JPH0211792Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electrode for a semiconductor device. When checking the static characteristics of thyristors, diodes, etc., for example, checking the bevel surface or checking the diffusion state of a semiconductor device, it is performed either with a pellet or with a semiconductor device incorporating a pellet. These will be explained with reference to FIG. 1, taking a thyristor as a semiconductor device as an example. FIG. 1 is a sectional view showing an example of a conventional thyristor. Note that a detailed explanation of the configuration of the thyristor will be omitted here because it will be shown later when explaining the present invention. First, the case of checking the static characteristics in the pellet state will be explained. In FIG. 1, an anode electrode 3 is provided under an aluminum alloy layer 2, for example, a silicon substrate (hereinafter referred to as a Si substrate) 1 as a semiconductor substrate. Further, on the upper side of the Si substrate 1, a gate electrode 4 is provided at the center, auxiliary gate electrodes 5 surrounding the gate electrode 4 on both sides thereof, and cathode electrodes 6 as main electrodes surrounding the auxiliary gate electrodes 5 on both sides. There is. The side surface of the Si substrate 1 is lapped to obtain a beveled shape, and the beveled surface 1a is further etched into a semi-mirror shape.
is formed. When the pellet 7 made of such a material is used to check for defects on the bevel surface 1a, for example, a voltage is applied between the cathode electrode 6 and the anode electrode 3 to check the breakdown voltage. At this time, the measurement terminal for applying voltage must be brought into contact with each electrode. This tends to damage the electrode surface, especially if the surface of the cathode electrode 6 is a molybdenum plate, a tungsten plate, etc., such as a molybdenum plate (hereinafter referred to as Mo plate) 8.
must be pressed together, and scratches will impair adhesion. If the Mo board 8 is pressed against a scratched object and a large current is passed through it, local concentration of current may occur, and depending on the degree of the scratch, the thyristor may be destroyed. Therefore, static characteristics are not often checked in the pellet 7 state, and checks are generally performed with the pellet 7 incorporated in a seal, as described below. Next, this state will be explained. That is, a protective silicone rubber 9 is applied to the beveled surface 1a. Furthermore, on the surface of the cathode electrode 6 of the pellet 7 ,
Mo board 8 is placed on it. The Mo plate 8 is the gate electrode 4,
A hole is provided on the surface of the gate electrode 4 so as not to contact the surface of the auxiliary gate electrode 5, and a hole is dug into the surface of the auxiliary gate electrode 5 in accordance with the shape of this electrode. And lead line 1
After 0 is attached to the gate electrode 4, the thyristor is obtained by sandwiching copper posts 11 and 12 as seals from above and below and bringing them into contact with each other under pressure. In this way, the beveled surface 1a of the thyristor is checked for defects in the state in which the Mo plate 8 is closely attached to the surface of the cathode electrode 6. That is, a predetermined voltage is applied between the cathode electrode 6 and the anode electrode 3. At this time, bevel surface 1
If the withstand pressure of a is lower than a predetermined value, the thyristor is disassembled in order to take out the pellet 7 from the seal,
Also, peel off the silicone rubber 9. Then, the beveled surface 1a is reprocessed to increase the withstand pressure. After reprocessing, silicone rubber 9 is applied to seal pellets 7 and the like in the seal, and then the air inside the seal is replaced with nitrogen. In this way, in the case of a breakdown voltage failure, the thyristor must be disassembled or replaced with nitrogen, which is very time-consuming. The present invention has been devised to eliminate such drawbacks, and the object is to provide an electrode for a semiconductor device whose static characteristics can be checked in the form of a pellet without damaging the main electrode. Hereinafter, the present invention will be explained based on FIGS. 2 to 7. 2 to 7 show the manufacturing process of an embodiment of the present invention, and in the figures, the same reference numerals as in FIG. 1 indicate parts having the same functions. FIG. 2 is a plan view showing a state in which an electrode is provided on a Si substrate, and FIG. 3 is a cross-sectional view taken along the line X-X' in FIG. , an anode electrode 3 is formed in this layer. Furthermore, aluminum is deposited to a predetermined thickness on the upper part of the Si substrate 1. This portion is then etched to form a circular gate electrode 4 in the central portion. Approximately 2/3 of the radius of the cathode electrode 6' as the main electrode is formed around the gate electrode 4.
The auxiliary gate electrode 5 is formed to have a predetermined width and to radiate at right angles in four directions. Furthermore, an electrode is formed from this electrode to the outer peripheral edge of the Si substrate 1, and this electrode is used as a cathode electrode 6' through which a large current flows.
divided into separate cathode electrodes 6'' with a small area that allows checking of static characteristics.
