JPS6110986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in thyristors, particularly light-triggered optical thyristors.

Conventional so-called photothyristors, which perform turn-on switching by irradiation with light, are better than conventional gate thyristors because of both the problem of insulation between the gate circuit and the main circuit, which was a problem with conventional thyristors, and the improvement of the rate of increase in the rated critical on-state current. It has advantageous characteristics compared to type thyristors. However, in order to increase the withstand pressure of the optical thyristor, it is necessary to increase the thickness of the semiconductor wafer.
The depth of the pn junction must be increased, resulting in an insufficient amount of light penetration, resulting in extremely low optical trigger sensitivity. Furthermore, when attempting to obtain sufficient optical trigger sensitivity, the conventional optical thyristor structure has the disadvantage that the practical withstand voltage is extremely low, at most several hundred volts.

The present invention aims to simultaneously improve the contradictory characteristics of voltage resistance and optical trigger sensitivity as described above, and to provide an optical thyristor with high voltage resistance and high trigger sensitivity.

The photothyristor of the present invention includes a phototransistor portion that receives light and a thyristor portion that receives current, and is configured so that the thyristor is triggered by the phototransistor output current obtained by shining light on the phototransistor portion. It has characteristics.

Basic Structure As shown in FIG. 1, the thyristor wafer 10 of the present invention includes a first emitter layer P _E (p) of a first conductivity type (for example, p type), a first emitter layer of a second conductivity type (for example, n type), A base layer N _B (n), a second base layer P _B (p) of the first conductivity type, and a second emitter layer N _E of the second conductivity type.
(n), the main thyristor part T _h consisting of 4 layers of pnpn
and a collector layer P _C of the first conductivity type (for example, p type).
(p), a third base layer N, _B (n) of the second conductivity type (for example, n-type), and a third emitter layer P, _E of the first conductivity type.
(p) Auxiliary transistor part T consisting of pnp three layers
_r , and the second base layer P _B (p) and the collector layer P _C (p) are electrically connected. A cathode electrode k is connected to the second emitter layer N _E (n), an anode electrode a is connected to the first emitter layer P _E (p), and the third emitter layer P, _E (p) is connected to the cathode electrode k. Control electrode e is connected. In the illustrated operation example, a load R 0 and a DC power source E 0 are connected in series between the anode electrode terminal A and the cathode electrode terminal K, and a load R ₀ and a DC power source E ₀ are connected in series between the cathode electrode terminal K and the control electrode terminal E. A load R ₁ and a DC power source E ₁ are connected in series with each other. The auxiliary transistor portion T _r has a function of shifting to an on state when the light L is irradiated toward the light receiving portion in the region including the base thereof.

Operating Principle The operating principle of turn-on switching of the thyristor of the present invention can be explained as follows.

When the light L is irradiated in the direction of the arrow toward the region including the base of the auxiliary transistor portion T _r , the auxiliary transistor portion T _r functions as a phototransistor, and a collector current i _c is generated therein. This collector current i _c acts as a gate current (trigger current) i _G of the main thyristor portion T _h and turns the main thyristor portion T _h into an on state. As a result, an on-current i _A flows from the anode electrode a to the cathode electrode k.

In this case, since the auxiliary transistor portion T _r simply functions to supply a trigger current to the main thyristor portion T _h , its withstand voltage is sufficient to be several tens of volts or less at most. Therefore, in the thyristor of the present invention, the depth from the surface of the auxiliary transistor portion T _r to the base layer n is, for example, 10 to 20
It can be designed to be as shallow as microns. Therefore, the optical trigger sensitivity is much higher than that of the conventional type, which uses direct light to trigger a thyristor with a withstand voltage of several hundred volts or more.Furthermore, since it is gated by the amplified phototransistor output current, it is possible to It has the feature that it can be driven by the gate input voltage.

