JPH09223791A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC switch capable of preventing mistaken ignition and easy to manufacture. SOLUTION: This AC switch is constructed into a Darlington connection structure where an output terminal of a driving stage bidirectional thyristor 12 is directly connected with a gate terminal of an output stage bidirectional thyristor 14. The driving stage bidirectional thyristor 12 is adapted such that a first thyristor 12a where a first rsistor R1 is connected with an anode electrode and a cathode electrode and a second thyristor where a second resistor R2 is connected with the anode electrode or the cathode electrode are anti- parallely connected, and the first thyristor 12a, the second thyristor 12b, the first resistor R1, and the second resistor R2 are disposed symmetrically on the same chip and are integrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power photocoupler as an AC switch, and more particularly to prevention of false ignition of a drive stage triac of an AC switch in which a drive stage triac (TRIAC) and an output stage triac are Darlington connected. .

[0002]

2. Description of the Related Art Conventionally, it is known to use a TRIAC as an AC switch. A triac can be represented by an equivalent circuit in which two thyristors are connected in antiparallel. Normally, the triac has a gate turn-on function as a bidirectional three-terminal thyristor. A power photocoupler using this triac as shown in FIG. 8 is known. In FIG. 8, a drive stage triac 12 is a triac capable of light ignition (light turn-on), and is turned on by irradiating light from a light emitting element 11 such as a light emitting diode. The output terminal of the drive stage triac is directly connected to the gate terminal of the output stage power triac 14, and when the drive stage triac turns on, the power stage triac of the output stage also turns on, and high AC power can be controlled.

In the prior art shown in FIG. 8, a resistor R is provided between the output terminal of the drive stage triac and the input terminal of the power triac of the output stage in order to increase the potential drop of the drive stage triac and prevent malfunction. Inserting.

FIG. 9 shows the voltage-current (V _TM -I _TM ) characteristics of the drive stage triac and the power of the output stage with and without a resistor (with R) and without resistor (without R). triac of voltage - current (V _TM -
I _™ ) characteristics. In all current region and the resistor R is present, the power triac ON voltage V _TM of the output stage is smaller than the ON voltage V _TM of the drive stage triac. Therefore, with the configuration such as the equivalent circuit shown in FIG. 8, it is possible to prevent erroneous ignition of the drive stage triac.

The power photocoupler shown in the equivalent circuit of FIG. 8 is specifically (a) external wiring (metal wiring) of each individual element on a circuit board represented by SSR (Solid State Relay). 10, the method of connecting the power triac element 14, the resistance element 13 and the light emitting element 11 at the output stage to the coupler element composed of the drive stage triac element by the metal wiring (first method), (b) FIG.
Predetermined lead frames 401, 403, 4 as shown in
The light emitting element 11, the drive stage triac chip 221, and the output stage power triac chip 222 are mounted on the die pad of No. 05, respectively.
3, there is a method (second method) in which the bonding pads are connected to each other or the bonding pads and the lead frame are connected to each other in the bonding step using the Al wire 224 and sealed with a resin sealing body. The device according to the second method is generally called a power photocoupler or an optically coupled AC switch (or simply AC switch). As shown in FIG. 11, the light emitting element 11 and the drive stage triac chip 221 are molded using a translucent resin encapsulant 226 and a resin encapsulant 225 such as a silicone resin to form a coupler element. In this coupler element,
The light emitted from the light emitting element 11 is reflected at the interface between the translucent resin encapsulant 226 and the resin encapsulant 115, and is irradiated onto the drive stage triac chip 221, and the drive stage triac is turned on.

[0006]

In the product in which the individual elements represented by the SSR are combined as in the first method described above,
The step of incorporating the resistance element can be easily incorporated into the flow of a series of manufacturing steps such as the solder printing step, the element mounting step, the reflow step, and the washing step, and it is not necessary to add a new step. However, in the bare chip type semiconductor device (AC switch) in which the individual chips 11, 221, 222 are mounted on the lead frames 401, 403, 405 and wiring is performed in the bonding process like the second method, the resistance is In order to incorporate the element 13,
Further, the above-described SSR manufacturing process is required by using the resistance element 13 as an individual element. That is, it is necessary to connect and assemble the resistance element on the circuit board by an external wiring (metal wiring) or the like by the manufacturing process of the SSR. That is, in order to connect the resistance element 13 in the second method, it is necessary to add a new step, and there is a drawback that the product cost becomes high.

In view of the above problems, it is an object of the present invention to prevent erroneous operation of a drive stage triac in a device of the type in which bare chips are connected by bonding. More specifically, the object of the present invention is to generate a constant potential drop in the entire output current range from the holding current I _H of the drive stage triac to the maximum surge current I _TSM , thereby turning on the drive stage triac. Voltage V
It is an object of the present invention to provide a novel structure of a power photocoupler in which the _TM is increased and the malfunction of the drive stage triac is prevented.

