JPS62188272A - Semiconductor device including static induction thyristor - Google Patents

Abstract

PURPOSE:To enable the conduction and interruption to be controlled by means of light by making the light irradiation complementary to each other. CONSTITUTION:The figure furnishes an example of photosensitive elements D1, D2 connected to a gate or Si thyristor Q in series and in parallel therewith subject to the complementary light irradiation, i.e., when the element D1 is irradiated with light D2 is not irradiated, and vice versa. When D1 is in a conducting state, D2 is in an interrupted state. When D1 is in a conducting state, the Si thyristor Q is interrupted, and when D2 is in a conducting state, the Si thyristor Q is in a conducting state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device using a static induction thyristor whose gate includes an optically controlled element.

Conventional thyristors, which basically have a p n p n p layer structure, have the drawback that it is difficult to switch off using the gate electrode, and even if it is possible to switch off the switch off using the gate electrode, the speed is extremely slow. It had On the other hand, the electrostatic induction iristor (hereinafter referred to as 81 thyristor), which has a diode structure in which the gate is shifted to the right, has the advantage of being extremely easy to shut off using the gate, and that the shutoff time is quick. ing. A cross-sectional view of a typical example of a Sl thyristor is not shown in FIG.

FIGS. 1<a> to 1(d) are cross-sectional views of structural examples of Sl thyristors in the circuit configuration of the present invention, which will be described later.

FIGS. 1(a) and 1(b) are cross-sectional views of typical examples of surface gate structures of Sl thyristors. FIG. 1(C) is an example of the buried goo 1 structure, and FIG. 1(d) is an example of the insulated gate type S.
This is an example of the cross-sectional structure of an L thyristor.

FIG. 1 (a), (b), (C) p regions 11 and 1
4 is the anode area, gate area, n+ order battlefield 13
The cathode region, i-region 2 which seems to be an n-region, constitutes a channel. Typically the semiconductor material is silicon. n
++ region 13 is a cathode region. 11', 13'. 1
4' is an anode electrode made of Al, MO, W, All 'J or other fully bent or low resistance polysilicon or a multilayer structure thereof, and a sawode T.
The i-pole is the gate electrode. 15 is SjO□, S b
3N4, A120a1AJLN, etc., or a composite insulating layer or multilayer insulating layer thereof. The n region 16 has a relatively high impurity density, is formed in a thin layer, and is a layer for suppressing hole injection from the anode.

In FIG. 1(d), the n-middle region 21 is an anode region, the i-region 22 is a region constituting a channel, and the n-middle region 2
3 is a cathode region, and n region 1 or 27 is a region for suppressing hole injection from the anode. The pvA region 28 has a structure in which it reaches the surface at a predetermined point in the vertical direction in the figure, and is usually directly connected to the cathode region by an electrode. 25 is the above-mentioned insulating layer. 21', 23.
24 is the anode electrode, cathode electrode, and insulated gate electrode described above. The operation of the SI Zyristor, the dimensions of each region, and the impurity density are described in detail in the specification of ``Electrostatic 10 Iristor j'' published by the present inventors in Japanese Patent Application Laid-Open No. 55-99774.

The Sl Zyristor has the feature that it can easily cut off direct current and can do so at a high speed because it controls conduction and cutoff by controlling the potential distribution in the vicinity of the cathode with a gate voltage. The structure shown in Fig. 1(a'') can produce a voltage with approximately the same forward blocking voltage and reverse breakdown voltage, but the structures shown in Fig. 1(b), (C), and (d) have a Compared to the structure shown in Figure (a), the same forward blocking voltage can be achieved with an element that is approximately half the thickness, the operating speed is faster, and the forward voltage drop is smaller.
This has the disadvantage that the reverse breakdown voltage is low. Therefore, when using the 81 thyristors shown in FIGS. 1(b), 1(c), and 1(d) where reverse breakdown voltage is required, a Schottky diode or the like is connected in series.

Figure 2 (a) and (11) show junction type and insulated gate type S.
■Shows the thyristor symbol mark.

