International Business Machines Corporation

James L Walsh

Narasipur G Anantha

Harsaran S Bhatia

Richard R Konian

Joseph R Cavaliere

Robert A Henle

Michel S Michail

Herbert I Stoller

Santosh Prasad Gaur

John S Lechaton

Gurumakonda R Srinivasan

An NTL (Non-Threshold Logic) NOR logic circuit exhibits a small signal swing, effected by establishing a pseudo threshold level by utilizing a low voltage power supply and a combination of NPN bipolar devices arranged to provide an essentially noise immune circuit having high DC gain and high AC noise tolerance.

Noise immune NTL logic network

A half current switch comprising: at least one input transistor, a load resistance connected between a first voltage reference and the collector of the input transistor, a constant-current resistance connected between the emitter of the input transistor and a second voltage reference, and a feedback means including at least one feedback connected to the constant-current resistance. The feedback means further includes means for biasing the feedback transistor to drive a current through the constant current resistance which, when flowing, increases with an increasing main current and decreases with a decreasing main current through the input transistor. The feedback means thus causes a constant current to be drawn by the input transistor when it is conducting, thereby controlling the capacitance of the input transistor while maintaining the output level constant. In a preferred embodiment, the feedback means comprises a PNP transistor with its base connected to the collector of the input transistor, with its emitter connected to the first voltage reference, and with its collector connected to the emitter of the input transistor. The PNP transistor not only acts as a feedback device to control current, but also acts to prevent oscillations when a speed-up capacitor is used in the circuit.

Half current switch with feedback

A dynamic memory cell has a P+ injector region surrounded by an N+ region in an N- layer on an N+ layer. The injector region is placed between N+ source and drain regions. Holes injected into the N-layer are trapped by the high-low junctions at the N+, N- interfaces and are detected by sensing the source-drain current. Current levels are used to establish binary one and zero levels in the cell. Four masks in an aligned procedure simplify fabrication.

High density memory cell

The present invention provides a method for planarizing a non-uniform thickness of oxide, for example silicon dioxide as is formed over oxide-filled trenches used in deep dielectric isolation in integrated circuits. The oxide is removed by a planarizing resist-etching process so that etching in thicker resist areas proceeds at a rate slower than etching in thinner resist areas. A referred etchant is HF gas and etching is preferably at an elevated temperature.

Method of planarizing silicon dioxide in semiconductor devices

A high speed, unity gain, emitter follower OR circuit is disclosed including first and second pairs of emitter-connected complementary bipolar transistors with the bases of the NPN transistors being connected together and the bases of the PNP transistors being connected commonly to an input line. One of the NPN transistors id diode-connected (base to collector). The emitter of the other NPN transistor is connected to an output terminal. The input line is connected to the emitters of a pair of OR input NPN transistors and to a first current source. A second current source is coupled to the diode-connected NPN transistor.

Unity gain emitter follower bridge circuit

A complementary bipolar transistor circuit characterized by low power dissipation and fast response for driving capacitive loads in response to input logic signals. An emitter follower series-connected pair of complementary transistors provide an output signal at the junction between their commonly connected emitters. The NPN transistor of the pair of transistors is directly driven by an input signal applied to its base. The PNP transistor of the pair of transistors is driven through a second series-connected NPN transistor and Schottky diode, the second NPN transistor base also receiving said input signal. The forward voltage of the Schottky diode is less than the V.sub.be of the PNP transistor. The PNP transistor nominally is held off and conducts only on negative-going input signal transitions to discharge the capacitive load. The NPN transistor of the pair of transitors conducts only on positive-going input signal transitions to charge the capacitive load. The circuit can be extended to perform NOR logic and to provide a pair of output signals in phase opposition to each other.

Complementary transistor inverting emitter follower circuit

A complementary bipolar transistor circuit characterized by the same output impedance for positive and negative input voltage transitions, only a single collector path delay between input and output for both senses of input voltage transitions and very low standby power consumption. Provision is made for simultaneously actuating an emitter follower series-connected first pair of complementary transistors with signals having voltage swings which are only a fraction of the V.sub.be necessary to forward bias each base-emitter diode of the first pair of transistors. The actuation is accomplished using a second pair of complementary transistors having collector electrodes connected to respective bases of the first pair of transistors of similar kind. One of the remaining electrodes of each of the second pair of transistors are connected to each other. In a driver circuit species of the invention, the bases of the second pair of transistors are connected to each other and receive the input signal. In a logic circuit species of the invention, the emitter of one of the second pair of transistors is connected to the base of the other of the second pair of transistors. NOR logic is performed by connecting additional transistors in parallel with said one of the second pair of transistors, the bases of the additional transistors receiving respective logic input signals. The output from the driver circuit as well as from the logic circuit is derived from the commonly connected emitters of the first pair of transistors. The first pair of transistors conduct only during the transitions of the input signals.

