JP2007318111A - Semiconductor device and electronic apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion device having a wide detectable illuminance without widening a range of an output voltage or an output current. <P>SOLUTION: There are provided a photoelectric conversion element, a photoelectric conversion device including an amplifier circuit electrically connected to the photoelectric conversion element, and a bias switching means for inverting a bias applied to the photoelectric conversion device, and by using the bias switching means, the bias applied to the photoelectric conversion device is inverted, it is possible to widen a detectable illuminance of the photoelectric conversion device without widening a range of an output voltage or an output current. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor device, and particularly to a semiconductor device having a photoelectric conversion device and a transistor. Further, the present invention relates to an electronic device using the semiconductor device.

  Many photoelectric conversion devices generally used for electromagnetic wave detection are known. For example, devices having sensitivity from ultraviolet rays to infrared rays are collectively called optical sensors. Among them, those having sensitivity in the visible light region with a wavelength of 400 nm to 700 nm are particularly called visible light sensors, and are used in many devices that require illuminance adjustment and on / off control according to the human living environment. .

  Particularly in a display device, the brightness around the display device is detected and the display luminance is adjusted. This is because it is possible to reduce wasteful power by detecting ambient brightness and obtaining appropriate display brightness. For example, such an optical sensor for brightness adjustment is used in a mobile phone or a personal computer.

  Further, not only the brightness of the surroundings but also the brightness of the backlight of a display device, particularly a liquid crystal display device, is detected by an optical sensor to adjust the brightness of the display screen.

In such an optical sensor, a photodiode is used for a sensing portion, and an output current of the photodiode is amplified by an amplifier circuit. For example, a current mirror circuit is used as such an amplifier circuit (see, for example, Patent Document 1).
Japanese Patent No. 3444093

  In the conventional optical sensor, since the output current or the output voltage reaches a wide range when trying to detect even high illuminance, there is a problem that it is difficult to use as a photoelectric conversion device and power consumption increases.

In view of the above problems, an object of the present invention is to obtain a photoelectric conversion device with a wide detectable illuminance range without expanding the range of output voltage or output current.

  A semiconductor device according to the present invention includes a photoelectric conversion device including a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element, and bias switching means for inverting a bias applied to the photoelectric conversion device. Yes. By reversing the bias applied to the photoelectric conversion device using the bias switching means, it is possible to widen the detectable illuminance range without widening the range of output voltage or output current.

  Note that the amplifier circuit includes two or more transistors including at least the first transistor. The incident light is detected by the photoelectric conversion element, the bias applied to the photoelectric conversion device is reversed, and a current generated in the photoelectric conversion element. And detection based on a voltage generated in the photoelectric conversion element applied between the gate and the source of the first transistor. Therefore, the purpose of the detection range of the illuminance, output current, output voltage, etc. by changing the properties of the transistors constituting the photoelectric conversion device, for example, the crystallinity of the channel formation region, the threshold value and the S value (subthreshold value) It is also possible to change according to.

  One embodiment of the present invention is a semiconductor device having an illuminance detection function, and the semiconductor device is applied to a photoelectric conversion device including a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element, and the photoelectric conversion device. Bias switching means for inverting the bias to be applied, the amplifier circuit includes at least two transistors including at least the first transistor, and the gate electrode of the first transistor is connected to the first transistor via the photoelectric conversion element. The photoelectric conversion element detects incident light, and the bias switching unit reverses the bias with a predetermined illuminance as a boundary, and also detects with the current generated in the photoelectric conversion element. The detection is performed by switching between the voltage applied to the photoelectric conversion element applied between the gate and the source of the first transistor.

  One embodiment of the present invention is a semiconductor device having an illuminance detection function, which includes a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element, and a bias applied to the photoelectric conversion apparatus. And a bias switching means for causing the amplifier circuit to include two or more transistors including at least a first transistor, and the photoelectric conversion element detects incident light, and the photoelectric conversion element is detected when the light is below a predetermined illuminance. When the light exceeds a predetermined illuminance, it is detected by applying a voltage generated in the photoelectric conversion element between the gate and the source of the first transistor, and the bias switching means uses the predetermined illuminance as a boundary. The bias is reversed.

  One embodiment of the present invention is a semiconductor device having an illuminance detection function, which includes a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element, and a bias applied to the photoelectric conversion apparatus. The amplifying circuit has at least two transistors including at least the first transistor, and the gate electrode of the first transistor is connected to the first transistor of the first transistor through the photoelectric conversion element. The photoelectric conversion element is electrically connected to the electrode, detects the incident light, is detected by a current generated in the photoelectric conversion element when the light is below a predetermined illuminance, and the first is when the light exceeds the predetermined illuminance Detected by applying a voltage generated in the photoelectric conversion element between the gate and source of the transistor, and the bias switching means is characterized by inverting the bias with a predetermined illuminance as a boundary. .

  One embodiment of the present invention is a semiconductor device having an illuminance detection function, which includes a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element, and a bias applied to the photoelectric conversion apparatus. The amplifying circuit includes at least a first transistor and a second transistor, and the bias is applied from the first terminal and the second terminal of the photoelectric conversion device, The terminal is electrically connected to the first electrode and the gate electrode of the second transistor and the gate electrode of the first transistor through the photoelectric conversion element, and the first terminal is connected to the first electrode of the first transistor. The second terminal is electrically connected to the first transistor and the second electrode of the second transistor, the photoelectric conversion element detects incident light, and the light has a predetermined illuminance. Below, it is detected by a current generated in the photoelectric conversion element, and when light exceeds a predetermined illuminance, it is detected by a voltage generated in the photoelectric conversion element, and the bias switching means reverses the bias with the predetermined illuminance as a boundary. To do.

  In the above structure, the amplifier circuit includes a plurality of first transistors. The photoelectric conversion element includes a p-type semiconductor layer, an n-type semiconductor layer, and an i-type semiconductor layer provided between the p-type semiconductor layer and the n-type semiconductor layer.

  Note that in this specification, being connected is synonymous with being electrically connected. Therefore, in the configuration disclosed by the present invention, in addition to a predetermined connection relationship, other elements (for example, a switch, a transistor, a capacitor, an inductor, a resistor, a diode, etc.) that can be electrically connected are arranged. May be. Of course, it may be arranged without interposing other elements in between, and being electrically connected includes the case of being directly connected.

Note that in this specification, the inversion of the bias applied to the photoelectric conversion device only needs to invert the potential relationship applied to the photoelectric conversion device, and does not necessarily require the same potential difference before and after inversion. In this specification, the transistor is described as a thin film transistor; however, the present invention is not limited to this.

According to the present invention, the detectable illuminance range can be widened without expanding the range of the output voltage or output current. Therefore, a high-performance photoelectric conversion device can be obtained.

  Hereinafter, one embodiment of the present invention will be described. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of the embodiment. Note that in the structures of the present invention described below, reference numerals indicating the same parts are denoted by the same reference numerals in different drawings, and detailed description of the same portions or portions having similar functions is omitted.

(Embodiment 1)
An embodiment of a semiconductor device of the present invention will be described with reference to FIG. A semiconductor device illustrated in FIG. 1A includes a photoelectric conversion device 101, bias switching means 102, a power source 103, a terminal V ₀ , and a resistor 104. Note that the photoelectric conversion device 101 includes a thin film integrated circuit including a photoelectric conversion element 115 and a thin film transistor (Thin Film Transistor (TFT)) as illustrated in FIG. 1B, and the thin film integrated circuit includes at least a thin film transistor. The current mirror circuit 114 includes a thin film transistor 112 and a diode-connected thin film transistor 112. Note that in this embodiment, the thin film transistor included in the current mirror circuit 114 is an n-channel thin film transistor. The photoelectric conversion device is also referred to as a photo IC.

  One terminal 121 of the photoelectric conversion device 101 is connected to one electrode of the power source 103 via the bias switching means 102, and the other terminal 122 of the photoelectric conversion device 101 is connected to the other electrode of the power source 103 via the resistor 104. It is connected. Note that the current obtained from the photoelectric conversion device 101 is output as a voltage from a terminal V 0 connected to the terminal 121 using the resistor 104.

  Next, the photoelectric conversion device 101 will be described with reference to FIG. The terminal 121 is connected to the gate electrode and the first electrode (one of the source electrode and the drain electrode) of the thin film transistor 112 through the photoelectric conversion element 115, and the second electrode (the other of the source electrode and the drain electrode) of the thin film transistor 112 is connected to The terminal 122 is connected. The terminal 121 is also connected to the first electrode (one of the source electrode and the drain electrode) of the thin film transistor 113. On the other hand, the second electrode (the other of the source electrode and the drain electrode) of the thin film transistor 113 is connected to the terminal 122. Note that the gate electrode of the thin film transistor 113 is connected to the gate electrode of the thin film transistor 112.

  In the semiconductor device illustrated in FIG. 1A, when light is applied to the photoelectric conversion element 115, electrons and holes are generated, and current is generated. Note that the current mirror circuit 114 has a function of amplifying a current obtained from the photoelectric conversion element 115. FIG. 1B shows a case where there is one thin film transistor 113, that is, a case where the current obtained from the photoelectric conversion element 115 is doubled. However, when a higher current is desired, the gate electrode is a thin film transistor. A plurality of units 116 each including the thin film transistor 113 connected to the gate electrode 112 may be provided in parallel between the terminal 121 and the terminal 122. For example, as shown in FIG. 2, when the number of units is n and the current obtained from the photoelectric conversion element 115 is i, approximately (n + 1) times the current (n + 1) × i is output from the photoelectric conversion device 101. be able to. Note that since the current obtained from the photoelectric conversion element 115 has illuminance dependency, illuminance, that is, irradiated light can be detected. Here, the illuminance is detected by outputting the current obtained from the photoelectric conversion device 101 as a voltage from the terminal V 0 using the resistor 104.

