U.S. patent number RE28,928 [Application Number 05/622,094] was granted by the patent office on 1976-08-10 for integrated circuit comprising supply polarity independent current injector.
This patent grant is currently assigned to U.S. Philips Corporation. Invention is credited to Cornelis Maria Hart.
United States Patent |
RE28,928 |
Hart |
August 10, 1976 |
Integrated circuit comprising supply polarity independent current
injector
Abstract
Integrated circuit suitable for any desired supply polarity by
means of a rectifier bridge two rectifiers of which are designed as
current injectors.
Inventors: |
Hart; Cornelis Maria
(Eindhoven, NL) |
Assignee: |
U.S. Philips Corporation (New
York, NY)
|
Family
ID: |
27351738 |
Appl.
No.: |
05/622,094 |
Filed: |
October 14, 1975 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
320964 |
Jan 4, 1973 |
03829718 |
Aug 13, 1974 |
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Foreign Application Priority Data
Current U.S.
Class: |
327/565; 257/577;
327/577; 327/578; 327/587 |
Current CPC
Class: |
H01L
27/0233 (20130101); H01L 27/0821 (20130101); H03K
19/091 (20130101) |
Current International
Class: |
H01L
27/02 (20060101); H03K 19/091 (20060101); H01L
27/082 (20060101); H03K 19/082 (20060101); H03K
003/26 (); H03K 019/08 () |
Field of
Search: |
;357/35,36,40,23,76
;307/303,304 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
DTL NAND gate, Electronics; pp. 116 and 117, June 26,
1967..
|
Primary Examiner: James; Andrew J.
Attorney, Agent or Firm: Trifari; Frank R. Nigohosian;
Leon
Claims
What is claimed is:
1. An integrated circuit comprising:
a. a semiconductor body comprising semiconductor circuit elements
and a carrier zone,
b. means for supplying electrical potential to said semiconductor
body,
c. a rectifier bridge disposed at said semiconductor body and
comprising bridge arms, said bridge comprising two respective first
rectifier elements disposed in said carrier zone and .[.said
rectifier.]. included in respective first ones of said bridge arms
to form part of said bridge, said rectifier elements being
electrically connected between said potential supplying means and
said carrier zone,
d. further rectifier elements disposed in second ones of said
bridge arms, and
e. means for automatically ensuring the appropriate supply current
polarity to said semiconductor elements, said means comprising
current injector elements respectively disposed in said second
bridge arms and being in current supply relationship with said
circuit elements.
2. An integrated circuit as claimed in claim 1, wherein said
current injector elements comprise lateral transistors.
3. An integrated circuit as claimed in claim 1, wherein said
circuit elements comprise circuit zones for receiving current from
respective said current injector elements and said current injector
elements comprise a zone having an edge area substantially larger
than that of each of said circuit element zones.
4. An integrated circuit as claimed in claim 1, wherein said first
rectifiers comprise vertical transistors disposed in said carrier
zone and that respectively comprise collector regions, emitter
regions that are connected to said potential supply means .Iadd.and
base regions that are cross-connected to said supply means
.Iaddend.through resistors.
5. An integrated circuit as claimed in claim 4, wherein said
resistors comprise extensions of said base zones of said vertical
transistors provided in said carrier zone.
6. An integrated circuit as claimed in claim 5, wherein said
extensions further comprise a part of said current injector
elements.
7. An integrated circuit as claimed in claim 5, wherein said
resistors comprise extensions of said emitter zones of said
vertical transistors, said extensions projecting into said base
zones.
8. An integrated circuit as claimed in claim 1, wherein said first
rectifiers comprise vertical transistors provided in said carrier
zone and disposed proximity to said current injector elements so as
to be supplied with the required base currents thereby.
9. An integrated circuit as claimed in claim 1, wherein said
current injector element and the zones of said circuit elements to
be supplied with current are laterally surrounded by a highly doped
zone, so as to prevent injection currents from leaking away.