A diode is formed on the drain side of an electrostatic dielectric II transistor (hereinafter referred to as SIT).

FIG. 3 shows a typical example of a conventionally well-known photosensitive semiconductor device. FIGS. 3(a) to 3(1) show structural examples of a photosensitive element integrated or connected to the gate of an Sr zyristor in a circuit configuration of the present invention to be described later.

(a) is a photoconductive element. An i region 32, which can almost be regarded as an insulator, is provided above the n medium region 31. 31' and 32' are A-mic electrodes, and in this example, 32' is a transparent electrode of rn 20° and SnO2 or the like. When 32' is difficult to become an ohmic electrode, a <i9<, n'' region may be provided on the surface of the i region 32 and then the transparent electrode 32 is provided.
When electron-hole pairs are generated in the region 32, current begins to flow. In this figure (a), the electrode 32' is a shotgun? ! When it is bipolar, if a voltage is applied so that the potential on the Schottky electrode side is lower than that on 31', it also operates as a Schottky diode that is sensitive to light.

L represents incident light. The figure (b) shows a phototransistor. The n-middle region 44, the n-region 43, the n''" region 42, and the n-region 41 are an emitter region, a base region, a high-resistance layer, and a collector region, respectively. 41' is a collector electrode, and 44' is an emitter transparent electrode. n medium area 4
4. The n-region 43 is made thin like a normal bipolar transistor. Most of the light is absorbed in the n-region 42. When a positive voltage is applied to 41', photoexcited electrons flow into the n+ collector region and are absorbed, and holes flow into the p base region, which is a floating fri region, and are accumulated.

When holes are accumulated in excess, the potential barrier to electrons in the base region decreases, allowing electrons to flow from the emitter region into the base region and into the rector region. (C
) The figure shows a thyristor that is excited by light. n middle area 55
, n middle region 51 is one cathode region and one anode region. 55' is a transparent electrode, and 51' is an anode electrode. When light is irradiated with a positive voltage being applied to 51', electrons and holes that are photoexcited in the i-da 1 region enter the n region 52 and the Dfrt region 54, respectively. The barrier potential decreases, and electrons from the cathode region 1,
A ball is injected from the anode ml and conduction occurs. (C) The optical thyristor shown in the figure has carrier injection amplification mechanisms on both sides. Most sensitive to light. (d) The figure is an example of a pIn photodiode. 63' is a transparent electrode, and 61' is an electrode. 6
1' is applied to the positive voltage. (a), (b), (C),
In either case (d), most of the irradiated light is i
region or n-region to generate electron and hole pairs.

Therefore, if the electric field strength in this region is set to a level slightly lower than the avalanche electric field, more carriers will be generated by the avalanche multiplication mechanism, and the sensitivity will be further improved. Since Figure 3 shows a very representative and simple example, it goes without saying that Haku has many variations.

Of course, it is a photosensitive semiconductor device that exhibits the photovoltaic effect.

So far, the Sl thyristor and the photosensitive semiconductor device have been described. The Sl→Neuristor is extremely distinctive in that it can increase both operating voltage and current and perform high-speed switching. However, when considering high power applications such as DC power transmission, it is almost difficult to handle all of this high power with one Sl thyristor. Therefore, for example, if the forward blocking voltage is 5,000 volts or 10,000 volts, the conducting current is 100 volts.
0A 7. A series-parallel connection of Sl thyristors is required, such as connecting a plurality of Sl thyristors in series to increase the withstand voltage, and further connecting them in parallel to generate current. At times like this, S
[It is easier to control the conduction and cut-off of a thyristor using light than to control it using electrical signals. On the other hand, regarding Sr thyristors that are controlled by light, the inventors of the present application have already received J.
"Electrostatic induction type optical thyristor" application specification m. However, the invention described in the above-mentioned Japanese Patent Publication No. 61-1908,
The method for optical control is related to a turn-off operation, that is, an optical trigger operation, and the turn-off operation is based on an electrical turn-off in a gate circuit. In the same case, conduction is performed using light, but electrical gate turn-off is used for interruption.

