DE1015152B - Method and device for manufacturing semiconductor devices - Google Patents

Description

GERMAN

When melting the electrode metal for the purpose of alloying it with a semiconductor, there is often a Uniform wetting, which is necessary to achieve an alloy layer of uniform thickness is difficult to achieve. Aluminum, for example, tends to form an oxide layer. Gold that as a carrier of doping substances such as indium or antimony, preferably with a content of van; about. 1 per cent., which is often used, tends to melt when it is melted for droplet formation, the depth of penetration of the alloy layer becoming uneven. The mentioned, Difficulties can be overcome by placing the foil on top of the semiconductor Electrode metal, a mechanical pressure is exerted by means of a pressure body, the pressure surface of which the surface of the semiconductor to be alloyed is plane-parallel. However, the molten electrode, metal " squeezed out sideways. According to an earlier proposal, it becomes the simultaneous one. Alloying several electrodes used a shape adapted to the semiconductor device, their parts according to the insertion, the semiconductor and the electrode foils. clamped together before insertion into the furnace will. However, such solid shapes are difficult to produce with the required accuracy, especially for complicated semiconductor shapes, their. Electrodes partly in recesses are to be attached to a semiconductor surface.

The invention relates to a method: for the production of semiconductor devices, in which an im essential single crystal semiconductor body, e.g. B. of germanium, silicon or an intermetallic Connection of elements of III. and V. Group of the Periodic. Systems, with an or several metallic electrodes, which with the semiconductor placed one on top of the other and with the application of mechanical pressure by heating be combined. "

An improvement and simplification is achieved according to the invention in that the insert unit consisting of semiconductor and electrode metal is embedded in powder of a substance that does not react with the constituents of the insert (graphite, magnesium oxide, aluminum oxide or the like) in preparation for the alloying process and in this state, the Heating is suspended until the alloy is formed. When pressed together, the powder forms a shape that adapts itself precisely to the enclosed insert unit, with the powder exerting pressure on all sides like a liquid on the insert. As a result, the mutual position of the individual parts of the insert is retained even when it becomes liquid. This is not only the desired uniform thickness of the resulting processes and devices
for the manufacture of semiconductor devices

Applicant:

Siemens-Schuckertwerke

Aktiengesellschaft,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Dipl.-Phys. Reimer Emeis, Pretzfeld,
has been named as the inventor

Alloy layers, but also the preservation of the external shape or surface configuration of the electrodes, secured, because as a result of the same pressure of the powder on all sides, a lateral leakage of electrode material is impossible. The amount of powder with the enclosed insert can be put into a solid hollow mold be introduced from a simple shape, z. B. in. A metallic hollow cylinder, the open ends be completed by cylindrical press stamps preferably made of solid graphite, these can sawn off a graphite rod in the form of a disk and be provided with longitudinal channels drilled through for the extraction of gases.

A suitable ^{device 1} , consisting of several parts, for performing the method is shown in FIGS. 1 to 4, for example.

Fig. 1 shows a. Pipe section 2 made of metal, for. B. steel or brass, in which a bottom 3 made of the same material, which is offset in diameter, fits into its shoulder. Above the bottom there is preferably colloidal graphite powder, which is compressed by means of a likewise metal stamp 5 with moderate pressure to form a durable pill 4α. Then punch 5 and bottom. 3 is removed, and the pipe section 2 is turned over so that the pipe end closer to the pill 4a is at the top, as shown in FIG. 3. A second pill is shown in FIG. 2 by means of a second. Pipe section 6 produced, which has the same inside width as the pipe section 5, but a greater wall thickness. It is offset on the inside at one end so that the weaker pipe section 2 just fits into it, as can be seen in FIG. The pipe section 6 is, according to Fig. 2 with the remote end over the ground. 3 placed inside

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this end fits in completely. In. the pipe section 6 closed off at the bottom in this way a suitable amount of graphite powder poured and using the punch 5 to a durable pill 4 pounds? compressed. Then the stamp 5 is removed again.