10. An integrated circuit as claimed in claim 1 suitable for
alternating-current supply, wherein a capacitor element is
connected between an injecting zone of the current injector element
and the carrier zone. .Iadd. 11. An integrated circuit,
comprising:
a. at least one circuit element;
b. bias supply terminals for biasing said circuit element; and
c. means for automatically ensuring the appropriate polarity bias
to said circuit element, said means comprising a bridge rectifier
circuit electrically connected to said terminals and that comprises
in each of two arms thereof a current injector coupled to said bias
receiving circuit element, said current injectors comprising
respective rectifying junctions, which, upon forward biasing, can
inject carriers from a region outside said circuit element and
cause collection of carriers by an active zone of said circuit
element so as to bias said circuit element. .Iaddend..Iadd. 12. An
integrated circuit as in claim 11, wherein said bridge rectifier
circuit further comprises first rectifiers in respective other arms
thereof. .Iaddend..Iadd. 13. An integrated circuit as in claim 12,
wherein said first rectifiers comprise respective vertical n,p,n,
transistor structures and each of said current injectors comprises
a lateral pnp, transistor, said vertical transistor structures
having their respective base regions electrically connected to
their respective collector regions. .Iaddend. .Iadd. 14. An
integrated circuit as in claim 13, wherein said integrated circuit
comprises a semiconductor body comprising a carrier zone that forms
part of said rectifying junction and that comprises said collector
regions of said vertical transistor structures..Iaddend..Iadd. 15.
An integrated circuit as in claim 13, wherein said vertical
transistor structures have common base regions and common collector
regions. .Iaddend..Iadd. 16. An integrated circuit as in claim 13,
wherein said supply terminals are connected to respective emitter
regions of said vertical transistor structures and to respective
emitter regions of said lateral transistors. .Iaddend..Iadd. 17. An
integrated circuit as in claim 13, wherein each said supply
terminal is connected to a respective said emitter region of said
vertical transistor structures and cross-connected through a
resistor to a respective said base region of said vertical
transistor. .Iaddend..Iadd. 18. An integrated circuit as in claim
11, wherein each of said current injectors comprises at least three
successive regions separated from each other by rectifying
junctions, said regions respectively constituting an injecting
region that is separated from said circuit element by at least one
rectifying junction, an intermediate region adjoining said
injecting region and a collecting region adjoining said
intermediate region. .Iaddend. .Iadd. 19. An integrated circuit as
in claim 18, wherein said collecting region comprises said active
zone of said circuit element, said active zone being separated from
said injecting region by at least two rectifying junctions and
being biased by said supplied current. .Iaddend..Iadd. 20. An
integrated circuit as in claim 18, wherein said collecting region
comprises an intermediate injector zone disposed between said
injecting region and said zone of said further circuit element.
.Iaddend..Iadd. 21. An integrated circuit as in claim 18, wherein
said collecting region forms a collector zone of a first transistor
and an emitter zone of a second transistor, wherein said active
zone comprises the collector zone of said second transistor.
.Iaddend..Iadd. 22. An integrated circuit comprising a circuit
element a rectifier bridge that comprises plural rectifiers
included in respective arms of said bridge, a number of said
rectifiers comprising current injector means for supplying current
to a circuit element and biasing a zone of said element so that
said element is rendered conductive. .Iaddend..Iadd. 23. An
integrated circuit comprising:
a. a circuit element;
b. a semiconductor element comprising a carrier zone;
c. plural supply terminals;
d. means for ensuring the appropriate supply polarity to said
circuit element, said means comprising a rectifier bridge that
includes plural rectifiers electrically connected between said
carrier zone and respective said supply terminals and located in
respective arms of said bridge; and
e. said rectifier bridge further comprising p,n junctions formed
with said carrier zone and located in respective other bridge arms,
said p,n junctions comprising a current injector for supplying
current to said
further circuit element. .Iaddend..Iadd. 24. An integrated circuit
as in claim 17, wherein said resistors comprise extensions of said
vertical transistor emitter regions which form islands within said
vertical transistor base regions. .Iaddend.
Description
The invention relates to an integrated circuit comprising a
semiconductor body and means for automatically ensuring the proper
supply polarity, which means comprise two rectifiers having the
same pass direction which are connected between a carrier zone of
the semiconductor element and two supply terminals.
In a known integrated circuit of this type the said rectifiers
shunt the main current paths of two transistor amplifiers in a
manner such that on application of one supply polarity one
amplifier is rendered operative because the associated rectifier is
cut off, whereas the other amplifier is short-circuited by its
associated rectifier.
The object of the present invention is not at all to duplicate
amplifier stages but to ensure in a simple manner that a supply
current of the appropriate polarity reaches amplifiers or other
circuit elements on the semiconductor body.