  The bias switching unit 102 inverts the potential relationship, that is, the bias supplied to the terminal 121 and the terminal 122 of the photoelectric conversion device 101 using the power source 103 with a predetermined illuminance as a boundary. In FIG. 1, two types of power supplies 103a and 103b are used. However, the present invention is not limited to this as long as the bias applied to the photoelectric conversion device 101 is inverted. Of course, the voltage applied to the photoelectric conversion device 101 before and after inversion does not need to be the same.

  Further, since the output voltage output from the terminal Vo is also reversed by reversing the bias applied to the photoelectric conversion device 101, the output may be obtained from the terminal V0 via switching means (not shown) for inverting the output. .

  Photodetection in the case where voltage is applied to the photoelectric conversion device 101 using the power source 103a will be described with reference to FIG. It is assumed that Vdd is supplied to the terminal 121 connected to the positive electrode side of the power supply 103a, and the potential of Vss is supplied to the terminal 122 connected to the negative electrode side. At this time, the first electrode of the thin film transistor 113 functions as a drain electrode and the second electrode functions as a source electrode, and the thin film transistor 112 and the thin film transistor 113 are non-conductive in an initial state where light is not irradiated.

  When the photoelectric conversion element 115 is irradiated with light, a current is obtained as described above, the thin film transistor 112 becomes conductive, and the current i flows through the thin film transistor 112. Note that at this time, the first electrode of the thin film transistor 112 is a drain electrode, the second electrode is a source electrode, and the thin film transistor 112 is diode-connected. In addition, a current i flows to each of the gate electrode and the source electrode of the thin film transistor 113 because the same potential is supplied to the gate electrode and the source electrode of the thin film transistor 112. Therefore, a current value I of about 2 × i is obtained from the photoelectric conversion device 101. FIG. 4 (10 in FIG. 4) shows the relationship of the current value | I | (ie, output current | I |) obtained from the photoelectric conversion device 101 with respect to the illuminance at that time. In FIG. 4, the horizontal axis and the vertical axis represent logarithmic illuminance L and current value | I |, respectively. The current value | I | represents the absolute value of the current value I. When light detection is performed, the output voltage from the semiconductor device, that is, the output voltage from the terminal V0 in FIG. 1 is set to V1 to V2 and the detectable current range from the photoelectric conversion device 101 is set to I1 and I2 or less. 4, the detectable illuminance range in the semiconductor device when the power supply 103 a is used is L1 or more and L2 or less, that is, the range (A).

  Next, a case where the predetermined illuminance at which the power source 103 is switched by the bias switching unit 102 shown in FIG. The power source 103b is used by switching, and the photoelectric conversion device 101 in this case is illustrated in FIG. Note that the terminal 121 connected to the negative electrode side of the power supply 103b is supplied with a potential of Vss, and the terminal 122 connected to the positive electrode side is supplied with a potential of Vdd. That is, the bias applied to the photoelectric conversion device 101 is reversed from that of the power source 103a illustrated in FIG. At this time, the first electrode of the thin film transistor 113 functions as a source electrode and the second electrode functions as a drain electrode, and the thin film transistor 112 and the thin film transistor 113 are in a non-conduction state in an initial state where light is not irradiated.

  When light is applied to the photoelectric conversion element 115 while the thin film transistor 112 is not conducting, an open circuit voltage Voc proportional to the logarithmic value of illuminance is generated. Therefore, the potential of the first electrode and the gate electrode of the thin film transistor 112 and the gate electrode of the thin film transistor 113 connected thereto is Vss + Voc. Therefore, the gate-source voltage of the thin film transistor 113 becomes Voc, and the thin film transistor 113 becomes conductive. Therefore, the current i ′ flows through the thin film transistor 113. When Vdd> Vss + Voc, the first electrode of the thin film transistor 112 is a source electrode, and the second electrode is a drain electrode. Therefore, since the gate-source voltage Vgs of the thin film transistor 112 is zero, the thin film transistor 112 is non-conductive. Note that the off-state current of the thin film transistor 112 is not considered at this time.

  In this way, the current value i ′ is obtained from the photoelectric conversion device 101. The relationship of the output current from the photoelectric conversion device 101 to the illuminance at that time is shown as 11 in FIG.

As described above, in this embodiment, the output voltage from the semiconductor device, that is, the output voltage from the terminal V0 in FIG. 1 is set to V1 to V2 and the detectable current range is set to I1 and I2. Therefore, the detectable illuminance range in the photoelectric exchange device when using the power supply 103b can be set to L2 or more and L3 or less, that is, the range (B) as shown in FIG. Note that either the characteristics of the range (A) or the range (B) may be used for the detection of the illuminance L2, but here the illuminance range in the range (B) is set to L2 because the predetermined illuminance at which the power source 103 is switched is L2. L2 <L ≦ L3.

  By reversing the bias applied to the photoelectric conversion device in this way, it is possible to widen the detectable illuminance range without expanding the range of the output voltage or output current.

  Note that FIG. 4 describes the case where the absolute value | I | of the current value obtained from the photoelectric conversion device 101 in the illuminance range (B) is equal to or greater than I1 and equal to or less than I2, but as illustrated in FIG. The current value obtained in the range (B) may vary greatly. In such a case, the output voltage becomes wide, making it difficult to use as a semiconductor device and increasing power consumption.

  As described above, in the range (A), the characteristics of the photoelectric conversion element 115 are used for detecting the illuminance, and in the range (B), the open circuit voltage Voc obtained from the photoelectric conversion element 115 and the characteristics of the thin film transistor 112 are used. Therefore, the output current in the range (B) can be changed by changing the characteristics of the thin film transistor. Therefore, by controlling the characteristics of the thin film transistor, an output current can be obtained within a desired range in the range (B). Therefore, the ranges of the output currents in the range (A) and the range (B) should be closer. Is possible. For example, when the threshold voltage of the thin film transistor 113 is controlled, the relationship of the output current with respect to the illuminance (11 in FIG. 5) is shifted in the vertical axis direction, that is, the current value obtained with respect to the illuminance can be greatly increased or decreased. It becomes possible. For example, when the threshold voltage of the thin film transistor is changed in the positive direction, the output current (11 in FIG. 5) shifts to a lower direction, and when the threshold voltage is changed in the negative direction, the output current (in FIG. 5). 11) shifts higher. However, the threshold value control of the thin film transistor is performed within a range where the thin film transistor is not a depletion type transistor, that is, normally on. Since the output current can be freely set as described above, the detectable illuminance range can be widened without expanding the range of the output current and hence the output voltage.

  Further, by controlling the S value (subthreshold value) of the thin film transistor, the slope of the relationship of the output current to the illuminance (11 in FIG. 5) can be freely set. For example, if the S value is increased, the slope of 11 in FIG. 5 can be reduced, and if the S value is reduced, the slope of 11 in FIG. 5 can be increased. Therefore, the relationship of the output current to the illuminance in the range (A) and the range (B) can be made the same or different. For example, in the latter case, when detecting high illuminance, it is possible to reduce the illuminance dependency as compared with low illuminance. In such a case, the light detection range of the semiconductor device can be further expanded. Thus, a semiconductor device having desired illuminance dependence can be obtained according to the purpose.

  Further, the difference in output current between the range (A) and the range (B) is that the resistance connected to the photoelectric conversion device 101, that is, the resistance value of the resistance 104 in FIG. Thus, the same output voltage may be obtained. Specifically, as shown in FIG. 6, the switching unit 107 that can be switched simultaneously with the bias switching unit 102 is used to switch the resistor 104a and the resistor 104b, and the current flowing through the photoelectric conversion device 101 is output as a voltage from the terminal V0. It ’s fine.

  In the above description, the illuminance is detected using the characteristics of the photoelectric conversion element 115 in the range (A) with the predetermined illuminance as the boundary, and the open voltage Voc obtained from the photoelectric conversion element 115 and the characteristics of the thin film transistor 112 in the range (B). However, the characteristics using the predetermined illuminance as a boundary may be reversed. For example, in the range (A) in FIG. 4, the output current | I | obtained from the photoelectric conversion device 101 is decreased to 11 in FIG. 4 by decreasing the current amplification factor of the current mirror circuit 114, while the range (B ), The output current | I | may be increased to 10 in FIG. In this way, when the illuminance is detected by reversing the relationship between the output currents in the ranges (A) and (B), the open circuit voltage Voc obtained from the photoelectric conversion element 115 and the thin film transistor 112 in the range (A). In the range (B), the characteristics of the photoelectric conversion element 115 can be used.

  Note that although an n-channel thin film transistor is used as the thin film transistor included in the current mirror circuit 114 in this embodiment, a p-channel thin film transistor may be used. FIG. 7 shows an example of an equivalent circuit diagram of the photoelectric conversion device when a p-channel thin film transistor is used for the current mirror circuit. In FIG. 7, the current mirror circuit 203 includes a thin film transistor 201 and a thin film transistor 202. The terminal 121 is connected to the terminal 122 through the thin film transistor 201 and the photoelectric conversion element 204. The terminal 121 is connected to the terminal 122 through the thin film transistor 202. Note that the gate electrode of the thin film transistor 202 is connected to the gate electrode of the thin film transistor 201 and a wiring connecting the thin film transistor 201 and the photoelectric conversion element 204. Note that a plurality of units each including the thin film transistor 202 may be provided in parallel as in FIG.

