SE468731B - WEAKLY TYRISTOR SYSTEM - Google Patents

Description

; f Ü V7? 4 (; u / .-.... \. emitter transitions are short-circuited using one with the thyristor integrated MOS drop power transistor. Due to the fact that the the transistor is integrated with the thyristor, it is not possible to optimize the design of the thyristor and of the extinguishing towers independently. Furthermore, it is difficult to at high current density to avoid parasitic effects, which make extinguishing impossible in the intended manner.

DESCRIPTION OF THE INVENTION The invention aims to provide a system of initial show specified stroke, - which requires low control power, both for ignition and for extinguishing, - which can carry load current with low joint voltage cases and thus small joint losses, - which can work at high voltages, - in which parasitic effects are avoided, whereby the components can be allowed to operate at high current densities, and - at which the design of the thyristor structure can be optimized independent of the extinguishing transistor.

What characterizes a thyristor system according to the invention appears from the appended claims.

DESCRIPTION OF FIGURES The invention will be described in more detail below with reference to conclusion to attached figures 1-5. Fig. 1 shows a principle diagram for a system according to the invention. Fig. 2a shows a section through a part of the semiconductor body where they are in the system constituent bipolar transistor and thyristor structures and ' The ignition MOS transistors are trained. Fig. 2b shows, seen from the cathode side, emitter and base layers of one of the the thyristor modules included in the system, as well as some of the system included and on the semiconductor body mounted control and the contact layers. Fig. 3 shows how in one embodiment it separate semiconductor body, in which the extinguishing transistor of the system 468 73? is trained, is arranged on the semiconductor body, in which other transistor structures of the system and thyristor structures are trained, but separate from the latter semiconductor body of an electrically insulating layer.

DESCRIPTION OF EMBODIMENTS Fig. 1 shows a schematic diagram of an embodiment of a systems according to the invention. It includes a first half- conductor body H1, in which a plurality of modules TM1, TM2, TM3 etc. are provided, as well as a second semiconductor body H2, in which a MOS field effect transistor MN2 for switching off the component is educated. The semiconductor bodies are made of silicon. Transistor MN2 can, for example, be made in so-called SOS technology (SOS = con On Sapphire).

The system has an anode connection A and a cathode connection C.

Both of these connections are connected to all the modules.

The extinguishing transistor M2 is connected between the cathode connection C and a conductor B, which is a low resistive connection to all modules. The control of the transistor is arranged for supply of a control signal Goff for switching off the system.

A conductor D forms a connection to all the modules for supply of an ignition signal Gon.

The modules are identical to each other. Each module contains a PNP-type bipolar transistor structure QPO between systems met anode and cathode connections. Two bipolar transistors structures, a PNP transistor QP1 and an NPN transistor QN1, are connected to each other so that they in a known manner constitute one thyristor structure, which is in series with a resistor Rn connected between the system's anode and cathode connections. One MOS field effect transistor MN1 for ignition of thyristor structures the tour is in series with resistors RD and Rs connected between the anode-side base layer of the thyristor structure and its cathode-side emitter layer. The control of the transistor is connected to the conductor D. for supplying the ignition signal Gon. The conductor B is via one resistor Rpl connected to the cathode side of the thyristor structure C "7? 4 4- Ö / \ J1 C, | \ base layer, which can be connected by means of the transistor M2 with the cathode connection C for shunting the thyristor structure cathode-side emitter junction for extinguishing the system.

Transistors M1 and MN2 are N-channel transistors of enriched type (normally non-conductive).

Fig. 2a shows one of the modules TM1 etc in the form of a section through the semiconductor body H1. Closest to its lower surface in the figure this has a strongly P-doped layer 1, which constitutes the QPO emitter of the sistor and the anode side of the thyristor structures emitter. Closest to this layer is an N-doped layer 2 and a weaker N-doped layer 3 which later forms the thyristor the anode-side base layer of the structures and the QPO base of the transistor layer. Layer 2 prevents it by its stronger doping barrier layer as in block voltage across the system (anode positioned relative to the cathode) is formed at the transition between layers 3 and 4-4a from reaching the anode emitter layer 1. De the now mentioned layers are common to all modules.

A collector layer 4, 5, also common to all modules 6 is arranged closest to the opposite surface of the semiconductor body. This layer consists of two P-doped layers 4 and 5 and a strong P-doped layer 6, and it constitutes the collector QPO of the transistor. cod layer.

