DE1213925B - Semiconductor component with partially negative voltage characteristics and a semiconductor body with four zones as well as a method for manufacturing - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

HOIl

German class: 21g-11/02

Number:
File number:
Registration date:
Display day:

S83899 VIIIc / 21g
February 26, 1963
April 7, 1966

The invention relates to a semiconductor component with partially negative voltage characteristics, a semiconductor body with four successive zones, of which at least three consecutive have an alternating conductivity type, and each with one electrode the two outer zones and a control electrode on one of the two central zones.

By means of structures of the form npnp or pnpn, as is shown, for example, in FIG. 1, it is known to be possible to produce components with negative voltage characteristics. Such an arrangement has due to the current dependency of the current amplification factor W ₁ of one sub-transistor, which is formed by zones 1, 2 and 3, and the current amplification factor x _{2 of} the second sub-transistor, which is formed by zones 2, 3 and 4, when switched as a diode, a falling characteristic when the two outer pn junctions are biased in the forward direction, ie when terminal 11 is applied to the negative pole and terminal 12 to the positive pole of a voltage source. The course of this characteristic can be influenced by a control current I _Si . For this purpose, one of the two central zones, which form the base zones of the two partial transistors, in the present example the p-conducting central zone 2, is provided with an electrode. By applying a voltage between terminals 11 and 13, the ignition voltage of the entire npnp path can be reduced by polarizing this voltage accordingly. A large current can be ignited with a small control output, which is analogous to the gas discharge current gate. However, such an arrangement has in common with the current gate that deletion is only possible through the main circuit between terminals 11 and 12 containing the load resistor or with very high currents at the control electrode, which is a disadvantage for certain applications, especially in the low-current area is.

The present invention is intended to provide a way that enables such Four-layer structures to avoid this disadvantage. An arrangement shall be given which over the control electrode and with low power is to be extinguished.

A semiconductor arrangement has already become known which has four zones of alternating conductivity type and in which the two outer zones and one of the two central zones are contacted, in which the current amplification factor of the two

Semiconductor component with partially negative
Voltage characteristics and a
Semiconductor body with four zones and method for manufacturing

Applicant:

Siemens & Halske Aktiengesellschaft,
Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Named as inventor:

Dr. Richard Wiesner, Munich

Sub-transistors is set so that their sum becomes a value that is not greater than 1.1, added. A well-known semiconductor component is z. B. constructed so that that sub-transistor which contains the outer zone adjoining the uncontrolled central zone, a value for the Has current amplification factor which is not greater than 0.1, while the other sub-transistor one has a value for the current amplification factor lying between 0.9 and 1.0.

The present invention is based on the consideration that the current gain factor has a current-dependent value, that is to say that the condition that K ₁ should not be greater than 0.1 and a ₂ should assume a value between 0.9 and 1 only for a narrow one The forward current range must be met, so that extinguishing with low power is only possible for a few values of the current in the ignited state, if the component is constructed in the known manner. In contrast, such a semiconductor component is constructed according to the invention in such a way that the current dependency of the current amplification factors Oi ₁ and a _{2 of} the partial transistors formed by an outer zone and the two central zones is set by known means so that the sum of the decrease in X ₁ and the increase of < % ₂ assumes a value between 1.0001 and 1.1 depending on the forward current in the ignited state over a large forward current range. According to the teaching of the invention, it is achieved by appropriate adjustment of the rise in the current gain factor x ₂ to the fall of K ₁ that for a large forward current

609 557/241

3 4

The area of the maximum stress on it for the sum of K ₁ and a ₂ collapses. If this

reached value is only very little above 1, so that the state is reached, the four-shift ignites. the

the deletion of the component via a broad condition for this is that Oc ₁ + a _{2 is} greater or

Current range can be done with low power. equals 1. Because of the tension breakdown

