DE1110317B - Semiconductor arrangement with at least one p-n junction and alloyed electrodes - Google Patents

Description

GERMAN

PATENT OFFICE

G19712 Vmc / 21g

REGISTRATION AG: 26 _r MAY 1956

NOTICE THE REGISTRATION AND OUTLOOK EDITORIAL:

JULY 6, 1961

The invention relates to semiconductor arrangements a monocrystalline semiconductor body with alloyed electrodes and with at least one p-n junction.

The ones used in the arrangement near the invention Semiconductors are those with a diamond crystal structure and electron conduction. Semiconductors, like z. B. germanium and silicon; are either referred to as p-conductive or η-conductive, depending on the type and the sign of the electrical charge carrier, the nature of which depends primarily on the nature of the predominant Activator depends.

Despite the fact that the semiconductor arrangements, which were produced by the previously known alloying methods, work quite satisfactorily, an improvement in terms of the current gain and the reduction of the nonlinearity at large currents can be achieved with the semiconductor arrangement according to the invention, especially in the case of Hälbleiteranordnimgen for high-performance operation. This is also the case compared to the older proposal, according to which the alloy material should consist of 0.1 to 2 or 10 "% gallium and the remainder of indium in order to achieve a well-emitting pn junction in a transistor. To form a semiconductor crystal of germanium, to apply liquid gallium to the surface of the area to be converted, to which indium, preferably less than 60 ⁰ Zo, can also be added.

The arrangements according to the invention take advantage of the fact that the separation coefficient of indium in a semiconductor crystal depends on the temperature and on the melting point of the semiconductor material decreases rapidly up to a temperature of about 400 ° C. This temperature dependence the deposition coefficient of indium in germanium is shown in "curve B" in FIG. Taking this temperature dependency into account, an acceptor alloy could be specified, which is significantly superior to the previously known.

In the semiconductor device according to the invention, the alloy material consists of at least one Electrode made from 0.02 to 0.1 percent by weight gallium and the remainder from indium. In addition, that educates Alloy material makes extensive contact with the semiconductor body.

Some possible embodiments of the semiconductor arrangements according to the invention are described in the description explained in more detail on the basis of the drawings.

Fig. 1 shows a graph of the separation coefficients " About activators as a "function of the temperature;

Semiconductor device

with at least one p-n junction

and alloyed electrodes

Applicant:

General Electric Company,
Schenectady, NY (V. St. A.)

Representative: Dr.-Ing. W. Reichel, patent attorney,
Frankfurt / M. 1, Parkstrasse, 13

Claimed priority;
V. St. v. America May 27, 1955

Ann Dixon Warner and Robert Noel Hall,

Schenectady, NY (V. St. A. %
have been named as inventors

Fig. 2 is a cross section through a p-n area rectifier;

Fig. 3 is a cross section of another embodiment corresponding to Fig. 2;

Fig. 4 is a cross section through a p-n-p junction transistor;

Fig. 5 is a schematic cross section of an n-p-n junction transistor, and

Figure 6 is a graph showing the improved Shows properties of the arrangement of Fig. 5 in comparison with arrangements of a similar type.

When alloying electrodes under; formation of a recrystallization layer was originally does not take into account that the separation coefficients of some impurities are strongly temperature-dependent are. The deposition coefficient of an impurity in a growing semiconductor body is that Ratio of the amount of impurity, per unit mass, that is present in the growing body separates, to the amount of the impurity per unit mass in the melt, with which see .der growing body is in balance. Among the three commonly used acceptors for germanium, namely gallium ,. Aluminum; and indium, it was previously assumed that only indium was suitable possesses mechanical properties .. Gallium is liquid at room temperature and is therefore used for production

109 620/345

3 4

unsuitable for alloy transitions. Aluminum is related to these better properties forms a brittle eutectic with germanium and is particularly pointed out in FIG. 6. The amount of is therefore also not suitable. Indium, on the other hand, gallium added to indium is critical as a is malleable, melts easily and for a long time, due to the small addition, results in an alloy that keeps the track favorable properties have been preferred. There are 5 disadvantages of the essentially pure indium however, it has been found that indium has in electrical while adding a lot of gallium the By no means ideal for the production of alloys because of their mechanical properties Alloy transitions with n-germanium bodies for the production of alloy surface rectification or alloy contacts with p-germanium bodies tern and transistors makes unsuitable. If the is. The usefulness of an acceptor when the BiI- io percentage of gallium is 1 percent by weight an alloy contact with a half-step, then one becomes rich in gallium Conductor body depends on whether there is a sufficiently high second solid phase with a low proportion of solidification of the activator in the recrystallized half-point the contacts made with it mechanically

conductor layer is installed. This depends in the first place on unsuitable. -

Line from an excess of the activator and the 15 In Fig. 2, a rectifier is shown. Of the

Deposition coefficients from. Earlier, measuring rectifiers 10 containing a semiconductor wafer 11

Solutions of the deposition coefficient at high levels from η-germanium and two electrodes 12 and 13,