An object of the present invention is to provide an electrostatic induction thyristor whose conduction and interruption can be controlled by light and a device including the electrostatic induction thyristor.

The present invention will be described in detail below with reference to the drawings.

FIG. 4 is a circuit example of an Sl thyristor whose operation is controlled by light according to the present invention, in which the aforementioned photosensitive semiconductor element is connected to the gate of the Sl thyristor. In FIG. 4, Q is an Sl thyristor, and D, DI, and D2 are photosensitive semiconductor elements. ■) is a bias power supply. There are various types of S Renairista, so depending on them, V7
You can choose the value of . For example, if a forward voltage of 5000 pol 1- can be blocked by applying a reverse gate bias of -30 volts to the gate, then {circle around (2)} may be selected to a value of about -30 volts.

FIG. 4(a) shows an example in which a photosensitive element is connected in series and in parallel to the gate of an Sl thyristor. Light irradiation has a complementary relationship. That is, when Dl is irradiated with light, D2 is not irradiated with light, and when D2 is irradiated with light, D is not irradiated with light aD.
When l is in a conductive state, D2 is in an 'ijA'lfi state. When Dl is conducting, the Sl thyristor is cut off. When uD2 is conducting, the Sl thyristor is conducting.

FIG. 4(b) shows a case where the power source V)l is connected in series to D2 in the example shown in FIG. 4(a). This is used when making the conduction state of the 81 thyristor more complete, or when using the Mo5sr thyristor. In the case of a junction type Sl thyristor, the value of t' is approximately 1 at most. Mo5s
In the case of the r thyristor, the sl thyristor, which can be as high as 1vb, has a lower reverse breakdown voltage, as in the examples shown in Fig. 1 (b), (c), and (d), and the If reverse withstand voltage is required, please refer to Figure 4 (C
, ), a Schottky diode or the like may be connected in series with the 81 thyristor.

For example, when configuring an AC/DC converter for direct current transmission of 1 million volts using 81 thyristors with a maximum forward blocking voltage of 5000 volts, at least 200 Sl
Thyristors must be connected in series. In such a case, as shown in FIG. 5, it is sufficient to connect the required number of Sl thyristors in series. Since the gates are controlled by light, even if many gates are connected in series,
It is easy to operate all Sl thyristors simultaneously and synchronously.

The light may be irradiated by guiding the light using an optical fiber or the like so that the light is uniformly irradiated to a predetermined location on the photosensitive element. In any case, since the operation is not very fast, a clad fiber is sufficient. In addition, the cladding Jl tends to make the light intensity within the fiber cross section more uniform. Of course, depending on the application, it is also effective to use a focusing fiber.

FIG. 5(b) shows an example in which a resistor Rn is connected in parallel to 81 thyristors connected in series.

This is because resistors of equal value are connected in parallel so that the voltage applied to each Sl thyristor becomes uniform when the Sl thyristor is in the cut-off state. The higher the resistance value, the better, as long as it can be considered to be smaller than the resistance value of the S I 4j iristor in the cut-off state. For example, ha is selected such that 1=1MΩ. Of course, depending on the application, it may be larger or smaller than this.

Although the example of FIG. 5 shows an example of series connection in the example of FIG. 4(a), it goes without saying that the example of FIG. 4(b) may also be used.

Furthermore, when handling a large current, it is sufficient to connect the required number of devices configured as shown in FIG. 5 in parallel. Although FIGS. 4 and 5 show junction type Sl thyristors, Mo5s I thyristors may also be used.

So far, an example has been described in which a light-controlled Sr thyristor circuit is constructed by connecting a photosensitive semiconductor element to the gate of the Sl thyristor. It goes without saying that the Sl thyristor itself can be made into an element controlled by light, and in that case, in the operations shown in FIGS. 4 and 5,
Naturally, when the thyristor is brought into a conductive state, a means for introducing light into the thyristor is provided, and the operation of direct light irradiation is included.
If the structure shown in ) and (d) is constructed with transparent electrodes on either side so that light reaches the high resistance region, it will immediately become a light-controlled 81 thyristor.