An arrangement is therefore proposed, at 5 at the middle transition 6 there is another

of the deletion of the four-shift worker on the tax increase in electricity, which leads to a further discharge of the

low-power electrode through a special middle barrier layer 6 so that it closes

Constellation of the current amplifications depending on the direction of flow comes to lie and in turn

speed of the amperage of the system pass- charge carriers are injected. To achieve a small

the stream is achieved. io forward voltage on the whole system, d. H. one

For a more detailed explanation of the invention, the residual voltage in the ignited state, the following first aims at the mode of operation of the four-man so that the flow control as far as possible is entered into. With the polarity of the four-layer it follows, ie that Ot ₁ + oc _{2 is} much greater than 1, that in the manner indicated in FIG Barrier layer 6 is as intense as possible.
effective zones 1 and 4 in the neighboring · It has been shown, however, that for the tilting middle zones 2 and 3. The middle transition is biased in mechanism this intensive enrichment at the blocking direction. By injecting middle barrier layer is not essential. It is entirely possible for charge carriers from the two outer zones that the middle blocking layer also remains an increase in the blocking current at the middle over- 20 in the ignited state in the blocking direction. To gang 6 causes. With increasing voltage, the one extinction of the system with a small current grows to reverse current and thus the injection of the minority reach, this is precisely this constellation in which the carrier from the two outer zones. This current mean pn transition leads to little or no increase at the transitions 5 and 7 to the direction of flow, particularly advantageous, an increase in the partial current amplifications Oc ₁ 25 since then there is already a low charge carrier transfer and Oc ₂ . The increase in current at the two outer decreases leads to higher voltages at the middle junctions, which can lead to an increase in the charge carrier barrier layer. As soon as this voltage concentration is caused in the two central zones as a result of the operating voltage in the main circuit reduced with increasing voltage increasing blocking and the voltage drop at the load resistor overcurrent can be caused by simultaneous 30 steps, the four shifters extinguish. From this Be charge carrier multiplication at the middle pn covers it follows that when a gang 6 or by utilizing the four-layer punch is built up in such a way that the middle barrier-through effect on one of the two base zones 2 also occurs in the ignited layer State can only be increased a little or 3 even further. Due to the fact that it does not come in the flow direction at all, even with an increase in the current via the two outer 35 very low control currents, the four-junctions 5 and 7 can be extinguished and the current layers can grow.

Reinforcements will eventually also include an increase based on the investigations

the carrier concentration on the middle pn four-layers, as z. B. from the essays

Transition 6 achieved. So there is an enrichment Proceedings IRE of December 1954, p. 1761, and

from are known about the two outer transitions 5 and 7 in 40 of September 1956, p. 1174, results

projected minority carriers on both sides of _{the middle for the voltage F 23} at the middle pn junction

leren pn junction 6, d. that is, the space charge on a controlled four-shift worker is an expression of

middle transition 6 is broken down, and the locking of the form

^kT i ~ ί 1_ Ly ₂₃ 4. ⁷ ^ ⁺ «« -!) - «1 ·

1 - Oi ₁ LX ₁ J - «2

Here ^ - the well-known temperature- ⁵ ° ^s0 ^ t ^ r ° means no longer injecting, ie, « _1} and« _{2 /}

q ^F both become zero. if
voltage, / _S23 the reverse current at the middle

Junction, / the total current and / _{s /} the control | Ct ₁ J _st - J (0C ₁ + « ₂ - 1) |
current, the polarity of which is in the direction of "delete"

is set, the in F i g. 1 shown arrow 55 corresponds to the order of magnitude of a very small blocking direction. Oc ₁ j and a _2j are the so-called currents / _S23 comes, so F ₂₃ becomes very large, ie, there are inverse current gains. Oc ₁ J is the flow rate, extinction can occur. As can be seen from the strengthening considerations, if the mean over- flow is visible in the flow state, this is injecting with the smaller control gear 6, that is, it acts as an emitter and the current J _st the case, the smaller Oc ₁ + a ₂ in the beÜbergang 5 than Collector, while <x is _2j for the 60 standing total current. If the value of this transition is 7 as the collector transition and the mean expression z. B. 10 ~ ² , then the extinguishing current around junction 6 is considered to be the emitter. be two orders of magnitude smaller than the total: From this equation it follows that as soon as current 7.