From the above, by reversing the bias applied to the photoelectric conversion device according to the present invention, it is possible to widen the detectable illuminance range without widening the range of output voltage or output current. In addition, it is possible to change the light detection range, the output current, the output voltage, and the like according to the purpose by changing the properties of the thin film transistor constituting the photoelectric conversion device, for example, the threshold value and the S value.

8A and 8B are cross-sectional views of a structure example of the photoelectric conversion device 101 illustrated in FIG.

  In FIG. 8A, 310 is a substrate, 312 is a base insulating film, and 313 is a gate insulating film. Since light to be detected passes through the substrate 310, the base insulating film 312, and the gate insulating film 313, it is preferable to use materials having high light-transmitting properties for all of these materials.

  The photoelectric conversion element 115 in FIG. 1 includes a wiring 319, a protective electrode 318, a photoelectric conversion layer 111, and a terminal 121. Note that the photoelectric conversion layer 111 includes a p-type semiconductor layer 111p, an n-type semiconductor layer 111n, and an intrinsic (i-type) semiconductor layer 111i sandwiched between the p-type semiconductor layer 111p and the n-type semiconductor layer 111n. However, the present invention is not limited to this, and the photoelectric conversion element only needs to have a first conductive layer, a second conductive layer, and a photoelectric conversion layer sandwiched between these two conductive layers. Note that the photoelectric conversion layer is not limited to the above and may have a stacked structure of at least a p-type semiconductor layer and an n-type semiconductor layer.

  First, for the p-type semiconductor layer 111p, a semi-amorphous silicon film containing a Group 13 impurity element such as boron (B) may be formed by plasma CVD, or after forming the semi-amorphous silicon film, An impurity element may be introduced.

Note that a semi-amorphous semiconductor film is a film including a semiconductor having a structure intermediate between an amorphous semiconductor and a semiconductor (including single crystal and polycrystal) films having a crystal structure. This semi-amorphous semiconductor film is a semiconductor film having a third state that is stable in terms of free energy, and is a crystalline film having short-range order and lattice distortion, and has a grain size of 0.5 to 20 nm. And can be dispersed in the non-single-crystal semiconductor film. The semi-amorphous semiconductor film has its Raman spectrum shifted to a lower wavenumber than 520 cm ⁻¹ , and diffraction peaks of (111) and (220) that are derived from the Si crystal lattice are observed in X-ray diffraction. The Further, in order to terminate dangling bonds (dangling bonds), hydrogen or halogen is contained at least 1 atomic% or more. In this specification, for convenience, such a semiconductor film is referred to as a semi-amorphous semiconductor (SAS) film. Furthermore, by adding a rare gas element such as helium, argon, krypton, or neon to further promote the lattice distortion, the stability can be improved and a good semi-amorphous semiconductor film can be obtained. Note that a microcrystalline semiconductor film (a microcrystalline semiconductor film) is also included in the semi-amorphous semiconductor film.

The SAS film can be obtained by glow discharge decomposition of a gas containing silicon. A typical gas containing silicon is SiH ₄ , and Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _{4, and the} like can also be used. In addition, it is easy to form a SAS film by diluting a gas containing silicon with hydrogen or a gas obtained by adding one or more kinds of rare gas elements selected from helium, argon, krypton, and neon to hydrogen. Can be. It is preferable to dilute the gas containing silicon within a range of a dilution rate of 2 to 1000 times. Further, a gas containing silicon, a carbide gas such as CH ₄ and C ₂ H ₆ , a germanium gas such as GeH ₄ and GeF ₄ , F _{2, and the} like are mixed, so that the energy bandwidth is 1.5-2. It may be adjusted to .4 eV, or 0.9 to 1.1 eV.

  After the p-type semiconductor layer 111p is formed, a semiconductor layer (referred to as an intrinsic semiconductor layer or an i-type semiconductor layer) 111i and an n-type semiconductor layer 111n that do not contain an impurity imparting conductivity are formed in this order. Thus, the photoelectric conversion layer 111 including the p-type semiconductor layer 111p, the i-type semiconductor layer 111i, and the n-type semiconductor layer 111n is formed.

Note that in this specification, the i-type semiconductor layer means that the impurity concentration imparting p-type or n-type contained in the semiconductor layer is 1 × 10 ²⁰ cm ⁻³ or less, and oxygen and nitrogen are 5 × 10 ¹⁹ cm. Refers to a semiconductor layer that is ⁻³ or less. In addition, it is preferable that photoconductivity is 1000 times or more with respect to dark conductivity. Further, 10 to 1000 ppm of boron (B) may be added to the i-type semiconductor layer.

  As the i-type semiconductor layer 111i, for example, a semi-amorphous silicon film may be formed by a plasma CVD method. Further, as the n-type semiconductor layer 111n, a semi-amorphous silicon film containing a Group 15 impurity element such as phosphorus (P) may be formed, or a Group 15 impurity element is introduced after the semi-amorphous silicon film is formed. May be.

  Further, as the p-type semiconductor layer 111p, the intrinsic semiconductor layer 111i, and the n-type semiconductor layer 111n, not only a semi-amorphous semiconductor film but also an amorphous semiconductor film may be used.

  A wiring 319, a connection electrode 320, a terminal electrode 351, a source electrode and a drain electrode 341 of the thin film transistor 112, and a source electrode and a drain electrode 342 of the thin film transistor 113 are a refractory metal film and a low resistance metal film (such as an aluminum alloy or pure aluminum). ). Here, these wirings and electrodes have a three-layer structure in which a titanium film (Ti film), an aluminum film (Al film), and a Ti film are sequentially stacked.

  Further, protective electrodes 318, 345, 348, 346, and 347 are provided so as to cover the wiring 319, the connection electrode 320, the terminal electrode 351, the source and drain electrodes 341 of the thin film transistor 112, and the source and drain electrodes 342 of the thin film transistor 113, respectively. Is formed.

  These protective electrodes protect the wiring 319 and the like in the etching step when the photoelectric conversion layer 111 is formed. Note that the material of the protective electrode is preferably a conductive material whose etching rate is lower than that of the photoelectric conversion layer with respect to the gas (or etchant) for etching the photoelectric conversion layer 111. In addition, the material of the protective electrode 318 is preferably a conductive material that does not react with the photoelectric conversion layer 111 to form an alloy. Note that the other protective electrodes 345, 348, 346, and 347 are also formed using the same material and manufacturing process as the protective electrode 318.

  Further, a structure in which the protective electrodes 318, 345, 348, 346, and 347 are not provided may be employed. An example in which these protective electrodes are not provided is shown in FIG. In FIG. 8B, a wiring 404, a connection electrode 405, a terminal electrode 401, a source electrode and a drain electrode 402 of the thin film transistor 112, and a source electrode and a drain electrode 403 of the thin film transistor 113 are formed using a single conductive film. As such a conductive film, a titanium film (Ti film) is preferable. Further, in place of the titanium film, tungsten (W), tantalum (Ta), molybdenum (Mo), neodymium (Nd), cobalt (Co), zirconium (Zr), zinc (Zn), ruthenium (Ru), rhodium ( Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), or a single layer film made of an alloy material or a compound material containing the element as a main component, or these For example, a single layer film made of a nitride of, for example, titanium nitride, tungsten nitride, tantalum nitride, or molybdenum nitride, or a stacked film thereof can be used. By forming the wiring 404, the connection electrode 405, the terminal electrode 401, the source and drain electrodes 402 of the thin film transistor 112, and the source and drain electrodes 403 of the thin film transistor 113 as single layers, the number of depositions can be reduced in the manufacturing process. It becomes possible. Needless to say, the wiring 319, the connection electrode 320, the terminal electrode 351, the source and drain electrodes 341 of the thin film transistor 112, and the source and drain electrode 342 of the thin film transistor 113 shown in FIG. Can be used.

  8A and 8B illustrate an example of a top-gate thin film transistor in which the n-channel thin film transistors 112 and 113 each have one channel formation region (referred to as a “single gate structure” in this specification). However, a variation in on-state current value may be reduced by using a structure having a plurality of channel formation regions. In order to reduce the off-state current value, a lightly doped drain (LDD) region may be provided in the n-channel thin film transistors 112 and 113. An LDD region is a region where an impurity element is added at a low concentration between a channel formation region and a source region or a drain region formed by adding an impurity element at a high concentration. This has the effect of relaxing the electric field in the vicinity of the region and preventing deterioration due to hot carrier injection.

  In order to prevent deterioration of the on-current value due to hot carriers, n-channel thin film transistors 112 and 113 are arranged with an LDD region overlapped with a gate electrode with a gate insulating film interposed therebetween (in this specification, “GOLD (Gate -Drain Overlapped LDD) structure "). When the GOLD structure is used, the electric field in the vicinity of the drain region is further relaxed and the deterioration due to hot carrier injection is prevented, compared with the case where the LDD region is not formed overlapping the gate electrode. As described above, the GOLD structure is effective in reducing the electric field strength in the vicinity of the drain region, preventing hot carrier injection, and preventing a deterioration phenomenon.

