320 is connected in parallel to the FET 310, and the holes generated in the phototransistor 320 due to light reception cause the substrate bias effect of the FET 310. Therefore, the electrical characteristics of the FET 310 change, and the output optical signal current changes. Then, in addition to the optical signal current due to the phototransistor 320, the semiconductor device 300 outputs the drain current of the FET 310 whose threshold voltage is lowered due to the substrate bias effect. Therefore, the output current of the semiconductor device 300 is obtained by adding a large drain current of the FET 310 to the optical signal current in the low illuminance region, and the drain current of the FET 310 becomes inconspicuous in the high illuminance region, and the optical signal current becomes remarkable. It will be the one that became. For example, regarding the current path between the emitter and the collector of the phototransistor 320, the base region in the vicinity of the gate electrode 355 tends to be depleted due to the work function difference due to the gate electrode 355. Therefore, when the current flowing through the system is small, the current component due to the FET 310 increases. Therefore, only the output signal in the low illuminance region is pulled up, and the current range of the output signal is compressed with respect to the intensity range of the incident light as a whole.

As described above, according to the third embodiment, the electric charge or potential difference generated by the phototransistor 320 receiving photons is used to control the potential of the channel 314 of the FET 310, thereby logarithmically changing the electrical characteristics of the FET 310. Can be changed. Therefore, the signal corresponding to the incident light having a wide dynamic range can be compressed to an appropriate dynamic range and output.

As shown in FIG. 8, an N-type impurity diffusion layer 357 similar to the N-type impurity diffusion layer 356 may be formed on the surface of the N-type silicon substrate 351. The N-type impurity diffusion layer 357 can be formed in parallel with the N-type impurity diffusion layer 356.

(Fourth Embodiment)
Next, the semiconductor device according to the fourth embodiment will be described. The fourth embodiment includes the FET 310 and the phototransistor 320 as in the third embodiment, but the structure of the layers constituting them is different from that of the third embodiment. FIG. 9 is a plan view showing the semiconductor device according to the fourth embodiment. FIG. 10 is a cross-sectional view showing the semiconductor device according to the fourth embodiment. FIG. 10 corresponds to a cross-sectional view taken along the line I-I in FIG.

As shown in FIGS. 9 and 10, the semiconductor device 400 according to the fourth embodiment is formed in a P-well 362 formed on the surface of the N-type silicon substrate 361 and a groove (trench) surrounding the P-well 362. Includes the gate insulating film 364 and the gate electrode 365. An N-type impurity diffusion layer 366 is formed on the surface of the P well 362. The N-type silicon substrate 361 includes a portion that functions as a drain 313 and a portion that functions as a collector 323. The P-well 362 includes a portion that functions as a channel 314 and a portion that functions as a base 321. The N-type impurity diffusion layer 366 includes a portion that functions as a source 312 and a portion that functions as an emitter 322. As described above, in the fourth embodiment, the FET 310 has a configuration in which the FET 310 parasitizes over the entire circumference of the phototransistor 320.

The same operation as that of the third embodiment is performed in the fourth embodiment, and the same effect as that of the third embodiment can be obtained by the fourth embodiment. The fourth embodiment is preferable to the third embodiment in terms of area saving. On the other hand, the third embodiment does not require a groove (trench), and is therefore preferable to the fourth embodiment in terms of ease of manufacture.

Here, the characteristics of the semiconductor device 400 will be described. FIG. 11 is a graph showing the relationship between the gate bias and the photocurrent in the semiconductor device 400. FIG. 12 is a graph showing the relationship between the light intensity and the photocurrent in the semiconductor device 400. As shown in FIGS. 11 and 12, for each voltage (gate bias ( _VTG )) applied to the gate electrode 365 of the FET 310, a dark state with a light intensity of 0.01 [lux] and a light with a light intensity of about 100 [lux]. The difference in light current between the states is different. That is, in the range of approximately 0.5 [V] to 1.2 [V], the larger the gate bias, the smaller the amount of change in the photocurrent, and the dynamic range of the change in the photocurrent with respect to the change in the amount of received light is compressed. Will be done.