\ r / ι -i \ A deletion of the "four-shift worker over the tax

Oi ₁ JSt J ^ Ψ-ι-ROC ₂ ^ - X) 5 _{5 m} electrode it less power can thus with a

will be achieved, the argument of the logarithm smaller than Ί arrangement, at which Oc ₁ + Oe ₂ " ¹ in

-will, ie F ₂₃ comes to rest in the blocking direction ■. a wide passband about 10 ^"1 to 10 ~ ⁴

However, if the middle transition is in the reverse direction, is. .

Measures for influencing the current dependency of the current amplification factor are known per se. So z. B. by bridging an outer zone and the adjacent central zone with a resistor or a directional conductor influences the current dependence of the current amplification factor will. In addition, such an influence is also provided by a corresponding doping profile to achieve adjacent zones.

Particularly favorable measures for realizing the condition for W ₁ and ₂ result in the case of an asymmetrical structure of the arrangement. It is advantageous to adjust the current amplification factor for one of the two sub-transistors so that it increases approximately linearly and decreases linearly again after passing through a maximum, while the current amplification factor for the other sub-transistor increases significantly more slowly with increasing current strength. The maximum achievable value is below α = 1 in both cases.

For a low control power for erasing, it is also favorable that that sub-transistor whose Base zone is provided with the control electrode, a relatively steeply rising curve of the current gain and a high α, i.e. H. lying close to 1, has.

In FIG. 2, curve 8 represents the current dependence of the current amplification factor for a transistor which, for. B. has alloyed electrodes. The current gain reaches a maximum as a function of the current, after which it decreases more or less flat approximately linearly. The steepness of the drop depends essentially on the quality of the emitter, ie on the emitter efficiency and can be adjusted by setting the emitter efficiency accordingly, e.g. B. can be set by appropriate doping profile in the emitter and the base zone. A course of the current amplification factor according to curve 8 is to be aimed for for the partial transistor whose base zone is provided with the control electrode. On the other hand, a transistor with a poor emitter can be built in which the current gain then increases approximately linearly over a long distance up to the maximum according to the curve denoted by 9. Such a course of the current gain is to be aimed for for that partial transistor whose base zone is not contacted. The current gain of the four-layer system results from the summation of curves 8 and 9. In this way, a total current gain is obtained, the dependence of which on the current / is given by curve 10. By adjusting the rise of the current amplification factor a ₂ , the course of which corresponds to curve 9, to the fall of Ct ₁ , the course of which corresponds to curve 8, one obtains a curve with a long horizontal plateau, for which it applies that the one for Ot ₁ + a ₂ maximum value reached is only very slightly above 1.

In general it can be said that transistors with embedded electrodes, if no special ones, in the following explained in more detail doping measures are carried out, a course of Have current amplification factor according to curve 8, while transistors with diffused Transitions have a course of the current amplification factor which in principle corresponds to curve 9. An arrangement according to the invention can thus, for. B. be constructed so that the transitions of the the sub-transistor containing the outer zone adjoining the controlled central zone has alloyed junctions are, while the transition between the uncontrolled central zone and that adjacent to it Outer zone is a diffused transition.

Regardless of whether the junctions are alloyed or diffused, the course of the current gain factor but also by an ohmic shunt connecting an outer zone with the neighboring one Central zone connects, can be set so that it corresponds to that of curve 9. With small ones Voltage in the main circuit is, at relative to the blocking resistance of the bridged junction selected low value of the ohmic shunt, some of the charge carriers over the ohmic Drain shunt. However, since the current gain factor α is current-dependent, this means a smaller α-value than without shunt. With increasing voltage and with increasing current over the outer junction, the resistance of the outer junction decreases and the shunt becomes more and more ineffective. A minority carrier injection is obtained through this ohmic shunt the bridged outer zone into the adjoining central zone, which becomes essential with increasing tension increases more slowly than would be the case without the shunt. From these considerations it follows also that the steepness of the increase in current gain depends on the value of the bypass resistance depends.

Also by bridging an outer zone with the adjacent central zone by a non-linear shunt, so z. B. by a judge, the course of the current amplification factor can be influenced.

