DE3443784A1 - GATE SHUT-OFF THYRISTOR - Google Patents

Description

-A-

Gate turn-off thyristor

DESCRIPTION

The invention relates to a gate turn-off thyristor and, more particularly, to an electrode structure of a metallized Electrode in the contact area of the connecting wire on the chip surface of a gate turn-off thyristor.

In this day and age it is of the utmost importance, like the growing desire to save energy and raw materials, can be encountered. With a view to such a situation, new functional elements were developed in the field of power electronics and the demand for such functional elements has increased remarkably these days. Gate turn-off thyristors are used as elements for inverters or breaker circuits attracted special attention. This is because it is a gate turn-off thyristor excellent and ideal properties as a high-speed switching element compared with any other conventional transistor or high-speed switching thyristor, owns. The main characteristics of a gate turn-off thyristor can be described as follows will.

(1) Because a gate turn-off thyristor has the ability of self-interruption as in the case of a conventional

union high-speed switching thyristor inevitably necessary breaker circuit is not required, and accordingly it becomes possible to make devices smaller and lighter close.

(2) The ON-OFF control of an element can be made with less Tax performance to be carried out.

(3) A thyristor with a short turn-off time can, compared with a conventional high-speed switching thyristor, can be obtained in a relatively simple manner.

(4) An element with large reverse voltage and large current can be easily manufactured.

(5) The compatibility for surge currents corresponds to the compatibility of a thyristor. Gate turn-off thyristors, which have the advantages described above, are now mainly used in industrial electrical machines, converters, power supplies etc. and will be used in the future these are largely used in other areas as well.

An example of the construction of such a gate turn-off thyristor is in German patent N6449 E / 42 DE32O0-807 described.

In general, a thyristor has a PNPN four-layer structure having a p-type emitter layer, a η-type base layer, a p-type base layer and a Η-type emitter layer. On the surfaces of the p-type emitter layer, the p-type base layer and the emitter layer of the η-type are e.g. a metallized anode electrode in ohmic contact (hereinafter referred to as the A-electrode designated), a metallized gate electrode (hereinafter referred to as

denoted as the G electrode) and a metallized cathode electrode (hereinafter referred to as K-electrode) is provided. A small current flows from the G-electrode to the K-electrode, the thyristor is activated when a prescribed voltage is applied between the A- and K-electrodes is that the Α electrode has a positive potential, switched from the OFF state to the ON state and on large main current (AN current) flows from the Α-electrode to the K-electrode. This means that the thyristor is considered to be contactless Switch can be operated. In the case of an ordinary thyristor, the control function of the G-electrode remains however, not obtained when the thyristor is switched from the OFF state to the ON state. To one To allow such ordinary thyristor to return from the ON state to the OFF state, the following is necessary:

(1) To make the ON current smaller than the holding current or vice versa,

(2) forcibly interrupting the current by reversing the direction of current flow between the A and K electrodes. On the other hand, a gate turn-off thyristor has the same basic structure as an ordinary thyristor, but differs but differs from an ordinary thyristor in that a gate turn-off thyristor has the ability to Owns self-interruption. In particular, if a reverse current (current from the K-electrode to the G-electrode) between the G and K electrodes of the gate turn-off thyristor in the ON state, the gate turn-off thyristor flows can be switched from the ON state to the OFF state.

The structure of the chip of a conventional gate turn-off thyristor can now be described with reference to Figs. Fig. 1 is a plan view of a gate turn-off thyristor chip 100. A glass passivation 109 is provided on the edge of the chip 100. A metallized gate electrode 106 is inside the glass passivation 109 and a metallized cathode electrode 107 is further provided inside, this fits into the electrode 106 in the form of the teeth of a comb. These electrodes are against each other isolated by a protective oxide film 108. An example of such a comb-shaped electrode structure is in Japanese Patent Laid-Open Nos. 117276/1982 and 37658/1981.

FIG. 2 is a sectional view taken along line 2-2 in the chip 100 shown in FIG. 1. For example, a p-type base layer 103 and a p-type emitter layer 102 are placed on and under a base layer 101 of the η-type of an n-type silicon single crystal substrate. As a p-type impurity, gallium, boron or the like diffuses. An n-type emitter layer 104 containing η-type impurities such as phosphorus, is formed by diffusion in partial areas on the upper surface of the p-type base layer 103. On the Surfaces of the p-type emitter layer 102, the p-type base layer 103 and the n-type emitter layer 104 For example, a metallized anode electrode is used in ohmic contact 105, a metallized gate electrode 106 and a metallized cathode electrode 107 are formed. Fig. 3 Fig. 3 is a sectional view of the structure taken along the line

3-3 of the chip 100 in FIG. In general, the metallized layer has the metallized Anode electrode 105 has a multiple metallized structure made of, for example, Al-Mo-Ni-Au, Al-Zn-Ni-Au or Cr-Ni-Au, so that the Chip 100 can be attached to a cooling plate or the like by soldering. For the metallized layers of the metallized gate electrode 106 and the metallized cathode electrode 107, Al is used as Al for formation the fine structure which is necessary in order to obtain the desired functions of the gate turn-off thyristor is.