The gate bias is preferably a voltage at which the FET 310 can maintain a weakly inverted state. For example, in the example shown in FIG. 11, when the gate bias exceeds 1.2 [V], the FET 310 is strongly inverted and the leakage current becomes large, which may make it difficult to detect the optical signal current.

FIG. 13 is a graph showing the output characteristics of the semiconductor device 400. FIG. 13 shows the output characteristics of the current output of the semiconductor device 400 obtained by performing current-voltage conversion using an integrator amplifier. As shown in FIG. 13, the dynamic range of the change in the intensity of the irradiated light is 120 dB, while the dynamic range of the change in the output signal voltage is 60 dB, and the range is 60 dB (1000 times) smaller. Has been done. That is, the dynamic range can be compressed. Therefore, when the semiconductor device 400 is used as an image pickup device, an image having a wide dynamic range can be obtained with one pixel output. Such an image pickup device is suitable for imaging a moving image, and is particularly suitable for an in-vehicle camera such as an in-vehicle stereo camera for detecting a fast-moving object. It is also suitable for application to surveillance cameras by taking advantage of the fact that it can capture images in a wide dynamic range.

The gate bias may be controlled automatically according to the ambient brightness, or may be manually set by the user according to preference. As shown in FIGS. 12 and 13, the range of the output current of the semiconductor device can be controlled according to the gate bias.

As shown in FIG. 14, it is preferable that the metal film 372 connected to the gate electrode 365 is formed so as to cover the portion of the P well 362 that functions as the channel 314 of the FET 310. An insulating film 371 is formed between the metal film 372 and the N-type impurity diffusion layer 366.

According to this configuration, it is possible to more reliably suppress the malfunction of the FET 310 due to the irradiation of the channel 314 with light. Generally, the FET is configured on the assumption that it is used in a dark state, and when it is irradiated with light, there is a possibility that a problem such as an increase in off-leakage current may occur. In the example shown in FIG. 14, since the metal film 372 functions as a light-shielding film, the reliability of normal operation can be improved.

(Fifth Embodiment)
Next, the semiconductor device according to the fifth embodiment will be described. FIG. 15 is a circuit diagram showing a semiconductor device according to the fifth embodiment. FIG. 16 is a cross-sectional view showing the semiconductor device according to the fifth embodiment.

As shown in FIG. 15, the semiconductor device 500 according to the fifth embodiment includes the FET 510 and the photoelectric conversion material 520 connected to the channel 514 of the FET 510. The FET 510 is an N-channel MOS transistor including a gate 511, a source 512, a drain 513 and a channel 514. The photoelectric conversion material 520 is, for example, a cadmium sulfide (CdS) film. CdS has the property that the resistance value decreases as the amount of light received increases.

As shown in FIG. 16, the semiconductor device 500 includes an element separation film 553a formed on the surface of the P-type silicon substrate 551, an element separation film 553b in a region surrounded by the element separation film 553a, and an element separation film 553a. Includes a gate insulating film 554 and a gate electrode 555 between the element separation film 553b. A P-well 552 is formed on the surface of the P-type silicon substrate 551 in the region surrounded by the element separation film 553a, and a CdS film 557 is formed on the surface of the P-well 552 in the region surrounded by the element separation film 553b. There is. An N-type impurity diffusion layer 556s for a source is formed on the element separation film 555a side of the gate electrode 555 between the element separation membrane 553a and the element separation film 553b, and an N-type impurity diffusion for drain is formed on the element separation film 553b side. Layer 556d is formed. A power supply voltage VDD is supplied to the CdS film 557. The P-well 552 includes a portion that functions as a channel 514.

In the semiconductor device 500, when the photoelectric conversion material 520 is irradiated with light, the resistance value of the photoelectric conversion material 520 changes according to the amount of light received, so that the potential of the P well 552 also changes according to the amount of light received. That is, when the CdS film 557 is irradiated with light, the potential of the channel 514 of the FET 510 rises in the positive direction. Here, the amount of increase in the potential of the channel 514 (back region) increases in proportion to the amount of light received. Therefore, due to the substrate bias effect, the threshold voltage of the FET 510 decreases according to the amount of received light, and if the gate voltage is constant, the output current increases. Further, if the operating region of the FET 510 is a subthreshold region, the output current changes logarithmically with respect to a change in the threshold voltage, so that the output current changes significantly. Further, by changing the gate voltage, it is possible to control the amount of change in the output current according to the amount of received light.

