JPS604260A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a gate turn-OFF thyristor which can control large current by improving the structure of uniform contact of a gate electrode part with a cathode electrode part. CONSTITUTION:In accordance with the groups of thyristor elements arranged by splitting into the center A and the outer periphery B of a substrate 100, two cathode side compensating plates 111 and 112 arranged to disk form in the former and ring form concentrically thereto, which are in sliding contact with the cathode electrode 106. Each plate 111 and 112 is in sliding contact with a cathode side coolant 113. A gate electrode plate 118 of ring form is arranged in the middle between said two plates 111 and 112, while the intermediate gate connection C of the semiconductor substrate 100 is in sliding contact with said plate 118. Since the plate 118 receives pressure force from the coolant 113 via insulation spacer 119 and an elastic element 120 such as a spring, the contact thereof with the connection C in a large area is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a semiconductor device having a control electrode. do.

(Background) As a semiconductor switching device that can control large currents,
Tairisters have been used and are widely used. As applied equipment becomes larger in capacity, Twiristors of several hundred ampere class have already been put into practical use. There is.

On the other hand, recently, gate turn-off thyristors (hereinafter referred to as GT), which can turn off the current by controlling the gate
O-thyristors (called "O-thyristors") have been developed, and their application to power supplies such as inverters that require a high degree of controllability is becoming active.

GTO thyristors are also becoming larger in current as the capacity of applied devices increases, and currently, GTO thyristors with a NiL current (value of main current that can turn off the gate) of 1000 amperes have been developed.

Gate turn-off of the GTO thyristor is performed by drawing out accumulated carriers in the semiconductor single crystal substrate due to the main current into the gate circuit through the gate terminal within a short time.

At this time, a large off-gate current that reaches about one-fourth of the main current flows through the gate.

Therefore, the GTO Zyristor needs to have a structure that can tolerate a large gate current.

As is well known, a large current GTO thyristor has a structure in which a large number of minute thyristor elements of one unit are arranged in parallel in a silicon semiconductor single crystal substrate.

One main electrode, an anode electrode, is formed on one main surface of the substrate, and the other main electrode, a cathode electrode, is formed on the other main surface of the substrate opposite to the anode surface. It is formed.

1. A gate electrode, which is a control electrode, is formed on the same surface as the cathode surface so as to surround all of the plurality of cathode electrodes. Note that the various electrodes mentioned above are generally formed of an aluminum vapor deposited film.

As a container for the high-current GTO Zyristor as described above, a single-story press-contact package with good heat dissipation properties is generally used.

The anode electrode of the semiconductor substrate is fixed to an anode-side compensating plate made of a metal having a coefficient of thermal expansion similar to that of silicon, such as tungsten, through a gap material such as aluminum. Furthermore, the anode-side compensating plate is made of a metal with good thermal conductivity.
It is in sliding contact with a cooling body made of copper, for example.

The cathode electrode of the semiconductor substrate is slidably contacted with a cathode-side compensating plate made of a metal having a coefficient of thermal expansion similar to that of silicon, such as tungsten. The cathode side compensation plate is made of metal with good thermal conductivity.

A gate electrode of a semiconductor substrate 1 that is slidably in contact with a cooling body made of copper, for example, is connected to an internal gate lead at one or more points on the semiconductor substrate, and the internal gate lead is further connected to an external lead. Ru.

The container also has a cylindrical body made of an insulating material such as ceramic, and has surfaces of the anode side and cathode side cooling bodies opposite to the semiconductor substrate side exposed to the outside, so that a lead outside the gate can be exposed to the outside. It has an airtight structure that allows it to pass through to the outside of the container.

By sandwiching and suppressing the anode side and cathode side cooling bodies, the flat pressure contact package can be assembled into various application devices while maintaining the several sliding contact surfaces in an electrically and thermally low resistance state. It is used in a complex way.

7' As described above, the gate structure of the GTO thyristor needs to be small so that it can tolerate a large gate current.

For this purpose, in the conventional high-current GTO Xyrisk, (1) the electrode tip is made of silver, etc. with a thick wire diameter, which can obtain the necessary gate current capacity in the tread part of the semiconductor substrate; (2) A method of pressing internal gate leads made of a metal with good conductivity, or (2) providing a plurality of aluminum internal gate leads m on the outer periphery of the semiconductor substrate that can fit the necessary gate current container. Methods such as ultrasonic welding are being implemented.