The side to which light is irradiated may be the cathode side or the anode side. It is sufficient to use a transparent electrode on either side. If the semiconductor @ ratio is S=, the depth of incidence of the given light is 20~
30 μm 1 f 1 degree. Therefore, in the structure shown in FIG. 1, when light is irradiated from the anode side, the p+ region 11
or the sum of the thicknesses of p+ region 11 and n region 16 (p+ region 21 and n region 27) is desirably as thin as possible, and must be at least sufficiently thinner than the incident depth of light. For example, the p-region thickness is about 1μI11 or less, the impurity density is about 1xlQ''cm-' or more, n
The thickness of the region 16 is about 1 μm or less, the impurity density is lX10c
Select something like 100 m or more. The depth of the gate region is usually several μm, although it depends on the gate interval and the impurity density in that region. Therefore, if the electrodes are made transparent, they can be controlled using light. I
When the resistance is high with only transparent electrodes such as n2O and 1111Sno2, metal electrodes such as AL may be arranged at key points. This will be explained using the example shown in FIG. 1(b). Electron-hole pairs are generated in the 1fi4 region 12 by light irradiation. If a positive voltage is applied to the anode, the generated electrons flow into the n-region 16 and charge the n-region 16 negatively. When the amount of charge increases to a certain extent, hole injection begins to occur from the anode region. Holes generated by light and balls injected from the anode flow toward the cathode. A portion flows into the p+gegu region and a portion flows into the cathode region. At this time, the barrier to electrons that had formed on the entire surface of the cathode is lowered. Electron injection begins to occur from the cathode, resulting in a conductive state. In order to further reduce the forward voltage drop during conduction, it is necessary to The magnitude of the insertion resistor RgL is approximately equal to the reverse bias applied to the gate by R)u[z, assuming that the current flowing through the gate is 1. This gate-source resistance can be easily made using polysilicon.

1(a>, (c), and (d) may be similarly designed. In FIG. 1(C), a resistor is inserted between the p region 2h and the cathode region.

FIGS. 6 to 8 are similar to FIGS. 1<a) to (d),
An example of the structure of the S[thyristor] according to the present invention is shown.

Compared to the structure shown in FIG. 1, FIG. 6 shows a structure in which the current flowing through the gou I~ is reduced and the main current is increased. It has a Wr structure in which an insulating layer 17 such as 5j02 is provided on the lower surface of the p+ region 14. The structure is such that a polysilicon resistor is inserted between the gate and source. A polysilicon resistor is provided at a predetermined location in the vertical direction in the figure. The equivalent circuit is as shown in FIG. 6(b), and the gate-source resistance Rt#λ may be connected externally.

FIG. 7 shows an example in which the potential V5 wall on the cathode side is also eliminated by accumulation of carriers, instead of connecting a resistor between the gate and source. For example, a negative voltage is applied to the gate electrode 14, but this voltage is completely masked by the holes flowing into the vicinity of the gate, the potential barrier on the other side of the cathode disappears, and electron injection from the cathode occurs intensely.

The structure of the hole injection hole from the anode is the same as in the previous examples.

In FIGS. 6 and 7, the electrodes 13' and 14' are made of low resistance polysilicon, In, O. , Sn'02, or other transparent electrodes. This is done to allow heat sinking from the anode side. If you don't need to worry too much about the heat sink, you can use a transparent anode electrode and shift the light source from the anode side. Of course, it goes without saying that light may be irradiated from both sides.