The invention is characterized in that the said rectifiers form
part of a rectifier bridge whose pn junctions which, are formed
with the carrier zone and are included in two other bridge arms,
form part of a current injector for supply current to further
circuit elements of the integrated circuit. The invention is
related to an invention with respect to current injectors which is
described in our co-pending Dutch Pat. application No. 7,107,040
(PHN 5,476). In contradistinction to this prior proposal the
present invention relates to two current injector structures, the
injecting zone of one structure being polarized in the forward
direction and that of the other in the reverse direction with
respect to the substrate zone, the carrier zone itself being
connected to the supply terminals not directly but via the
aforementioned rectifiers.
It is known to provide a correct supply polarity by means of a
rectifier bridge comprising four rectifiers. The invention utilizes
the recognition that the two other rectifiers of this bridge may be
provided so as to be capable of acting as current injectors. The
term "current injector" is used herein to mean a multilayer
structure having at least three successive layers, or regions,
which are separated from each other by rectifying junctions, which
layers include a first layer, referred to as injecting layer, which
is separated from the circuit element to be supplied with current
by at least one rectifying junction, and an adjoining second layer
consisting of a semiconductor material, which is referred to as
intermediate layer, the injecting layer being connected to a supply
terminal, whilst charge carriers are injected from the injecting
layer into the intermediate layer and are collected by the third
layer of the current injector, referred to as collecting layer,
which adjoins the intermediate layer, a zone of one of the circuit
elements to be supplied with current, referred to as zone to be
biassed, which is separated from the injecting layer and hence from
the supply terminal connected thereto, by at least two rectifying
junctions, collects, across a rectifying junction bounding this
zone, charge carriers from one of the layers of the current
injector and thus is supplied with current, the said zone being
directly connected to the pattern of metallic interconnections.
Embodiments of the invention will now be described, by way of
example, with reference to the accompanying diagrammatic drawings,
in which:
FIG. 1 is a layout of the structure of a semiconductor body
according to the invention,
FIG. 2 is a side elevation thereof,
FIG. 3 is the equivalent circuit diagram of this structure,
FIG. 4 shows a modification of the left-hand part of the circuit
diagram shown in FIG. 3, and
FIGS. 5, 6 and 7 are layouts of structures which correspond to the
circuit diagram of FIG. 4.
The semiconductor body shown in FIGS. 1 and 2 comprises a substrate
of n.sup.+-polarity on which a weakly n-doped zone 4 is epitaxially
grown. In this n-type zone 4, hereinafter referred to as carrier
zone, vertical npn transistors and lateral pnp transistors have
been formed. A supply terminal 1 is connected to an emitter 5 of a
first npn vertical transistor, the base 6 of which is connected by
a metal interconnection 3 to the carrier zone 4 which serves as the
collector of the transistor 5, 6, 4. Owing to this connection 3 the
transistor 5, 6, 4 in known manner serves as a rectifier diode
D.sub.1, shown in FIG. 3. Similarly a supply terminal 2 is
connected to an emitter 7 of a vertical npn transistor which has a
base 6 and a collector 4 in common with the transistor 5, 6, 4.
Thus this second transistor 7, 6, 4 forms the rectifier D.sub.2 of
FIG. 3. The supply terminals 1 and 2 are also connected to p-type
regions 9 and 10 respectively of lateral current injectors, the
zones 9 and 10 serving as the injecting layers and the carrier zone
4 serving as the intermediate layer, whilst a p-type collecting
layer 11, which surrounds the injecting layers 9 and 10 but is
separated therefrom by the intermediate layer 4 and hence is not
directly connected to a supply terminal, collects the injected
charge carriers and transfers them to semiconductor elements to be
supplied with current.
This is effected in that the zone 11 -- hereinafter referred to as
intermediate injector zone -- extends nearly to a large number of
semiconductor elements which are to be supplied with current and
only two of which are shown in the form of vertical npn transistors
formed in the carrier zone 4. The carrier zone 4 serves as the
emitter of these vertical transistors, which in FIGS. 1 and 2 have
their base zones denoted by 15 and 16 respectively and their
collectors by 17 and 18 respectively. Since the base zones 15 and
16 are close to the collecting zone 11 but are separated therefrom
by the substrate zone 4, the charge carriers collected by the zone
11 will partly reach the zones 15 and 16 and so ensure the supply
of current to the respective transistors.