As described above, according to the fifth embodiment, the electric charge or potential difference generated by the photoelectric conversion material 520 receiving photons is used to control the potential of the channel 514 of the FET 510, thereby making the electrical characteristics of the FET 510 logarithmic. Can be changed to. Therefore, the signal corresponding to the incident light having a wide dynamic range can be compressed to an appropriate dynamic range and output.

(Sixth Embodiment)
Next, the optical sensor according to the sixth embodiment will be described. FIG. 17 is a diagram showing an optical sensor according to a sixth embodiment. FIG. 18 is a circuit diagram showing an example of a specific configuration of the optical sensor according to the sixth embodiment.

The optical sensor 600 according to the sixth embodiment includes any of the semiconductor devices according to the first to fifth embodiments. Therefore, the output signal of the optical sensor 600 changes according to the amount of incident light.

As shown in FIG. 18, the photosensor 600 includes a photodetector 601, an operational amplifier 602, a resistor 603 and a resistor 604. The photodetector 601 includes any of the semiconductor devices according to the first to fifth embodiments, the source of the semiconductor device is grounded, one end of the resistor 603 is connected to the drain, and the other end of the resistor 603 is the operational amplifier 602. It is connected to the inverting input terminal (-) of. A signal is input from the input terminal 605 to the non-inverting input terminal (+) of the operational amplifier 602. A resistor 604 is connected as a feedback resistor between the output terminal 606 and the inverting input terminal (−).

In the optical sensor 600, the operational amplifier 602 is based on the ratio of the sum of the resistance value R _SD between the source and drain of the FET included in the photodetector 601 and the resistance value R ₆₀₃ of the resistance 603 to the resistance value R ₆₀₄ of the resistance 604. The gain is determined. When light is incident on the photodetector unit 601, the potential of the channel of the FET included in the photodetector unit 601 changes, and the threshold voltage changes. If the gate voltage (gate bias) of the FET is constant, the drain current changes and the resistance value _RSD changes, so that the gain of the operational amplifier 602 also changes according to the amount of incident light. Therefore, the range of the drain current can be controlled according to the gate bias, and the gain of the operational amplifier 602 can be controlled.

As described above, according to the sixth embodiment, an output signal corresponding to the amount of incident light can be obtained. Further, since the photodetector 601 includes any of the semiconductor devices according to the first to fifth embodiments, the output signal is dynamic according to the amount of incident light by appropriately designing the circuit shown in FIG. The range can be controlled. For example, the load to be driven can be variously changed according to the amount of incident light. That is, it is possible to control from a small motor used for toys to a large motor used for driving a vehicle according to the amount of light received.

The operational amplifier 602 is not limited to the non-inverting amplifier circuit, and the operational amplifier may be an inverting amplifier circuit, an integrator circuit, or the like.

(7th Embodiment)
Next, the image pickup apparatus according to the seventh embodiment will be described. FIG. 19 is a diagram showing an image pickup apparatus according to a seventh embodiment. FIG. 20 is a diagram showing a pixel array.

As shown in FIG. 19, the image pickup apparatus 700 according to the seventh embodiment includes a main body portion 703 and a lens portion 702. The main body 703 includes a pixel array 701. As shown in FIG. 20, the pixel array 701 includes a plurality of semiconductor devices 400 arranged in an array. The gate insulating film 364 and the gate electrode 365 formed in the groove (trench) are shared between the adjacent semiconductor devices 400.

In the image pickup apparatus 700, the pixel array 701 uses the distribution of the optical signal obtained through the lens unit 702 as an image. Since the semiconductor device 400 is included in the pixel array 701, it is possible to compress and output a signal corresponding to an image having a wide dynamic range to an appropriate dynamic range.

(8th Embodiment)
Next, the stereo camera according to the eighth embodiment will be described. FIG. 21 is a diagram showing a stereo camera according to the eighth embodiment.