According to FIG. 3, the pipe section 2 with the pill 4a is placed over a graphite piston 7, which can be sawn off a graphite rod and provided with some narrow gas channels 12. On the easily accessible top of the pill 4ka the individual:, preferably circular parts 8 cc to 8 c of the insert unit individually, as concentrically as possible, loosely placed, z. B. first an aluminum foil 8 b, the thickness of which can be about 0.05 mm, with a diameter of about 9 mm, on it an about 0.4 mm thick disk a, us p-conductive silicon with a diameter of about 10 mm and on top of this a gold foil with about 1% antimony content, about 0.05 mm thick and with a diameter of approximately 9 mm. Then the tube piece 6 with the pill 4 & is placed on the upper end of the tube piece 2, the punch 5 is inserted from above and slowly pushed down so that the pill. 4 b and later also the insert unit 8 a to 8 c and the pill 4 up can be pushed down onto the piston 7, by applying more force to the. Punches 5 are then the pills, 4 α and 4 b deformed again until, as shown in FIG. After removal of the stamp 5 and the upper pipe section 6, the upper end of the pipe section 2 is shown in FIG. 4 by a: second, graphite piston. 9 completed. The whole thing can be done by one. elastic frame. 10 held together: are, which can be provided with a pressure screw 11 for the purpose of setting the desired pressing pressure.

With this device, even more complicated shapes with more than make two electrodes. Thus, FIG. 5 shows, as an example, the enlarged sectional profile of a transistor, consisting of from a semiconductor wafer 16 with grooves in which the emitter electrode 14 is attached, while on the raised central part the base electrode! 13 and the collector electrode 15 are to be attached to the underside.

In order to bring about the formation of the alloy, the device according to FIG. 4 is used with that in the powder embedded semiconductor device in a heating furnace, with preferably subjected to electrical heating of the required alloy temperature. In the case of the above Example of a p-conducting silicon wafer with an aluminum foil on one side, and an antimony-containing gold foil on the other side of the Disc, good results have been achieved by heating it up to a temperature of 800 ° C. V2 minutes after this temperature had been reached, the heating power was switched off and, after cooling to 250 'bis 200 ° C the items are removed from the Ofeo. Mixtures can also be used instead of the above-mentioned types of powder consisting of a uniform substance suitable substances are used. It can be of particular advantage to add a substance to the powder, through which oxygen is bound. In this case, the heating can be even in the natural. Take place in an air atmosphere, while it is otherwise more advantageous heating in a vacuum or under Carrying out protective gas, however, was also possible when using. pure graphite powder through heating A perfect alloy formation is achieved in a normal atmosphere.

Claims (5)

PATENT TRANSP. L CIIE: 1. A method of manufacturing semiconductor devices, in which a substantially single crystalline Semiconductor body and electrode metal placed on top of one another and using mechanical Pressure can be merged by heating, characterized in that the Semiconductor and electrode metal insert unit for preparing the alloying process in powder one with the. Components, the use of non-reactive substance embedded and in this state is subjected to heating until the alloy is formed. 2. The method according to claim 1, characterized in that that the powder is first pressed into pill form, combined with the insert and the whole thing after being pressed into a solid hollow mold. 3. Device for performing the method according to claim 1, characterized in that that a solid hollow form of. easier, ahead of time wise cylindrical shape at least on one side with a movable punch as a closure organ is provided. 4. Apparatus according to claim. 3, characterized in that the stamp is made of the same, however, solidified substance exists like the embedding powder. 5. Apparatus for performing the method according to claim 2, consisting of two pieces of pipe same clear width, but with different wall thicknesses, of which the stronger inside, see above is offset so that one end of the weaker fits into it, and from a bottom that is in diameter is offset in such a way that it extends into the weaker piece of pipe up to the shoulder and into the offset The end of the thicker piece of pipe fits in completely. 1 sheet of drawings © 709 660/343 8.57