Each module has one arranged in an opening in the collector layer heavily N-doped individual thyristor emitter layer 7. This layer is arranged in a P-doped layer 4a, 5a which constitutes the cathode-side base layer of the thyristor structure. For leader B contacting this layer is closest to that of the semiconductor body surface provided with a strongly P-doped area 6a. Layer 4a in the right part of the figure next to the surface of the body constitutes the channel area of the transistor MN1, the source region of which is that of thyristor emitter region 7 connected N-doped region 8 and whose drain area consists of the base layer 3. The resistance in the base layer layer 3 forms the resistor RD shown in Fig. 1. 468 751 Between the area 7 and the channel area extends a thin and weaker N-doped region 8. The resistance of this region is the resistor Rs shown in Figure 1. _ The area 4a is connected to its left part in the figure layer 4 by means of a bridge 40 of P-conducting material.

This results in a partial bridging of the thyristor the emitter junction of the structure (short-circuited emitter) and thus partly in a known manner an increase of the thyristor's dU / dt resistance and partly to a certain extent a facilitation of the thyristor structure quenching. By appropriate choice of the bridge's 40 dimensions and conductivity, the partial bridging of the emitter the transition is given the desired degree of efficiency. The bridge can extend along a larger or smaller part of the area 4a rand, but the bridge must not extend into the area for transistor MNl.

A layer 20 of polysilicon forms the gate of the transistor MN1 and is separate from the semiconductor body of a thin silica layer. The layer 20 is, as schematically shown in the figure, connected it with a conductor pattern 21 of polysilicon (polycrystalline silicon) which, possibly in combination with a metal pattern, constitutes the leader D.

A silicon dioxide layer 13 is arranged on the surface of the semiconductor body and provided with openings for contacting the various parts of the body areas and of the polysilicon layers. A metal layer 12 contacts transistor QPO collector layer 6. A further metal layer 15 contacts the emitter region of the thyristor structure 7 and the part of the same located closest to the transistor MN1 collector layer. A gap between the metal layers 12 and 15 above for the oxide layer 13a allows the current from the thyristor structure to the cathode contact must flow through the area 6, under which the gap located part constitutes the resistance Rn.

A metal layer 17 contacts the area 6a and forms or is connected to the conductor B. On top of the metal layers 12, 15, 17 are an additional oxide layer 14 is provided, and on top of this _ » -3 731 "ß CT * layer, a continuous metal layer 16 is provided, which through openings in the oxide layer 14 contacts the metal layer 12 and constitutes the cathode connection of the system.

The components shown in the schematic diagram in Figure 1 are also exposed in Figure 2. The resistors Rp1 and Rp2 are lateral resistance of areas 4a and Sa. Transistor QPO in Figure 1 is shown in Figure 2 as a part QPO2 to the right of the thyristor module in the figure, and some QPO1 to the left of the thyristor the module.

The P-doped region 4a has relatively low doping to obtain keep the threshold voltage of the transistor MN1 low. Area 5a has stronger doping than the layer 4a to give low latency voltage drop.

As mentioned above, the transistor QPO collector layer 4-6 is formed a continuous layer provided with openings for the thyristor modules. The openings and thyristor modules can be for example, be distributed over the surface of the semiconductor body in one two-dimensional grid pattern.

Figure 2b shows an example of the design of a thyristor module and its connection layer. The solid line 101 constitutes the boundary line between the layer 4 and the layer 3, and it solid line 102 the boundary line between the layer 3 and the council 4a. In doing so, the bridge 40 between the layers tet 4 and the area 4a. The solid line 103 forms the boundary the line between area 8 and areas 4a and 7, respectively the solid line 104 forms the boundary line between the area 7 and areas 4a-5a and 8, respectively. The dotted line 20 constitutes the control of the transistor MN1, and the one under the control the lower part of the region 4a constitutes the channel region of the transistor.

The metal layer 15 contacts the layer 4 in the contact areas 15a l5e and the area 7 in the contact area 15f. The metal layer 17 contacts area 5a (via areas 6a) in the contact areas l7a - l7e. The metal layer 12 contacts the collector layer 4-6 in a plurality of contact areas, of which only the closest ones u: v - 468 731 the areas l2a - l2f located in the thyristor module are shown in Figs. clean.

Figure 3 shows schematically how the semiconductor body or it semiconductor layer H2, in which the extinguishing transistor M2 is formed dad, is placed isolated from the semiconductor body H1 but electrically connected at B and C. The body / layer H2 can then as mentioned above to be made in SOS technology, the layer 30 consists of sapphire.

In Figure 4, the semiconductor body / layer H2 is placed on semiconductor body H1 but isolated from it by a layer 30a.

Figure 5 shows a particularly advantageous mounting method for the semiconductor body H2. It is mounted here with so-called Flip- chip technology to the semiconductor body's H1 contact points C and B so that these connections become very low-impedance. In order to make Goff externally accessible, connect the Goff connector to one metal surface 31 which is isolated from the semiconductor body H1 with a layer 30b (e.g., silica layer) and extends under the body H2.