[0008]

To achieve the above object, a semiconductor device according to the present invention has a first bidirectional three-terminal thyristor 12 used as a drive stage triac and an output, as shown in the equivalent circuit of FIG. An AC switch including at least a second bidirectional three-terminal thyristor 14 used as a power triac for a stage, wherein the first bidirectional three-terminal thyristor 12 directly connects a first resistor R1 to an anode electrode. The first lateral thyristor 12a and the second lateral thyristor 12b in which the second resistor R2 is directly connected to the anode electrode are connected in antiparallel, and the first resistor R1, the second resistor R2, and the first resistor R2 are connected. The first feature is that the lateral thyristor 12a and the second lateral thyristor 12b are integrated structures formed on the same chip. . The second bidirectional three-terminal thyristor 14 may be a vertical type or a lateral type. Further, in the first aspect of the present invention, this first bidirectional 3
One output terminal of the terminal thyristor 12 is the second bidirectional 3
The Darlington connection structure is connected to the gate terminal of the terminal thyristor 14.

In the above first feature, preferably, as shown in FIGS. 2 and 3, first and second resistors R1 and R2 are provided.
Is made of polysilicon, and this polysilicon resistance is the first
And the integrated structure formed on the second lateral thyristors 12a and 12b. More specifically, as shown in FIG. 3, it is formed on the oxide film 5 formed on the surface of the semiconductor substrate forming the n ⁻ base layer 1 of the first and second lateral thyristors 12a and 12b. is there.

Preferably, in the first feature, as shown in the plan view of FIG. 2, the first and second resistors R1 and R2 have a shape based on a rectangle having a long side and a short side, respectively. And the first and second resistors R1 and R2
Of the first lateral thyristor 12a and the anode of the second lateral thyristor 12a are disposed between the first and second resistors R1 and R2 so that their long sides are parallel to each other. The regions 22 are arranged together and the first and second ralthy thyristors 12a, 12
b has a structure that is symmetrical with respect to the plane pattern. That is, it has a symmetrical structure that is a mirror image of each other with respect to the straight line XX ′. Here, “based on a rectangle” means that the corners of the rectangle may have some roundness, or even a rectangle close to an ellipse. Further, it means that there may be some bent portions on the long side, which means a shape that is considered to be approximately rectangular.

Further, preferably, in the first feature, the first and second lateral thyristors 12a, 12 are provided.
Reference numeral b denotes a three-terminal thyristor capable of light firing (also referred to as light trigger or light turn-on). As shown in FIGS. 2 and 3, light irradiation windows 91 and 92 are provided in the cathode regions 41 and 42. Is to have on top of. More preferably, the first and second lateral thyristors 12
The lifetime τ ₁ of the minority carrier in the base regions 31 and 32 of a and 12b is the second bidirectional three-terminal thyristor 1.
4 is longer than the lifetime τ ₂ of the minority carrier in the base region 4. More specifically, the lifetime τ ₂ of the minority carriers in the base region of the second bidirectional three-terminal thyristor 14 is preferably about 4 μs to 10 μs,
Drive stage first and second lateral thyristors 12a,
Minority carrier lifetime τ in the base region of 12b
_{A value of 1} is preferably about 8 μs to 12 μs.

More preferably, the values of the first and second resistors R1 and R2 in the first characteristic are 50 to 100.
It is 0Ω.

With the configuration of the first characteristic, the desired potential drop is achieved by selecting the resistance values of the first and second resistors R1 and R2 for the first and second lateral thyristors 12a and 12b. Since it can be given, the false firing of the first bidirectional three-terminal thyristor 12 as the drive stage can be prevented. Further, by forming the resistors R1 and R2 of polysilicon, it is not necessary to consider the change in the resistance value due to light irradiation, and the degree of freedom in design is increased. Moreover, since the structure is easily integrated on the same chip, the manufacturing is easy, the manufacturing process is simplified, and the production cost is reduced.
In addition, the symmetric structure (mirror image relationship) as shown in FIG. 2 simplifies QC (characteristic check), makes the electric field distribution and the potential distribution uniform in the chip, and prevents current concentration. Although an equivalent circuit for light ignition is shown in FIG. 1, the technical idea of the present invention is to
The invention is not limited to the photocoupler, and it goes without saying that a predetermined current may be passed through the first bidirectional three-terminal for driving and the gate of the thyristor to electrically drive the thyristor.

The second characteristic of the present invention is, as shown in the equivalent circuit of FIG. 4, a first bidirectional 3-terminal thyristor 12 used as a drive stage and a second bidirectional 3-terminal thyristor used as an output stage. 14 and at least A
C switch, which is a first bidirectional 3-terminal thyristor 1
A second lateral thyristor 12a having a cathode electrode directly connected to a first resistor R1 and a second lateral thyristor 12b directly connected to a cathode electrode for a second resistor R2 are connected in antiparallel to each other. 1st resistance R1, 2nd resistance R2, 1st lateral thyristor 12a, and 2nd
The lateral thyristor 12b is an integrated structure formed on the same chip, and the first bidirectional 3-terminal thyristor 1
One output terminal of 2 is the second bidirectional three-terminal thyristor 1
4 is the Darlington connection structure connected to the gate terminal of No. 4.

In the above second feature, preferably, as shown in FIG. 5, the first and second resistors R1 and R2 are made of polysilicon, and the resistors R1 and R made of this polysilicon are used.
2 is the first and second lateral thyristors 12a, 12
That is, it is an integrated structure formed on the upper part of b.

