JPS5989461A - Thyristor - Google Patents

Abstract

PURPOSE:To increase a di/dt capability and photo sensitivity by forming a plurality of pilot thyristors so as to be surrounded by current collecting electrodes formed to the base layer of the thyristor and connecting the gate electrodes and emitter electrodes of these pilot thyristors in succession. CONSTITUTION:The current collecting electrodes 26 are formed to the surface of the P base layer 23 of the main thyristor 25 consisting of a semiconductor layer on which four of a P emitter layer 21, an N base layer 22, the P base layer 23 and N emitter layers 24d are laminated. A plurality of the pilot thyristors are formed surrounded by the current collecting electrodes 26. The first pilot thyristor 28 with a light-receiving element 27 and the second and third pilot thyristors 29, 30 with electric gates are formed. Mutual gate electrodes and emitter electrodes of these pilot thyristors are connected electrically in succession.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thyristor with increased di/d tolerance and high sensitivity.

[Technical background of the invention and its problems]

With the increase in capacity and voltage of power conversion devices such as thyristor pulp for DC power transmission, there is a strong demand for replacing the thyristors in use with original trigger thyristors. When optically triggered thyristors are used in high voltage power conversion equipment,
Electrical insulation between the main circuit and control circuit and countermeasures against inductive disturbances are made easier, allowing equipment to be significantly smaller and lighter.

However, the currently available optical trigger energy is weaker than electrical trigger energy, so it has been necessary to increase the optical sensitivity of the optical trigger thyristor by several tens of times in terms of the gate sensitivity of the electrically triggered thyristor. In general, thyristor games.

When the sensitivity is increased, the thyristor becomes more likely to malfunction due to sudden voltage noise from the main circuit, such as a lightning surge. The permissible voltage increase rate that does not cause malfunction even when overvoltage is applied is called dv/dt tolerance. By reducing the area of the light receiving part and reducing the displacement current generated in this part, dy/at can be reduced without sacrificing photosensitivity.
The withstand capability can be increased, but if the light receiving area is made smaller, the conduction area at the initial stage of turn-on will be reduced, and the withstand capability (di
/dt slip resistance) decreases. dv/dt.

It is an important technical challenge to realize a photo-triggered thyristor with high photosensitivity without sacrificing major thyristor characteristics such as ai/dt and withstand capacity.

FIG. 1 shows a cross-sectional view of a typical optically triggered thyristor.

Four layers of semiconductors with different conductivity types are formed on a semiconductor wafer such as silicon, and 1 is called the P emitter layer, 2 is the N pace layer, 3 is the P base layer, and 4 is called the N emitter layer. There is. In the center of the semiconductor wafer, a pilot thyristor comprising an N emitter layer 4a is arranged in a responsive circular shape, and in the center, the P base layer 3 is exposed and a light receiving part 5 is arranged.
It is said that On the N emitter layer 4a, a conductor Q5a made of a vapor-deposited layer of aluminum or the like is formed. A main thyristor side is formed in a circular shape corresponding to the pilot thyristor 10, and a cathode electrode 5b is deposited on the 70N emitter 4b. A short circuit part 7 is provided in the N emitter 14b,
The P base layer 3 and the cathode electrode 5b are short-circuited at a predetermined interval. A dv/dt compensation electrode 8 is provided on the outer periphery of the main iris star, and the dv/dt compensation electrode 8 is electrically coupled to the electrode 5a by a conductor 9. P emitter I
An anode electrode 6 made of metal such as tungsten is attached to the Hibiki 1 by a method such as an alloy method.

When an optical trigger signal with a light amount of ~ is irradiated onto the light receiving section 5 of the optical trigger silis φ configured in this way, N
The photocurrent ph mainly occurs in the depletion layer regions on both sides of the central junction J2 formed by the space layer 2 and the P base layer 3.
' begins to flow. The photocurrent Iph shown by the broken line in FIG.
The current flows to an external circuit consisting of a load 12 and a power supply 13. P base lateral resistance R1 of the P base layer 3 through which the photocurrent Iph flows
The voltage drop v1 occurring at both ends of the voltage biases the junction J3 consisting of the P base layer 3 and the N emitter layer 4a in the forward direction. Inner peripheral part 4 of the N emitter 4a with the deepest forward bias
If the voltage of a' ■1 is more than the diffusion potential of 33, then 4
The injection of electrons from the a' portion rapidly increases, and the pilot thyristor is turned on from the 4 a' portion. This turn-on stream Ip is 4 a-5a-9-8-3-7-5
It flows out to the external circuit via b. Ip functions as a gate current for the main thyristor, and Ip turns on the main thyristor, which turns on the photo-triggered thyristor. As is clear from the above description, the photosensitivity of the photo-triggered thyristor is determined by the P-base lateral resistance R1, and the larger R1 is, the higher the photosensitivity is.

