Sprague Electric Company

Allegro Microsystems, LLC

Solid State Scientific Corporation

Wing K Huie

Alexander H Owens

David S Pan

Mark A Halfacre

Michael J Zunino

A vertical NPN transistor is fabricated in a silicon integrated circuit substrate growing an N-type epitaxial layer, forming a preliminary P-type base region in the surface of the epitaxial layer, covering the surface with a protective glass layer, selectively etching a hole in the glass layer at an emitter-designated place over the preliminary base region, depositing N-type impurities through the hole into the silicon surface to become the emitter, implanting P-type impurities, of a kind that diffuse faster than the N-type impurities, through the hole into the epitaxial layer and heating to at least anneal the substrate. The hole is then filled to provide electrical contact to the emitter.

Method for making an NPN transistor with controlled base width

A method for making an integrated circuit includes forming patches of a silicon nitride mask over the areas where a high-current vertical DMOS and/or NPN transistor, where a vertical NPN transistor and where the NMOS and PMOS transistors of a CMOS pair are to be formed. The nitride mask also includes patches over a network of P-type isolation walls, and two special patches over two special areas at which N+ plugs for the DMOS and NPN transistors are to be formed. A heavy field oxide is grown everywhere except at the nitride patches. The two special patches are selectively removed and by heating and diffusing phosphorous from a POCl.sub.3 source from 950.degree. C. to 1100.degree. C. for at least 30 minutes, two very high conductivity N+ phosphorous plugs are formed through the epitaxial layer at a concentration of over 10.sup.20 phosphorous atoms/cm.sup.3, while the nitride serves to prevent the sensitive channel regions of the DMOS and CMOS transistors from phosphorous doping. This results in close self-alignment of the N+ plugs and their associated DMOS and NPN transistors leading to low on-resistance, to higher IC component density, to a high throughput rate at manufacturing and low cost.

Method of making integrated circuit with high current transistor and

The manufacture of an integrated circuit including an isolated vertical PNP, an isolated vertical NPN and isolated CMOS transistors is described. The PNP transistor has a shallow densely doped emitter made simultaneously with the source and drain of the PMOS transistor. The PNP base is made simultaneously with lightly doped portions of the LDD source and drain of the NMOS transistor. The PNP collector is made simultaneously with the P-well in which the NMOS transistor is formed. A P-buried layer in the isolated vertical PNP transistor provides a low collector resistance and is formed simultaneously with the P-buried layer of the NMOS transistor that extends the P-well there and better isolates the NMOS transistor from the substrate. And the N-buried layer providing superior isolation of the PNP with respect to the substrate is formed simultaneously with the N-buried layer of the vertical NPN transistor. All four of these transistors provide and are well suited for use in analog signal handling circuits. All are capable of operating at up to 15 volts. And both bipolar transistors have a high gain bandwidth.

Method for making bipolar/CMOS IC with isolated vertical PNP

A silicon integrated circuit includes a vertical power DMOS transistor and a vertical NPN transistor in separate epitaxial pockets by a method including simultaneously forming a plurality of D-well regions in the DMOS transistor and the base region in the NPN transistor, and including simultaneously forming the elemental source regions and the emitter region. N-type buried layers are provided simultaneously in the DMOS and the NPN transistors, respectively. Also formed simultaneously are two N+ plugs connecting the two buried layers, respectively, to the epitaxial surface of the integrated circuit die. None of these economically attractive simultaneous steps requires deviation in either device from optimum geometries. Also disclosed are compatible and integrated steps for forming small signal CMOS transistors. This method also includes a full self-alignment of gate, source and channel regions in the DMOS transistor as well as in the CMOS transistors.

Method for making a vertical power DMOS transistor with small signal

An integrated circuit including CMOS transistors and an EPROM device by a method including selectively implanting threshold adjusting atoms of P-type in the channel regions of the N-type transistors while exposing the whole device area of the P-channel transistor. Subsequently, the sources and drains of the N-channel transistors are selectively implanted using the gates as a self-aligning mask portion. The PN-junction capacitance of the sources and drains of the N-channel transistors are thereby kept low and not subject to the degrading effects of the threshold adjusting implant. The P-channel is also affected and source drain capacitances there are reduced so that the speed of all three types of transistors are enhanced. Only high-yield process steps are included.

Method of making a fast IGFET

A CMOS EPROM or the like is made wherein the basic memory device or EPROM device is an N-channel IGFET (insulated gate field effect transistor) having a control gate self-aligned with an underlying floating gate. The sources and drains of the EPROM devices as well as the sources and drains of peripheral N-channel transistors, are made by implanting with arsenic and with phosphorous. When heated, the faster diffusing phosphorous outruns, and extends from the bulk of, the arsenic so that these sources and drains extend slightly under the adjacent gate. This extension of the drain in the memory device enables a faster programming capability. A similar but oppositely directed lateral extension of all these sources and drains reduces the leakage to the substrate and reduces the chances of shorts to the substrate due to slightly misaligned metal to source and drain contacts.

Method for double doping sources and drains in an EPROM

CMOS transistors are fabricated in a P substrate using N- well regions. These wells are positioned to prevent aluminum spiking in the N channel devices. After P guard rings are formed for both P and N channel devices, additional masking and implantation are performed to produce N guard rings in the P channel devices. Before the transistors are formed, an implantation of P type impurities is performed causing the P channel devices, when they are formed, to have a PMOS buried channel.

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North Wales, PA, United States of America

Wing K Huie