DE2316354A1 - SEMICONDUCTOR THYRISTOR - Google Patents

Description

The invention relates to a semiconductor thyristor with an anode electrode on one surface and a gate as well Wire electrode on an opposite surface, with the gate electrode in ohmic contact with a base region of the semiconductor body and the cathode electrode in ohmic contact connection with an emitter region stands within the base region, and parts of the base region extend through the emitter region and into ohmic contact connection with the cathode electrode to form punctiform shunts.

For high-frequency thyristors in the form of thyristor-controlled rectifiers for high power, it is known to use cathode

Fs / ba emitter shunts

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To provide for emitter shunts in specific training, to reduce cathode-emitter injection and one Provide a way for the reverse current to allow the charge carriers left behind in the base area to operate remove. In this way, the distribution density the shunt points or the shunt areas and in particular the ratio of the shunt areas to the cathode-emitter area in order to improve the dV / dt characteristic and the switch-off time of the thyristor «, by increasing the / ratio of the shunt areas in the cathode-emitter area or the distribution density of the shunt points usually reduces the effectiveness of the thyristor, because its speed of propagation becomes smaller. Resulting from the reduction in the speed of propagation resulting deterioration in the characteristic of the thyristor leads to high current concentration in small Areas. This high current density in small areas creates a voltage drop in the forward direction, to the switch-on range expands further and the mean current densities decrease over this range. Inside this Time interval, the local temperature is raised to a level by instantaneous power concentration which can at least lead to a deterioration in the performance of the thyristor, if not even to its destruction * The increased switch-on time also leads to increased switch-on power losses. The total switch-on power loss is particularly critical when the thyristor is used for high-frequency Use cases to be used. It is known that the switching losses very rapidly with the increase in frequency increase. In addition, the performance of the semiconductor device is greatly reduced because of the turn-on losses make up a predominant part of the total losses »Usually a thyristor is switched off by before the Applying the voltage the current is reduced, on this

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In this way, significantly less power is consumed or converted into heat when switching off. This results in, that for the high-frequency operation of thyristors, the switch-on losses must be reduced to a minimum and the switch-off time must be shortened. Furthermore, the Reverse voltage applied in the shortest possible time and the dV / dt characteristic kept high. Besides, it is desirable to increase the service life of such semiconductor arrangements as possible.

The invention is based on the object of a semiconductor thyristor in the form of a controlled rectifier, especially for high power and for high frequency To create operation whose dV / dt characteristic is further improved and in which the switch-on power and so that the thermal load on the boundary layer can be further improved, with an increase at the same time should result in the service life.

This object is achieved according to the invention on the basis of the semiconductor thyristor according to claim 1 mentioned at the outset solved in that the point shunts are in the area of the vertices of equilateral triangles, and that the edge of the gate electrode lying next to the emitter area in the area of an apex of the equilateral triangle lies, which is determined by the point shunts closest to the gate electrode, thereby for the Gate current to determine a channel area between the point shunts.

Further features and configurations of the invention are the subject matter of further claims. '_;

The features and advantages of the invention also emerge from the following description of an exemplary embodiment.

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game in conjunction with the characterizing the invention both individually and in any combination Claims and the drawing. Show it:

Fig. 1 is a plan view of a thyristor according to the Invention;

Figure 2 is a section along line 2-2 of Figure 1;

4 and 5 plan views of various others

Embodiments of the invention; ■.

6 and 7 show a plan view and a side view in the case of a transistor with an integrated gate control;

8 shows the circuit diagram which is implemented in a thyristor according to FIGS. 6 and 7.

Of the. The purpose of a cathode shunt in thyristors is to prevent the premature ignition of the Thyristor by voltage surges on the cathode-anode line and also the creation of a current path for Charge carriers in the base area, so the thyristor quickly switches off when the current is reduced or reversed in its direction. With smaller thyristors and These cathode shunts at the edges of the cathode-emitter area can therefore be reduced in power realize, which are arranged opposite the gate area. With larger thyristors with higher power such an edge shunt is not sufficient to maintain a suitable dV / dt characteristic. Point shunts are therefore provided in the cathode-emitter area. However, it is obvious that a magnification the shunt areas in unfavorable proximity

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The gate area the current flowing through the gate as far as ■ can take over that the thyristor can no longer be ignited. By suitable arrangement of the gate area with respect to the point shunts in the cathode-emitter area, a channel ignition with high propagation speed is possible, whereby the dV / dt characteristic of the thyristor can be maintained and even improved.

1 and 2 is in one embodiment of the invention a thyristor 10 ignitable from an edge or side area on a substrate or a normally mounted as heat dissipation carrier, these mounting elements as anode electrodes for the P-type Serve the emitter area to which they are connected. The PNPN layer structure of the semiconductor wafer results by the further presence of an N-conductive base region 14 and a P-conductive base region 13, as well as the cathode-emitter region 12. The gate electrode 15 is in ohmic contact with the P-conducting base region 13, whereas a cathode contact or the cathode electrode in ohmic contact connection with the N-conductive Emitter area 12 is. A plurality of cathode point shunts 17 run through the N-type emitter region 12 and are in ohmic contact with the cathode electrode 16.

