JPH02222573A - Switching device - Google Patents

Abstract

PURPOSE:To obtain a switching device which enable a photodetective element to optimize control circuit elements keeping an advantage that the photodetective element can be formed on a semiconductor substrate on which a switching element has been formed by a method wherein the switching element and elements which constitute a control circuit are formed on a first conductivity type region provided onto the surface of a second conductivity type semiconductor substrate. CONSTITUTION:A switching device S1 is provided with a photodetective element DA1 which generates and electric power receiving light rays, a switching element T1 driven by the power generated by the photodetective element DA1, and a control circuit DR1, where the switching element T1 is possessed of a first conductivity type region 5 as its component part formed on the surface of a second conductivity type semiconductor substrate 2 and at least an element T2 out of elements which constitute the control circuit DR1 is formed on the first conductivity type region 5 or a first conductivity type region separately formed on the surface of the substrate 2. For instance, the photodetective element DA1 is formed in laminating on the semiconductor substrate 2 on which the switching element T1 and the element T2 of the control circuit DR1 have been formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a switching device.

[Conventional technology]

Conventionally, some switching devices include a light receiving element that receives light and generates power, a switching element that is driven by the power generated by the light receiving element, and a control circuit. FIG. 8 shows a conventional semiconductor device of this type, and this switching device was proposed by the applicant of the present application in Japanese Patent Application No. 239169/1982. FIG. 9 is an equivalent circuit diagram of this switching device.

The switching device 100 includes a light receiving element 101, a field effect transistor 102 which is a switching element, and
It is equipped with a control circuit consisting of a thin film transistor 103 and resistive elements 104 and 105, and a light receiving element 101 and each element 103 to 1 for the control circuit are provided on a semiconductor substrate 106 on which a field effect transistor 102 is formed.
05 is formed of semiconductor thin films (P-type semiconductor layer, i-type semiconductor layer, and n-type semiconductor layer) and is made into one chip. This switching device 100 has a simpler manufacturing process, fewer parts, and is more practical at low cost than when the light-receiving element and control circuit are formed separately using so-called dielectric separation. has many advantages.

[Problem to be solved by the invention]

However, in this switching device 100, it is difficult to optimize the light receiving element 101 and each of the control circuit elements 103 to 105. Since each element constituting the light-receiving element and the control circuit is simultaneously formed using a semiconductor thin film, it is difficult to optimize each element. Among the elements for the control circuit, it is particularly efficient to use the thin film transistor 103 as a transistor optimized by the structure of the semiconductor thin film forming the photoelectric conversion element.

Furthermore, depending on the structure of the light receiving element, it may be difficult to simultaneously form elements for a control circuit.

This invention was made in view of the above circumstances, and
It has the advantage that the light receiving element can be formed on the semiconductor substrate on which the switching element is formed (one chip is possible), and it is also easy to optimize each element for the light receiving element and control circuit. It is an object of the present invention to provide a switching device with a large degree of freedom in design that can easily accommodate diversification of structure.

Ca! Means for Solving the Problem] In order to solve the problem, a light receiving element that receives light and generates power according to claims 1 to 9, a switching element driven by the power generated by the light receiving element, and a control device are provided. A switching device equipped with a circuit has the following configuration.

That is, in the invention according to claims 1 to 9, the switching element is an element having as a constituent part the first conductivity type region formed on the surface portion of the second conductivity type semiconductor substrate, and the switching element is an element having a first conductivity type region formed on the surface portion of the second conductivity type semiconductor substrate, at least one of said first
The structure is such that it is formed in a conductivity type region or a first conductivity type region separately provided on the surface of the second conductivity type semiconductor substrate.

In the second aspect of the invention, the light receiving element generates electric power using a photoelectric conversion layer formed of a semiconductor thin film.

In the invention as set forth in claim 3, the light-receiving element is formed by laminating a plurality of photoelectric conversion layers, and each photoelectric conversion layer has an absorption coefficient α (λ) for incident light of a wavelength λ in the semiconductor thin film, and a carrier collection coefficient of the semiconductor thin film. When the length is L, L≦1/α(
2 to photoelectrically convert light with a wavelength of λ).