Next, consider a case where voltage noise with a sudden rise is applied between the anode electrode 6 and the cathode electrode 5b of this photo-triggered thyristor. When voltage noise is applied between the anode electrode 6 and the cathode electrode 5b of the photo-trigger thyristor, unlike the case where the light-receiving part is irradiated with a photo-trigger signal, the displacement current Id flows through the entire junction area of the photo-trigger thyristor.

If the junction capacitance of the central junction J2 directly below the light receiving part is C□, then the displacement current Id flowing through 01 is the displacement current Id2 flowing through the allowable HC2, and the displacement current Id2 flowing through the allowable HC2 is flows. The equivalent circuit of the optical trigger thyristor at this time is shown in FIG. 2. As is clear from the figure, the N emitter layer 4 of the pilot thyristani
The bias voltage Vj of the diode D1 consisting of a and the P space layer 3 is the difference Vl' between the voltage "1ZV2'" across R1 and R2.
V2' cell is displayed. The value of Vj=■1'-■2' is J
3, the pilot thyristor becomes dV
/dt) to trigger. In this case, by adjusting the value of R2, Vj
If the O value is kept low, J3 will be less likely to be forward biased even if voltage noise is applied, and the dv/dt resistance of the pilot thyristor can be improved regardless of the value of R4. By the above method, the conventional original trigger thyristor has been designed to improve its light sensitivity and dv/dt tolerance. However, conventional optically triggered thyristors have the following drawbacks.

That is, in the conventional optically triggered thyristor, R1 and R2 are increased and the effect of the dv/dt compensation electrode is used to improve the optical sensitivity and d.
Although improvements have been made to v/dt tolerance, unnecessary I/rc
When R2 is increased, the gate l18 degree of the main thyristor 11 becomes larger, which causes a problem in that the dv/dt tolerance of the main thyristor 11 decreases. As is clear from the equivalent circuit in FIG. 2, R2 is the sum of the P base layer resistance R1 under the P base layer resistance immediately below the section 14 at 64 in the pile 1 diagram. Junction J3' formed by N emitter 4b and P base layer 3
The bias voltage of is determined by R2'', so by increasing R2 by deepening the groove 14 and increasing R2/, the light sensitivity of the pilot thyristor can be increased without reducing the dv/dt withstand capacity of the main thyristor U. However, since the gate sensitivity of the main thyristor U decreases, there is a problem that the turn-on of the pilot thyristor U is delayed as well as the turn-on of the pilot thyristor U.As a result,
The on-current at the initial stage of light turn-on concentrates on the pilot thyristor, and the d1/dt tolerance decreases by a factor of V. Thus, dv/dt.

Conventional thyristors have limitations in improving photosensitivity without impairing di/d tolerance.

[Purpose of the invention]

The present invention was made in consideration of such circumstances, and
The purpose of this is to improve di/dt resistance and optical intensity without sacrificing characteristics such as dv/dt resistance.
The objective is to provide a cyrisk with increased gate sensitivity).

[Summary of the invention]

The present invention has a structure in which a plurality of pilot thyristors are formed so as to be surrounded by a current collecting electrode formed on the base layer of the thyristor, and the niece gate electrode and emitter electrode of these pilot thyristors are sequentially electrically connected. .

〔Effect of the invention〕

According to the present invention, it is possible to increase the gate sensitivity of each pilot thyristor without reducing the dv/dt singing resistance, and it is also possible to increase the diameter of the light receiving part by more than 2 to 3 times compared to the conventional one. becomes. As a result, the following advantages can be obtained. Since the gate sensitivities of the second, third, etc. pilot thyristors can be increased, current concentration in the first pilot thyristor is significantly reduced, resulting in di/dt
Anger increases. Still constituted a light thyristor. 1 go,
The optical coupling efficiency between the light receiving section and the optical transmission system is improved, the driving current of the light emitting diode can be reduced, and a highly reliable system can be achieved. Furthermore, when compared with the same -dv/dt tolerance, the photosensitivity is significantly improved compared to the case where the present invention is not implemented. Furthermore, since the leakage current distribution during high-temperature operation is the same as the displacement current distribution when overvoltage is applied, the present invention is effective in preventing malfunctions due to leakage current, and greatly improves the effective temperature characteristics of the thyristor. can be improved.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 3 and 4 show the configuration of the thyristor according to the embodiment, FIG. 3 is a plan view of the arrangement, and FIG. 4 is a sectional view of the thyristor.