The stereo camera 800 according to the eighth embodiment includes the image pickup apparatus 700 according to the seventh embodiment. Then, as shown in FIG. 21, the stereo camera 800 is mounted on a vehicle 801 such as a passenger car, and captures a moving image of the situation in the traveling direction while the vehicle 801 is moving. When the control device to which the stereo camera 800 is connected detects an object 803 that leads to a traffic accident in the moving image, measures such as deceleration are promptly taken.

The ambient brightness may change abruptly while the vehicle 801 is moving, but since the stereo camera 800 includes an image pickup device 700 suitable for capturing an image of a subject having a wide dynamic range, even in such a case. , You can get a movie with a wide dynamic range. For example, even when an image is taken outside a bright tunnel while traveling in a tunnel, it is possible to obtain a moving image without overexposure. Therefore, the safety of the vehicle 801 equipped with the stereo camera 800 can be enhanced.

In the seventh embodiment and the eighth embodiment, the pixel array 701 replaces the semiconductor device 400 according to the fourth embodiment with the semiconductor device of the first, second, third or fifth embodiment. It may be included.

(9th embodiment)
Next, the blower device according to the ninth embodiment will be described. FIG. 22 is a diagram showing a blower device according to a ninth embodiment.

The blower 900 according to the ninth embodiment includes the optical sensor 600 and the motor 901 according to the sixth embodiment. The motor 901 adjusts the rotation speed according to the output current from the optical sensor 600. For example, the brighter the place, the larger the output current from the optical sensor 600, and the higher the speed of the motor 901. Therefore, the air volume of the blower 900 such as a fan can be automatically adjusted according to the brightness of the surroundings. For example, the air volume can be controlled according to the sunlight during the day.

The blower 900 is not limited to a fan, and may be a ceiling fan, a wall-mounted fan, a circulator, or a dryer.

The photoelectric conversion unit is not limited to a photodiode, a phototransistor, or a photoelectric conversion material, and may be a photoconducting device, a photovoltaic cell, a phototube, a photomultiplier tube, or the like. Further, the conductive type of the semiconductor region constituting the semiconductor device may be the reverse conductive type as in the above embodiment. For example, the field effect transistor may be a P-channel transistor.

100, 200, 300, 400, 500 Semiconductor device 110, 210, 310, 510 Field effect transistor (FET)
111, 211, 311, 511 Gate 112, 212, 312, 512 Source 113, 213, 313, 513 Drain 114, 214, 314, 514 channels (back area)
120 Photodiode 220 Photodiode 221 Cathode 222 Anode 320 Phototransistor 321 Base 322 Emitter 323 Collector 520 Photodetector conversion material 600 Optical sensor 700 Imaging device 800 Stereo camera 900 Blower

Japanese Unexamined Patent Publication No. 2000-196961

Claims (5)

Field effect transistor and
A photoelectric conversion unit connected to the channel of the field-effect transistor and changing the threshold voltage of the field-effect transistor,
Have,
The photoelectric conversion unit has a phototransistor having a bipolar structure.
The base of the phototransistor and the channel are at the same potential as each other.
The emitter of the phototransistor and the source of the field effect transistor are at the same potential.
The collector of the phototransistor and the drain of the field effect transistor are at the same potential.
The first semiconductor region of the first conductive type including the emitter and the source, and
A second semiconductor region of the second conductive type including the base and the channel,
A third semiconductor region of the first conductive type including the collector and the drain, and
Have,
The second semiconductor region is below the first semiconductor region.
The third semiconductor region is below the second semiconductor region.
A groove is formed to reach the third semiconductor region, and the groove is formed.
It has a gate insulating film and a gate electrode in the groove.
When the voltage applied to the gate electrode is in the range of 0.5 [V] to 1.2 [V], the amount of change in the photocurrent decreases as the voltage increases, and the amount of light applied to the phototransistor. The semiconductor device according to the above description, wherein the dynamic range of the change of the photocurrent with respect to the change of the above is compressed . The semiconductor device according to claim 1 , wherein the semiconductor device is formed above the groove and has a light-shielding film that blocks light from entering the channel. The semiconductor device according to claim 1 or 2 , further comprising an operational amplifier whose gain is controlled by the output of the field effect transistor. An imaging device comprising the semiconductor device according to any one of claims 1 to 3 . An optical sensor comprising the semiconductor device according to any one of claims 1 to 3 .

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