Further, preferably, in the above-mentioned second feature, as shown in FIG. 5, first and second resistors R1 and R2 are provided.
Is a shape based on a rectangle having a long side and a short side, respectively, and is separated from each other so that the long sides of the first and second resistors R1 and R2 form "substantially the same straight line". It is arranged respectively. As is clear from FIG. 5, the center lines of the resistors R1 and R2 are slightly different from each other and are not exactly the same straight line, but in the sense of allowing such a difference, the term "substantially the same straight line" is used here. Is expressed. When this "substantially collinear line" is regarded as the center line, the anode region 21 and the cathode region 41 of the first lateral thyristor 12a are arranged on one side of the center line, and the anode region 21 and the cathode region 41 of the first lateral thyristor 12a are arranged on the other side of the center line. The anode region 22 and the cathode region 42 of the second lateral thyristor 12b are arranged, and the plane pattern has a symmetrical structure (rotationally symmetric structure) with respect to the point P at the center of the center line.

Further, preferably, in the above-mentioned second feature, the first and second lateral thyristors 12a, 12 are provided.
b is a three-terminal thyristor capable of light firing,
As shown in FIGS. 5 and 6, window portions 91, 9 for light irradiation are provided.
2 is provided above the cathode regions 41 and 42. More preferably, the minority carrier lifetime in the base regions 31, 32 of the first and second lateral thyristors 12a, 12b is less than the minority carrier lifetime in the base region of the second bidirectional three-terminal thyristor 14. It's a long time. More specifically, the second bidirectional 3
It is longer than the lifetime τ ₂ of the minority carrier in the lifetime of the minority carrier in the base region of the terminal thyristor 14. More specifically, the lifetime τ ₂ of minority carriers in the base region of the second bidirectional three-terminal thyristor 14 is appropriately 4 μs to 10 μs, and the first and second lateral thyristors 12a of the drive stage are suitable. , 12
Minority carrier lifetime τ in the base region of b
_{A value of 1} is preferably about 8 μs to 12 μs.

More preferably, in the second feature, the values of the first and second resistors R1 and R2 are 50 to 100.
It is 0Ω.

With the configuration of the above-mentioned second characteristic, a desired potential drop can be achieved by selecting the resistance values of the first and second resistors R1 and R2 for the first and second lateral thyristors 12a and 12b. Since it can be given, the false firing of the first bidirectional three-terminal thyristor 12 as the drive stage can be prevented. Further, by forming the resistors R1 and R2 of polysilicon, it is not necessary to consider the change in the resistance value at the time of light irradiation, and the degree of freedom in design is increased. Moreover, since the structure is easily integrated on the same chip, the manufacturing is easy, the manufacturing process is simplified, and the production cost is reduced.
Further, by adopting the point-symmetrical structure as shown in FIG. 5, characteristic inspection and the like can be simplified, and further, current concentration in the chip can be prevented. Note that FIG. 4 shows an equivalent circuit in the case where the first bidirectional three-terminal thyristor for driving is light-ignited, but this is an example, and it goes without saying that it may be electrically driven.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an equivalent circuit of a power photocoupler according to a first embodiment of the present invention. As shown in FIG. 1, in the power photocoupler of the first embodiment of the present invention, two lateral thyristors 12a, 12b capable of light ignition are connected in anti-parallel and bidirectional 3 of the driving stage.
A terminal thyristor (triac) 12 is configured, and the anode of each of the lateral thyristors 12a and 12b is
The resistors 13a and 13b are connected. The output terminal of the bidirectional thyristor of the driving stage is connected to the gate terminal of the bidirectional three-terminal thyristor 14 as the power triac of the output stage. Further, in the first embodiment of the present invention, as shown in FIG. 1, gallium arsenide (GaAs) for irradiating the bidirectional thyristor 12 of this drive stage with light and turning on the bidirectional thyristor 12 of this drive stage.
A light emitting element 11 such as a light emitting diode (LED) is provided.