P emitter layer 21, N base layer 22, P base layer 2s,
A collector electrode 26 is formed on the surface of the P base 1230 adjacent to the N emitter @ 24dK of the main thyristoro consisting of four laminated semiconductor layers of the N emitter @ 24d. A plurality of pilot thyristors are formed. Here, a first pilot thyristor 28 having a light receiving section 27 and second and third pilot thyristors 29 and 30 each having an electric gate are formed. The main iris is formed around the periphery of the current collecting electrode 26, around the pilot thyristor. The first pilot thyristor roof is constructed by forming an annular N emitter 24a around the light receiving section 27, and disposing an emitter electrode 31 on the surface thereof. Further, the second pilot thyristor is surrounded by the current collecting electrode 26 in the P base layer 23, and the N emitter layer 24b, 2 is surrounded by the current collecting electrode 26.
4c are formed independently, and these N emitters 1i
Emitters 32 and 33 are provided on the surfaces of the capacitors 24 b and 24 c, respectively, and gate electrodes Q 34 r 35 are formed on the P base layer 23. Therefore, the wiring layer 36 of AIM etc. (therefore, the emitter electrode 31 of the first pilot thyristor 28 and the gate electrode 34 of the second pilot thyristor 29 are connected to the emitter electrode 32 of the second pilot thyristor 29 and the third pilot thyristor 36). The gate ionization 35 is electrically connected, and furthermore, the emitter electrode 33 of the third pilot thyristor and the gate electrode 34 of the second pilot thyristor are electrically connected.

37 and 38 are the cathode electrode and anode electrode of the main thyristor 25.

Now, by applying a positive voltage to the anode terminal and a negative voltage to the cathode terminal of the thyristor configured in this way, the light receiving portion 27
When the photo-gate signal hν is irradiated, a photocurrent Iph is generated in the depletion layer region of the central junction of the first pilot thyristor 28, and the photocurrent Iph is generated through the short-circuit portion 39 provided between the cathode electrode 37 and the cathode electrode 37. The above cathode electrode 37C・
It flows in. As a result, the photocurrent Iph generates a lateral potential difference in the P base 1@23 of the first pilot thyristor region. As a result, the first pilot thyristor 28
The N emitter 24a of is forward biased. When the deepest potential of this forward bias voltage approaches the value of the built-in potential of the junction between the N emitter layer 24a- and the P paste layer 23, the N emitter layer '24
The injection of electrons from h to P pace sound 23 increases rapidly, and the first pilot thyristor turns on. Then, the turn-on current of the first pilot thyristor flows into the second pilot thyristor 29 via the wiring layer 36, thereby turning on the second pilot thyristor U. . By turning on the second pilot thyristor, the third pilot thyristor 30
turns on. Furthermore, the third pilot thyristor 3
The turn-on current of 0 flows into the gate electrode 34 of the second pilot thyristor, and flows through the current collecting electrode 26 and the short circuit 39 to the cathode electrode 37. This current functions as the gate current of the main thyristor 25, and the main thyristor 25
turns on.

On the other hand, when voltage noise with a large dy/dt value is applied between the anode terminal and the cathode terminal, P pace noise 23
A displacement current flows across the entire surface. This displacement current works in the same way as the photocurrent described above, and each pilot has one syringe.