  Further, the thin film transistors 112 and 113 constituting the current mirror circuit are not limited to the above-described top gate thin film transistors, but may be bottom gate thin film transistors, for example, inverted staggered thin film transistors.

  Further, the wiring 314 is a wiring connected to the wiring 319 and extends above the channel formation region of the thin film transistor 113 of the amplifier circuit and serves as a gate electrode.

  The wiring 315 is a wiring connected to the terminal 121 connected to the n-type semiconductor layer 111n through the connection wiring 320 and the protective electrode 345, and is a drain wiring (also referred to as a drain electrode) or a source wiring (source electrode) of the thin film transistor 113. (Also referred to as an electrode).

  Since light to be detected passes through the interlayer insulating film 316 and the interlayer insulating film 317, it is desirable to use materials having high light-transmitting properties. Note that the insulating film 317 is preferably formed using an inorganic material, for example, a silicon oxide film (SiOx) film, in order to improve the fixing strength. An inorganic material is preferably used for the sealing layer 324, and these insulating films can be formed by a CVD method or the like.

  The terminal electrode 350 is formed in the same process as the wiring 314 and the wiring 315, and the terminal electrode 351 is formed in the same process as the wiring 319 and the connection electrode 320. Note that the terminal 122 is connected to the terminal electrode 350 through the auxiliary electrode 348 and the terminal electrode 351.

  Note that the terminal 121 is mounted on the electrode 361 of the substrate 360 with solder 364. The terminal 122 is formed in the same process as the terminal 121, and is mounted on the electrode 362 of the substrate 360 with solder 363.

  8A and 8B, light is incident on the photoelectric conversion layer 111 from the substrate 310 side as indicated by arrows in the drawing. As a result, a current is generated, and light can be detected.

By reversing the bias applied to such a photoelectric conversion device, the detectable illuminance range can be expanded without expanding the range of the output voltage or output current. In addition, it is possible to change the light detection range, the output voltage, and the like according to the purpose by changing the properties of the thin film transistors constituting the photoelectric conversion device, for example, the threshold value and the S value.

  In this embodiment, current characteristics obtained when the bias applied to the photoelectric conversion device is reversed will be described with reference to FIGS.

  9 and 10A and 10B show the illuminance dependence of the output current obtained when a bias is applied to the photoelectric conversion device shown in FIG. In FIG. 2, the number of units 116 is 100.

  In FIG. 9, ELC indicates illuminance dependence in output current obtained from a photoelectric conversion device having a current mirror circuit formed using a thin film transistor in which an island-shaped semiconductor region is crystallized by an excimer laser. Yes. CW indicates the illuminance dependence of the output current obtained from a photoelectric conversion device having a current mirror circuit formed by a thin film transistor in which an island-shaped semiconductor region is crystallized by a continuous wave laser (Continuous Wave Laser). The forward direction and the reverse direction indicate bias directions applied to the photoelectric conversion device. The state in FIG. 3A is the forward direction, and the state in FIG. 3B is the reverse direction. In addition, what extracted the illumination dependence in the case of ELC is shown in FIG.

  From FIG. 9, the output current of the photoelectric conversion device using the thin film transistor having the island-shaped semiconductor region crystallized by the excimer laser and the island-shaped semiconductor region crystallized by the continuous wave laser are obtained only when the reverse bias is applied. It is observed that there is a difference in the output current of the photoelectric conversion device using the thin film transistor. This is derived from the crystallinity of the island-shaped semiconductor region in the thin film transistor. As described in the first embodiment, the illuminance of light is detected using the characteristics of the photoelectric conversion element when a forward bias is applied and the open-circuit voltage Voc obtained from the photoelectric conversion element and the characteristics of the thin film transistor when a reverse bias is applied. Because it is. Therefore, it can be seen that the illuminance dependence of the output current obtained from the photoelectric conversion device can be changed by the crystallinity of the island-shaped semiconductor region. Note that this can also be changed depending on the S value of the thin film transistor and the threshold value of the thin film transistor, which are affected by the crystallinity of the island-shaped semiconductor region. Thus, the photoelectric conversion device can have a desired illuminance dependency. From the above, it is possible to widen the detection range of illuminance without widening the range of output voltage or output current by reversing the bias applied to the photoelectric conversion device, and light detection according to the purpose A semiconductor device having a function can be obtained.

  In the case of ELC, for example, if the predetermined intensity for reversing the bias applied to the photoelectric conversion device is set to 100 lx and the output current range is set to 20 nA or more and 5 μA or less, the lower limit of the detected illuminance range is about 0.5 lx and the upper limit is 100,000 lx or more. It can be. Therefore, the detectable illuminance range can be expanded without expanding the output current range.

  In addition, the relative sensitivity and standard visibility curve of the photoelectric conversion apparatus of this invention are shown in FIG. FIG. 11 shows that the relative sensitivity of the photoelectric conversion device of the present invention is very close to the standard visibility. Therefore, the photoelectric conversion device of the present invention can obtain a visual sensitivity close to that of the human eye, so that it can have higher performance when used as an optical sensor.

  Note that this embodiment can be combined with any of the embodiment mode and other embodiments as appropriate.

  In this embodiment, a semiconductor device including a photoelectric conversion device to which the present invention is applied and a manufacturing method thereof will be described. An example of a partial cross-sectional view of the photoelectric conversion device is illustrated in FIGS. 8 and 12 to 14 and will be described with reference to FIGS.

  First, an element is formed over a substrate (first substrate 310). Here, AN100 which is one of glass substrates is used as the substrate 310.

  Next, a silicon oxide film containing nitrogen (film thickness: 100 nm) is formed as a base insulating film 312 by plasma CVD, and further a semiconductor film such as an amorphous silicon film containing hydrogen (film thickness: 54 nm) is exposed to the atmosphere. Are stacked. Alternatively, the base insulating film 312 may be stacked using a silicon oxide film, a silicon nitride film, or a silicon oxide film containing nitrogen. For example, a film in which a silicon nitride film containing oxygen is stacked with a thickness of 50 nm and a silicon oxide film containing nitrogen is stacked with a thickness of 100 nm may be formed as the base insulating film 312. Note that the silicon oxide film or silicon nitride film containing nitrogen functions as a blocking layer for preventing diffusion of impurities such as alkali metal from the glass substrate.

  Next, the amorphous silicon film is crystallized by a solid phase growth method, a laser crystallization method, a crystallization method using a catalytic metal, or the like, so that a semiconductor film having a crystal structure (crystalline semiconductor film), for example, polycrystalline A silicon film is formed. Here, a polycrystalline silicon film is obtained by a crystallization method using a catalytic element. First, a nickel acetate solution containing 10 ppm of nickel in terms of weight is applied with a spinner. Note that a nickel element may be dispersed over the entire surface by sputtering instead of coating. Next, heat treatment is performed for crystallization, so that a semiconductor film having a crystal structure is formed. Here, after heat treatment (500 ° C., 1 hour), heat treatment for crystallization (550 ° C., 4 hours) is performed to obtain a polycrystalline silicon film.

  Next, the oxide film on the surface of the polycrystalline silicon film is removed with dilute hydrofluoric acid or the like. After that, irradiation with laser light (XeCl: wavelength 308 nm) for increasing the crystallization rate and repairing defects left in the crystal grains is performed in the air or an oxygen atmosphere.

As the laser light, excimer laser light having a wavelength of 400 nm or less, or the second harmonic or the third harmonic of a YAG laser is used. Here, a pulsed laser beam having a repetition frequency of about 10 to 1000 Hz is used, the laser beam is condensed to 100 to 500 mJ / cm ² by an optical system, and irradiated with an overlap rate of 90 to 95%. May be scanned. In this embodiment, laser light irradiation is performed in the atmosphere at a repetition frequency of 30 Hz and an energy density of 470 mJ / cm ² .

Note that an oxide film is formed on the surface by irradiation with laser light because it is performed in the air or in an oxygen atmosphere. Although an example using a pulse laser is shown in this embodiment, a continuous wave laser may be used. In order to obtain a crystal with a large grain size when crystallizing a semiconductor film, continuous oscillation is possible. It is preferable to apply a second to fourth harmonic of the fundamental wave using a solid-state laser. Typically, a second harmonic (532 nm) or a third harmonic (355 nm) of an Nd: YVO ₄ laser (fundamental wave 1064 nm) may be applied.

In the case of using a continuous wave laser, laser light emitted from a continuous wave YVO ₄ laser having an output of 10 W is converted into a harmonic by a non-linear optical element. There is also a method of emitting harmonics by putting a YVO ₄ crystal and a nonlinear optical element in a resonator. Then, it is preferably formed into a rectangular or elliptical laser beam on the irradiation surface by an optical system, and irradiated to the object to be processed. At this time, the energy density of approximately 0.01 to 100 MW / cm ² (preferably 0.1 to 10 MW / cm ²⁾ is required. Then, irradiation may be performed by moving the semiconductor film relative to the laser light at a speed of about 10 to 2000 cm / s.

  Next, in addition to the oxide film formed by the laser light irradiation, the surface is treated with ozone water for 120 seconds to form a barrier layer made of an oxide film having a total thickness of 1 to 5 nm. This barrier layer is formed to remove a catalyst element added for crystallization, for example, nickel (Ni) from the film. Here, the barrier layer is formed using ozone water, but the surface of the semiconductor film having a crystal structure is oxidized by a method of oxidizing the surface of the semiconductor film having a crystal structure by irradiation with ultraviolet rays in an oxygen atmosphere or the oxygen plasma treatment. Alternatively, the barrier layer may be formed by depositing an oxide film of about 1 to 10 nm by a method such as plasma CVD, sputtering, or vapor deposition. Further, the oxide film formed by laser light irradiation may be removed before forming the barrier layer.