The system is turned on by a short positive voltage pulse Gon the conductor D and thus the conductors of the transistors are supplied MNl. The latter then become conductive, with an electron flow obtained from areas 7-8 via MN1 into the base layer 3. This in turn gives rise to a hole injection from the emitter l in in the base, and this over the entire emitter-base transition 1-2-3.

Part of this residual current flows to the parts of the collector areas 4-6 which are contacted by the cathode contact - transistor QPO1 and QPO2 lead. A second part of the hole current flows via the NPN transistor QN1 and causes electron injection from the emitter area 7. This provides thyristor function of the thyristor structure QP1 - QN1, and the thyristor continues to conduct current with a low conduction voltage drop even after that the transistor MN1 after the control pulse Gon has returned to non-conductive condition. Ü * - CO m U4 In order to facilitate the extinguishing, it has been found to be advantageous to design the component so that a not insignificant part of the total current will flow through the transistor parts QPO. A suitable ratio between the currents is for example 80% of the current in the thyristor parts and 20% of the current in the transistor parts. The relationship between the currents can be controlled by means of the area ratio between the transistors and the thyristor parts. In order for the desired power distribution to be obtained, it has proved important that of the transistor parts total area is significantly larger than the total of the thyristor parts area, for example 3 to 20 times larger.

The system is switched off by a positive control voltage pulse Goff the control of the transistor MN2 is supplied, this transistor becomes conductive and short-circuits the conductor B and thus the thyristor the base layers 4a-5a of the structures to the cathode C. If the product of thyristor current and lateral resistance Rpl is less than about 0.5 V ceases the electron injection from the emitter area 7. Under the extinguishing process, most of the neck current is taken over by system parts QPO. In the base layer 3 existing holes disappear out through the transistor part and the transistor MN2 via the conductor B.

When the tail is gone, both the thyristor and transistor parts cease to lead, and the component has been turned off.

To obtain effective extinguishing, the conductor / conductor pattern is performed B saw that it gets low resistance. For the same purpose, extinguishing the transistor MN2 with as low a voltage drop as possible.

Because it is separate, it can easily be given large dimensions and thus low joint voltage drop. It has further been shown advantageous to use as a quench transistor a MOS transistor N-type, because this type of transistor has the best possible league conductance per unit area.

In its non-conductive state, the system can handle high block voltages. (anode A positive with respect to cathode C), wherein the transition between the base layer 3 and the collector layer 4 is II blocking.

By using MOS components both for ignition and for switching off the system requires very little control power. The an- The MOS components can further be made with low strength pacitans, which further reduces control requirements and gives the system high speed.

By passing the dominant part of the load current of the thyristor part with its low voltage drop gets the system low joint losses.

The separate quench transistor has been shown to provide an effective shutdown of the system, even at high current densities, for example of the order of 500 A / cm2. For the efficient the extinguishing helps the system to have a low basic doping (the doping in the N-base layer 3). Extinguishing is further facilitated that the relatively low hollow current from the transistor structure the turn QP1 effectively shunts to the cathode through it relatively low resistive layer 5a. The shunting of the thyristor parts cathode emitter transitions that occur during the extinguishing process further facilitated substantially by that with each thyristor module series-connected resistor Rn. This resistance limits the current but to each individual thyristor emitter. During the extinguishing process resistance will mean that the potential of a tyrant high current toremitters are raised, thereby shunting the emitter the transition automatically becomes more efficient.

In a system according to the invention, so-called latch-up is avoided (undesired thyristor effect) during the extinguishing process. To this contributes that the transistor MN1 source region 8 is has relatively weak doping and thus low injection efficiency. Further can easily stream the area 8's built-in series resistance limited to harmless levels. To this beneficial effect is to be obtained, the series resistance in area 8 should be of at least the same order of magnitude as the equivalent resistance sen in P-bases 4a-5a.

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ON 10 751 The system described above is only an example of one CÜ preferred embodiment of the invention, and other embodiments forms are conceivable within the scope of the invention.

For example, semiconductor materials other than silicon can be used. Although the above-described PNP structure of the transistor QPOs have been shown to be most beneficial, so natively these are designed as NPN transistors.

The bridge 40 for partial short circuit of the thyristor part todemitter transition may be omitted.

In the embodiment described above, for clarity only a few modules were shown. The number of thyristor modulus and their dimensions and spacing, as well as the dimensions of the transistor parts may in each particular case adapted to the current requirement for power management capability at the system.