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

Example 1 As shown in FIG. 2, a silicon single crystal thyristor wafer 100 includes a p-type first emitter layer P E (p), an n-type first base layer N _B (n), and a p-type first emitter layer P _E (p). The four layers of the second base layer P _B (p) and the second emitter layer N _E (n) of the n-type are sequentially adjacent to each other, and there is a pn layer between the layers.
Main thyristor part 10 made of junctions J ₁ , J ₂ and J ₄
1, the p-type second base layer P _B (p) is used as a p-type collector layer P _C (p), and further n
A third base layer N' _B (n) of type P and a third emitter layer P' _E (p) of p type are provided, and the pnp3 layers are successively adjacent to each other to form pn junctions J ₄ and J ₅ between the layers to form an auxiliary transistor section. 102 is built-in. An anode electrode 105 of an M _O plate is alloy-soldered to the first main surface 104 on the first emitter layer P _E (p) side of this thyristor wafer 100 via an A vapor deposition layer, etc., and the second emitter layer N _E ( A cathode electrode 107 is provided on the second main surface 106 above n), and a control electrode 108 is provided on the third emitter layer P' _E (p) by the A vapor deposition method or the like. Note that to form these p-type and n-type layers, techniques such as impurity diffusion, selective diffusion, epitaxial single crystal growth, and alloying, which are known as thyristor manufacturing techniques, are used.

When the element having the above configuration is irradiated with light L from a mercury lamp or the like on the surface 109 on which no electrode is formed on the auxiliary transistor portion 102, the auxiliary transistor portion 102 becomes a phototransistor that is excited by light and turns on. In order to become
A collector current is generated from the control electrode 108 toward the collector layer P _C (p). This current flows from the second base layer P _B (p) to the pn junction J ₃ to the second emitter layer N _E
Since the current flows in the path of (n)→cathode electrode 107, main thyristor portion 101 is triggered and the gap between anode electrode 105 and cathode electrode 107 is turned on.

As a light source, in addition to a mercury lamp, for example, a light emitting diode, an infrared laser, etc. can also be used.

Example 2 The thyristor wafer 200 shown in FIG.
As in the embodiment, the p-type first emitter layer P _E
(p), n-type first base layer N _B (n), p-type second base layer
Base layer P _B (p) and n-type second emitter layer N _E
(n) are successively adjacent to each other, and a pn junction J ₁ ,
The main thyristor part 202 where J ₂ and J ₃ were made and the p-type second base layer P _B (p) are used as a p-type collector layer P _C (p), and on top of that, an n-type third base layer is formed. layer N′ _B (n) and p-type third emitter layer P′ _E
Auxiliary transistor part 201 in which pn junctions J ₄ and J ₅ are created between layers by sequentially adjoining three pnp layers by providing (p)
and the auxiliary transistor portion 20.
A conductive layer 203 is formed on the surface of the second base layer P _B (p) between the second emitter layer N _E (n) and the second emitter layer N E (n).
are connected. Therefore, the resistance R _L which is a component of the collector resistance of the auxiliary transistor portion 201, that is, the auxiliary transistor portion 201
and the second base layer P _B of the main thyristor portion 202
(p) becomes lower, and the output of the auxiliary transistor 201 increases. Therefore,
This thyristor has the effect of making driving with a high gate input voltage stronger. In addition,
This conductive layer 203, like the cathode electrode 204 and control electrode 205, is formed by vapor-depositing aluminum, ohmic metal, or the like.

Example 3 The thyristor wafer 300 shown in FIG.
As in the embodiment, the p-type first emitter layer P _E
(p), n-type first base layer N _B (n), p-type second base layer
Base layer P _B (p) and n-type second emitter layer N _E
(n) are sequentially adjacent to each other, and a Pn junction J ₁ ,
The main thyristor part 303 where J ₂ and J ₃ were made and the p-type second base layer P _B (p) are used as a p-type collector layer P _C (p), and on top of that, an n-type third base layer is formed. layer N′ _B (n) and p-type third emitter layer P′ _E
Auxiliary transistor part 301 in which pn junctions J ₄ and J ₅ are created between the layers by sequentially adjoining three pnp layers by providing (p)
and a plurality of second emitter layers N _E (n) of the main thyristor portion 303 (for example, 5
Electrodes 304, 30 are arranged on the surface thereof and serve as cathode electrodes of the main thyristor part 303.
₄ , . Multiple auxiliary electrodes 302, 30
2,... as the plurality of second emitter layers N _E (n), N
_E (n), . . . are connected to the surfaces 305, 305, . . . of the second base layer P _B (p) between them. With this configuration, the second emitter layer N _E
(n) and the second base layer P _B (p) bonding surface 3
The area of 06, 306, ... is each auxiliary electrode 302, 3
The area is sufficiently larger than the area of the planar shape of 02, .