Next, an amorphous silicon film containing an argon element serving as a gettering site is formed with a thickness of 10 to 400 nm, here 100 nm, over the barrier layer by a sputtering method. The amorphous silicon film containing an argon element is formed in an atmosphere containing argon using a silicon target. In the case where an amorphous silicon film containing an argon element is formed using a plasma CVD method, the film formation conditions are as follows: the flow ratio of monosilane to argon (SiH ₄ : Ar) is 1:99, and the film formation pressure is 6.665 Pa. The RF power density is 0.087 W / cm ² and the film formation temperature is 350 ° C.

  Thereafter, the catalyst element is removed (gettering) by performing a heat treatment for 3 minutes in a furnace heated to 650 ° C. As a result, the concentration of the catalytic element in the semiconductor film having a crystal structure is reduced. A lamp annealing apparatus may be used instead of the furnace.

  Next, the amorphous silicon film containing an argon element which is a gettering site is selectively removed using the barrier layer as an etching stopper, and then the barrier layer is selectively removed with dilute hydrofluoric acid. Note that during gettering, nickel tends to move to a region with a high oxygen concentration, and thus it is desirable to remove the barrier layer made of an oxide film after gettering.

  Note that in the case where the semiconductor film is not crystallized using a catalytic element, the above-described barrier layer formation, gettering site formation, heat treatment for gettering, gettering site removal, barrier layer removal, etc. This step is unnecessary.

  Next, after forming a thin oxide film with ozone water on the surface of the obtained semiconductor film having a crystalline structure (for example, a crystalline silicon film), a mask made of resist is formed using a first photomask, and a desired film is formed. Semiconductor films (referred to as “island semiconductor regions” in this specification) 331 and 332 that are separated into island shapes by etching are formed (see FIG. 12A). After the island-shaped semiconductor region is formed, the resist mask is removed.

Next, if necessary, a small amount of impurity element (boron or phosphorus) is doped in order to control the threshold value of the thin film transistor. Here, an ion doping method in which diborane (B ₂ H ₆ ) is plasma-excited without mass separation is used.

  Next, the oxide film is removed with an etchant containing hydrofluoric acid, and at the same time, the surfaces of the island-shaped semiconductor regions 331 and 332 are washed, and then an insulating film containing silicon as a main component to be the gate insulating film 313 is formed. Here, a silicon oxide film containing nitrogen (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) with a thickness of 115 nm is formed by a plasma CVD method.

  Next, after a metal film is formed over the gate insulating film 313, patterning is performed using a second photomask to form gate electrodes 334 and 335, wirings 314 and 315, and a terminal electrode 350 (FIG. 12B). reference). As this metal film, for example, a film in which tantalum nitride (TaN) and tungsten (W) are stacked in a thickness of 30 nm and 370 nm, respectively, is used.

  Further, as the gate electrodes 334 and 335, the wirings 314 and 315, and the terminal electrode 350, in addition to the above, titanium (Ti), tungsten (W), tantalum (Ta), molybdenum (Mo), neodymium (Nd), cobalt (Co ), Zirconium (Zr), zinc (Zn), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), aluminum (Al), gold (Au) ), Silver (Ag), copper (Cu), or a single layer film made of an alloy material or a compound material containing the element as a main component, or a nitride thereof, for example, titanium nitride, tungsten nitride A single layer film made of tantalum nitride or molybdenum nitride, or a laminated film thereof can be used.

  Next, an impurity imparting one conductivity type is introduced into the island-shaped semiconductor regions 331 and 332, so that the source and drain regions 337 of the thin film transistor 112 and the source and drain regions 338 of the thin film transistor 113 are formed (FIG. 12). (See (C)). In this embodiment, an n-channel thin film transistor is formed, and n-type impurities such as phosphorus (P) and arsenic (As) are introduced into the island-shaped semiconductor regions 331 and 332.

  Next, after forming a first interlayer insulating film (not shown) including a silicon oxide film by CVD with a thickness of 50 nm, a step of activating the impurity element added to each island-like semiconductor region is performed. This activation process is performed by a rapid thermal annealing method (RTA method) using a lamp light source, a method of irradiating a YAG laser or an excimer laser from the back surface, a heat treatment using a furnace, or a combination thereof. By different methods.

  Next, a second interlayer insulating film 316 including a silicon nitride film containing hydrogen and oxygen is formed with a thickness of 10 nm, for example.

  Next, a third interlayer insulating film 317 made of an insulating material is formed over the second interlayer insulating film 316 (see FIG. 12D). As the third interlayer insulating film 317, an insulating film obtained by a CVD method can be used. In this embodiment, in order to improve the fixing strength, a silicon oxide film containing nitrogen formed with a thickness of 900 nm is formed as the third interlayer insulating film 317.

  Next, heat treatment (300 to 550 ° C. for 1 to 12 hours, for example, in a nitrogen atmosphere at 410 ° C. for 1 hour) is performed to hydrogenate the island-shaped semiconductor film. This step is performed in order to terminate dangling bonds of the island-shaped semiconductor film with hydrogen contained in the second interlayer insulating film 316. Note that the island-shaped semiconductor film can be hydrogenated regardless of the presence of the gate insulating film 313.

  Further, as the third interlayer insulating film 317, an insulating film using siloxane and a stacked structure thereof can be used. Siloxane has a skeleton structure with a bond of silicon (Si) and oxygen (O). As a substituent, an organic group containing at least hydrogen (for example, an alkyl group or an aryl group) is used. Further, the substituent may contain a fluoro group.

  In the case where an insulating film using siloxane and a stacked structure thereof are used as the third interlayer insulating film 317, a heat treatment for hydrogenating the island-shaped semiconductor film is performed after the second interlayer insulating film 316 is formed. Next, a third interlayer insulating film 317 can be formed.

  Next, a resist mask is formed using a third photomask, and the first interlayer insulating film, the second interlayer insulating film 316, the third interlayer insulating film 317, and the gate insulating film 313 are selectively formed. Etch to form contact holes. Then, the resist mask is removed.

  Note that the third interlayer insulating film 317 may be formed as necessary. When the third interlayer insulating film 317 is not formed, the first interlayer insulating film and the first interlayer insulating film 316 are formed after the second interlayer insulating film 316 is formed. The second interlayer insulating film 316 and the gate insulating film 313 are selectively etched to form contact holes.

  Next, after a metal laminated film is formed by a sputtering method, a resist mask is formed using a fourth photomask, and the metal film is selectively etched, so that a wiring 319, a connection electrode 320, and a terminal electrode 351 are formed. Then, the source and drain electrodes 341 of the thin film transistor 112 and the source and drain electrodes 342 of the thin film transistor 113 are formed. Then, the resist mask is removed. Note that the metal film of this example is formed by stacking three layers of a Ti film with a thickness of 100 nm, an Al film containing a trace amount of Si with a thickness of 350 nm, and a Ti film with a thickness of 100 nm.

  8B, the wiring 404, the connection electrode 405, the terminal electrode 401, the source and drain electrodes 402 of the thin film transistor 112, and the source and drain electrodes 403 of the thin film transistor 113 are formed using a single conductive film. When it does, a titanium film (Ti film) is preferable from the viewpoints of heat resistance and electrical conductivity. Further, in place of the titanium film, tungsten (W), tantalum (Ta), molybdenum (Mo), neodymium (Nd), cobalt (Co), zirconium (Zr), zinc (Zn), ruthenium (Ru), rhodium ( Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), or a single layer film made of an alloy material or a compound material containing the element as a main component, or these For example, a single layer film made of a nitride of, for example, titanium nitride, tungsten nitride, tantalum nitride, or molybdenum nitride, or a stacked film thereof can be used. By forming the wiring 404, the connection electrode 405, the terminal electrode 401, the source electrode and the drain electrode 402 of the thin film transistor 112, and the source electrode and the drain electrode 403 of the thin film transistor 113 into a single layer film, the number of depositions can be reduced in the manufacturing process. Is possible.

  Through the above steps, top-gate thin film transistors 112 and 113 using a polycrystalline silicon film can be manufactured. Note that the S value of the thin film transistors 112 and 113 can be changed depending on crystallinity of the semiconductor film or an interface state between the semiconductor film and the gate insulating film.

  Next, after forming a conductive metal film (such as titanium (Ti) or molybdenum (Mo)) that hardly reacts with a photoelectric conversion layer (typically amorphous silicon) to be formed later, A mask made of a resist is formed using this photomask, and a conductive metal film is selectively etched to form a protective electrode 318 covering the wiring 319 (see FIG. 13A). Here, a 200 nm thick Ti film obtained by sputtering is used. Note that the connection electrode 320, the terminal electrode 351, and the source electrode and the drain electrode of the thin film transistor are also covered with the same metal film as the protective electrode 318. Therefore, since the conductive metal film also covers the side surface of the electrode where the second Al film is exposed, the conductive metal film can also prevent diffusion of aluminum atoms into the photoelectric conversion layer.