These methods are suitable for semiconductor substrates with a diameter of 30 to 40 mm.
m, high current GTO thyristors. The former is called the center gate method, and the latter is called the peripheral gate method, depending on the position of the gate extraction portion on the surface of the semiconductor substrate.

As the controllable current became even larger, the size of the GTO Cyrisk board also increased, and 60wIφ versions, like the conventional Cyrisk, were also commercialized. At this time, a new idea has become necessary for the structure of the lead in the gate of the GTO thyristor.

As mentioned above, in a large diameter GTO thyristor, a large number of unit thyristor elements are arranged in parallel.

At the time of gate turn-off, a turn-off current flows from each thyristor element toward the gate lead-out portion unevenly distributed in the center or periphery, and is concentrated in the gate lead-out portion.

Since the turn-off gate current flows laterally within the semiconductor substrate or through the gate electrode, a potential drop occurs according to the respective electrical resistances. That is, due to the uneven distribution of the gate extraction portion, a false direction M (potential gradient) is generated in the semiconductor substrate.

The lateral potential gradient e, [, which occurs during gate turn-off
This causes variations in turn-off times among multiple unit-reinput elements. That is, unit/lead resistor elements located close to the gate extraction portion are turned off earlier, and those located further away are turned off later.

As a result, the main current will concentrate on the unit silicate element that is located relatively far from the gate extraction part and turns off later in time3. This tendency is caused by the following:
This becomes more noticeable as the substrate size of the GTo thyristor becomes larger, and this becomes an obstacle to improving the controllable current.

Therefore, with the increase in the diameter of the GTo Tsilisk board,
Game with less lateral potential drop at turn-off) ffW
It is necessary to develop a new structure.

For this purpose, several methods have been proposed in which a gate electrode plate made of gold 6 is pressed over a large area against the gate electrode of the substrate together with the cathode compensating plate described above. Shi〃・shi,
It is extremely difficult to press the cathode electrode plate and the gate electrode plate selectively and precisely on a surface having a large diameter and a narrow shape or pattern.

As another method, it has been proposed to separate the cathode electrodes, which are divided into a large number of parts, into two groups, one on the center side and the other on the peripheral side of the substrate surface, and provide a gate extraction part in the middle.

An example of the structure of the substrate portion of such a GTO thyristor is shown in FIGS. 1 and 2. FIG. 1 is a plan view of the main surface side where a cathode electrode and a gate electrode are arranged, and FIG. 2 is an XY cross-sectional view of FIG. 1. J centrosome substrate 1ooFi
, ps conductivity type υ first layer (P emitter) 101, N
It is composed of a second layer (N base) 102 of conductivity type, a third layer (P bene) 103 of P conductivity type, and a fourth layer (N emitter) 104 of N conductivity type. ■A junction is formed between them.

P emitter 101 is exposed on one main surface of substrate 100,
Anode hybrid 105iC, connected to d-ζts.

The N emitter 104 is exposed on the other main surface of the substrate 100 in a state where it is divided into a large number of parts, each of which is connected to the power sword electrode 10.
6 is ohmically connected.

This example is a so-called "G' with intermediate gate pattern".
l”0 Twilista and Nemi May 04 I Hill II
on the radius formed by the equiangular angle, and on the center 11i of the semiconductor substrate.
It is divided and arranged into A and an outer peripheral part B. An intermediate gate connection portion C, which will be described later, remains between the center N emitter and the outer peripheral N emitter.

The P base 103 is located on the same main surface as the N emitter 104.
The gate electrode 107 is exposed so as to surround the N emitter 104 and is connected to the gate electrode 107 which surrounds the cathode 106.

The N base 102 is exposed at the end surface of the semiconductor substrate 100 together with the P emitter 101 and the P space 103, and is covered with an insulating surface stabilizing material 108 for stabilizing the voltage mutuality state of the semiconductor device. .

The anode electrode 105 is mounted on an anode-side compensating plate 109 made of metal whose thermal tensile coefficient is similar to that of the semiconductor substrate 100. On the other hand, although not shown, the cathode electrode 106 is pressed into contact with a cathode-side compensating plate made of a metal having a coefficient of thermal expansion similar to that of the semiconductor substrate 100 at the stage of assembling the container. .

As shown in FIGS. 1 and 2, the GTO silice with an intermediate gate pattern has a large number of fine cathode electrodes, i.e., unit twine elements, in a central part A and an outer peripheral part B.
An intermediate gate connection C is provided which divides the gate into two groups.