When the light L is irradiated in the direction of the arrow toward the region including the base of the auxiliary transistor portion 301, the collector current i _c changes as follows: conductive layer 301 → auxiliary electrode 302 → second base layer P _B (p) → pn junction J ₃ → third Since the current flows along the path from the second emitter layer N _E (n) to the cathode electrode 304, the bonding surfaces 306, 306, . . . facing the auxiliary electrodes 302, 302, . Therefore, like the conventional high-frequency thyristor, the area of the initial turn-on region is significantly increased, and the rated critical on-current increase rate and high-frequency current carrying capacity can be greatly improved.

Example 4 The thyristor wafer 400 in FIG. 5 has a p-type first emitter layer P _E (p), n
A p-type first base layer N _B (n), a p-type second base layer P _B (p), and an n-type second emitter layer N _E (n) are sequentially adjacent to each other, and a p-n junction J is formed between the layers. ₁ , _J2 and _J3
and the p-type second base layer P _B (p) as a p-type collector layer P _C
(p) and a third n-type base layer N′ _B on top of it.
(n) and a p-type third emitter layer P′ _E (p) are provided, and the pnp3 layers are successively adjacent to each other, forming pn junctions J ₄ and J ₅ between the layers.
The control electrode 401 of the auxiliary transistor part 403 is provided with an auxiliary transistor part 403 made of
In order to irradiate the third emitter layer P' _E (p) over a wide area, the third emitter layer P' _E (p) is formed into an unusual shape such as a finger shape or a snowflake pattern. (p) Provided on the surface. Therefore,
A large number of windows 402, 402, . . . for irradiating light L are formed in the gaps between the control electrodes 401 having irregular shapes in plan view.
Therefore, the light L can be effectively irradiated over a wide range of the auxiliary transistor portion 403,
Transistor operation can be performed over the entire emitter junction _J5 . As a result, the output of the auxiliary transistor section 403 increases and the main thyristor section 404 is driven by the high gate input voltage.
It is possible to improve the turn-on characteristics of , that is, the rate of increase in rated critical on-current, high-frequency current carrying capacity, etc.

Example 5 The thyristor wafer 500 in FIG. 6 has a p-type first emitter layer _PE , similar to the first and third examples.
(p), n-type first base layer N _B (n), p-type second base layer
Base layer P _B (p) and n-type second emitter layer N _E
(n) are successively adjacent to each other, and a pn junction J ₁ ,
The main thyristor part 502 where J ₂ and J ₃ were made, and the p-type second base layer P _B (p) are made into a p-type collector layer P _C (p), and on top of that, an n-type third base layer is formed. N′ _B (n) and p-type third emitter layer P′ _E
Auxiliary transistor part 501 in which pn junctions J ₄ and J ₅ are created between layers by sequentially adjoining three pnp layers by providing (p)
The main thyristor portion 502 has a plurality of second emitter layers N _E (n), N _E (n),
... and cathode electrodes 507, 50 on each surface thereof.
It has 7,... Furthermore, the auxiliary transistor portion 5
01 and the main thyristor portion 502, an n-type fourth emitter layer N' _E (n) is provided, and the first emitter layer P _E (p), the first base layer N _B (n), and the above An auxiliary thyristor part 503 is constructed in which the second base layer P _B (p) and the fourth emitter layer N' _E (n), which are four pnpn layers, are sequentially adjacent to each other and pn junctions J ₁ , J ₂ and J ₆ are provided between each layer. Configured. And a conductive layer 5 corresponding to the conductive layers 203 and 301 of the second and third embodiments.
04 is the second base layer P _B between the auxiliary transistor portion 501 and the fourth emitter layer N' _E (n).
(n) Provided on the surface. Furthermore, the fourth
Auxiliary thyristor electrode 5 on emitter layer N′ _E (n)
A plurality of auxiliary electrodes 50 electrically connected to 05
6, 506, ... are the respective second emitter layers N _E
(n), and connected to the surface of the second base layer P _B (p) so as to be located on the second base layer P _B (p) between N _E (n). For the element with the above configuration,
When the surface 509 on which no electrode is formed on the auxiliary transistor portion 501 is irradiated with light L, the auxiliary transistor portion 501 becomes a phototransistor that is _photoexcited and turns on. ) to generate a collector current i _C. This current i _C flows as a gate current along the path from the conductive layer 504 to the fourth emitter layer N' _E (n), turning on the auxiliary thyristor portion 503. Furthermore, the on-current i _AT of this auxiliary thyristor portion 503 is the auxiliary thyristor electrode 50
5→auxiliary electrode 506→each second base layer P _B (p)
→ Each second emitter layer N _E (n) → Each cathode electrode 507 flows as a trigger current to turn on the main thyristor portion 502 . In this way, in this thyristor, the auxiliary thyristor part 5
The collector current i _C of the auxiliary transistor portion 501 is amplified by the on-current i _AT of 03 and becomes the gate trigger current of the main thyristor. As a result, the driving of the main thyristor by the high gate input voltage is further strengthened, and the turn-on switching characteristics of the main thyristor are significantly improved.