In the invention set forth in claim 4, the light-receiving element is laminated on a semiconductor substrate on which a switching element and a control circuit element are formed. It is a field effect transistor in which a second conductivity type region of a two conductivity type semiconductor substrate is used as a drain region, and at least a first conductivity type region in which an element for the control circuit is formed is a field effect transistor in which a second conductivity type region of a two conductivity type semiconductor substrate is formed as a drain region. The region is separated from the first conductivity type region.

In the invention according to claim 6, the control circuit includes: a transistor having a control electrode and a pair of output terminals; a first resistive element connected between the control electrode and one output terminal of the transistor; a second resistive element connected between the electrode and the other output terminal of the transistor, and at least one of the transistor, the first resistive element, or the second resistive element is formed in a first conductivity type region on the surface of the semiconductor substrate. The first resistive element is connected in parallel to the light receiving element, and one output terminal of the transistor is connected to the gate of a field effect transistor that is a switching element.

In the invention according to claim 7, the first resistive element has a structure of a depression type field effect transistor, the gate and source of which are connected, and the source side is connected to the control circuit transistor. It is connected to an electrode, and its drain side is connected to the gate of a field effect transistor for a switching element.

In the invention according to claim 8, the second resistive element has a structure of a field effect transistor, and its gate and drain are connected, and its source side is connected to the control electrode of the control circuit transistor. The drain side is connected to the source of a field effect transistor for a switching element.

In the invention according to claim 9, the transistor of the control circuit is a field effect transistor, and the threshold voltage of the field effect transistor is lower than the threshold voltage of the field effect transistor that is the switching element. ing.

Note that the control circuit referred to in the present invention is a circuit that has a function of discharging charges in a control region such as the gate or base of a switching element when no light is irradiated to the light receiving element. In addition to being supplied from the light-receiving element to the control region of the switching element to turn on the switching element, the above charge is caused by the stray capacitance between the output region and the control region due to the pulse voltage applied to the output region of the switching element. It also includes those charged to the control area through.

[For production]

In the switching device according to any one of claims 1 to 9, the switching element has a first conductivity type region on the second conductivity type semiconductor substrate, and at the same time, the switching element is provided separately on the first conductivity type region or on the surface portion of the semiconductor substrate. This is a configuration in which an element constituting a control circuit, for example, a transistor, is provided in the first conductivity type region. Therefore, the control circuit transistor, for example,
There is no need to simultaneously form semiconductor thin-film light-receiving elements, and there is no need to be limited by the type of light-receiving elements, making it easy to optimize each element.

In terms of the relationship between the switching element and the switching element, the formation region of the control circuit transistor can be formed on the surface of the semiconductor substrate simultaneously with the formation of the first conductivity type region for the switching element, which is advantageous in terms of manufacturing. If a pulse voltage is input to the output region when it is in the off state, this pulse input will further apply to the gate or base of the switching element due to capacitive coupling, causing an unintended on state.
Cause. However, the device of the present invention can effectively prevent this unintended on state. When the switching element uses a second conductivity type semiconductor substrate, for example, for an output region, a portion of the pulse input is also transmitted to the first conductivity type region formed on the surface portion of the second conductivity type semiconductor substrate due to capacitive coupling. This is because it becomes an input signal to the control circuit, for example, makes a transistor in the control circuit conductive, and prevents pulse input to the gate or base of the switching element, thereby preventing an unintended on-state from occurring.

In a light receiving element, a plurality of photoelectric conversion layers are laminated, and each photoelectric conversion layer has an absorption coefficient of α (λ) for incident light of wavelength λ in its semiconductor thin film, and L is the carrier collection length of the semiconductor thin film. It is designed to photoelectrically convert light with a wavelength of ≦1/α (λ), and the thickness of each photoelectric change layer is L.
If it is below, the photoelectric conversion efficiency will be improved.

If the light-receiving element is laminated on a semiconductor substrate on which switching elements and control circuit elements are formed, it is easy to integrate the light-receiving element.