FIG. 2 is a plan view of the bidirectional thyristor 12 in the driving stage of the power photocoupler according to the first embodiment of the present invention, and FIG. 3 is a sectional view taken along line AA of the plan view of FIG. Is. In FIG. 3, p of the first lateral thyristor 12a is formed on a part of the surface of the n ⁻ base layer 1 made of an n ⁻ substrate or the like.
⁺ Anode region 21, p base region 31, n ⁺ cathode region 41 and p ^{+ of} the second lateral thyristor 12b
An anode region 22, a p base region 32, and an n ⁺ cathode region 42 are formed. The resistors R1 and R2 are the first and second
Above the lateral thyristors 12a, 12b, that is, n
^- is formed on the oxide film 5 on the surface of the base layer 1. As apparent from FIGS. 2 and 3, the n ⁺ cathode region 41 is formed on the surface of the n ⁺ cathode region 41 by the wiring 61 made of a conductive material such as Al to be the n ⁺ cathode electrode 61.
Is connected to the terminal T1 and the wiring 61 is connected to a resistor R2 made of polysilicon doped with impurities (so-called doped polysilicon). Similarly, the wiring 62 made of a conductive material such as Al is connected to the n ⁺ cathode region 42 and the terminal T2.
And a doped polysilicon resistor R1 are connected to each other. The wirings 61 and 62 have windows 91 and 92 for light irradiation, respectively, and are configured so that light is irradiated to the n ⁺ cathode regions 41 and 42 and the p base regions 31 and 32 in a floating state. . p base region 31 and p ⁺ anode region 22, and p base region 32 and p ⁺
As shown in FIG. 2, the anode region 21 is a p-layer (R having an impurity density of 5 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁸ cm ^−3).
_GK region) 7 and are connected to each other. The R _GK region 7 is a resistor for adjusting the gate sensitivity, and for example, in a power photocoupler of a few A class, the resistor may be designed to be 40 to 60 kΩ. Further, the p ⁺ anode region 21 is connected to the resistor R1 by a wiring 64 of a conductive material such as Al,
The p ⁺ anode region 22 is connected to the resistor R2 by a wiring 63 made of a conductive material such as Al. n ⁺ cathode region 4
1, 42 and p ⁺ anode regions 21 and 22 are formed by contact holes formed at predetermined places in the oxide film 5 formed on the surface of the n ⁻ substrate 1 to form wirings 61, 62 and 6, respectively.
3 and 64 are connected. Although illustration is omitted, in the first embodiment of the present invention as well, as shown in FIG.
The terminal thyristor and the output stage bidirectional three-terminal thyristor are mounted and assembled through steps such as bonding. When the light emitting device 11 shown in the equivalent circuit of FIG. 1 is turned on, electron-hole pairs are generated in the p base regions 31 and 32 and the n ⁻ base layer thereunder, and holes are generated in the p base region 3.
1, pn junctions between the n ⁺ cathode region 41 and the p base region 31 and between the n ⁺ cathode region 42 and the p base region 32 are forward biased, and the lateral thyristors 12a and 12b are turned on. 2 and 3, when the terminal T1 is negative and the terminal T2 is positive,
A current flows from the terminal T2 through the resistor R1 in the order of the p ⁺ anode region 21, the n ⁻ base layer 1, the p base region 31, and the n ⁺ emitter region 41, and reaches the terminal T1. When the terminal T1 is positive and the terminal T2 is negative, the current flows from the terminal T1 through the resistor R2 to the p ⁺ anode region 22, n.
^- the base layer 1, p base region 32, n ⁺ cathode region 4
It flows in the order of 2 and reaches the terminal T2. The voltage drop of the bidirectional thyristor of the drive stage according to the first embodiment of the present invention is about 0.6 V value at the pn junction between the p ⁺ anode regions 21 and 22 and the n ⁻ base layer 1, the resistance R1, R
The predetermined voltage drop determined by 2 is the main component.

The thickness of the doped polysilicon resistors R1 and R2 may be about 350 to 500 nm, but in an actual design, for example, when the on current I _TM = 1 mA, the on voltage V _{TM is set.}
Approximately 300 to 400Ω resistances R1 and R2 for = 1V
The thickness and dimensions (width, length) of the doped polysilicon resistor may be selected so that However, by inserting R1 and R2, the bidirectional thyristors 12a,
12b The turn-on voltage V _GT may become too large and may not turn on at a low voltage. Therefore, it is advisable to design in consideration of the required value of the minimum turn-on voltage V _GT . For example, if the turn-on voltage V _GT is 6 V, the resistance R1
Turn-on voltage V _GT is 1 at R2 = 50-400Ω
When the voltage is 2V, the resistances R1 and R2 may be set to 50 to 1000Ω.

In the first embodiment of the present invention, since the resistors R1 and R2 are formed of the doped polysilicon wiring layer, the resistance values of the resistors 1 and R2 are hardly changed by the light irradiation. FIG. 7 shows a comparison between the case where the resistors R1 and R2 are formed of the diffusion layer and the case where the resistors R1 and R2 are formed of the doped polysilicon wiring layer. Here, the diffusion layer means a case where the resistors R1 and R2 are formed by a layer formed by ion implantation or thermal diffusion of p-type impurities such as boron (B) in the n ⁻ base layer. As is clear from FIG. 7, when the doped polysilicon resistance is, for example, 10 kΩ or 300 Ω, the resistance value does not change depending on whether light is irradiated or not, but in the case of resistance by the diffusion layer, it is about 50 kΩ when light is not irradiated. It can be seen that the resistance of 1 becomes about 25 kΩ, which is half the value when there is light irradiation. This is because electron-hole pairs are generated by light irradiation and the resistance value of the diffusion layer changes. In other words, when using diffusion layer resistance, the power
In the photocoupler, the bidirectional three-terminal thyristor in the drive stage must be designed in consideration of the change in the resistance value depending on the presence or absence of light irradiation, which causes a design difficulty. This problem does not occur in the case of the doped polysilicon resistor in the form of. Further, since the doped polysilicon resistor may be formed on an insulating film such as an oxide film, the degree of freedom in selecting the pattern arrangement is large and the degree of integration is improved. Further, it is not necessary to consider the effect of the parasitic transistor like the diffusion layer resistance.

In the first embodiment of the present invention, the minority carrier lifetime τ _{1 in} the base region of the bidirectional three-terminal thyristor 12 in the driving stage is the minority carrier in the base region of the bidirectional three-terminal thyristor 14 in the output stage. Lifetime τ ₂
It is preferably longer. For example, the lifetime τ ₂ of minority carriers in the base region of the bidirectional three-terminal thyristor in the output stage is appropriately about 4 μs to 10 μs, and the lifetime τ ₁ of minority carriers in the base region of the lateral thyristors 12a and 12b in the driving stage τ ₁ Is 8 μs to 12 μ
s is suitable.