The intermediate gate connection part C functions to absorb the turn-off gate charge from the unit thyristor element m in the center part A and the unit thyristor element group in the outer peripheral part B at the time of gate turn-off. Dividing a unit Zyristor element group has the effect of reducing the lateral potential gradient during gate turn-off. However, in the case of this method, it is necessary to solve the problem of how to structure the cathode side compensation plate and the gate electrode plate, and it has not yet been put into practical use3. By attaching the substrate 100 to the anode side compensating plate 109, although their thermal expansion coefficients are approximated, the combined body may be slightly warped due to the bimetal effect. Particularly in the case of a GTO Zyristor that uses a large-diameter substrate, severe warping of the substrate is extremely harmful.

This is because, as mentioned above, in the GTO thyristor,
Since the cathode electrodes are formed separately, if the substrate is warped, a gap will be created between the cathode electrodes and the cathode-side compensation plate during mounting.

This means that at some point the Zyristor element becomes electrically open - and therefore some area of the semiconductor substrate becomes ineffective.

Such a phenomenon becomes more pronounced as the diameter of the semiconductor substrate becomes larger, and has the disadvantage that it becomes a factor that inhibits the increase in current of the GTO zyristor.

(Purpose) The present invention was made in order to eliminate the above-mentioned drawbacks, and its purpose is to make it suitable for use in various thyristors and power transistors including the above-mentioned intermediate gate type TO thyristor. Another object of the present invention is to provide a semiconductor device equipped with a gate electrode plate and a current control electrode plate.

(Summary) In order to achieve the above object, the present invention provides a structure in which a gate electrode plate having an M-plane shape substantially approximating the electrode shape of an intermediate three-way junction of a semiconductor substrate is provided with a rigid insulating element and The cathode-side cooling body is brought into pressure contact with the intermediate gate contact portion of the substrate No. 611 via the elastic element.

(Example) Below, the present invention will be described in detail with reference to the drawings.
3 is a sectional view of one embodiment of the present invention.

In this figure? The semiconductor substrate 100 has the intermediate gate pattern described above with respect to FIGS. 1 and 2. #Anode electrode tosF of conductor substrate 100
The anode-side compensating plate 109 holding the +if+ substrate 100 is attached with γi7 to the anode-side cooling body 110.
jl! IJJ concubine/1 bug.

The cathode electrode 106 of the semi-quadruple substrate 100 needs to be in sliding contact with the cathode-side compensating plates 111 and 112 in the same manner as described above. For this reason, in this embodiment, as shown in No. 30, the thyristor elements are arranged in a disc shape and concentrically with each other, corresponding to the thyristor element groups divided and arranged in the central part AJ and the outer peripheral part B of the I2 plate 100. Two annular cand side auxiliary tit plates 111 and 112 are provided, which are in sliding contact with the cathode electrode 106.

Further, each of the cathode-side compensating plates 111 and 112 slides into contact with the cathode-side cooling body 113.

An annular gate@electrode plate 118 is disposed at the intermediate pressure between the two cathode-side compensating plates 111 and 112, and the intermediate gate connection portion C of the semiconductor substrate 100 is in sliding contact with the gate electrode plate 118. Since the gate electrode plate 118 receives a pressing force from the cathode side cooling body 113 via an insulating spacer 119 and an elastic element 120 such as a spring, it is possible to contact the intermediate gate connection part C over a large area. Tohoru. The gate electrode plate 118 is insulated from the p cathode side compensating plates ill, 112 and the cathode cooling body 113 by an insulating spacer 119. .

Anode side and cathode side cooling body 1==10, 11
3 are elastic flanges 115, 116, 11, respectively.
7, it is welded and fixed to the insulating outer wall 114 of the container.

Note that the anode side compensating plate 109 is aligned and placed inside the outer wall 114 via a flexible material 124 such as Teflon or silicone bar.

Further, one end of an internal gate lead 121 is connected to the gate electrode plate 118, and the other end is welded to a gate pipe 122 that penetrates the outer wall 114.

The in-gate lead 121 has, for insulation from the cathode,
The ultimate sex treatment 123 is applied.

When mounted, the anode side and cathode side cooling bodies 110
, 113 from both sides (top and bottom in the figure) with a strong elastic force, each sliding contact portion can be brought into a state of electrically and thermally low resistance.