  However, in the case where the wiring 319, the connection electrode 320, the terminal electrode 351, the source and drain electrodes 341 of the thin film transistor 112, and the source and drain electrodes 342 of the thin film transistor 113 are formed using a single-layer conductive film, that is, FIG. As shown, when the wiring 404, the connection electrode 405, the terminal electrode 401, the source and drain electrodes 402 of the thin film transistor 112, and the source and drain electrodes 403 of the thin film transistor 113 are formed instead of these electrodes or wirings, a protective electrode 318 may not be formed.

  Next, the photoelectric conversion layer 111 including the p-type semiconductor layer 111p, the i-type semiconductor layer 111i, and the n-type semiconductor layer 111n is formed over the third interlayer insulating film 317.

  The p-type semiconductor layer 111p may be formed by forming a semi-amorphous silicon film containing a Group 13 impurity element such as boron (B) by plasma CVD, or after forming the semi-amorphous silicon film, 15 Group impurity elements may be introduced.

  Note that the wiring 319 and the protective electrode 318 are in contact with the lowermost layer of the photoelectric conversion layer 111, in this embodiment, the p-type semiconductor layer 111p.

  After the p-type semiconductor layer 111p is formed, an i-type semiconductor layer 111i and an n-type semiconductor layer 111n are sequentially formed. Thus, the photoelectric conversion layer 111 including the p-type semiconductor layer 111p, the i-type semiconductor layer 111i, and the n-type semiconductor layer 111n is formed.

  As the i-type semiconductor layer 111i, for example, a semi-amorphous silicon film may be formed by a plasma CVD method. Further, as the n-type semiconductor layer 111n, a semi-amorphous silicon film containing a Group 15 impurity element such as phosphorus (P) may be formed, or a Group 15 impurity element is introduced after the semi-amorphous silicon film is formed. May be.

  Further, as the p-type semiconductor layer 111p, the intrinsic semiconductor layer 111i, and the n-type semiconductor layer 111n, not only a semi-amorphous semiconductor film but also an amorphous semiconductor film may be used.

  Next, a sealing layer 324 made of an insulating material (for example, an inorganic insulating film containing silicon) is formed over the entire surface with a thickness (1 μm to 30 μm) to obtain the state shown in FIG. Here, a silicon oxide film containing nitrogen having a thickness of 1 μm is formed as the insulating material film by a CVD method. Adhesion is improved by using an inorganic insulating film.

  Next, after the sealing layer 324 is etched to provide openings, terminals 121 and 122 are formed by sputtering. The terminals 121 and 122 are laminated films of a titanium film (Ti film) (100 nm), a nickel film (Ni film) (300 nm), and a gold film (Au film) (50 nm). The fixing strength of the terminal 121 and the terminal 122 obtained in this way exceeds 5N, and has sufficient fixing strength as a terminal electrode.

  Through the above steps, the terminal 121 and the terminal 122 that can be soldered are formed, and the structure shown in FIG. 13C is obtained.

  In this manner, for example, a large number of photo IC chips (2 mm × 1.5 mm), that is, chips of a photoelectric conversion device can be manufactured from one large-area substrate (for example, 600 cm × 720 cm). Next, a plurality of photo IC chips are cut out individually.

  FIG. 14A shows a cross-sectional view of one cut out photo IC chip (2 mm × 1.5 mm), FIG. 14B shows a top view thereof, and FIG. 14C shows a bottom view thereof. In FIG. 14A, the total film thickness including the substrate 310, the element formation region 410, the terminal 121, and the terminal 122 is 0.8 ± 0.05 mm.

  Further, in order to reduce the total film thickness of the optical sensor chip, the substrate 310 may be cut and thinned by a CMP process or the like and then individually cut with a dicer to cut out a plurality of optical sensor chips.

In FIG. 14B, one electrode size of the terminals 121 and 122 is 0.6 mm × 1.1 mm, and the electrode interval is 0.4 mm. In FIG. 14C, the area of the light receiving portion 411 is 1.57 mm ² . In addition, the amplifier circuit portion 412 is provided with about 100 thin film transistors.

  Finally, the obtained optical sensor chip is mounted on the mounting surface of the substrate 360 (see FIG. 8A). Note that solders 364 and 363 are used to connect the terminals 121 and 361 and the terminals 122 and 362, respectively, and solder is formed in advance on the electrodes 361 and 362 of the substrate 360 by a screen printing method or the like. After the solder and the terminal electrode are in contact with each other, the solder reflow process is performed for mounting. The solder reflow process is performed, for example, in an inert gas atmosphere at a temperature of about 255 ° C. to 265 ° C. for about 10 seconds. In addition to solder, bumps formed of metal (gold, silver, etc.) or bumps formed of conductive resin can be used. Moreover, you may mount using lead-free solder in consideration of an environmental problem.

As described above, a semiconductor device can be manufactured. In addition, in order to detect light, the light may be blocked by using a housing or the like other than light incident on the photoelectric conversion layer 111 from the substrate 310 side. Note that any material may be used for the housing as long as it has a function of blocking light. For example, a metal material or a resin material having a black pigment may be used. With such a structure, a more reliable semiconductor device having a light detection function can be obtained.

  In this embodiment, the case where the amplifier circuit included in the semiconductor device is formed using an n-channel thin film transistor is described. However, a p-channel thin film transistor may be used. Note that a p-channel thin film transistor can be manufactured in the same manner as an n-channel thin film transistor if an impurity imparting one conductivity type to the island-shaped semiconductor region is replaced with a p-type impurity such as boron (B). Next, an example in which an amplifier circuit is formed using a p-channel thin film transistor is described.

  An example of an equivalent circuit diagram of a photoelectric conversion device in which an amplifier circuit, for example, a current mirror circuit is formed of a p-channel thin film transistor, is as shown in FIG. 7, and a cross-sectional view thereof is shown in FIG. Note that FIG. 15 illustrates the p-channel thin film transistors 201 and 202 and the photoelectric conversion element 204 extracted from FIG. Note that components similar to those in FIG. 8 are denoted by common reference numerals, and detailed description of the same portions or portions having similar functions is omitted. As described above, a p-type impurity, for example, boron (B) is introduced into the island-shaped semiconductor region of the thin film transistor 201 and the island-shaped semiconductor region of the thin film transistor 202, and the thin film transistor 201 has a source region and a drain region 241, A source region and a drain region 242 are formed in the thin film transistor 202. The photoelectric conversion layer 222 included in the photoelectric conversion element has a structure in which an n-type semiconductor layer 222n, an i-type semiconductor layer 222i, and a p-type semiconductor layer 222p are sequentially stacked. Note that the n-type semiconductor layer 222n, the i-type semiconductor layer 222i, and the p-type semiconductor layer 222p are formed using the same materials and manufacturing methods as the n-type semiconductor layer 111n, the i-type semiconductor layer 111i, and the p-type semiconductor layer 111p, respectively. Can be formed.

  Note that this embodiment can be combined with any of the embodiment mode and other embodiments as appropriate.

  In this embodiment, an example of a semiconductor device in which an amplifier circuit is formed using a bottom-gate thin film transistor and a manufacturing method thereof will be described with reference to FIGS.

  First, a base insulating film 312 and a metal film 511 are formed over a substrate 310 (see FIG. 16A). In this embodiment, for example, a film in which tantalum nitride (TaN) and tungsten (W) are stacked by 30 nm and 370 nm is used as the metal film 511.

  In addition to the above, the metal film 511 includes titanium (Ti), tungsten (W), tantalum (Ta), molybdenum (Mo), neodymium (Nd), cobalt (Co), zirconium (Zr), and zinc (Zn). , Ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), aluminum (Al), gold (Au), silver (Ag), copper (Cu) Or a single layer film made of an alloy material or a compound material containing the element as a main component, or a single layer film made of these nitrides, for example, titanium nitride, tungsten nitride, tantalum nitride, or molybdenum nitride Can be used.

  Note that the metal film 511 may be directly formed over the substrate 310 without forming the base insulating film 312 over the substrate 310.

  Next, the metal film 511 is patterned to form gate electrodes 512 and 513, wirings 314 and 315, and a terminal electrode 350 (see FIG. 16B).

  Next, a gate insulating film 514 that covers the gate electrodes 512 and 513, the wirings 314 and 315, and the terminal electrode 350 is formed. In this embodiment, an insulating film containing silicon as a main component, for example, a silicon oxide film containing nitrogen with a thickness of 115 nm by a plasma CVD method (composition ratio Si = 32%, O = 59%, N = 7%, H = 2%), a gate insulating film 514 is formed.

  Next, island-shaped semiconductor regions 515 and 516 are formed over the gate insulating film 514. The island-shaped semiconductor regions 515 and 516 may be formed using a material and a manufacturing process similar to those of the island-shaped semiconductor regions 331 and 332 described in Embodiment 2 (see FIG. 16C).

  After the island-shaped semiconductor regions 515 and 516 are formed, a mask 518 is formed so as to cover a region other than the source region and the drain region 521 of the thin film transistor 501 and the source region and the drain region 522 of the thin film transistor 502, and one conductivity type is imparted. Impurities are introduced (see FIG. 16D). As an impurity of one conductivity type, phosphorus (P) or arsenic (As) is used as an n-type impurity when an n-channel thin film transistor is formed, and p-type impurity is used when a p-channel thin film transistor is formed. Boron (B) may be used. In this embodiment, phosphorus (P) which is an n-type impurity is introduced into the island-shaped semiconductor regions 515 and 516, and a source region and a drain region 521 of the thin film transistor 501, a channel formation region between these regions, a source region of the thin film transistor 502, and A drain region 522 and a channel formation region are formed between these regions. Note that if necessary, a minute amount of an impurity element (boron or phosphorus) may be doped in the channel formation region in order to control the threshold value of the thin film transistor.