To control the minority carrier lifetime in the base regions of the lateral thyristors 12a and 12b,
Electron beam irradiation, proton irradiation, Au, for the base region
A method such as injecting a heavy metal such as Pt or irradiating with He radiation may be used. For example, in the first embodiment of the present invention, when the lifetime is 7 μs, 2 × 10 ¹² electrons /
Irradiation with an electron beam of cm ² is sufficient. Life time is 8μ
The electron beam irradiation at s is 5 × 10 ¹¹ electrons / cm ² . Electron beam irradiation when the lifetime is 12 μs
It is 1.1 × 10 ¹¹ electrons / cm ² . Life time is 1
At 3 μs, it is not necessary to irradiate the base region of the n ⁻ silicon semiconductor substrate 1 with an electron beam. Therefore, the electron beam irradiation for controlling the lifetime τ ₁ of the present invention is 5 ×.
A value of 10 ¹¹ electrons / cm ² or less is suitable. In this way, the lifetime τ ₁ of minority carriers in the base region of the bidirectional three-terminal thyristor 12 in the driving stage is made longer than the lifetime τ ₂ of minority carriers in the base region of the bidirectional three-terminal thyristor 14 in the output stage. , Α _pnp of the lateral thyristors 12a and 12b of the drive stage while maintaining the high (dV / dt) c withstand capability of the bidirectional three-terminal thyristor of the output stage.
Can be increased, and high sensitivity of the gate of the lateral thyristor can be realized.

However, in the Darlington-connected power photocoupler, the bidirectional three-terminal thyristor 1 of the driving stage is used.
If the lifetime τ _{1 of} 2 is set too long, the forward voltage drop V _F of the bidirectional thyristor 12 in the driving stage gradually decreases, and a small amount of current still flows in the driving stage side, so that the entire power photocoupler. The (dV / dt) c withstand capability of is in the region determined by the (dV / dt) c withstand capability on the drive stage side. Therefore, the lifetime τ ₁ = 13
It is not preferable to make it longer than μs.

As shown in FIG. 2, the bidirectional three-terminal thyristor 12 of the drive stage according to the first embodiment of the present invention has a symmetrical structure which is a mirror image of each other with respect to the straight line XX '. At times, for example, resistors R1 and R2
Can be inspected based on the same value, and the inspection process can be simplified. Further, with such a symmetrical arrangement, the potential distribution and the electric field distribution in the chip are made uniform, current concentration does not occur, and the effect of preventing false firing becomes stronger.

The bidirectional three-terminal thyristor 12 of the drive stage according to the first embodiment of the present invention described above may be mounted on a lead frame or the like by a conventionally known method as in the case shown in FIG. That is, the light emitting element 11, the bidirectional 3-terminal thyristor 12 in the driving stage, and the bidirectional 3-terminal thyristor 14 in the output stage are mounted on a predetermined lead frame similar to that shown in FIG. By bonding and resin sealing, the power photocoupler according to the first embodiment of the present invention is completed. The light emitting element 11 and the bidirectional thyristor in the driving stage may be resin-sealed by using a conventionally known method, as in the case shown in FIG. Therefore, according to the first embodiment of the present invention,
A new assembly process is not added by adding the resistors 13a and 13b, and the production cost is reduced. Further, by controlling the lifetimes τ ₁ and τ ₂ , the optical gate sensitivity can be improved while keeping the (dV / dt) c withstand capability high, so that the drive current of the LED 11 for light ignition is significantly reduced, and the drive circuit It can be simplified or omitted.

FIG. 4 is a diagram showing an equivalent circuit of the power photocoupler according to the second embodiment of the present invention. As shown in FIG. 4, the power optocoupler according to the second embodiment of the present invention comprises two lateral thyristors 12 capable of optical ignition.
a and 12b are connected in anti-parallel to form a bidirectional three-terminal thyristor 12 of the driving stage, and resistors 13a and 13b are connected to the cathodes of the lateral thyristors 12a and 12b, respectively. The output terminal of the drive stage bidirectional thyristor is connected to the gate terminal of the output stage bidirectional three-terminal thyristor 14, and the drive stage bidirectional thyristor 12 is connected.
It is equipped with a light emitting element 11 such as a light emitting diode (LED) for irradiating light to the device and turning on the bidirectional thyristor 12 of this driving stage.