Lateral potential differences VlrVt and v3 are generated in the P pace sound 23 in the mouth region, respectively. However, as mentioned above, since the N emitter layer 24a of the first pilot thyristor U is connected to the gate electrode 34 of the second pilot thyristor υ via the emitter electrode 31 and the wiring layer 36, P pace sound 23 in thyristor U area
A lateral potential difference v2 generated in the first pilot thyristor is applied to the N emitter layer 524a of the first pilot thyristor. The lateral potential difference v1 and the second
(This is the difference from the lateral potential difference v2 that occurs in the P pace sound 23 in the irosotothyristoric region. Similarly, the bias voltage applied to the N emitter layer 24b of the second pilot thyristor U is The lateral potential difference v2 generated in the P base layer 23 and the lateral potential difference 23 generated in the P base 23 of the third pilot thyristor region, and the bias voltage applied to the N emitter layer 24c of the third pilot thyristor is: Lateral direction' generated in the P paste layer 23 of the third pyroft thyristary region
is the difference between the potential difference (3) and the lateral potential difference v2 of the P base layer 23 generated in the second pilot thyristor region.

Here, each pilot thyristor, dv/dt
The withstand capacity is for each N emitter core 24a, 24b, 24
determined by the voltage biased to c, when its value approaches the built-in potential of the respective junction, injection of electrons from the N emitter begins abruptly and each pilot thyristor turns on dv/dt. However, as mentioned above, the voltages biased to the N emitter pins 24a+24b124c of the valley pilot thyristor 28° and 28° are respectively V.

-V2. v2-v8. v3-v2, and all of its values can be kept extremely lower than the built-in potential of the junction of each pilot thyristor 2B, 29° N emitter 4z4a, z4blz4c. Therefore, P base 1 ambiguity 2 of each pilot thyristor area
If the geometrical shape and P base resistance of each viroft thyristor are set so that the lateral potentials generated at 3 are equal, the light receiving part 27 of the first pyroft thyristor can be adjusted without reducing the dv/dt resistance. The diameter can be increased.

In this way, according to the present example, the gate sensitivity of each pilot thyristor can be increased without any deterioration in dv/dt withstand capacity or low withstand capacity, and the diameter of the light receiving part can be made 2 to 3 times larger than the conventional one. I can do it. Therefore, the gate sensitivities of the second and third viroft thyristors can be increased, so that current concentration in the first viroft thyristor is reduced and the d1/dt withstand capacity is increased. Furthermore, the optical coupling efficiency between the light receiving section and the optical transmission system is improved, and the sliding and current of the light emitting diode can be reduced. Furthermore, dv/d t il+
4. If the desire is the same, the photosensitivity can be greatly improved.

Note that the present invention is not limited only to the above embodiments.

In the embodiment, the optical thyristor was illustrated, but the light receiving section 27
The present invention can be similarly applied to an electrically triggered thyristor in which a gate electrode is formed. In addition, the shape and arrangement of the pilot thyristors may be determined according to the specifications, and in short, a plurality of pilot thyristors are arranged so as to be surrounded by current collecting electrodes provided on the P pace layer, The N emitter electrode and gate electrode of each pilot thyristor may be electrically connected in sequence.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing an example of a conventional structure thyristor, and Figure 2 is a block diagram showing an example of a conventional structure.
The figure is an equivalent circuit diagram thereof, FIG. 3 is a plan view of a thyristor showing one example of the present invention, and FIG. 4 is a new configuration diagram of a thyristor according to the same implementation. 25... Main thyristor, 28... First viroft thyristor (former thyristor), 29... Second pilot thyristor, 30... Third pilot thyristor, 2
4a to 24 (1...N emitter layer, 26...collecting electrode, 27...light receiving section, 31.32.33...emitter electrode, 34.35...gate electrode, 36...・Wiring layer, 37... cathode electrode, 38... anode electrode. Applicant's representative Patent attorney Takehiko Suzue Figure 2? Figure 3 Figure 4

Claims (2)

[Claims] (1) The emitters of a plurality of pilot thyristors that share three semiconductor layers other than the emitter layer of the main thyristor in the space layer of the main thyristor, which is composed of four semiconductor layers laminated with alternating conductivity types. In the thyristor in which the layers are separated from the emitter layer of the main thyristor and formed to have the same conductivity type as the emitter layer of the raw thyristor, each of the pilot thyristors is placed on a base layer in contact with the emitter layer of the main thyristor. A gate electrode is formed on each base layer which is arranged inside the provided current collecting electrode and which is sandwiched between the emitter layers of each pilot thyristor, and an emitter electrode is provided on the emitter layer of each pilot thyristor. A thyristor characterized in that the gate electrode and the gate electrode are sequentially electrically connected. (2) The thyristor according to claim 1, wherein one of the plurality of pilot thyristors is driven to fire by an optical trigger signal.