The transition from the ON state to the OFF state of the gate turn-off thyristor, namely the changes in the anode current (ON current) i_, the gate current I _n and the anode-cathode voltage v. in relation to the time course of the switch-off process are plotted, for example, on the vertical axes as a function of time t on the horizontal axes in FIGS. 6A, 6B and 6C. Fig. 6D shows the positional relationship of i, i and v .. As a factor in developing the performance of a gate turn-off thyristor, the turn-off gain (G "") can be considered. G "" is represented by a ratio of Ι _φπη (controllable ON current) and Ι-, π (peak value of the reverse gate current) as shown in the following equation (1).

^G off

Accordingly, the gate current i flows in the opposite direction at the time of switching off with a strength of i " _M. " = ¹ IGR ^{= 1} TGoZ ⁰ Of " ^{In an element with Ζ} · ^Β ·

and G ~~ = 4 becomes the value of I _n ~ 50A and thus flows in

Oil liK

large reverse gate current. The controllable ON current Imp _{0 of} the gate turn-off thyristor is expressed by equation (2), in which the current I_- _{o is} inversely proportional to the effective width (S) of the cathode electrode.

¹ TGQ ^{= 4}

In this equation, V _R "denotes the reverse gate voltage, V / p the thickness of the p-type base layer 103, T the length of the cathode electrode 107, S the width of the cathode electrode 107, and 5 denotes the average resistivity of the p-type base layer 103 Type under the η-type emitter layer 104.

Consequently, in order to obtain a predetermined resistance of the gate turn-off thyristor with a large controllable ON current I _{m /} -, _n at the same time, it is necessary to make the effective cathode electrode width (S) as small as possible and accordingly it is necessary to make a fine one To form structure. For this reason, Al is suitable and is generally used for the metallized layers of the metallized cathode electrode 107 and the metallized gate electrode 106. On the other hand, for reasons of cost, in assembling a gate turn-off _{thyristor having an I t} _, q of about 200A or less, a method of soldering the metallized anode electrode 105 to a heat sink is employed, and in view of the metallized cathode and gate electrodes 107, 106 a method is generally used in which, as shown in FIG. 7A in different

3 A 43 784

Shown on a larger scale, a thin, outwardly leading Al wire 300 with a diameter of about 300 to μπι on the Al-metallized surface by ultrasonic welding However, since both Ljqq and I are as above assume large values, if thin Al wires are used, a plurality of wires is necessary to be arranged in parallel by ultrasonic welding, resulting in inefficient assembling work.

In order to avoid the above-described disadvantages of a conventional gate turn-off thyristor, it is the task of Invention of providing a gate turn-off thyristor in which the connecting wires to the metallized cathode and / or gate electrode with high reliability and high Assembly efficiency without deteriorating the gate turn-off thyristor performance can.

The invention comprises a gate turn-off thyristor with a first base layer of a first semiconductor conductivity type, a second base layer of a second semiconductor conductivity type which is provided adjacent to the one surface of the first base layer, a first Emitter layer of the second semiconductor conductivity type that of the opposite surface of the first base layer is provided adjacent and a second emitter layer of the first semiconductor conductivity type, which on subregions is formed on the surface of the second base layer, the surface profile of the second emitter layer Shaped to match the teeth of a comb, metallized electrodes are shaped to each

Ohms see contact with the surfaces of the first emitter layer, the second base layer and the second emitter layer, and the gate turn-off thyristor described above characterized in that at least one contact area for connecting a connecting wire to the metallized electrode on the second emitter layer a solderable metallized Has electrode structure.

Further features and usefulnesses of the invention emerge from the description of an exemplary embodiment based on the figures. From the figures show:

1 shows a plan view of a conventional gate turn-off thyristor chip;

FIG. 2 is a sectional view of the assembly taken along line 2-2 of that shown in FIGS Chips is added;

3 is a sectional view of the assembly taken along line 3-3 of the chip shown in FIG is;

4 shows a plan view of the gate turn-off thyristor chip of an embodiment according to the invention;

FIG. 5 is a sectional view of the assembly taken along line 5-5 of the chip shown in FIG is;

FIGS. 6A, 6B and 6C show changes in the anode current i ", gate current α «and the anode-cathode voltage v., e.g. as a function of the time of the shutdown process

and FIG. 6D shows a positional relationship of FIG

¹ G ^{and V} A ^;

and

7A shows a conventional method for connecting a connecting wire to a metallized cathode ■ '· * .- ♦ '- "

electrode or a metallized gate electrode and FIG. 7B shows a method according to the invention. '"

In the drawings, identical reference characters indicate identical or corresponding parts.