Normally, the semiconductor structure is produced by starting from an N-conductive substrate, which is the N-conductive Base area 15 forms. Then the P-conductive emitter region 11 and the P-conductive base region 13 are in the Semiconductor body diffused in during separate or simultaneous diffusion steps. The cathode-emitter area 12 is then formed by suitable masking of the P-conductive base region 13 around the diffusion regions to limit and the cathode-emitter area 12 and the point

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to train shunts 17.

The switching on of a thyristor begins in the emitter area next to the gate area, by adding charge carriers from the emitter area are injected into the P-type base region and charge carriers penetrate through the interface between the P-type base region and the N-type base region until has formed a current path to the anode region. This is shown schematically with dashed arrows 21 in FIG. 2. This switch-on area extends over the emitter area, around the entire area between the cathode-emitter area and the anode-emitter area, as indicated by arrow 22, to be filled. The speed with which forms the switch-on area is also referred to as the speed of propagation. About each of the point shunts 17 there is an area of influence within which the lateral voltage drop is insufficient is large to trigger a significant charge injection and therefore to bring about an involvement in this area. Thus, the cause of the decrease is the cathode-emitter injection (dV / dt) also responsible for hindering the expansion of the switch-on area after initial ignition. ,

The extent to which the expansion of the switch-on range is influenced can be determined by a suitable Arrangement of the cathode point shunts with respect to the gate electrode can be improved »Since the next to a shunt lying gate area supplies current within the sphere of influence of the cathode point shunts and the Thyristor cannot fire with this, this area can be eliminated, as indicated in FIG. 1 with the reference numeral 23 will. Thus, the current injected from the gate area is mainly used to trigger the closing and is not lost. As indicated by the dashed arrows 24 indicated, the current going out from the gate area into the

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Channel directed between the cathode point shunts because the edge next to the cathode emitter area of the gate area is designed such that it lies approximately at the apex of an equilateral triangle, which is determined by the two adjacent point shunts 17. The point shunts limit the speed of propagation not in these channels, resulting in a high switch-on speed.

In Fig. 3, a thyristor 30 is shown in which the Gate area arranged in the middle of the semiconductor structure is. The gate electrode 31 is in ohmic contact with the P-conductive base region 32, whereas the Cathode electrodes 33 in ohmic contact connection with the cathode emitter regions 34 and the cathode point shunts 35 stand. The gate electrode 31 is designed in the areas 36 and 37 in such a way that edges 38 and 39 lie in the vertex determined by the neighboring point shunts and not in the sphere of influence of the adjacent point shunts 35. The structure according to FIG. 3 can be used to generate the active Area of the thyristor in comparison with the structure according to FIG. 1 to double or the switch-on time somewhat by generating the gate current in the center of the two cathode-emitter areas, as a modification of the embodiment according to FIG. 1, where the gate electrode is on a lateral edge of the cathode-emitter area is arranged.

According to a further embodiment, the power capacity of the thyristor can further be achieved by a structure according to FIG Fig. 4 can be enlarged by not only inside the Kathoden-Emitterbe.reiches point shunts are provided, but by a metallization over the edges of the cathode-emitter area shunts with the

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P-type base to be attached in areas that do not lie next to the gate electrode. This thyristor 40 has a gate electrode 41 in an ohmic contact connection with a P-type base region 42, next to the cathode-emitter region 43. The cathode electrode 44 is in ohmic contact with the cathode-emitter area 43 and cathode point shunts 45 and also at certain points 46 along the perimeter of the P-type Base area 42. The gate electrode 41 is designed in area 47 in such a way that charge carrier injection emanating from the gate is eliminated in those points immediately adjacent to the areas of point shunts so that the current injected from the gate into channels flows, which both between the point connections as well as between these and the adjacent edge of the cathode-emitter area.

When manufacturing thyristor-controlled rectifiers with the highest possible power, it is usually preferable to build this up in a circular configuration with the gate in the center and from an annular one Cathode-emitter area is surrounded. Such a structure is shown in Fig. 5 and has a gate electrode 51 which is in ohmic contact with a P-conductive base region 52 in which an annular cathode-emitter region 53 is diffused. An annular cathode electrode 45 extends over the cathode-emitter area 53. and is in ohmic contact with this and with the cathode point shunts 54. The gate electrode 51 is designed along its edge in this way. ensure that those areas are eliminated that are on closest to cathode point shunts * This results in twelve in the illustrated embodiment effective gate edges 56, from which the injected gate current according to the dashed arrows 57 in channels

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runs between groups of cathode point shunts, which increases the speed of propagation and thus the effective switch-on time is significantly improved by avoiding gate currents that directly affect the point shunts are directed. The thyristor 50 can also be provided with edge shunts 58 in order to protect its Further improve the dV / dt characteristic.