The first conductivity type region in which the control circuit element is formed is
If it is separated from the first conductivity type region for the switching element, malfunction of the switching element is suppressed.

If the transistor of the control circuit is a field effect transistor and the threshold voltage of this field effect transistor is lower than the threshold voltage of the field effect transistor which is the switching element, the switching element will be cut off. speed increases.

〔Example〕

Hereinafter, one embodiment of the switching device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of a switching device of the present invention, and FIG. 2 shows an equivalent circuit diagram of this switching device.

The switching device S1 includes a photoelectric conversion element array (light receiving element) DAl, a field effect transistor (hereinafter referred to as rFETJ) T1 as a switching element, and a control circuit DRI consisting of a field effect transistor T2 and resistive elements R1 and R2. and a transistor T1
．． The array DA is placed on the semiconductor substrate 2 on which T2 is formed.
I and resistive elements R1 and R2 are formed in a laminated manner,
It has a one-chip configuration. The first embodiment conventionally
A feature of the present invention is that the control circuit transistor, which is formed in layers on a semiconductor substrate using a semiconductor Wt film, is formed in a P-type (first conductivity type) region 5 of the semiconductor substrate.

First, the transistor Tl, which is a switching element, will be explained. That is, n-type (second conductivity type) low resistance (n
゛) A plurality of PH5, 5a, etc., which are first conductivity type regions, are formed spaced apart from each other on the surface of the semiconductor substrate 2 having the region 2a and the high resistance (n) region 2b, on the high resistance region 2b side. has been done. On the surface of each of the two layers 5, 5a..., there are further n' layers fia, 5b..., which are second conductivity type regions.
is formed. Here, the n0 layers 5a and 5b are connected outside the cross-sectional view. On the surface of the semiconductor substrate 2 on which each of the above regions is formed, each of the two layers 5.
Electrodes 8 made of PolySi or the like are formed so as to straddle between the electrodes 5a.

Then, this electrode 8 is connected to the insulated gate G, as described above.

layers 5a, 5b as source S1 n around each P layer 5, 5a
type semiconductor substrate 2 as a drain D, and the n' layers 5a and 5b.
A plurality of double-diffused field effect transistors TI... are constructed using the surface of the two layers 5.5a sandwiched between the semiconductor substrate 2 and the n-type semiconductor substrate 2 as a channel formation region. A drain electrode (not shown) is formed on the back surface of the semiconductor substrate 2 or on the side of the front surface of the semiconductor substrate 2.

An insulating film 7b that also serves as a protective film is provided on the upper surface of each electrode 8...
A conductive thin film 9 such as Al is formed thereon between each transistor T1. As shown in the figure, this conductive thin layer 1i19 has each n0 layer 5a,
5b and each of the two layers 5, 5a-..., and is used as a source electrode. On the other hand, each electrode 8... is connected at a place not shown,
Further, since the drain D of each transistor T1 is a part of one semiconductor substrate 2 as described above, this is also electrically connected. Therefore, each transistor T1
...are connected in parallel.

Next, the transistor T2 constituting the control circuit DRI will be explained. That is, the high resistance region 2 of the semiconductor substrate 2
On the surface of the second layer 5, which is a first conductivity type region, formed on the b side surface, n9 layers 11 and 12, which are second conductivity type regions, are formed at a distance. Furthermore, an electrode 14 made of PolySi or the like is formed on the surface of the semiconductor substrate 2 via an insulating film 13 so as to straddle the n' layers 11 and 12.

Then, this electrode 14 is connected to the insulated gate G, and the n''!11
．． 12 is the source S or drain D (in the figure, the n0 layer 12
The transistor T2 is configured with the n'' layer 11 as a source S, the n'' layer 11 as a drain D), and the surface of the P layer 5 sandwiched between the n0 layers 11 and 12 as a channel formation region.