FIG. 5 is a plan view of the bidirectional thyristor 12 of the power photocoupler driving stage according to the second embodiment of the present invention, and FIG. 6 is a sectional view taken along line BB of the plan view of FIG. is there. In FIG. 6, the p ⁺ anode region 21 is connected to the output terminal T2.
Only the cross section of the lateral thyristor 12a connected to is shown, and the other lateral thyristor 12b connected in anti-parallel to this lateral thyristor 12a is not shown. Further, the resistance R1 (see FIG. 5) connected to the n ⁺ cathode region 41 of the lateral thyristor 12a does not appear in the cross section of FIG. 6, and is therefore shown by using an equivalent circuit expression. That is, it is shown in an equivalent circuit that the n ⁺ cathode region 41 is connected to the terminal T1 via the resistor R1. In FIG. 6, n ^- consists substrate such n ^- base layer 1
P ⁺ of the first lateral thyristor 12a on a part of the surface of
An anode region 21, a p base region 31, and an n ⁺ cathode region 41 are formed. Although not shown, the p ⁺ anode region 22, the p base region 32, and the n ⁺ cathode region 42 of the second lateral thyristor 12b are similarly formed on the surface of the n ⁻ base layer 1. 5
It will be clear from the surface arrangement of. As shown in FIG. 5, the n ⁺ cathode region 21 and the p base region 32 are connected by the p region (R _GK region) 7 having an impurity density of 5 × 10 ¹⁶ cm ⁻³ to 1 × 10 ¹⁸ cm ^−3. N ⁺ cathode region 22
And the p base region 31 are connected to each other. The R _GK region 7 is a region for adjusting the gate sensitivity of the lateral thyristors 12a and 12b, and is usually selected to be about 40 to 60 kΩ for a power photocoupler of several A class. As is clear from FIGS. 5 and 6, the wiring 61 made of a conductive material such as Al also serving as the cathode electrode 61 of the first lateral thyristor 12a formed on the surface of the n ⁺ cathode region 41 has a resistance formed of a doped polysilicon layer. The resistor R1 which is connected to R1 and is made of this doped polysilicon layer is connected to the terminal T1 through the wiring 63 of a conductive material such as Al. Wiring 6
3 is p ⁺ of the second lateral thyristor as shown in FIG.
It is in contact with the p ⁺ anode region 22 through a contact hole formed in the upper surface of the anode region 22. On the p ⁺ anode region 21 of the first lateral thyristor, a wiring 64 made of a conductive material such as Al also serving as an anode electrode is formed and connected to the terminal T2. Also terminal T2
Is connected to a resistor R2 formed of a doped polysilicon layer, and the resistor R2 is connected to the n ⁺ cathode electrode 42 by a conductive wiring 62 which also serves as a cathode electrode of the second lateral thyristor.

Wirings 61 and 62 are windows 91 and 92 for light irradiation.
And n.sup. ⁺ Cathode regions 41 and 42 and p base regions 31 and 32 in a floating state are irradiated with light. The n ⁺ cathode regions 41 and 42 and the p ⁺ anode regions 21 and 22 are formed by contact holes formed at predetermined positions of the oxide film 5 formed on the surface of the n ⁻ substrate 1 so as to form wirings 61, 62, respectively.
It is connected to 63 and 64. Light emitting device 1 shown in FIG.
When 1 is turned on, electron-hole pairs are generated in the p base regions 31 and 32 and the n ⁻ base layer therebelow, and holes are accumulated in the p base regions 31 and 32, and the n ⁺ cathode regions 41 and p are formed. Between base regions 31 and n ⁺ cathode region 4
The pn junction between 2 and the p base region 32 becomes a forward bias, and the lateral thyristors 12a and 12b are turned on. When the terminal T1 is negative and the terminal T2 is positive in FIGS. 5 and 6, the current flows from the terminal T2 in the order of the p ⁺ anode region 21, the n ⁻ base layer 1, the p base region 31, and the n ⁺ emitter region 41. Finally, the terminal T1 is reached via the resistor R1. When the terminal T1 is positive and the terminal T2 is negative, the current flows from the terminal T1 to the p ⁺ anode region 2
2, the n ⁻ base layer 1, the p base region 32, and the n ⁺ emitter region 42 flow in this order and reach the terminal T2 via the resistor R2. The voltage drop of the bidirectional thyristor in the drive stage according to the second embodiment of the present invention is p ⁺ anode region 2
1, 22 and the n ⁻ base layer 1 at the pn junction of about 0.
As in the first embodiment, the main component is the value of 6 V and the predetermined voltage drop determined by the resistors R1 and R2.

In an actual design, resistors R1 and R2 of about 300 to 400 Ω may be inserted to set the ON voltage V _TM = 1 V when the ON current I _TM = 1 mA. However, by inserting R1 and R2, the bidirectional thyristors 12a and
The 2b turn-on voltage V _GT may become too large and may not turn on at a low voltage. Therefore, it is preferable to design in consideration of the required value of the minimum turn-on voltage V _GT . For example, if the turn-on voltage V _GT is 6 V, the resistors R1 and R2
= Turn-on voltage V _GT of 12V for 50 to 400Ω
In this case, the resistances R1 and R2 may be set to about 50 to 1000Ω.

The resistors R1 and R2 according to the second embodiment of the present invention.
Is formed of doped polysilicon, its resistance value does not change by light irradiation, as shown in FIG. Further, the doped polysilicon resistors R1 and R2 may be arranged on an insulating film such as an oxide film, and the degree of freedom of pattern arrangement is large, and a diffusion layer is formed in the n- base layer 1 to form the resistors R1 and R2. There is no effect of the parasitic transistor unlike the case. The doped polysilicon resistor may be formed by doping undoped polysilicon to a predetermined resistance value by ion implantation after CVD, or CV.
AsH ₃ (arsine), PH ₃ (phosphine) in D
Alternatively, the doped polysilicon may be directly CVD-deposited using a predetermined dopant gas such as B ₂ H ₆ (diborane). Patterning of doped polysilicon is performed by well-known photolithography technique, SF ₆ , CF ₄ , CC.
It may be formed in a predetermined pattern by reactive ion etching (RIE) using l ₄ or SiCl ₄ .