A high speed current switch logic circuit wherein a first and a second transistor are operated in a current switching mode and wherein a third and a fourth transistor are provided whereby the current switching operation of the first and second transistor causes current switching operation of the third and fourth transistors and push pull switching of power to a load.

Push pull switch utilizing two current switch circuits

An all-NPN bipolar transistor driver circuit characterized by low standby power dissipation and fast response, particularly at high input driving conditions. The bases of a pair of NPN transistors are commonly connected to an input terminal. The emitter of a third NPN transistor is connected to the collector of one transistor of the transistor pair and to an output terminal. The collector of the other transistor of the transistor pair is connected to the base of the third NPN transistor. The base and collector of the third NPN transistor are coupled to a first biasing means. The emitters of the transistor pair are connected to a second biasing means through respective resistors so that those emitters may be independently biased. The values of the biasing means are set, relative to the lowest input voltage excursion occurring at the input terminal so that no current flows through transistor pair during the lowest input voltage excursion. Various circuit extensions, based on the above driver circuit, are also described to provide logic functions represented by output logic signals which are in-phase as well as out-of-phase relative to the applied input logic signals.

All-NPN transistor driver and logic circuit

A method for making a bipolar filamentary pedestal transistor having reduced base-collector capacitance attributable to the elimination of the extrinsic base-collector junction. Silicon is deposited upon a coplanar oxide-silicon surface in which only the top silicon surface of the buried collector pedestal is exposed through the oxide. Epitaxial silicon deposits only over the exposed pedestal surface while polycrystalline silicon deposits over the oxide surface. The polycrystalline silicon is etched away except in the base region. An emitter is formed in the base region and contacts are made to the emitter, base and collector regions.

Selective epitaxy method for making filamentary pedestal transistor

A method for making a high performance bipolar transistor characterized by self-aligned emitter and base regions and minimized base and emitter contact spacing. The disclosed method comprises forming a recessed oxide-isolated structure having opposite conductivity epitaxial layer and substrate. Multiple layered mass of alternating silicon nitride and silicon dioxide layers are placed over the base region and over the collector reach-through region. Polycrystalline silicon is deposited between the mesas. The mesas are undercut-etched to expose the extrinsic base region which is ion implanted. Then, the mesas are removed to expose the emitter and intrinsic base regions as well as the collector reach-through regions. The latter exposed regions are ion implanted appropriately. Contacts are made directly to the emitter and collector reach-through regions and indirectly via the polysilicon to the base region.

Self aligned method for making bipolar transistor having minimum base to

A method for manufacturing a high performance bipolar device and the resulting structure which has a very small emitter-base spacing is described. The small emitter-base spacing, reduces the base resistance compared to earlier device spacing and thereby improves the performance of the bipolar device. The method involves providing a silicon semiconductor body having regions of monocrystalline silicon isolated from one another by isolation regions and a buried subcollector therein. A base region is formed in the isolated monocrystalline silicon. A mask is formed on the surface of the silicon body covering those regions designated to be the emitter and collector reach-through regions. A doped polycrystalline silicon layer is then formed through the mask covering the base region and making ohmic contact thereto. An insulating layer is formed over the polysilicon layer. The mask is removed from those regions designated to be the emitter and collector reach-through regions. The emitter junction is then formed in the base region and the collector reach-through formed to contact the buried subcollector. Electrical contacts are made to the emitter and collector. The doped polycrystalline silicon layer is the electrical contact to the base regions.

High performance bipolar device and method for making same

A small variable resistor is used as a precision terminating resistor in an integrated circuit interconnection structure. The structure involves the use of a driver circuit connected to and driving a plurality of loads which are connected to a transmission line. The transmission line is terminated by the precision variable terminating resistor. The last load in the series of loads is located in the integrated circuit chip which has the variable terminating resistor. The absolute value of the variable resistor is difficult to control. The absolute value of any conventional integrated resistor is hard to control in manufacturing. However, by making the value of the resistance proportional to a voltage which itself is proportional to a deviation from a reference voltage, it is possible to obtain a much more precise value of resistance.

Integrated circuit interconnection structure having precision

A method is given for fabricating vertical NPN and PNP structures on the same semiconductor body. The method involves providing a monocrystalline semiconductor substrate having regions of monocrystalline silicon isolated from one another by isolation regions. Buried regions are formed overlapping the juncture of the substrate and epitaxial layer and are located in at least one of the regions of isolated monocrystalline silicon. The P base region in the NPN designated regions and a P reach-through in the PNP designated regions are formed simultaneously. The emitter region in the NPN regions and base contact region in the PNP regions are then formed simultaneously. The P emitter region in the PNP regions is then implanted by suitable ion implantation techniques. A Schottky Barrier collector contact in the PNP regions are formed. Electrical contacts are then made to the PNP and NPN transistor elements. A PNP device may be fabricated without the formation of an NPN device if it is so desired.

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Hyde Park, NY, United States of America

James L Walsh