Although FIGS. 6 and 7 show a structure in which a gate is provided only on the cathode side, a gate structure may also be provided on the anode side. If the electrons accumulated in the 1'1 region 16 remain as they are, they will have to go through annihilation due to recombination or the like. If the anode side is also introduced with the Goo 1~ structure, this problem will disappear. An example is shown in FIG. Also on the anode side, an n+ region 18 is provided adjacent to the p+ anode region 11. An insulating region 19 is provided. Similar to the cathode side, the anode area 11 and n+ area 18 are also on the anode side.
If a reverse bias is applied to the question, region 12 is not n- but has a very high resistance! It may be in the fr4 range. In the structure shown in FIG. 8, a polysilicon resistor may be built between p+ region 11 and n+ region 18. The impurity density and thickness of regions 12 and 16 are disclosed in JP-A-55-99774@rShi7!
2-induction thyristor” application specification and Japanese Patent Application Laid-open No. 55-1087
68@r Electrostatic Inductive 8g+t Iristor" may be selected as described in the application specification. The gist of the present invention is to integrate or connect a photosensitive element to the gate of an Sl thyristor so that it can be quenched (turned off by light) with light, and when the thyristor is on, the carriers accumulated at the gate of the thyristor are transferred to the thyristor. The thyristor is turned off by irradiating the photosensitive element connected to the gate with light, making it conductive, and discharging it. That is, Example FIG. 4 (
The circuit configurations shown in a) to (C) and FIGS. 5(a) and (b) are the main parts of the present invention. In the end, in the present invention, the important part is that the gate is turned on by light, and moreover, the gate is turned off by light.
That's why there is.

The configuration of the light-controlled SI thyristor of the present invention is
Of course, /u is not limited to the example described here.

Not shown in FIGS. 4 and 5, a light control S
Of course, it is better to use l thyristors.

Well, it goes without saying that 6 would be better if the conductivity type was completely reversed. All you have to do is reverse the polarity of the voltage. In the case of a junction type, it is preferable to sandwich an insulating layer such as SA02 between the cathode and gate because this reduces the capacitance and increases the withstand voltage at the same time. It is also effective to provide a gate in the cut region even in the case of a junction gate type. Even in a structure in which the gate is provided on the anode side, it is often effective to sandwich an insulating layer. In the case of a junction gate, a Schottky gate may be used instead of a pn junction.

The light source for controlling the S■ thyristor may be any light source that can generate electron-hole pairs in a semiconductor and can switch at high speed. It may be a semiconductor laser or a light emitting diode. For example, a GaAlAs-based heterojunction laser or a light emitting diode may be used. Of course, a semiconductor laser or a light emitting diode made of other materials may also be used.

Of course, other lasers may also be used. In short, any light source with a required intensity of 1q and capable of high-speed modulation is sufficient. Depending on the type of laser, a solid state or gas laser may be used. These lights may be directly irradiated, or may be guided to a predetermined location using a fiber.

The optically controlled thyristor 81 of the present invention can be easily manufactured using conventionally known lithography technology, diffusion/ion implantation technology, crystal technology, shrimp growth technology, etching technology, oxidation technology, CVD technology, wiring technology, etc.

The semiconductor device of the present invention, which allows the S1 thyristor to perform high-speed switching of large voltages and large currents, to be controlled by light, is extremely effective when connecting multiple S1 thyristors in series or parallel, or in series and parallel. This technology is of high industrial value.

[Brief explanation of drawings]

Figures 1 (a) to (d') are examples of disconnection iNi structures of electrostatic induction thyristors, Figures 2 (a) and (b) are symbol marks of i% induction thyristors, and Figure 3 is various types of light sources. In the control half-body element, (a) is a photoconductive element, (b) is a phototransistor, (C) is a photothyristor, (d) is a photodiode, and Fig. 4 (a) to (C) are the devices of the present invention. Circuit configuration, Figure 5 (
a) and (b) are examples of the present invention in which an Sr zyristor circuit including a photosensitive semiconductor element is connected in series to the gate, and FIGS. 6(a), 7, and 8 are examples of the present invention. A diagram showing an example of the structure of the electrostatic induction thyristor part in the circuit configuration, which is the main part, and FIG. 6(b) is an explanatory diagram of a circuit that reduces the voltage drop in the forward direction.し し Ｇ Ｇ Ｇ Ｚ z2 Cd) ム /Z (C) t7rtg ＜a ) (b) ＾ ＾ ＾ ＾ ＾ ｜ 7 7− ≠ and Zon Ja++ g (Cnmut, 12 I etc.) Cd) Zeng pu 醇; CO) Wei qIS1! M/2 (b) N6 diagram and 72 Ng diagram