In the second embodiment of the present invention, the lifetime τ ₁ of minority carriers in the base region of the bidirectional three-terminal thyristor 12 in the driving stage is the minority carrier in the base region of the bidirectional three-terminal thyristor 14 in the output stage. Lifetime τ ₂
It is preferably longer. For example, the lifetime τ ₂ of minority carriers in the base region of the bidirectional three-terminal thyristor in the output stage is appropriately about 4 μs to 10 μs, and the lifetime τ ₁ of minority carriers in the base region of the lateral thyristors 12a and 12b in the driving stage τ ₁ Is 8 μs to 12 μ
s is suitable.

To control the minority carrier lifetime in the base regions of the lateral thyristors 12a and 12b,
Electron beam irradiation, proton irradiation, Au, for the base region
A method such as injecting a heavy metal such as Pt or irradiating with He radiation may be used. In the case of electron beam irradiation, since the electron beam has a strong penetrating force on silicon, the lifetime of minority carriers in the base region may be controlled by irradiating the entire semiconductor substrate with the electron beam. By these lifetime controls, α _pnp of the lateral thyristors 12a and 12b of the drive stage is controlled.
Increase. However, in the Darlington connection power photocoupler, the bidirectional three-terminal thyristor 1 of the drive stage is used.
If the lifetime τ _{1 of} 2 is set too long, the forward voltage drop V _F of the bidirectional thyristor 12 in the driving stage gradually decreases, and a small amount of current still flows in the driving stage side, so that the entire power photocoupler. The (dV / dt) c withstand capability of is in the region determined by the (dV / dt) c withstand capability on the drive stage side. Therefore, the lifetime τ ₁ = 13
It is not preferable to make it longer than μs.

The bidirectional three-terminal thyristor 12 of the driving stage according to the second embodiment of the present invention described above may be mounted on a predetermined lead frame or the like by a conventionally known method, as shown in FIG. That is, the light emitting element 11 such as a GaAs light emitting diode and the bidirectional three-terminal thyristor 14 at the output stage are mounted on a predetermined lead frame, and Au is mounted.
The power photocoupler according to the second embodiment of the present invention is completed by bonding with a wire, an Al wire, an Al ribbon, etc. and sealing with a resin. The light emitting element 11 and the bidirectional thyristor in the driving stage may be resin-sealed by using a conventionally known method as in FIG. Therefore, according to the second embodiment of the present invention, by adding the resistors 13a and 13b, no new assembly process is added, and the production cost is reduced. In the second embodiment of the present invention, FIG.
The central point P of the semiconductor chip as shown in FIG.
Since the pattern arrangement is rotationally symmetrical with respect to, the characteristic inspection can be simplified and stable manufacturing can be performed. In addition, by arranging the patterns in point symmetry, the potential distribution and electric field distribution within the chip are made uniform and current concentration is eliminated,
Stable operation becomes possible. Furthermore, the lifetime τ ₁ , τ
₂ controls, tau _1> tau ₂ and while maintaining high (dV / dt) c capability of bidirectional thyristors of the output stage by, can improve the optical gate sensitivity.

As described above, in the first and second embodiments of the present invention, the lateral thyristors 12a, 12 capable of light ignition are used.
I explained the power photocoupler using b,
The technical idea of the present invention is not limited to the power photocoupler, and it goes without saying that an electrically driven lateral thyristor may be used as the lateral thyristor in the driving stage. In this case, the window portions 91 and 92 for light irradiation shown in FIGS. 2, 3, 5, and 6 are unnecessary,
P base region 3 of the lateral thyristors 12a and 12b
Of course, 1 and 32 are not floating and are connected to predetermined gate terminals so that they can be driven by a gate current.

[0038]

According to the present invention, a power circuit in which a bidirectional thyristor resistor of a drive stage capable of light ignition is integrated on the same chip.
It is possible to easily prevent malfunction of the photo coupler. Regarding this malfunction prevention, since resistance elements are integrated on the same chip, in the product of the type that connects the bare chips by bonding while maintaining the same effect as the conventional technology of inserting the resistance elements by combining the individual elements. Also, the number of parts can be reduced and the manufacturing process can be simplified, and a remarkable effect can be obtained in reducing the product cost. That is, according to the present invention, it is possible to provide an inexpensive power photocoupler that does not malfunction.

Further, according to the present invention, since the resistance formed on the surface of the bidirectional thyristor in the drive stage is formed of doped polysilicon, the resistance value does not change depending on the presence or absence of light irradiation, and the design is easy. Have. Further, according to the present invention, since a doped polysilicon layer is formed on an insulating film and wiring is made of a conductive material (Al) as a resistance, the relationship with other wiring patterns and the effect of a parasitic transistor like diffusion resistance are taken into consideration. There is an advantage that it can be designed without putting it in.

Further, the bidirectional thyristor of the drive stage of the present invention has a symmetrical structure in its plane pattern having a mirror image relationship and a point symmetric arrangement, so that the resistance R1 at the product inspection stage,
The measurement of R2 can be simplified, QC is facilitated, and stable manufacturing is possible. Further, by adopting the symmetrical arrangement pattern, the area utilization efficiency is increased and the chip size can be reduced. Moreover, the symmetrically arranged structure realizes a uniform potential distribution, which further prevents false ignition.