In the equivalent circuit diagram of FIG. 3, the structure 9, 10,
4, 11 is shown as a transistor T.sub. 3 having two emitters, which
each correspond to one of the zones 9 and 10, a common base, which
corresponds to the zone 4, and a common collector, which
corresponds to the zone 11. The structures 4, 15, 17 and 4, 16, 18
correspond to transistors T.sub.4 and T.sub.5 respectively of the
equivalent circuit diagram, and the structures 11, 4, 15 and 11, 4,
16 correspond to a transistor T.sub.6 of FIG. 3, the zone 11
serving as the emitter of the transistor T.sub.6, the carrier zone
4 as its base and the zones 15 and 16 as its collectors. The
currents collected by the collectors of the transistor T.sub.6 are
used to supply base current to the transistors T.sub.4 and T.sub.5
respectively, but also indirectly to supply collector current to
the transistor T.sub.5 in that the base zone 15 of the structure 4,
15, 17, which corresponds to the transistor T.sub.4, is connected
by a metal interconnection 19 to the collector zone 18 of the
structure 4, 16, 18 which corresponds to the transistor
T.sub.5.
The structure shown requires a minimum number of masks and
diffusion steps and provides the large advantage that a wide
variety of semiconductor elements of the integrated circuit may be
supplied with current without a separate metallic connection
pattern to each of these semiconductor elements being required.
Thus, in addition to leads 21 and 22 between the supply terminal 1
and the zones 5 and 9 and between the supply terminal 2 and the
zones 7 and 10 respectively, only metal interconnections between
the semiconductor elements, one of which is shown by 19, are
required. (These leads and interconnections are shown schematically
in FIGS. 1 and 2, but in practice they will be provided as metal
conductors on an insulating film, for example an oxide film, on the
semiconductor body; if desired, in order to reduce the resistance
of the intermediate injector zone 11 this zone may be coated at
least locally by a metal conductor at areas at which this conductor
does not hinder the aforementioned interconnection pattern).
The circuit described operates as follows:
When the semiconductor body is connected to the supply source, the
terminal 1 being, for example, positive with respect to the
terminal 2, current will flow from the terminal 1 through the lead
21, the pn junction between the zones 9 and 4, which is polarized
in the forward direction, the interconnection 3 and the pn junction
between the zones 6 and 7, which is operated in the forward
direction, to the terminal 2. As a result the carrier zone 4
assumes a potential which but for the voltage drop across the diode
D.sub.2, i.e., the emitter base threshold voltage between the zones
7 and 6, is equal to the potential of the terminal 2. Because the
zone 9 is polarized in the forward direction with respect to the
zone 7, charges will be injected from the zone 9 into the zone 4 to
be largely collected by the zone 11, because this zone 11 entirely
surrounds the zone 9. Thus the zone 11 assumes a potential nearly
equal to that of the zone 9, i.e., that of the terminal 1. The
ensuing current flowing to the zone 11 is evenly divided between
the further zones 15, 16 provided near the zone 11 and further
p-type zones of circuit elements to be supplied with current. The
injecting edge of the zone 11 is large with respect to the edge of
each of the collecting zones 15, 16 and with respect to those of
the said further p-type zones. In this respect the zone 10 will
also collect part of the current from the zone 11, which
consequently is to be considered as a loss current, but because the
collecting power of the zone 10 for charges from the zone 11 is
small compared with the collecting power of the zone 11 for charges
from the zone 9, in other words because the current gain of the
transistor T.sub.6 in the condition shown is considerably greater
than if the transistor T.sub.6 were operated in the inverse
direction, in which case the emitter and collector would be
interchanged, this loss current is negligible in practice.
When the polarity of the voltage at the supply terminals 1, 2 is
reversed, the completely symmetrical construction will cause the
zone 11 to similarly continue to inject charge into the zones 15
and 16 to be supplied with current.
In order to reduce the voltage drop across the structure 7, 6, 4,
i.e., across the diode D.sub.2, in the circuit shown in FIG. 2 the
rectifiers D.sub.1 and D.sub.2 are replaced by transistors T.sub.1
and T.sub.2 connected as rectifiers, either one or the other of
these transistors being conducting. These transistors have their
emitters, which correspond to the zones 5 and 7 respectively in
FIGS. 1 and 2, connected to the supply terminals 1 and 2
respectively, whilst their bases are connected via resistors
R.sub.1 and R.sub. 2 to current supply terminals 2 and 1
respectively, i.e., each to the terminal other than that to which
its emitter is connected. If now, for example, the terminal 1 is
positive with respect to the terminal 2, the transistor T.sub.1
will be cut off, whereas the transistor T.sub.2 is rendered
conducting via the resistor R.sub.2 , but in this case the voltage
difference between its emitter and collector, which correspond to
the zones 7 and 4 respectively in FIG. 1, now is equal only to the
voltage drop across a transistor which is just not driven into
saturation, which voltage drop in practice may be, for example, 0.1
volt, whereas in the configuration of the embodiment shown in FIGS.