Claims (13)

[Claims] (1) A gate circuit consisting of a first photosensitive semiconductor element D_1 and a reverse gate bias power supply connected in series with the first photosensitive semiconductor element D_1 is connected in parallel between the gate and cathode of the electrostatic induction thyristor, and the second photosensitive semiconductor element In the configuration in which the element D_2 is connected to the gate and cathode of the electrostatic induction thyristor, the first and second photosensitive semiconductor elements are provided with first and second means for irradiating light to the first and second photosensitive semiconductor elements, respectively; The light pulse L_1 is irradiated onto the photosensitive semiconductor element D_1, and D
When _1 is in a conductive state, the second photosensitive semiconductor element D_2 is not irradiated with light and D_2 is in a blocked state;
When D_2 is irradiated with a light pulse L_2 and D_2 is in a conductive state, no light is irradiated on D_1 and D_1 is in a blocked state, and the light irradiation is complementary to each other,
A semiconductor device including a static induction thyristor, wherein the static induction thyristor is cut off when the D_1 is in a conductive state, and the static induction thyristor is in a conductive state when the D_2 is in a conductive state. . (2) A semiconductor device including a static induction thyristor according to claim 1, characterized in that a forward bias power source Vg' is further connected in series to the second photosensitive semiconductor element D_2. (3) The electrostatic induction thyristor according to claim 1 or 2, characterized in that a Schottky diode or a pin diode having a predetermined reverse breakdown voltage is connected in series with the electrostatic induction thyristor. Semiconductor devices including. (4) A semiconductor device including an electrostatic induction thyristor, characterized in that a plurality of semiconductor devices including the electrostatic induction thyristor according to any one of items 1 to 3 are connected in series. (5) In order to equalize the voltage applied to each electrostatic induction thyristor when all of the plurality of electrostatic induction thyristors are in a cut-off state, resistors R_n of equal value are connected in parallel between the anode and cathode of each electrostatic induction thyristor. 5. A semiconductor device including a static induction thyristor according to claim 4, wherein the electrostatic induction thyristor is connected to a thyristor. (6) A semiconductor device including a capacitive induction thyristor, characterized in that a semiconductor device including a capacitive induction thyristor according to claim 5 is further connected in parallel. (7) Electrostatic induction according to any one of claims 1 to 6, wherein the light irradiation to the photosensitive element is guided by an optical fiber. Semiconductor devices including thyristors. (8) A semiconductor comprising the electrostatic induction thyristor according to any one of claims 1 to 7, characterized in that a photo-controlled electrostatic induction thyristor is used as the photosensitive semiconductor element. Device. (9) A semiconductor device including the electrostatic induction thyristor according to any one of claims 1 to 8, wherein the electrostatic induction thyristor has a surface-junction gate structure. (10) A semiconductor device including the electrostatic induction thyristor according to any one of claims 1 to 8, wherein the electrostatic induction thyristor has a buried gate structure. (11) A semiconductor device including the electrostatic induction thyristor according to any one of claims 1 to 8, wherein the electrostatic induction thyristor has an insulated gate structure. (12) Claim 1, wherein the electrostatic induction thyristor is a light-controlled electrostatic induction thyristor.
A semiconductor device comprising the electrostatic induction thyristor according to any one of Items 8 to 8. (13) The electrostatic induction thyristor is an optically controlled electrostatic induction thyristor, and includes means for irradiating light, and includes an operation of transitioning to a conductive state by directly introducing a light pulse. A semiconductor device comprising the electrostatic induction thyristor according to any one of claims 1 to 8.