The separated cathode electrode 6'' is provided independently in a part of the outer circumferential direction of the cathode electrode 6'.Here,
The cathode electrode 6' and the separated cathode electrode 6'' are provided on the surface of the same diffusion layer 1b (the part of the surface of the Si substrate 1 surrounded by a dotted line) diffused in the Si substrate 1.The separated cathode electrode 6'' The position where is provided is not limited to the embodiment, but may be any position as long as it is on the same surface of the diffusion layer 1b as the large current cathode electrode 6'. Further, regarding the area and shape, any shape may be used as long as the static characteristics can be checked and the purpose of the predetermined current capacity is achieved. Now, during the process of the pellet 7' made of the above-mentioned material, the static characteristics are checked. That is, when checking the voltage resistance of the beveled surface 1a, a predetermined voltage is applied between the separated cathode electrode 6'' and the anode electrode 3.At this time, by bringing the measurement terminal into contact with the separated cathode electrode 6'', It will hurt. However, since the electrode plate explained in FIGS. 4 and 5 is not pressed into contact with this surface,
Large currents do not flow through this portion, and local concentration of current does not occur. In addition, when checking for poor diffusion in the Si substrate 1, a predetermined voltage is applied between the separated cathode electrode 6'' and the anode electrode 3, and a voltage is applied to the gate electrode 4, and the determination is made based on the on/off operation. The electrode 3 may also be scratched by the measurement terminal, but this is not a problem because the material in pressure contact with the surface is a copper post, which is softer than the hard Mo board.Also, the gate electrode 4 is also scratched by the measurement terminal. This may cause scratches, but the same can be said for bonding the lead wire 10 to this part as shown in FIG . proceeds to the next step, i.e. the fourth step.
The electrode plate shown in FIGS. 6 and 5 is placed on the surface of the pellet 7' and the thyristor is manufactured through the steps shown in FIGS. 6 and 7. Next, these steps will be explained. Fig. 4 is a plan view showing the electrode plate, Fig. 5 is a sectional view taken along line Y-Y' in Fig. 4, Fig. 6 is a plan view showing the electrode plate placed on the surface of the pellet, Fig. 7 is a sectional view showing the state of a completed thyristor. In FIGS. 4 and 5, an electrode plate such as a molybdenum plate or a tungsten plate, for example, a molybdenum plate (hereinafter referred to as Mo plate) 8' is slightly larger in the outer circumferential direction so as not to come into contact with the surface of the aforementioned separated cathode electrode 6''. A part of P is cut out.Also,
In order to prevent the Mo plate 8' from coming into contact with the surfaces of the gate electrode 4 and the auxiliary gate electrode 5, a hole Q is formed in the central part facing the surface of the gate electrode 4, and a hole Q is provided in the part facing the surface of the auxiliary gate electrode 5. Gate electrode 5
A recess R that is slightly larger than the surface shape is provided. If the static properties of the pellet 7' are checked and there are no problems, silicone rubber 9 is applied to the beveled surface 1a as shown in FIGS. 6 and 7. Furthermore, the above-mentioned Mo plate 8' is placed on the surface of the pellet 7' for alignment. That is, Mo
Place the plate 8' so that it contacts only the cathode electrode 6'. Next, as shown in FIG. 7, a lead wire 10 is attached to the gate electrode 4, and a good thyristor can be obtained by sandwiching these wires between copper posts 11 and 12 and pressurizing them from above and below. . As explained above, according to the present invention, it is possible to check the static characteristics of a pellet without damaging the main electrode. At this time, if the product is found to be defective, it can be reprocessed in pellet form.
There is no need for laborious field work or nitrogen replacement work. Furthermore, by cutting the electrode plate so that it does not come into contact with the separated main electrode, the number of positioning points is increased compared to the conventional one, and the accuracy of alignment when placed on the pellet is improved. Therefore, in the electrode of the semiconductor device according to the present invention, a separate main electrode is provided independently in a part of the main electrode, and a cut is made so that it does not come into contact with the electrode plate placed on top of the separate main electrode. The number of man-hours required for reprocessing defective products can be greatly reduced.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of a conventional thyristor, Figs. 2 to 7 are views showing each part of an embodiment of the thyristor according to the present invention, and Fig. 2 shows a state in which electrodes are provided on a Si substrate. 3 is a sectional view taken along the line X-X' in FIG. 2, FIG. 4 is a plan view showing the electrode plate, and FIG. 5 is a sectional view taken along the line Y-Y' in FIG.
FIG. 6 is a plan view showing the electrode plate placed on the surface of the pellet, and FIG. 7 is a sectional view showing the completed thyristor. 1...Si substrate (silicon substrate), 1b...diffusion layer, 3...anode electrode, 4...gate electrode, 5
...Auxiliary gate electrode, 6,6'...Cathode electrode,
6″...separated cathode electrode, 7,7′ ...pellet, 8,8′...Mo plate (molybdenum plate).

Claims (1)

[Scope of utility model registration request] A separate main electrode is provided on the surface of the same diffusion layer that is diffused on one side of the semiconductor substrate, so that the main electrode and a part of the main electrode do not need to be pressed into contact with each other, and are provided independently so as to serve as an assembly positioning mark for the pressure-welding electrode plate. An electrode for a semiconductor device, characterized in that an electrode plate is pressed against a surface of the main electrode by removing a portion corresponding to the separated main electrode so as not to contact the separated main electrode and any electrode other than the main electrode. .