Another possibility of assigning a course of the current amplification factor according to curve 9 achieve is also given that the doping pill, which is used to form the outer zone in the middle zone is alloyed, adding material of both doping character. With such, in itself known arrangement so the outer transition is made by alloying a metal pill, contains impurities of the same and the opposite conductivity type as the semiconductor body the neighboring central zone. The concentration of the latter impurities in the recrystallization layer in comparison to the former is on the one hand so large that a noticeable injection of Minority carriers from the alloyed electrode occurs in the adjacent central zone and on the other hand so small that there is still no blocking effect in the other direction. Such a contact corresponds to in principle of a parallel connection of an emitter with an ohmic bridge. One can imagine that in the recrystallization zone, n- and p-conductive areas arise next to one another. If the middle zone adjacent to the outer zone has η conductivity, then the p-conducting areas are the minority carrier injection into the central zone, while the η-conductive areas the ohmic shunt generate, which becomes more and more ineffective as the current increases. With such an alloy Transition, the outer zone has the same conductivity type as the adjacent central zone and in general a higher conductivity like this. The course of the current amplification factor, i.e. the Adjustment of the rise of curve 9 to the fall of

Curve 8 can be determined by the doping of the alloy pill, i.e. H. by choosing the right concentration the activators. Another way to achieve a curve shape according to curve 9 is the incorporation of recombination centers in the emitter-pn junction area, e.g. B. 7, or in the Base zone, e.g. B. 3, or the crystal surface in the vicinity of the emitter-pn junction, e.g. 7, with to provide a high surface recombination.

As a material for the semiconductor crystal from which the four-layer is made, silicon or germanium, as well as other semiconductor materials or semiconducting compounds, so z. B. an A _ni B _v connection can be used. The individual zones can be produced in a manner known per se by alloying or diffusing in appropriately doping substances. To produce a pp + contact, i.e. a contact that is effective as an emitter and at the same time contains the ohmic bridging, z. B. in p-conducting germanium indium, which contains an admixture of 2% arsenic, can be alloyed. In this way a pp + contact is obtained. The p-conductive zone then corresponds, for example, to the zone denoted by 3 in FIG. 1, the ρ + zone to the. zone denoted by 4, while zone 1 is p-conducting and zone 2 is n-conducting. The transitions 5 and 6 are expediently produced according to the usual alloying process.

Claims (7)

Claims: 30 1. Semiconductor component with partially negative voltage characteristics, a semiconductor body with four successive zones, of which at least three successive ones have an alternating line type, and each with an electrode on the two outer zones and a control electrode on one of the two Central zones, characterized in that the current dependence of the current amplification factors Ct ₁ and a ₂ by one each. Outer zone and the two central zones formed sub-transistors is set by known means so that the sum of the drop in Ct ₁ and the increase in ₂ depending on the forward current in the ignited state over a large forward current range has a value between 1.0001 and 1.1 accepts. 2. Semiconductor component according to claim 1, characterized in that the current amplification factor Oi ₁ , of the sub-transistor containing the outer zone adjoining the controlled central zone, initially rises approximately linearly and relatively steeply with increasing current intensity and after passing through a maximum, where Oc _{1 is} always less than 1 is, approximately linearly decreases again, and that at the same time a ₂ increases significantly more slowly than a _x linearly with increasing current strength and also always remains smaller than 1. 3. Semiconductor component according to claim 1 or 2, characterized in that one, in particular the non-controlled central zone with the adjacent outer zone by an ohmic one or non-ohmic resistance is bridged. 4. Semiconductor component according to one of claims 1 to 3, characterized in that both outer zones have the opposite conductivity type as the respective adjacent central zone exhibit. 5. Semiconductor component according to one of claims 1 to 3, characterized in that the The outer zone adjacent to the non-controlled central zone has the same line type, but one has higher conductivity than the adjacent central zone. 6. A method for producing a semiconductor component according to any one of claims 1 to 5, characterized in that the junctions of the sub-transistor containing the controlled central zone are alloyed. 7. The method for producing a semiconductor component according to one of claims 1 to 5, characterized in that the transition between the uncontrolled central zone and the adjacent outer zone is diffused. Considered publications:
German Auslegeschriff No. 1123 402;
French Patent No. 1,264,134;
U.S. Patent No. 2,993,154;
Wescon Conv., Part 3, 1958, No. 3, pp. 172-174. 1 sheet of drawings 609 557/241 3.66 © Bundesdruckerei Berlin