An insulating film 13b which also serves as a protective film is formed on the upper surface of the electrode 14, and a part of the insulating film 13b is removed by etching or the like as shown in the figure. Then, conductive thin film 1 such as AI
5, the transistor T2, the first and second resistive elements R1 and R2, and the photoelectric conversion element array DAI are connected as shown in the equivalent circuit of FIG. Here, the transistor T2 is formed in the second layer 5 in which one of the transistors T1 is formed, but the invention is not limited to this, and the first conductivity type region 5.5a... is formed in a portion not shown in the paper. may be connected with

As is clear from the figure, transistors T1 and T2 are
Part of it (2 layers, n9 layers, Po1yS through an insulating film)
Since the transistors T2 and T1 have the same structure, the control circuit transistor T2 and the transistor T1 can be formed simultaneously on the same semiconductor substrate.

In addition, the transistor T2 performs threshold voltage control by ion implantation between the source and drain.
The gate threshold voltage is set lower than the gate threshold voltage of 1. By doing so, the transistor T1 can be quickly turned off (OFF) when light is interrupted.

If the threshold voltage of the gate of the transistor T2 is higher than the threshold voltage of the gate of the transistor T1, the transistor T2 will be in the cut-off state before the transistor T1 is cut off during the discharge of the accumulated charge at the gate of the transistor T1. , the subsequent discharge is caused by the first and second resistive elements R1
, R2, it takes a long time for the transistor T1 to enter the cut-off state.

On the other hand, if the threshold voltage of the transistor T2 remains lower than that of the transistor T1, the above condition will not occur and the gate charge of the transistor T1 can be quickly discharged.
It is possible to put it in a cut-off state.

Further, as shown in FIG. 1, a photoelectric conversion element array DAI, which is a light receiving element, a first resistive element R1, and a second resistive element R2 are stacked with an insulating film 20 in between.

First, the photoelectric conversion element array DAI is composed of a plurality of photoelectric conversion elements Di connected in series. Each photoelectric conversion element DI includes a conductive thin film (Ni-Cr or transparent conductive film, etc.) 31, a photoelectric conversion layer 32, and a transparent conductive film 3.
Consists of 3. The photoelectric conversion layer 32 includes a first conductivity type (for example, P type) semiconductor layer 35 made of amorphous silicon or the like;
A semiconductor layer 36 having a relatively low valence electron control impurity concentration and a second conductivity type (for example, n-type) semiconductor layer 37 are stacked in this order. The transparent conductive film 33 is made of, for example, In, O
It is a film with good light transmittance. Each transparent conductive 1
j! 33 is a conductive thin film 31 of the next stage photoelectric conversion element DI.
This makes each photoelectric conversion element D1.
... are connected in series.

On the other hand, the first resistive element R1 includes a resistive layer made of amorphous silicon or the like similarly to the photoelectric conversion layer,
This resistive layer has a structure in which a first conductivity type semiconductor layer 42, a semiconductor layer 43 with a relatively low valence electron control impurity concentration, and a second conductivity type semiconductor 1i44 are laminated in this order. And on top of this resistive layer, Aj! A pair of electrodes 41a, 4 made of conductive thin films such as
1b, and the space between the spaced apart electrodes is covered with an insulating film 45 capable of blocking light.

On the other hand, the second resistive element RA2 also includes a resistive layer made of amorphous silicon or the like similarly to the photoelectric conversion layer. It has a structure in which a low concentration semiconductor layer 53 and a second conductivity type semiconductor layer 54 are laminated in this order. A conductive thin film 51 such as Ni--Cr is formed on the back surface of this resistive layer, and a conductive electrode 55 such as A1 that can block light is formed on the surface. In this structure, the second resistive element RA2 has rectifying properties as shown in the equivalent circuit of FIG.

These elements are connected as shown in FIG. 1.2 by a conductive thin film made of Ni-Cr or A1 or a transparent conductive film made of Ingot or the like. Further, as shown in the figure, a portion of the insulating film 20 is removed by etching or the like to connect the transistors T1 and T2 formed on the semiconductor substrate 2 through a window.

Here, the operation of the switching device S1 will be briefly explained with reference to FIG.

Upon receiving light, an electromotive force is generated in the photoelectric conversion element array DAI. When this electromotive force is received, a charging current flows through the gate capacitor 1c of the transistor T1 via the resistive element R2, and the source potential of the transistor T2 is put into a reverse bias state higher than the gate potential, and the transistor T2 is turned off. It is in. As the gate capacitance C is charged, the gate voltage of the transistor T1 increases, and the transistor T1 becomes conductive.