Although the present invention has been mainly explained above in the case where it is applied to a large current GTO thyristor, those skilled in the art will recognize that the structure of the present invention can be applied not only to GTO thyristors but also to general thyristors or power transistors. It will be easy to understand.

Further, although an example has been described in which the unit thyristor element group is divided into two parts, a central part and an outer peripheral part, it is also possible to divide it into three or more parts. In this case, the cathode-side compensating plate is pressed according to each element group, and the plurality of intermediate goo rings are pressed by the elastic elements at the boundaries of 7, respectively.
Of course.

(Effects) As is clear from the above description, according to the configuration of the present invention, the unit thyristor element groups separated by the intermediate gate connection portion, that is, the unit thyristor element groups in the center portion A and the outer peripheral portion B, are separated by the intermediate gate connection portion. , respectively i + ta ni force y - tol!
Ila [L & i1x O, r: rj 1x2Fc contact M
Therefore, the warpage of the substrate within the range of each cathode compensating plate can be reduced to approximately half of the amount of warpage of the entire substrate.

As a result, the difference in height due to the warpage of the substrate in each unit thyritta group can be absorbed by the plastic deformation of the cold 711 body 1.13 on the cathode side, which has a hardness of /J. , cathode electrode and cathode i+:Q
(The plates 111 and 112 come into uniform pressure contact with the tli 4.

Furthermore, according to the present invention, the gate electrode plate 118 having a shape approximating the shape of the intermediate gate connection portion of the plate is
By the elastic element 120 and the cathode side cooling body 113, n
Since it is pressed against the gate electrode independently of the cathode side compensation plates 111 and 112, uniform contact between the gate electrode plate 11B and the gate electrode 107 is also possible.

Due to the uniform welding structure of the gate electrode portion and the cathode electrode portion as described above, in the GTO Zyristor of the present invention, even if the diameter of the semiconductor substrate is increased, no voids are formed on each sliding contact surface. The second effect of the present invention is that the current capacity of the gate electrode plate 118 can be increased.3. Since the structure presses the gate electrode plate 118 against the contact portion C, the lead resistance of the gate electrode can be reduced compared to the conventional method of taking out the gate from the center of the board or the method of taking out the gate by ultrasonic welding of aluminum wire. This enables good operation even when turning off a large current at the gate.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a semiconductor substrate of an intermediate gate type TO thyristor suitable for applying the present invention, and FIG.
3 is a sectional view taken along the line X-Y in the figure, and FIG. 3 is a sectional view of a semiconductor device according to an embodiment of the present invention. 100...Semiconductor substrate, 105...Anode? ! Pole, 106... Cathode electrode, 107... Gate electrode, 109... Anode side compensation plate, 110... Anode side cooling body, 111, 112... Cathode side compensation plate, 113... Cathode Side cooling body, 118... Gate electrode plate, 119... Insulating spacer, 120... Elastic element

Claims (4)

[Claims] (1) Separate two or more PN junctions between a semiconductor substrate formed therein, a lth main electrode formed on a first main surface of the semiconductor substrate, and a second main surface of the semiconductor substrate! a plurality of second main electrodes divided into at least two groups, a central part and an outer peripheral part;
a control II electrode formed to surround the main electrode; a first compensation plate connected to the ff5i main electrode; a first cooling body slidingly contacted to the first compensation plate; and a second main electrode. between a plurality of second compensating plates in sliding contact for each group, a second cooling body in sliding contact with the plurality of second compensating plates, and the plurality of second compensating plates. A semiconductor device comprising at least one control electrode plate disposed and in sliding contact with the control electrode, and elastic means for pressing the control electrode plate against the i[t control electrode. (2) The patented device is characterized in that a control electrode contact portion is left between the second main electrode group at the center and the second main 'wL electrode group at the outer periphery. (3) The second compensating plate slidingly in contact with the second main electrode group at the center is circular; the second compensating plate slidingly contacting the second main electrode group at the outer periphery is annular; 2. The semiconductor device according to claim 1, further comprising an annular control electrode plate disposed between the compensating plates. (4) the elastic means is provided between the second cooling body and the control electrode plate, and an insulating member is provided between the elastic means and the control electrode plate;
This insulating member is connected to the control electrode plate and the 22nd genus of the 22nd ilI compensating droplet is connected to the control electrode plate.
1. Semiconductor device described in Section 1.