  Next, the mask 518 is removed, and a first interlayer insulating film, a second interlayer insulating film 316, and a third interlayer insulating film 317 (not shown) are formed (see FIG. 16E). The materials and manufacturing steps of the first interlayer insulating film, the second interlayer insulating film 316, and the third interlayer insulating film 317 may be based on those described in Embodiment 2.

  Next, contact holes are formed in the first interlayer insulating film, the second interlayer insulating film 316, and the third interlayer insulating film 317, a metal film is formed, and the metal film is selectively etched to form a wiring 319. The connection electrode 320, the terminal electrode 351, the source and drain electrodes 531 of the thin film transistor 501, and the source and drain electrodes 532 of the thin film transistor 502 are formed. Then, the resist mask is removed. Note that the metal film of this example is formed by stacking three layers of a Ti film with a thickness of 100 nm, an Al film containing a trace amount of Si with a thickness of 350 nm, and a Ti film with a thickness of 100 nm.

  In addition, the wiring 319 and its protective electrode 318, the connection electrode 320 and its protective electrode 533, the terminal electrode 351 and its protective electrode 538, the source and drain electrodes 531 of the thin film transistor 501, its protective electrode 536, and the source and drain electrodes of the thin film transistor 502 In place of the wiring 532 and the protective electrode 537, the wiring 404, the connection electrode 405, the terminal electrode 401, the source and drain electrodes 402 of the thin film transistor 112, and the source and drain electrodes 403 of the thin film transistor 113, respectively, in FIG. Each wiring and electrode may be formed using a single conductive film.

  As described above, bottom-gate thin film transistors 501 and 502 included in the amplifier circuit 503 can be manufactured (see FIG. 17A).

  Next, the photoelectric conversion layer 111 including the p-type semiconductor layer 111p, the i-type semiconductor layer 111i, and the n-type semiconductor layer 111n is formed over the third interlayer insulating film 317 (see FIG. 17B). For the material and manufacturing process of the photoelectric conversion layer 111, Embodiment Mode and Example 2 may be referred to.

  Next, a sealing layer 324 and terminals 121 and 122 are formed (see FIG. 17C). The terminal 121 is connected to the n-type semiconductor layer 111n, and the terminal 122 is formed in the same process as the terminal 121.

  Further, a substrate 360 having electrodes 361 and 362 is mounted with solder 364 and 363. Note that the electrode 361 on the substrate 360 is mounted on the terminal 121 with solder 364. Further, the electrode 362 of the substrate 360 is mounted on the solder 363 terminal 122 (see FIG. 18A).

  In the semiconductor device illustrated in FIG. 18A, light that enters the photoelectric conversion layer 111 enters mainly from the substrate 310 side; however, the present invention is not limited to this. 18B, a housing 550 may be provided in a region other than the region where the photoelectric conversion layer 111 on the substrate 360 side is formed. Note that the housing 550 may be made of any material having a function of blocking light, and may be formed using, for example, a metal material or a resin material having a black pigment. With such a structure, a more reliable semiconductor device having a light detection function can be obtained.

  Note that this embodiment can be combined with any of the embodiment mode and other embodiments as appropriate.

  In this embodiment, a circuit for performing bias switching will be described with reference to FIGS. 19 to 23 as an example of the bias switching means in FIG.

  The circuit shown in FIG. 19 is a circuit that inverts the bias applied to the photoelectric conversion device when the output voltage obtained by outputting the current obtained from the photoelectric conversion device 101 in FIG. 1 as a voltage reaches a certain value. That is, it is a circuit that reverses the bias with a predetermined illuminance as a boundary. In the circuit of FIG. 19, the bias is reversed when the output voltage exceeds Vr with the reference voltage Vr as a boundary.

19 and 20, 901 is a photosensor output V _PS , 902 is a reference voltage generation circuit for determining a reference voltage Vr, 903 is a comparator, and 904 is an output buffer. Here, the output buffer 904 is the first stage. 904a, second stage 904b, and third stage 904c. Although only three stages of output buffers are shown, it is possible to have four or more stages, and it is also possible to design only one stage. Note that the photosensor output V _PS corresponds to the output obtained from the terminal V ₀ in FIG. Further, the comparator 903 and the output buffer 904 correspond to the bias switching unit 102 and the power source 103 in FIG. 1, respectively, and 905 corresponds to the photoelectric conversion element 101 and the resistor 104.

  FIG. 20 shows a specific circuit configuration of FIG. 19. The comparator 903 includes p-channel thin film transistors 911 and 913, n-channel thin film transistors 912 and 914, and a resistor 921. The reference voltage generation circuit 902 includes resistors 923 and 924, and these are used to determine the reference voltage Vr.

  In FIG. 20, only the first stage 904 a is described for the output buffer 904, and the first stage is formed by a p-channel thin film transistor 915 and an n-channel thin film transistor 916. Note that in FIG. 20, an n-channel thin film transistor is a single-gate thin film transistor having one gate electrode; however, in order to reduce off-state current, a thin film transistor having a plurality of gate electrodes, that is, a multi-gate thin film transistor, for example, a gate You may form with the double gate thin-film transistor which has two electrodes. Note that the other stages may be formed using a circuit similar to 904a.

  In FIG. 20, one stage of the output buffer 904 may be replaced with the circuit 942 illustrated in FIG. 22A and the circuit 944 illustrated in FIG. A circuit 942 illustrated in FIG. 22A is formed using an n-channel thin film transistor 916 and a p-channel thin film transistor 941, and a circuit 944 illustrated in FIG. 22B is formed using n-channel thin film transistors 916 and 943.

Note that an output voltage obtained by outputting a current obtained from the photoelectric conversion device as a voltage may be used as the photosensor output _VPS , or a voltage obtained by amplifying the output voltage with an amplifier circuit may be used.

  In FIG. 20, the reference voltage Vr is determined by the reference voltage generation circuit. However, when other reference voltages are desired, the reference voltage Vr may be directly input from the external circuit 931 as shown in FIG. However, some input voltages may be input from a circuit 932 that selects using a selector (analog switch or the like) (see FIG. 21B).

  Note that in the circuit illustrated in FIG. 20, the reference voltage Vr needs to be equal to or higher than the threshold voltage of the thin film transistors included in the comparator (Vth ≦ Vr when the threshold voltage is Vth). In order to satisfy this, it is necessary to adjust the reference voltage or the photosensor output voltage.

The output V _{PS of the} photosensor is input to the gate electrode of the p-channel thin film transistor 911 of the comparator 903, compared with the voltage value from the reference voltage generation circuit 902, and when the voltage value is smaller than the voltage value from the reference voltage generation circuit, 103 is connected to the power source 103a, and a current flows in the direction shown in FIG. Further, when the voltage value is larger than the voltage value from the reference voltage generation circuit, it is connected to the power source 103b of the power source 103, and a current flows in the direction shown in FIG.

  By reversing the bias applied to the photoelectric conversion device using the bias switching means as described above, the detectable illuminance range can be expanded without expanding the output voltage or output current range.

  Note that this embodiment can be combined with any of the embodiment mode and other embodiments as appropriate.

  In this embodiment, examples in which a semiconductor device obtained by the present invention is incorporated into various electronic devices as an optical sensor will be described. Examples of electronic devices to which the present invention is applied include computers, displays, mobile phones, and televisions. Specific examples of these electronic devices are shown in FIGS. 24, 25 (A) to 25 (B), 26 (A) to 26 (B), 27 and 28 (A) to 28 (B). Show.

  FIG. 24 shows an example in which the present invention is applied to a cellular phone. A main body (A) 701, a main body (B) 702, a housing 703, operation keys 704, an audio output unit 705, an audio input unit 706, a circuit board 707, a display A panel (A) 708, a display panel (B) 709, a hinge 710, a translucent material portion 711, and an optical sensor 712 are included. The present invention can be applied to the optical sensor 712.

  The optical sensor 712 detects light transmitted through the translucent material portion 711 and controls the luminance of the display panel (A) 708 and the display panel (B) 709 according to the detected illuminance of the external light, or the optical sensor 712. Illumination control of the operation key 704 is performed in accordance with the illuminance obtained in the above. As a result, the power consumption of the mobile phone can be reduced.

  Next, an example of a mobile phone different from the above is illustrated in FIGS. 25A and 25B, reference numeral 721 denotes a main body, 722 denotes a housing, 723 denotes a display panel, 724 denotes operation keys, 725 denotes an audio output unit, 726 denotes an audio input unit, and 727 and 728 denote optical sensors. It is.

  In the cellular phone shown in FIG. 25A, the luminance of the display panel 723 and the operation key 724 can be controlled by detecting external light with the optical sensor 727 to which the present invention is applied provided in the main body 721. is there.

  In addition, in the mobile phone illustrated in FIG. 25B, an optical sensor 728 is provided inside the main body 721 in addition to the structure in FIG. The light sensor 728 can detect the luminance of the backlight provided in the display panel 723 and control the luminance. Therefore, power consumption can be further reduced.