When it no longer receives light, the charge accumulated in the gate capacitor C begins to discharge, but in transistor T2, the gate voltage becomes forward biased higher than the source voltage, transistor T2 conducts, and the charge rapidly discharges. As a result, the gate voltage of the transistor T1 decreases, and the transistor T1 enters a cutoff state.

In order to rapidly charge and discharge the gate capacitance C of the transistor T1, it is preferable that the resistive element R2 is a rectifying element such as a diode.

Next, a second embodiment will be described.

FIG. 3 shows a second embodiment of the switching device of the present invention.

In the first embodiment, the control circuit transistor T2 has a first conductive region 5 for the transistor Tl, which is a switching element.
However, in the switching device S2 of the second embodiment, the control circuit transistor T2 is formed in a separate first conductivity type region separated from the first conductivity region for the transistor Tl on the surface portion of the semiconductor substrate 200. is formed.

In other words, the control circuit transistor T2 is connected to the semiconductor substrate 2.
On the surface of the high resistance region 2b side, the transistor TI
There is a first conductivity type region PH5'' which is separate from the P layer 5' which is a first conductivity type region for the first conductivity type, and is formed here.

It goes without saying that PJWs 5' and 5'' can be formed simultaneously even if they are separated.

On the surface of this PI'ii5', second conductivity type regions n''J'1ill', 12' are formed at a distance.The surface of the semiconductor substrate 2 on which each of the above regions is formed Above, the n0 layers 11', 1 are formed through an insulating film 13.
An electrode 14 made of PolySi or the like is formed so as to straddle the space between the electrodes 2'.

Then, this electrode 14 is insulated
', 12' are the drain D or source S (in the figure, the n' layer 12' is the source S, and the n''' layer 11' is the drain D), and the two layers 5 sandwiched between these n+ layers 11' and 12' are “
The transistor T2 is configured with the surface of the transistor T2 serving as a channel formation region.

In the second embodiment as well, the threshold voltage of the transistor T2 is set lower than that of the transistor Tl.

The other photoelectric conversion element array DA1 and the first and second resistive elements R1 and R2 are laminated on the semiconductor substrate 2 with an insulating film 20 in between, and each element is made of a conductive thin film made of Ni-Cr or AI. Alternatively, they are connected by a transparent conductive film made of Ingot or the like, and have the same configuration as the first embodiment.

Here, as in the second embodiment (by separating the first conductive region in which the transistor T1 serving as a switching element is formed and the first conductivity type region in which a transistor T2 for a control circuit is formed), noise can be reduced. In other words, when a high voltage is applied to the second conductivity type semiconductor substrate 2, which becomes the drain of the transistor T1, due to noise or the like, the gate electrode 8 of the transistor T1 is The potential increases and acts in the direction of making the transistor T1 conductive.However, the first conductivity type region 5# where the transistor T2 is formed is also separated from the first conductivity type region 5' where the transistor T1 is formed. Therefore, as the potential of the semiconductor substrate 2 rises, the potential increases and acts in the direction of making the transistor T2 conductive, thereby preventing the potential of the gate electrode 8 of the transistor T1 from rising. In this way, malfunction of the transistor TI due to factors other than optical input is prevented. The equivalent circuit of the switching device S2 of the second embodiment is the transistor T of FIG.
The second channel forming region (portion indicated by the dotted line) is not connected to the source. In this case, the channel forming region of the transistor T2 may be connected to the source of the transistor T1 via a high resistance in order to stabilize the DC potential.

Next, a third embodiment will be explained.

FIG. 4 shows a third embodiment of the switching device of the present invention, and FIG. 5 shows an equivalent circuit of this switching device. In the switching device S3 of the third embodiment,
The first resistive element R3 and the second resistive element R4 are also connected to the transistor T1. A major feature of this invention is that it is formed in the semiconductor substrate 2 on which T2 is formed, and a multilayer photoelectric conversion element, which is filed on the same date, is laminated on this semiconductor substrate 2 as a light receiving element.