1 and 2 it is about 0.6 volt. The resistors are proportioned so
that the base current of the transistor T.sub.2 still is small
compared with its emitter collector current, but the voltage
between the base and the emitter has the same sign as (and is only
slightly greater than) the voltage between the base and the
collector.
In the layout shown in FIG. 5 the resistor R.sub.1 and R.sub.2 are
formed as extensions 25 and 26 of the base zones 27 and 28 of the
transistor structures which correspond to 7, 6, 4 and 5, 6, 4
respectively. The terminal 1 is connected by a lead 29 to the
emitter 30 of one pnp transistor the collector of which in this
structure also is formed by the carrier zone 4 and by a lead 31 to
a contact pad 32 on the base resistor 25. Similarly the terminal 2
is connected by a lead 33 to the emitter 34 of the other pnp
transistor and by a lead 35 to a contact pad 36 on the base
resistor 26. The zone 11, the function of which entirely
corresponds to that which it has in the layout shown in FIG. 1, is
provided with fingers 37, 38 and 39 which partly embrace the zones
25 and 26.
Assuming the supply polarity to be such that the terminal 1 is
positive with respect to the terminal 2, there will be applied to
the zone 25 via the contact pad 32 a forward voltage which causes
the base zone 27 to be polarized in the forward direction with
respect to the emitter zone 34, so that the structure 34, 27, 4 is
rendered conductive and hence the substrate Zone 4 assumes
substantially the potential of the terminal 2. On the other hand
the zone 25, at least in the proximity of the contact pad 32, will
emit a considerable amount of charges into the substrate zone 4,
which are collected by the fingers 37 and 38 of the zone 11. At the
same time the transistor structure comprising the zones 30, 28 and
4 is rendered non-conductive, inter alia owing to the small voltage
difference between the zones 4 and 28, so that substantially no
current flows in this structure.
The base resistor formed by the zone 26 will, at least in the
proximity of the contact pad 36, collect current which is injected
from the fingers 38 and 39 of the zone 11 into the substrate zone
4, and this current is again to be regarded as a loss current. To
reduce this current the fingers 37, 38 and 39 preferably embrace
the resistance zones 25 and 26 partly only, as is indicated by
broken lines, for owing to the voltage drop across the resistance
zone 25 the voltage difference of this zone 25 relative to the
substrate zone 4 will be greatest in the proximity of the contact
pad 32, so that in this area the largest injection into the zone 11
takes place. Consequently, shortening the fingers 37 and 38 does
not greatly reduce the useful injection into the zone 11, but does
reduce the loss current flowing from the fingers 38 and 39 to the
zone 26.
FIG. 6 shows another solution of this problem which enables these
loss currents to be further reduced. In this embodiment the base
zones 27 and 28 are expanded so as to enable them to contain
resistance zones 42 and 41 respectively which are in the form of
(n-type) extended portions of the associate emitter zones 34 and 30
respectively. The terminal 1 here also is connected to the n-type
emitter zone 30 at the site of the contact pad 43 and also to the
p-type injection zone 9. Similarly the terminal 2 is connected to
the n-type emitter zone 34 at the site of the contact pad 44 and
also to the p-type injector zone 10. The ends 45 and 46 of the
resistance zones 41 and 42 more remote from the contact pads 43 and
44 respectively are connected to the base zones 27 and 28 via metal
interconnections 27 and 48 respectively.
Assuming again that the terminal 1 has positive polarity with
respect to the terminal 2, current flowing via the contact pad 43,
the resistance zone 41, the contact pad 45 and the metal
interconnection 47 will polarize the base zone 27 in the forward
direction with respect to the emitter zone 34, so that the
structure 34, 37, 4 becomes highly conducting and the carrier zone
4 substantially assumes the potential of the terminal 2.
Consequently the injector zone 9 will be polarized in the forward
direction with respect to the carrier zone 4, so that charges are
injected, which are collected by the zone 11. However, the
inclusion of the resistance zones 41 and 42 in the base zones 28
and 27 respectively prevents these base zones from giving rise to
undesirable collector action. This is inter alia due to the fact
that when the structure 34, 27, 4, which corresponds to the
transistor T.sub.2 in FIG. 4, is in the highly conducting condition
the inverse current conduction by the transistor T.sub.1, which
corresponds to the structure 30, 28, 4, is prevented.