Temperatures carried out, and it was assumed that the z. B. can consist of nickel or Fernico

the deposition coefficient of indium was so great, and in electrical contact with the two of each other

that there is enough indium in the recrystallized Ger- 20 opposite surfaces of the plate 11,

manium layer is incorporated. The electrode 12 is on the plate 11 by a

Fig. 1 is a graphical representation of the deposition layer 14, which contains 0.02 to 0.1 percent by weight formation coefficients of gallium and indium in Ger-gallium, while it is otherwise shown essentially as a function of temperature. borrowed from indium. The acceptor material 14 As can be seen, the deposition coefficient 25 forms a pn junction 16 with the semiconductor of gallium in germanium (curve A) less than plate 11, which is a third of a decade before the recrystallized region, within the temperature 15 of p-germanium lies. Since the alloy overrange from 400 to 900 ° C, while the deposit consists mainly of indium, it has the malleability of indium (curve B) when indium changes and forms a pliable contact of the alloy temperature from 900 to 400 ° C 30 between the plate 11 and the electrode 12, so drops by almost two decades. This decrease that no cracking or peeling of the connection of the deposition coefficient of indium occurs in Ger- at high operating temperatures,
The electrode 13 is connected to the semiconductor wafer 11 by a sufficient number of indium atoms in the through a solder 17, which deposits a good electrolytically recrystallized layer. At 400 ° C it has 35 tric and mechanical properties. This, therefore, a concentration of 10 ~ ⁵ parts indium in solder cannot achieve tin or an alloy with one of the recrystallized layers, while the small percentage of a donor rend for a contact more than 10 ~ ⁴ parts indium remainder of indium consists. For this purpose it may be necessary. a mixture of about 10 to 30 percent by weight

Since the melting temperature of germanium is about 40% of a donor, e.g. B. arsenic or phosphorus, in indium

941 ° C, one could assume that Germa- are used. Since the separation coefficient of

nium bodies could be heated up to 900 ^c C, indium in germanium is much smaller than that

so that the correct amounts of indium are included in the deposition coefficient of the donor in germanium,

Separate the recrystallization zone. However, it is made up of the electrical properties of the contact

For other reasons, it is desirable that junctions 45 be determined by the donor. On the other hand, since

if more indium is present on the germanium bodies at temperatures of borrowed, the alloy has

about 400 to 500 ° C can be generated. It is Z. B. practically the same mechanical properties

extremely difficult to compare the depth of diffusion as pure indium, i. that is, the alloy is sufficient

various impurities in the germanium body ductile in order to withstand temperature stresses without cracking

to be controlled at temperatures above 500 ° C. In addition, to withstand formation or flaking,

The rectifier 10 shown in FIG. 2 is shown in FIG

connecting wires and the solder used in the manufacture of the following manner. A plate 11 from

development of the semiconductor devices are used. η-germanium in monocrystalline form is made from

However, the main reason for making the η-conductive germanium crystal cut-out alloy junctions at a comparatively low 55th, the comparatively lower resistance temperature consists in the fact that the heat level is preferably less than 1 ohm-cm. treatment of the semiconducting properties of the Ger- The plate 11 can, for. B. a thin piece of germanium adversely affected if the germanium manium be about 0.05 cm thick, is heated to over 500 ° C. However, this may vary depending on the purpose

Gallium is liquid at room temperature and its arrangement is different. The length and

therefore for the production of alloy transitions with the width of the platelet are not critical, but can

Germanium not suitable per se, but tiny inches of about 0.67 cm.

Mixtures of gallium to indium result in the formation of a p-n junction in the German

Alloy, which is a very good combination of acne platelets 11 and the attachment of the electrode

represents receptors for germanium. With such a 65 12 by means of an acceptor alloy 14 on the one hand and

Alloy-made semiconductor arrangements have the soldering of the electrode 13 by means of a donor

zen more favorable electrical properties, namely alloy 17 on the other hand, can be in two independent

both as rectifiers and as transistors. frequent cuts can be made. Appropriate

Claims (5)