First, transistors TI and T2 have the same configuration as the example shown in FIG. Also here, the threshold voltage of the control circuit DRZ transistor T2 is set lower than that of the transistor T1.

On the other hand, the first resistive element R3 has a structure of a depletion field effect transistor, with its gate and source connected (short-circuited). To explain in detail, as follows, two layers 50, which are first conductivity type regions, are formed on the surface of the semiconductor substrate 2, and further, two layers 50 are formed on the surface of the semiconductor substrate 2.
n0 layers 51a and 5 which are second conductivity type regions are formed on the surface of the
1b are formed apart from each other. Then, in order to make it a depletion (normally on) type, the n
A thin layer 52 is formed so as to straddle the layers 51a and 51b. As described above, the semiconductor substrate 2 in which each region is formed
The n layer 51a,
An electrode 54 made of PolySi or the like is formed so as to straddle the space between the electrodes 51b. Then, this electrode 54 is connected to the insulated gate G1, the n0 layer 51a is connected to the drain D1, the n3
The layer 51b is used as a source S, and the gate and source are connected by a conductive layer 55 such as A1 as shown in the figure, forming a high resistance first resistive element R3 shown in FIG.

Further, the second resistive element R4 has a structure of a field effect transistor, with its gate and drain connected (short-circuited). A detailed explanation is as follows. The second layer 60, which is the first conductivity type region, is the semiconductor substrate 2.
Further, a second layer 60 is formed on the surface of the second layer 60.
The n+ layers 61a, 5 are formed on the surface of the semiconductor substrate 2, in which zero or more regions are formed with the n+ layers 61a, 61b, which are conductivity type regions, through an insulating film 63.
An electrode 64 made of PolySt or the like is formed so as to straddle between the electrodes 1b. Then, this electrode 64 is an insulated gate, the n+ layer 61a is a drain, and the n'' layer 6
1b serves as a source, and the drain and gate are connected by a conductive layer 65 such as A1 as shown in the figure, forming a nonlinear resistive element R4 having rectifying characteristics as shown in FIG. This resistive element R4 is equivalent to a diode.

In the third embodiment, as is clear from the figure, the first, second and
The resistive elements R3, R4 of transistors T2. TI and a part of it (2 layers, n layer, PolyS through an insulating film)
Since the electrodes (electrodes such as t) have the same structure, each of the above elements can be formed simultaneously in the same semiconductor substrate.

Next, the photoelectric conversion element DA2, which is a light receiving element, will be explained. The element DA2 consists of a photoelectric conversion section 70, a back electrode 71, and a front electrode 72, which are laminated in order in the thickness direction.
It is formed on the semiconductor substrate 2 with an insulating film 20' interposed therebetween. The back electrode 71 is partially connected to the gate of the transistor T1 and is made of a conductive M film made of Ni-Cr or the like.
The surface electrode 72 is, of course, a transparent conductive thin film made of l11m0* or the like. The photoelectric conversion unit 70 consists of three photoelectric conversion layers 73, 74, and 75 stacked in order in the thickness direction, and each of these photoelectric conversion layers is a first conductivity type (for example, P type) semiconductor layer made of amorphous silicon or the like. , a semiconductor layer (one layer) with a relatively low concentration of valence electron control impurities, a second conductivity type (
For example, n-type) semiconductor layers are stacked in this order.

Each element is formed by a conductive thin film made of Ni-Cr or A1 or a transparent conductive film made of In*Os.
The photoelectric conversion element DA2 is connected as shown in Figure 5.
and the semiconductor substrate 2 are connected to each other through the insulating film 2 as shown in the figure.
The connection is made by removing a part of 0' by etching or the like.

In the third embodiment, the light receiving element is a single photoelectric conversion element DA.
However, the light receiving element may be an array including a plurality of photoelectric conversion elements DA2, or may be a photoelectric conversion element array DAI shown in FIG. Further, either the first or second resistive element may be formed of a semiconductor thin film as in the conventional example shown in FIG.