An additional effect is that the zone 6 in FIGS. 1 and 2 and the
zones 27 and 28 in FIGS. 5 and 6 can directly collect injection
current from the zone 11. If this is regarded as an undesirable
phenomenon, these zones 6 or 27 and 28 are to be spaced by an
appropriate distance from the zone 11, or another provision is to
be made to ensure that these currents are avoided, for example by
the interposition of a finger-shaped p-type zone which may be
connected to the carrier zone 4. As an alternative, however, this
current may be turned to account, as is shown in FIG. 7, by
locating the base zones 51 and 52 of the npn-structures 5, 51, 4
and 7, 52, 4 respectively in the proximity of the zone 11, so that
part of the current from the zone 11 is used to render the relevant
transistor structure conductive. If, for example, the terminal 1 is
again positive with respect to the terminal 2, the pn-junction 9, 4
and the pn-junction 52, 7 will be polarized in the forward
direction. Thus, the four zones 9, 4, 52 and 7 form a
pnpn-structure which may become astable as a sufficient number of
free charges occur. These free charges are obtainable, for example,
by connecting resistors to suitably chosen points; the simplest
manner of producing these free charges is to apply a short duration
sufficiently high start pulse between the supply terminals or to
irradiate the semiconductor element with radiation of sufficient
intensity for a given time. When in this manner charge injection
from the injector zone 9 into the carrier zone 4 has been started,
charges will be collected by the zone 11 to be partly injected
again into the zone 4 in the proximity of the zone 52, by which
they are collected whereupon they will reach the supply terminal 2
via the zone 7. The injection current from the zone 9 will be
substantially entirely collected by the zone 11; because this zone
11, however, supplies current to a large number of circuit elements
-- in the same manner as is indicated in FIGS. 1 and 2 -- only a
small portion of this current will reach the zone 52. There this
current acts as the base current of the vertical transistor 7, 52,
4 and may be large enough to maintain this transistor in its highly
conducting condition.
In the examples described so far the injector zone 9 or 10 together
with the carrier zone 4 and the intermediate injector zone 11 forms
a lateral transistor. In principle the injector may also be
designed as a vertical transistor by starting from a p-type
substrate instead of from the n.sup.+-type layer of FIG. 2, forming
an epitaxial n-type layer corresponding to the carrier zone 4 of
FIG. 2 on the substrate, and by forming in this epitaxial layer
vertical transistor structures which correspond to 15, 17 and 16,
18 of FIGS. 1 and 2, rectifier structures which correspond to 3, 4,
5, 6, 7 in FIGS. 1 and 2, and injectors which correspond to zones 9
and 10 in FIGS. 1 and 2, which are similarly connected to the
supply voltage terminals. (Thus the zone 11 of FIGS. 1 and 2 is
dispensed with). When a supply voltage is applied the rectifier
structures will similarly ensure that the n-type epitaxial
substrate zone assumes a potential nearly equal to that of the
negative supply terminal, whilst the current from the injector zone
connected to the positive supply terminal will reach, through the
n-type epitaxial substrate zone, the p-type substrate and via the
latter may serve to supply current to the various transistor
structures on the semiconductor body. However, the advantage of
this solution that the zone 11 is dispensed with is offset by the
disadvantage that the operation of the substrate zone as a
low-resistance supply current conductor and as an emitter for the
structures corresponding to 15, 17 and 16, 18 of FIG. 1 is
performed with considerably less efficiency, because the favourable
effect of the n.sup.+-doped substrate of FIG. 2 is absent.
Further steps described in the aforementioned copending Patent
Application of prior date may advantageously be applied to the
aforedescribed embodiments. In particular the efficiency is
considerably increased by surrounding the intermediate injector
zone 11 and the zones to be supplied with current by an isolating
or n.sup.+-doped zone (shown shaded in FIG. 1) which, if desired,
may extend into the n.sup.+-doped substrate and substantially
prevents the injected charges from leaking away. In FIG. 7 a
similar step may be taken with respect to the intermediate injector
zone 11 and the rectifier structures 5, 51, 4 and 7, 52, 4.
Obviously all the dopings mentioned may be of the opposite types,
in which case the voltage polarities also will be reversed.
Furthermore, if desired, a supply alternating current may be
applied to the terminals 1 and 2; in this case the capacitance
between the zones 4 and 11 is preferably increased by providing
these zones with contact pads between which a capacitor is
connected.
* * * * *