Further, according to the present invention, the gate sensitivity can be improved while maintaining a high (dV / dt) c withstanding capability, the drive current of the light emitting element can be reduced, the drive circuit can be simplified, and a stable and reliable power photo diode can be obtained. The coupler can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is an equivalent circuit of a power photocoupler according to a first embodiment of the present invention.

FIG. 2 is a plan view of a bidirectional three-terminal thyristor of a driving stage used in the power photocoupler according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a bidirectional three-terminal thyristor of a drive stage used in the power photocoupler according to the first embodiment of the present invention.

FIG. 4 is an equivalent circuit of a power photocoupler according to a second embodiment of the present invention.

FIG. 5 is a plan view of a bidirectional three-terminal thyristor in a drive stage used in a power photocoupler according to a second embodiment of the present invention.

FIG. 6 is a step view of a bidirectional three-terminal thyristor of a drive stage used in a power photocoupler according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a change in resistance value due to light irradiation.

FIG. 8 is an equivalent circuit of a conventional power photocoupler.

FIG. 9 is a voltage-current characteristic of an output stage and a drive stage triac used in a conventional power photocoupler.

FIG. 10 is a diagram showing an internal structure of a power photocoupler.

FIG. 11 is a schematic cross-sectional view showing an optical coupling portion of a power photocoupler.

[Explanation of symbols]

1 n ^- base layer 5 insulating film 7 p layer ( _RGK region) 11 light emitting element 12 drive stage bidirectional thyristor 12a, 12b lateral thyristor 13, 13a, 13b, R1, R2 resistor 14 output stage bidirectional thyristor T1, T2 drive Output terminals of the two-stage bidirectional thyristor 21,22 p ⁺ Anode layer 31, 32 p Base layer 41, 42 n ⁺ Emitter device 61, 62, 63, 64 Conductive material wiring 21a, 22a p ⁺ Anode contact 41a, 42a n ⁺ Emitter contact 91,92 Light irradiation window 221 Photo triac (drive stage triac
Chip) 222 Power triac (output stage triac chip) 231, 232, 233 Au wire 224 Al wire 225 Resin encapsulant 226 Translucent resin encapsulant 401, 402, 403, 404, 405 Lead frame

Claims (10)

[Claims] 1. A first bidirectional 3 used as a drive stage.
An AC switch including at least a terminal thyristor and a second bidirectional three-terminal thyristor used as an output stage, wherein the first bidirectional three-terminal thyristor has a first resistor directly connected to an anode electrode. One lateral thyristor and a second lateral thyristor in which a second resistor is directly connected to the anode electrode are connected in anti-parallel, and the first and second resistors and the first and second lateral thyristors are on the same chip. A semiconductor having a Darlington connection structure formed above and having one output terminal of the first bidirectional three-terminal thyristor connected to a gate terminal on the second bidirectional three-terminal side. apparatus. 2. The semiconductor device according to claim 1, wherein the first and second resistors are made of polysilicon and are formed on the first and second lateral thyristors. 3. The first and second resistors have a shape based on a rectangle having long sides and short sides, and the long sides of the first and second resistors are parallel to each other. 2. The anode regions of the first and second lateral thyristors are arranged symmetrically with each other, and the anode regions of the first and second lateral thyristors are arranged together between the first and second resistors. Semiconductor device. 4. The semiconductor device according to claim 1, wherein the first and second lateral thyristors are three-terminal thyristors capable of light ignition. 5. The minority carrier lifetime in the base regions of the first and second lateral thyristors is longer than the minority carrier lifetime in the base region of the second bidirectional three-terminal thyristor. The semiconductor device according to claim 1. 6. A first bidirectional 3 used as a drive stage.
An AC switch including at least a terminal thyristor and a second bidirectional three-terminal thyristor used as an output stage, wherein the first bidirectional three-terminal thyristor has a first resistance directly connected to a cathode electrode. The first lateral thyristor and the second lateral thyristor in which the second resistor is directly connected to the cathode electrode are connected in anti-parallel, and the first and second resistors and the first resistor are connected.
And the second lateral thyristor are formed on the same chip, and one output terminal of the first bidirectional 3-terminal thyristor is connected to the gate terminal of the second bidirectional 3-terminal thyristor in Darlington connection. A semiconductor device having a structure. 7. The semiconductor device according to claim 6, wherein the first and second resistors are made of polysilicon and are formed above the first and second lateral thyristors. 8. The first and second resistors have a shape based on a rectangle having a long side and a short side, and the first and second resistors are arranged so that the respective long sides are arranged substantially on the same straight line. First and second resistors are formed separately, and the anode region and the cathode region of the first lateral thyristor are arranged together on one side with respect to the same straight line on which the first and second resistors are arranged. 7. The cathode region and the anode region of the second lateral thyristor are arranged together on the other side.
13. The semiconductor device according to claim 1. 9. The semiconductor device according to claim 6, wherein the first and second lateral thyristors are three-terminal thyristors capable of light ignition. 10. The minority carrier lifetime in the base regions of the first and second lateral thyristors is longer than the minority carrier lifetime in the base region of the second bidirectional three-terminal thyristor. The semiconductor device according to claim 6.