5 6 However, both processes are carried out simultaneously with tin solder, a tin arsenic solder or an indium. Then the germanium platelets 11 and solder containing 10 to 30 percent by weight of arsenic or phosphorus Electrodes 12 and 13, which are preferably made of Nikphor, can be soldered on. The contact with kel exist, as well as the thin layers of the donor zone 33 is supported by an acceptor solder of the above gate alloy 17 and the acceptor alloy 14 prepared according to 5 specified composition. Even though Kind of a packet stacked on top of each other and in no rectifying layer by alloying with a suitable furnace is heated and the base 33 is formed together, the base contact must alloyed. The alloy temperature can fluctuate somewhat, but a sufficient number of defect electrons ken; however, it is advisable to supply these between 400 to the base zone so that the transistor effect and 500 ° C should be selected so that no adverse effects occur. problems arise. The time of the heating can be selected as an example of the improvement in a vernpn transistor of FIG. 5 by using a different according to the thickness of the germanium plate 11. When using a base contact made from the above-mentioned acceptor alloy forming germanium platelets approximately 0.05 cm thick, reference is made to FIG. 6. This shows a satisfactory pn junction at a temperature. Figure is a graphical representation of the current temperature of 400 ° C in one minute. Gain _{factor a 0} as a function of the emitter. FIG. 3 shows another embodiment of the incoming current of the same transistor with two different arrangements from FIG. The rectifier of those base contacts recorded. Curve C, Fig. 3, differs from that of Fig. 2 in that Fig. 6 shows that the current amplification factor a _Q position of the nickel electrode 12 is a lead wire 18, 20 of an npn junction transistor with a base contact which can consist of nickel, directly is connected to the electrode from pure indium of about 0.94 at 0.1 mA on electrode body 19, which in turn drops by about 0.82 at 10 mA when the emitter current is alloyed to the n-germanium plate 11, as in FIG 0.01 mA is increased to about 10 mA. The connection described for the arrangement of FIG. 2 indicates a drop of more than 10%. The curve D was. The body 19 of the acceptor activator material 25 of Fig. 6 shows the more favorable course of the current contains an alloy of 0.02 to 0.1 weight gain _{factor a 0 of} the same transistor with percent gallium, the rest of which consists of indium. a base contact with an acceptor alloy made of through the alloying and cooling a thin gallium and indium. The curve D rises steadily from the region 20 of p-germanium in the chip 11 to the initial value at 0.01 amps, until the current generates 5 mA, which reaches a pn junction 21 with the main 30, and then falls slowly at 40 mA approximately on the body of the n-plate 11. the initial value. The two curves show that a further exemplary embodiment is shown in FIG. 4 that shows transistors with the gallium-indium alloy; this figure shows a transistor 22 with a high current amplification _{factor 0} even with a thin monocrystalline plate 23 with high emitter currents.
η-germanium, which expediently has a resistor 35. In a circuit with a grounded emitter, which has less than 1 ohm-cm and both of which are often used at low frequencies, the opposing main sides are two Mas power amplification of an amplifier stage propose 24 and 25 of the above-mentioned acceptor _{alloy from tkmal dßr size} (1; ' _{Therefore a very} gallium and indium applied by alloying VI - <v are. Before the recrystallized districts 26 and 27 40, a small drop from a _{0 shows} a sharp drop in the line made of p-germanium, the p-n junctions 28 and the power gain of the transistor stage are large 29. The distance between the p-n junctions 28 currents. Is z. B. the behavior of two transit and 29 is very small and amounts to about 0.0025 cm. Or less. Contact with the main body of the same, then the power gain is one The transistor 23 is produced by an electrode 30. The transistor with the base contact is made of pure indium represents, the z. B. from Fernico or nickel consist of 5 mA emitter current about 50, while the line can and the on the body of the plate 23 in stungsigungsicherung the same transistor at 5 mA appropriately loaded by a donor material 31 and use of a base contact made of gallium is solidified, which is from an alloy of indium and and indium over 900. Except this better one e.g. 10 to 30% »arsenic or phosphorus exist 50 can. Optionally, the contact with the main gene according to the invention can have further advantages body of the plate 23 also by a tin solder by the fairly constant value of a _Q. at or a tin arsenic solder can be made. In addition, a transistor amplifier depends on the usable un- are leads to the various electrodes pulled output lead from the linear relationship appropriate. 55 between input current and output current. There The arrangement according to FIG. 5 is a drawn a "in the circuit with a grounded base and the ra ^ T · ⁸ * ⁰ "· ^B -f? ^em ,? ^ehverfah £ ^{en we} . ^rden size - ^ * - in the circuit with earthed emit- Semiconductor body with a thin p-germanium 1 - a ₀ a & zone between two adjoining η-areas her- ter proportionality constants between the exhibited. The p-zone can have a thickness of 0.0025 cm 60 input current and the input current results in or less. Decrease of a ₀ at high currents a non-linearity The arrangement of Fig. 5 contains a first η-zone and a much smaller undistorted output 32, a thin p-zone 33 and a second n-zone 34 power,
lengthways in a monocrystalline germanium body. The pn junction35 serves as an emitter 65 PATENT CLAIMS:
and the junction 36 as a collector. The contact with the emitter zone 32 and the collector zone 34 is 1st semiconductor arrangement made of a monocrystalline produced by connections 37 and 38, respectively, with a NEN body with inlaid electrodes and with at least one pn junction, characterized in that the alloy material of at least one electrode consists of 0.02 to 0.1 percent by weight gallium and the remainder of indium and forms a large-area contact with the semiconductor body. 2. Arrangement according to claim 1, characterized in that that the semiconductor body is n-conductive and a further ohmic electrode is provided is. - ίο 3. Arrangement according to claim 2, characterized by a further alloyed in the same way Electrode with a second p-n over- 4. Arrangement according to claim 1, characterized in that that the monocrystalline semiconductor body has two η-conductive zones and a third p-conductive zone between these as well as two ohmic electrodes on the "first zones" and a third ohmic electrode on the third zone, the third electrode made of 0.02 to 0.1 percent by weight gallium and the rest consists of indium. 5. A method for producing a device according to claim 1, characterized in that When alloying the electrodes, a temperature of 400 ° C is preferred Temperature of 500 ° C but not exceeded will. Considered publications:
German patent specification no! 906 955. 1 sheet of drawings © 109 620/345 6.61