As shown in Figure 3, the extinguishing transistor MN2 can be fitted on the semiconductor body in which the main components of the system are formed. Alternatively, it may be different from said half-core. dark body (but preferably applied in the same capsule as this), whereby low-resistance connections are arranged between lan of both semiconductor bodies.

Alternatively, the system may be provided with a plurality of extinguishing transmissions. cysts, each preferably common to a group of thyristor modules.

As an alternative to the above-described and shown extinguishing transistor MN2, other extinguishing means can be used, eg others types of semiconductor components other than MOS transistors.

In the above-described embodiment of a system according to According to the invention, each thyristor module is provided with a transistor tor (MN1) for ignition of the thyristor module and thus of the system IN)

Claims (13)

U F 4 7 468 / O: temet. Alternatively, only certain thyristor modules can be provided with such transistors, the ignition of the system taking place by lateral spreading of charge carriers from these modules. In the above-described embodiment, the collector layer 4-6 of the transistor structure consists of a single continuous layer. Alternatively, the transistor structure of the system may be divided into a plurality of parts, each with its own collector layer. PATENT REQUIREMENTS Extinguishable thyristor system, characterized in that it comprises a first semiconductor body (H1) with a first and a second opposite main surface, which are provided with a first (A) and a second (C) main contact for the load current of the system, a first emitter layer ( 1) of a first conductor type (P) closest to the first main surface and connected to said first main contact (A), a base layer (2,3) of a second conductor type (N) adjacent to the first emitter layer, at the second main surface at least one more said second main contact (C) connected collector area (4,5,6) of said first line type (P), which together with the base layer (2,3) and said first emitter layer (1) forms a transistor structure (QPO), at said second main surface a plurality of two-layer modules, each comprising an area (4a, 5a) of said first line type (P), in which an individual thyristor emitter area (7) of said ß f Q 7:21 is connected to said second main contact 12: Oo .J second wire type ( N) is provided, each two-layer module together with said first base layer (2,3) and first emitter layer (1) forming a thyristor module (QPLQN1), at least some of the thyristor modules having a semiconductor body integrated MOS transistor (MN1) for ignition of the thyristor modules, which MOS transistor is connected between said first base layer (3) and the individual emitter layer (7) of the thyristor module, and in that the system comprises a extinguishing means (MN2) common to a plurality of thyristor modules, arranged to switching off the thyristor modules shunt the modules' individual emitter transitions (7-5a). Extinguishable thyristor system according to claim 1, characterized in that the individual emitter area (7) of a thyristor module is connected to said second main contact (C) via a first resistor (Rn) integrated in said collector area (4,5,6) for limiting the current of the thyristor module. Quenchable thyristor system according to claim 1, characterized in that the MOS transistor (MN1) of a thyristor module is connected to the individual emitter layer (7) of the module via a second resistor (8). Extinguishable thyristor system according to claim 3, characterized in that the second resistor (8) consists of an area (8) of said second line type arranged between the channel region (4a) of the MOS transistor and the individual emitter layer (7). (N). Extinguishable thyristor system according to claim 1, characterized in that the channel region of a MOS transistor (MN1) is formed by a part of that region (4a) of said first lead type (P) of the two-layer module included in the thyristor module. 13 468 751 Extinguishable thyristor system according to claim 1, characterized in that one of the source and drain regions of a thyristor module MOS transistor (MN1) is constituted by a part of said first base region (3). Extinguishable thyristor system according to claim 1, characterized in that the area (4a) of said first line type (P) of a two-layer module is partially connected to adjacent collector area (4) by means of a bridge (40) of material of said first line type (P). Extinguishable thyristor system according to claim 1, the core of the extinguishing means consists of a second MOS transistor (M2) formed in a second semiconductor body (H2) separated from the first semiconductor body. The extinguishable thyristor system according to claim 8, the core of said second semiconductor body (H2) is arranged connected to said first semiconductor body (H1) but separated therefrom by an electrically insulating layer (30a). The extinguishable thyristor system according to claim 8, characterized in that said second semiconductor body (H2) is arranged connected to said first semiconductor body (H1) via metallic contact areas (32, 33, 34). ll. Extinguishable thyristor system according to claim 8, core: ec: collated by ati: the second MOS transistor (MN2) consists of an N-type MOS transistor. Extinguishable thyristor system according to claim 1, the core and the layers of the semiconductor body and areas of said first conductor type are P-conducting and the body layers and areas of said second conductor type are N-conductive. . 4 6 '7 4 l 4 I' E LN 8 Extinguishable thyristor system according to claim 1,] cär1- sign drawing water the total area of said collector areas (4) is at least 3 times larger than the total area of the areas (4a, 5a) of the first line type (P) of said two-layer modules . v31 'f) IA