However, in this embodiment, as shown in the figure, only the light receiving part can be formed of a semiconductor thin film, so a photoelectric conversion element with a large degree of freedom and high efficiency can be obtained. The two layers 50 and 60 in which the functional elements R3 and R4 are formed are not directly connected to the two layers of the transistor TI. Therefore, for example, if a high voltage is generated in the second conductivity type semiconductor substrate 2, which becomes the drain of the transistor T1, due to noise or the like, the potential of the second layer 50, 60 increases accordingly, and the transistor T2 becomes conductive. The double-layer 50.6
0 can be connected to the source of the switching element with a high resistance, as shown in the equivalent circuit of FIG. 5, in order to stabilize the DC potential.

Further, the light-receiving element is made up of a plurality of photoelectric conversion layers laminated, and each photoelectric conversion layer has an absorption coefficient of the semiconductor thin film for incident light of wavelength λ as α(λ), and a carrier collection length of the semiconductor thin film as L. When photoelectrically converting light having a wavelength such that L≦1/α(λ), the photoelectric conversion efficiency is particularly good if the thickness d≦ of each photoelectric conversion layer is satisfied.

Next, a fourth embodiment will be explained.

FIG. 6 shows a fourth embodiment of the switching device of the present invention, and FIG. 7 shows an equivalent circuit of this switching device.

In the first to third embodiments, normally off (enhancement) type transistors were used for the control circuit transistors, but in the switching device S4 of the fourth embodiment, normally on type transistors were used for the transistors. something is being used.

As shown in FIG. 6.7, the fourth embodiment includes a switching element transistor T1 and a photoelectric conversion element array DAI having the same configuration as the second embodiment, and also includes a transistor T2' and a photoelectric conversion element array DAI. , a control circuit DR3 including this transistor T2' and a second photoelectric conversion element array DA3.

As shown in FIG. 6, the transistor T2' is formed by forming another conductive layer on the surface of the second conductive type semiconductor substrate 2 on the high resistance region 2b side, which is separated from the first conductive type region 5' where the transistor T1 is formed. It is formed in two layers 5# which are one conductivity type regions.

On the surface of this two layer 5# is an n layer 8 which is a second conductivity type region.
1.82 are formed spaced apart. Furthermore, an insulating H ¥! 83
so as to straddle between the n' layers 81 and 82 via
An electrode 84 made of PolySi or the like is formed.

A depletion (normally on) type transistor T2' is constructed by using this electrode 84 as a gate G, the n'' layer 82 as a source, the n'' layer 81 as a drain, and the thin single layer 88 as a channel.

Further, first and second photoelectric conversion element arrays DAI and DA31 are stacked on the semiconductor substrate 2 on which the transistors Tl and T2' are formed, with an insulating film 20 in between.

Here, the first and second photoelectric variable element arrays DAI,
DA3 has the same configuration as the photoelectric conversion element array shown in FIG. 1.3. In addition, each element is made of Ni-Cr or A
The connection shown in FIGS. 6 and 7 is made by a conductive thin film such as No. 1 or a transparent conductive film such as Into O.

In this way, the present invention can provide a switching device with a large degree of freedom in design without being restricted by the types of transistors that constitute the control circuit.

This invention is not limited to the above embodiments. For example, the switching element may be a bipolar transistor or a thyristor-equalized semiconductor element.

〔Effect of the invention〕

As described above, in the switching device according to the first to ninth aspects, each element can be easily optimized, and furthermore, it is easy to manufacture.

In the switching device according to the third aspect, the photoelectric conversion efficiency in the light receiving element can be made sufficient.

In the switching device according to the fourth aspect, it is easy to integrate the switching device.

In the switching device according to the fifth aspect, malfunction of the switching element can be suppressed.