As described above, the optical thyristor of the present invention includes an auxiliary transistor portion that receives light and a main thyristor portion that receives current, and the auxiliary transistor portion is configured such that the high voltage applied to the main thyristor portion is not applied. Therefore, it has the advantage of maintaining sufficiently high optical trigger sensitivity and being able to withstand high voltage.

In the embodiments of the present invention, a reverse blocking thyristor is shown as the thyristor, but other thyristors, such as a reverse conducting thyristor or a triax, can also exhibit similar effects. Also,
A similar effect can be obtained even when the p-type and n-type conductivity types of the thyristor are all reversed. Furthermore, as the semiconductor, in addition to silicon single crystal, for example, GaAS or SiC can also be used.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram explaining the basic structure and operating principle of the optical thyristor according to the present invention, Figures 2 and 3.
4 and 6 are the first and second embodiments of the present invention, respectively.
FIG. 5 is a schematic partial cross-sectional view of the fourth embodiment of the present invention. P _E (p) is the first emitter layer, N B (n) is the first emitter layer, and N _B (n) is the first emitter layer.
The base layer, P _B (p) is the second base layer, N _E (n)
is the second emitter layer, P _C (p) is the collector layer,
N' _B (n) is the third base layer, P' _E (p) is the third emitter layer, N' _E (n) is the fourth emitter layer, Th, 10
1, 202, 303, 404 and 502 are main thyristor parts, T _r , 102, 201, 301, 4
03 and 501 are auxiliary transistor parts, a and 105 are anode electrodes, k, 107, 204, 3
04 and 507 are cathode electrodes, e, 108, 2
05 and 401 are control electrodes, 203, 301 and 505 are conductive layers, and 302 and 506 are auxiliary electrodes.

Claims (1)

[Scope of Claims] 1. A first emitter layer of a first conductivity type, a first base layer of a second conductivity type adjacent to the first emitter layer, and a second base layer of the first conductivity type adjacent to the first base layer. base layer. a main thyristor portion comprising a second emitter layer of a second conductivity type adjacent to the second base layer;
a collector layer provided on the second base layer; an auxiliary transistor portion including a third base layer and a third emitter layer provided separately from the main thyristor portion; and a collector layer connected to the first emitter layer; a first main electrode connected to the second emitter layer, a control electrode connected to the third emitter layer, and a light receiving section provided in a region including the third base layer. A photothyristor, characterized in that the auxiliary transistor portion is made conductive by irradiating the photoreceptor with light, and the collector current thereof is applied to the main thyristor portion as a trigger current. 2. The optical thyristor according to claim 1, characterized in that an auxiliary electrode is provided on the second base layer. 3 A plurality of second emitter layers are provided, and these second
3. The optical thyristor according to claim 2, wherein a plurality of auxiliary electrodes are provided between the second main electrodes respectively provided on the emitter layer, and these auxiliary electrodes are electrically connected to each other. 4. Claim 1, characterized in that the control electrode has an irregular planar shape so that the third emitter layer can be irradiated with light incident through the periphery over a wide area. The optical thyristor described. 5 A fourth layer that shares the first emitter layer, first base layer, and second base layer of the main thyristor portion, is adjacent to the second base layer, and is provided separately from the main thyristor portion and the auxiliary transistor portion.
2. An optical thyristor as claimed in claim 1, characterized in that an auxiliary thyristor portion comprising an emitter layer is provided between the main thyristor portion and the auxiliary transistor portion.