  FIG. 26A illustrates a computer, which includes a main body 731, a housing 732, a display portion 733, a keyboard 734, an external connection port 735, a pointing mouse 736, and the like. FIG. 26B shows a display device such as a television receiver. This display device includes a housing 741, a support base 742, a display portion 743, and the like.

  FIG. 27 shows a detailed structure in the case where a liquid crystal panel is used as the display portion 733 provided in the computer in FIG. 26A and the display portion 743 of the display device in FIG. A liquid crystal panel 762 illustrated in FIG. 27 is incorporated in a housing 761 and includes substrates 751a and 751b, a liquid crystal layer 752 sandwiched between the substrates 751a and 751b, polarization filters 752a and 752b, a backlight 753, and the like. . Note that a light sensor portion 754 is formed in the housing 761.

  The optical sensor unit 754 manufactured using the present invention senses the amount of light from the backlight 753, and the information is fed back to adjust the luminance of the liquid crystal panel 762.

  28A and 28B are diagrams showing an example in which the photosensor of the present invention is incorporated in a camera, for example, a digital camera. FIG. 28A is a perspective view seen from the front side of the digital camera, and FIG. 28B is a perspective view seen from the rear side. 28A, the digital camera includes a release button 801, a main switch 802, a finder window 803, a flash 804, a lens 805, a lens barrel 806, a housing 807, and an optical sensor 814. In FIG. 28B, a viewfinder eyepiece window 811, a monitor 812, and operation buttons 813 are provided.

  When the release button 801 is pressed down to a half position, the focus adjustment mechanism and the exposure adjustment mechanism are operated, and when the release button 801 is pressed down to the lowest position, the shutter is opened. A main switch 802 switches on / off the power of the digital camera when pressed or rotated. A viewfinder window 803 is disposed on the front of the lens 805 on the front surface of the digital camera, and is a device for confirming a shooting range and a focus position from the viewfinder eyepiece window 811 shown in FIG. The flash 804 is arranged at the upper front of the digital camera. When the subject brightness is low, the release button is pressed to open the shutter and simultaneously emit auxiliary light. The lens 805 is disposed in front of the digital camera. The lens includes a focusing lens, a zoom lens, and the like, and constitutes a photographing optical system together with a shutter and a diaphragm (not shown). In addition, an imaging element such as a CCD (Charge Coupled Device) is provided behind the lens. The lens barrel 806 moves the lens position in order to focus the focusing lens, the zoom lens, and the like. During photographing, the lens barrel 805 is extended to move the lens 805 forward. Further, when carrying the camera, the lens 805 is moved down to be compact. In this embodiment, the structure is such that the subject can be zoomed by extending the lens barrel. However, the present invention is not limited to this structure, and the lens barrel is configured by the configuration of the imaging optical system in the housing 807. It is also possible to use a digital camera that can perform zoom shooting without extending the camera. The viewfinder eyepiece window 811 is provided on the upper rear surface of the digital camera, and is a window provided for eye contact when confirming the photographing range and the focus position. The operation buttons 813 are various function buttons provided on the rear surface of the digital camera, and include a setup button, a menu button, a display button, a function button, a selection button, and the like.

  When the optical sensor to which the present invention is applied is incorporated in the camera shown in FIGS. 28A and 28B, the optical sensor can detect the presence and intensity of light, thereby adjusting the exposure of the camera. It can be carried out.

  The optical sensor of the present invention can be applied to other electronic devices such as a projection television and a navigation system. In other words, it can be used for any object that needs to detect light. Power consumption can be reduced by feeding back the result of detecting light to an illumination control device or the like included in the electronic device.

  Note that this embodiment can be combined with any of the embodiment mode and other embodiments as appropriate.

FIG. 11 illustrates a semiconductor device of the present invention. The figure which shows the photoelectric conversion apparatus of this invention. The figure which shows the photoelectric conversion apparatus of this invention. 6A and 6B illustrate illuminance dependence in output current of the photoelectric conversion device of the present invention. 6A and 6B illustrate illuminance dependence in output current of the photoelectric conversion device of the present invention. FIG. 11 illustrates a semiconductor device of the present invention. The figure which shows the photoelectric conversion apparatus of this invention. Sectional drawing of the photoelectric conversion apparatus of this invention. The figure which shows the illumination intensity dependence in the output current of the photoelectric conversion apparatus of this invention. The figure which shows the illumination intensity dependence in the output current of the photoelectric conversion apparatus of this invention. The figure which shows the relative sensitivity and standard specific luminous efficiency curve of the photoelectric conversion apparatus of this invention. 10A and 10B illustrate a manufacturing process of a semiconductor device of the present invention. 10A and 10B illustrate a manufacturing process of a semiconductor device of the present invention. 10A and 10B illustrate a manufacturing process of a semiconductor device of the present invention. Sectional drawing of the photoelectric conversion apparatus of this invention. 10A and 10B illustrate a manufacturing process of a semiconductor device of the present invention. 10A and 10B illustrate a manufacturing process of a semiconductor device of the present invention. 10A and 10B illustrate a manufacturing process of a semiconductor device of the present invention. The figure explaining a bias switching means. The figure explaining a bias switching means. The figure explaining a bias switching means. The figure explaining a bias switching means. The figure explaining a bias switching means. The figure which shows the apparatus which mounted the semiconductor device of this invention. The figure which shows the apparatus which mounted the semiconductor device of this invention. The figure which shows the apparatus which mounted the semiconductor device of this invention. The figure which shows the apparatus which mounted the semiconductor device of this invention. The figure which shows the apparatus which mounted the semiconductor device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Photoelectric conversion apparatus 102 Bias switching means 103 Power supply 103a Power supply 103b Power supply 104 Resistance 104a Resistance 104b Resistance V0 Terminal 107 Switching means 111 Photoelectric conversion layer 111i i type semiconductor layer 111n n type semiconductor layer 111p p type semiconductor layer 112 Thin film transistor 113 Thin film transistor 114 Current Mirror circuit 115 photoelectric conversion element 116 unit 121 terminal 122 terminal 201 thin film transistor 202 thin film transistor 203 current mirror circuit 204 photoelectric conversion element 222 photoelectric conversion layer 222i i-type semiconductor layer 222n n-type semiconductor layer 222p p-type semiconductor layer

Claims (7)

A semiconductor device having an illuminance detection function,
A photoelectric conversion device including a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element;
Bias switching means for inverting the bias applied to the photoelectric conversion device,
The amplifier circuit has two or more transistors including at least a first transistor;
A gate electrode of the first transistor is electrically connected to a first electrode of the first transistor through the photoelectric conversion element;
The photoelectric conversion element detects incident light,
The bias switching unit inverts the bias with a predetermined illuminance as a boundary, is detected by a current generated in the photoelectric conversion element, and is generated in the photoelectric conversion element applied between the gate and source of the first transistor. A semiconductor device characterized by switching between detection by voltage. A semiconductor device having an illuminance detection function,
A photoelectric conversion device including a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element;
Bias switching means for inverting the bias applied to the photoelectric conversion device,
The amplifier circuit has two or more transistors including at least a first transistor;
The photoelectric conversion element detects incident light,
When the light is below a predetermined illuminance, it is detected by a current generated in the photoelectric conversion element,
When the light exceeds the predetermined illuminance, it is detected by applying a voltage generated in the photoelectric conversion element between the gate and source of the first transistor,
The semiconductor device according to claim 1, wherein the bias switching unit reverses the bias with the predetermined illuminance as a boundary. A semiconductor device having an illuminance detection function,
A photoelectric conversion device including a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element;
Bias switching means for inverting the bias applied to the photoelectric conversion device,
The amplifier circuit has two or more transistors including at least a first transistor;
A gate electrode of the first transistor is electrically connected to a first electrode of the first transistor through the photoelectric conversion element;
The photoelectric conversion element detects incident light,
When the light is below a predetermined illuminance, it is detected by a current generated in the photoelectric conversion element,
When the light exceeds the predetermined illuminance, it is detected by applying a voltage generated in the photoelectric conversion element between the gate and source of the first transistor,
The semiconductor device according to claim 1, wherein the bias switching unit reverses the bias with the predetermined illuminance as a boundary. A semiconductor device having an illuminance detection function,
A photoelectric conversion device including a photoelectric conversion element and an amplifier circuit electrically connected to the photoelectric conversion element;
Bias switching means for inverting the bias applied to the photoelectric conversion device,
The amplifier circuit includes at least a first transistor and a second transistor,
The bias is applied from a first terminal and a second terminal of the photoelectric conversion device,
The first terminal is electrically connected to the first electrode and the gate electrode of the second transistor and the gate electrode of the first transistor through the photoelectric conversion element,
The first terminal is also electrically connected to the first electrode of the first transistor;
The second terminal is electrically connected to a second electrode of the first transistor and the second transistor;
The photoelectric conversion element detects incident light,
When the light is below a predetermined illuminance, it is detected by a current generated in the photoelectric conversion element,
When the light exceeds the predetermined illuminance, it is detected by a voltage generated in the photoelectric conversion element,
The semiconductor device according to claim 1, wherein the bias switching unit reverses the bias with the predetermined illuminance as a boundary. In any one of Claims 1 thru | or 4,
The amplifier circuit includes a plurality of the first transistors. In any one of Claims 1 thru | or 5,
The photoelectric conversion element includes a p-type semiconductor layer, an n-type semiconductor layer, and an i-type semiconductor layer provided between the p-type semiconductor layer and the n-type semiconductor layer.   An electronic apparatus comprising the semiconductor device according to claim 1.

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