Another circular thyristor structure is shown in FIGS. To explain this thyristor structure reference is also made to the circuit according to FIG. This thyristor structure is capable of a Control current of 100 A with a turn-on time of less than 2 microseconds, with the dV / dt characteristic 400 V / microsecond. The thyristor shown consists of a semiconductor wafer 61, which is provided with a heat dissipation 62 via an alloyed area 63. is bonded, which lies between the anode emitter region 64 and the disk for heat dissipation. The anode base area 65 is formed from the silicon semiconductor material that is used in manufacture. The cathode base region 66 is built up in this starting material by a P diffusion. By two in principle annular and concentrically extending N diffusions within the cathode base region 66 are first and second cathode-emitter regions 67 and 68 are formed. A primary gate electrode 69 is in ohmic contact connection with the central region of the cathode base region 66, while a second floating gate electrode 70 this primary Surrounds gate electrode and at the same time serves as a cathode electrode for the cathode emitter region 67. The primary cathode electrode 71 is in ohmic contact with the outer annular cathode-emitter area 68, as well with the cathode point shunts 72 within this Cathode-emitter area are provided.

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Since the thyristor structure according to FIG. 6 shows a triple symmetry, an equivalent circuit diagram for the upper third of the structure shown is described below with reference to FIG. The anode connection A, the gate connection G and the cathode connection K of the equivalent circuit correspond in the thyristor structure according to FIG connected thyristor-controlled rectifier 81, the cathode of which is connected via a} resistor R to the primary cathode and whose anode is connected to the primary anode. When the thyristor-controlled rectifier 81 is switched on, a current is conducted via the conductors 82 and resistors R _{s connected} in parallel to the parallel gates of equivalent thyristor-controlled rectifiers 83 to 86. The resistor R represents the resistance of the cathode-base region between the gate electrode 69 and the region between the cathode-emitter region 67 and the anode-base region 65. The thyristor-controlled rectifier 81 is represented by the region of the thyristor 60 which is below the cathode-emitter region 67 lies. Of the

Resistance R is diffused through an N-type η

Realized area that the first cathode-emitter area 67 connects to the second cathode-emitter region 68. The outer edge of the diffused cathode-emitter area 67 is designed in such a way that certain areas 75 arise with which the floating cathode electrode 70 (floating Gate electrode) is ohmically connected to the. Gate configuration for the equivalent thyristor controlled Rectifiers 83-86 to create. The resistors R_ appear as resistances of the cathode base area 66 ;, between the gate electrodes and the inner edge of the second cathode-emitter region 68. For this described Partial construction of the thyristor 60 results in that shown

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Structure according to FIG. 6 is basically equivalent to three Thyristor-controlled rectifiers operated as drivers are those with 12 thyristor-controlled rectifiers connected in parallel Rectifiers are made in a monolithic integrated design.

It is obvious that due to the above-described basic design features for the Construction of thyristors can also be used to create additional switching and monolithic configurations, while maintaining the essential features of the invention lead to different geometric structures.

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ORIGINAL INSPECTED

Claims (5)

M06GP / G-960/1 claims 1.) Semiconductor thyristor with an anode electrode one surface and a gate and cathode electrode on an opposite surface, wherein the gate electrode is in ohmic contact connection with a base region of the semiconductor body and the Cathode electrode in ohmic contact connection with an emitter region is within the base region, and parts of the base region through the Run emitter area and in ohmic contact connection with the cathode electrode to form point-shaped shunts, so that the point shunts (17, 35, 45, 54, 72) lie in the area of the vertices of equilateral triangles »and that the edge of the next to the emitter area lying gate electrode in the area of an apex of the equilateral triangle, which is through the point shunts closest to the gate electrode is determined to thereby create a Determine the channel area between the point shunts. 2. Semiconductor thyristor according to claim 1, characterized in that the gate electrode is designed in such a way is that the gate current is limited in those areas which are closest to the gate electrode Point shunts are adjacent ». 309842/0913 MO6OP / G-96O / 1 3. Semiconductor thyristor according to claim 1, characterized in that the emitter region is ring-shaped is formed and surrounds the gate electrode. 4. Semiconductor thyristor according to claim 3, characterized in that a further ring-shaped There is an auxiliary emitter area which runs concentrically within the annular emitter area, and that a floating gate electrode connects this auxiliary emitter region and part of the base region. 5. semiconductor thyristor according to one or more of claims 1 to 4, characterized in that the Contact connection with the base region is provided at a plurality of points to channel the gate current align, which basically run between the point shunts. 309842/091 3