In the switching device according to the ninth aspect of the invention, the switching element can be shut off at high speed.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a first embodiment of the switching device of the present invention, FIG. 2 is an equivalent circuit diagram of this switching device, and FIG. 3 is a second embodiment of the switching device of the present invention. 4 is a schematic sectional view showing a third embodiment of the switching device of the present invention, FIG. 5 is an equivalent circuit diagram of this switching device, and FIG. 6 is a schematic sectional view showing the third embodiment of the switching device of the present invention. 7 is an equivalent circuit diagram of this switching device, FIG. 8 is a schematic sectional view of a conventional switching device, and FIG. 9 is a schematic sectional view of a fourth embodiment of the switching device. FIG. 3 is an equivalent circuit diagram of the device. 2... Second conductivity type semiconductor substrate 5.5'5"...
First conductivity type region 81-s4... Switching device DAl, DA2... Light receiving element T1... Switching element DRI-DR3... Control circuit R1,
R3...first resistive element R2, R4...second
Resistive element agent Patent attorney Takehiko Matsumoto PI DR2 Figure 7 R3 Figure 9 Yuge Koho Seisho (subject to voluntary amendment April 20, 1999 Description of contents of amendment to the specification No. 1 2) In the 7th line of the page, "Each photoelectric conversion layer" 1999 Patent Application No. 044122 is corrected to "Each photoelectric conversion layer." Name of the invention Switching device 1-3-1 Kasumigaseki Kogyo, Chiyoda-ku, Tokyo 3 Directors of the Technical Agency (1 idiot) 4. Sub-agents (as per the appendix subject to I-Kirita amendment)

Claims (1)

[Scope of Claims] 1. A switching device including a light-receiving element that receives light and generates power, a switching element that is driven by the power generated by the light-receiving element, and a control circuit, wherein the switching element includes a second The element has a first conductivity type region formed on a surface portion of a conductivity type semiconductor substrate as a constituent part, and at least one of the elements constituting the control circuit has the first conductivity type region or the second conductivity type region. 1. A switching device characterized in that the switching device is formed in a first conductivity type region separately provided on a surface of a type semiconductor substrate. 2. The switching device according to claim 1, wherein the light receiving element generates power by a photoelectric conversion layer formed of a semiconductor thin film. 3. The light-receiving element is composed of a plurality of photoelectric conversion layers laminated, and each photoelectric conversion layer has an absorption coefficient of the semiconductor thin film for incident light of wavelength λ as α(λ), and a carrier collection length of the semiconductor thin film as L: 3. The switching device according to claim 2, wherein light having a wavelength satisfying L≦1/α(λ) is photoelectrically converted. 4. The switching device according to any one of claims 1 to 3, wherein the light receiving element is laminated on a semiconductor substrate on which switching elements and control circuit elements are formed. 5. The switching element is a field effect transistor whose drain region is a second conductivity type region of the second conductivity type semiconductor substrate, and at least the first conductivity type region in which the control circuit element is formed is a field effect transistor. , the switching device according to any one of claims 1 to 4, wherein the first conductivity type region for the switching element is separated from the first conductivity type region. 6. The control circuit includes a transistor having a control electrode and a pair of output terminals, a first resistive element connected between the control electrode and one output terminal of the transistor, and a first resistive element connected between the control electrode and the other output terminal of the transistor. a second resistive element connected between terminals of the transistor;
At least one of the first or second resistive elements is formed in a first conductivity type region on the surface of the semiconductor substrate, and
2. A resistive element is connected in parallel to a light receiving element, and one output terminal of said transistor is connected to a gate of a field effect transistor which is a switching element.
6. The switching device according to claim 5. 7 The first resistive element has the structure of a depletion type field effect transistor, and its gate and source are connected, the source side is connected to the control electrode of the control circuit transistor, and the drain side is connected to the control electrode of the control circuit transistor. 7. The switching device according to claim 6, wherein the switching device is connected to a gate of a field effect transistor for a switching element. 8 The second resistive element has the structure of a field effect transistor, and its gate and drain are connected, the source side is connected to the control electrode of the transistor for the control circuit, and the drain side is connected to the control electrode of the transistor for the switching element. 8. The switching device according to claim 6, wherein the switching device is connected to a source of a field effect transistor. 9. The transistor of the control circuit is a field effect transistor, and the threshold voltage of the field effect transistor is lower than the threshold voltage of the field effect transistor serving as the switching element. The switching device according to any one of.