A chip structure of a gate turn-off thyristor according to the invention will be described with reference to Figs. Fig. 4 is a plan view of a chip of a gate turn-off thyristor according to the invention. The structure in cross section of the chip shown in FIG. 4 along the Line 2-2 is the same as that of Fig. 2 and the cross-sectional structure shown in Fig. 5 along line 5-5; The structure of the main part of the gate turn-off thyristor according to the invention is the same as that of a conventional one Gate turn-off thyristor, and therefore detailed description thereof will be omitted. The inventive Gate turn-off thyristor differs in structure compared to a conventional gate turn-off thyristor, in that the metallized structure of the contact areas of the connecting wires 107a, 106a of the metallized cathode and gate electrodes 107, 106 are formed as a solderable metallized layer for connecting the connecting wires, and that the metallized structure of the metallized cathode and gate electrodes 107, 106, which form the contact areas

107a, 106a of the connecting wires exclude, as an Al layer are formed, which is capable of forming a fine structure, so that the desired performance of the Gate turn-off thyristor can be achieved. As a solderable metallized structure of the contact areas 107a and 106a A multi-metallized structure made of Al-Mo-Ni-Au or Al-Zn-Ni-Au, for example, is used for the connecting wires. A vapor deposition process is used as the method for forming the multiple metallized structure in these parts or a combined process of vapor deposition, coating, etc. is used. As a method of forming the metallized Layers in these areas can be applied a process in which during the time of formation the Al-metallized layer that forms the contact areas 107a and 106a of the connecting wires excludes the Almetallized Layer also formed under the metallized areas 107a and 106a by a vapor deposition process and then a layered metallized structure of the metallized areas 107a and 106a is formed. Alternatively, a method can also be used in which the metallized areas 107a and 106a through a process different from the process of forming the Al-metallized layer of the regions 107 and 106 so that the metallized layer can be connected in the respective areas. An example a method of connecting the leads to the contact areas 107a and 106a of the leads is shown in FIG 7B. A solderable, nickel-plated connecting wire 400 made of relatively thin copper sheet or the like. is made is with a solder material 200 on the metallized cathode electrode 107a or the metallized

Gate electrodes 106a formed for connecting the connecting wires are soldered. _{It goes without saying} that, depending on the amount of I _GR »which is obtained from the amount of the current load limit (amount of I TG0) of the gate turn-off thyristor used, the invention can only be applied to a metallized cathode electrode part.

In addition, the invention is of course not limited by the gate turn-off thyristor described above and can also be applied to a semiconductor element such as a power transistor, which is a finely structured metallized Electrode has to be applied.

As described, the invention enables a gate turn-off thyristor to provide a high reliability, in which the connecting wires during the assembly work powerfully interconnected cores without that thereby the characteristics of the gate turn-off thyristor are deteriorated.

Claims (5)

PATENT ADVERTISEMENT DIPL.-PHYS. LUTZ H. PRÜFERD-8OOO MUNICH 90 FO 57-3235 3 A4 3784 P / Ka / hu Mitsubishi Denki Kabushiki Kaisha, Tokyo / Japan Gate turn-off thyristor PATENT CLAIMS 1 Λ gate turn-off thyristor with a first base layer (101) made of a semiconductor material of a first conductivity type, a second base layer (103) made of a semiconductor material of a second conductivity type, wherein the second base layer (103) is provided adjacent to a surface of the first base layer (101), a first Emitter layer (102) made of a semiconductor material of the second conductivity type, wherein the first emitter layer (102) is provided adjacent to the opposite surface of the first base layer (101), and a second Emitter layer (104) made of a semiconductor material of the first conductivity type, wherein the second emitter layer (104) in the partial area of the surface of the second base layer (103) is formed, the surface structure of the second PATENT ADVERTISEMENT DIPL.-PHYS. LUTZ H. PRÜFER · D-8000 MUNICH 90 - HARTHAUSER STR. 25d TEL (089) 640 640 Emitter layer (104) shaped like the teeth of a comb, and metallized electrodes (105, 106 and 107) are provided in such a way that they each see ohmic contact with the surfaces of the first emitter layer (102), the second base layer (103) and the second emitter layer (104) have, characterized in that at least one contact area (107a) for connecting a connecting wire to the metallized Electrode structure is provided. 2. gate turn-off thyristor according to claim 1, characterized in that a contact area (106a) for connecting a connecting wire to the metallized Electrode on the second base layer (103) has a solderable metallized electrode structure. 3. gate turn-off thyristor according to claim 2, characterized in that the solderable, metallized electrode structure of the contact area (107a and / or 106a) is a multi-metallized structure made of Al-Mo-Ni-Au or Al-Zn-Ni-Au, starting in the order below the side of the semiconductor of the first or the second conductivity type. 4. gate turn-off thyristor according to one of claims 1 to 3, characterized in that the first conductivity type is η-type and the second conductivity type is p-type is. - ο - 5. Gate turn-off thyristor according to one of claims 1 characterized in that the first conductivity type a p-type and the second conductivity type an n-type