Abstract: A truly complementary bipolar transistor structure and a combined bipolar and CMOS transistor structure are disclosed, each including a silicide layer formed upon a substrate that acts as an extrinsic base and gate. Optionally, a layer of polysilicon can be formed between the silicide layer and the substrate. An oxide layer (LTO) is formed or deposited over the silicide layer by chemical vapor deposition (CVD). Selected regions are defined and etched using a photoresist layer. Subsequent steps of implanting, etching and metalization are performed to produce transistors with reduced gate and extrinsic base resistances. Polysilicon may be used, instead of metal, as a contact in one embodiment of the invention.

Abstract: A dielectrically isolated island architecture in which the island is contoured inwardly to form one or more projections that penetrate a well separating two regions in the island to assure that the two regions will be electrically isolated without additional processing steps.

Abstract: A BiCMOS structure in which the bipolar transistor is preferably arranged vertically and the MOS transistors are formed on insulator. SIMOX techniques may be used to form a starting substrate.

Abstract: A process is disclosed which simultaneously forms high quality complementary bipolar transistors, relatively high voltage CMOS transistors, relatively low voltage CMOS transistors, DMOS transistors, zener diodes and thin-film resistors, or any desired combination of these, all on the same integrated circuit chip. The process uses a small number of masking steps, forms high performance transistor structures, and results in a high yield of functioning die. Isolation structures, bipolar transistor structures, CMOS transistor structures, DMOS transistor structures, zener diode structures, and thin-film resistor structures are also disclosed.

Abstract: A contact structure and a method for fabrication is disclosed for a semiconductor device that includes a plurality of semiconductor regions along the surface of the device, each region having a top surface and at least a sidewall surface, where a first part of the semiconductor regions are of a first conductivity type and a second part of semiconductor regions are of a second conductivity type. Select dielectric spacers are formed along the sidewalls of the select semiconductor regions of first conductivity type while a refractory metal such as titanium, molybdenum or tungsten is used to form contact on the sidewalls of the semiconductor regions of second conductivity type. This structure is most advantageous in bipolar, CMOS and BiCMOS transistor structures as it allows the formation of the sidewall spacers on emitter/gate contacts while having local metal interconnects with the reactive metal on the sidewall of the select base/source/drain contacts.

Abstract: A process is disclosed which simultaneously forms high quality complementary bipolar transistors, relatively high voltage CMOS transistors, relatively low voltage CMOS transistors, DMOS transistors, zener diodes and thin-film resistors, or any desired combination of these, all on the same integrated circuit chip. The process uses a small number of masking steps, forms high performance transistor structures, and results in a high yield of functioning die. Isolation structures, bipolar transistor structures, CMOS transistor structures, DMOS transistor structures, zener diode structures, and thin-film resistor structures are also disclosed.

Abstract: A semiconductor device comprising a MIS structure comprising a first electrically conductive film formed on an oxide film, a second electrically conductive film formed on at least a part of said first electrically conductive film, an insulator film formed on said second electrically conductive film, and a third electrically conductive film formed on said insulator film; and at least one electrode contact portion formed on said first electrically conductive film. A semiconductor device comprising a MIS capacitor having a diffusion layer inside the semiconductor substrate as a lower electrode with a first electrically conductive type being isolated using another diffusion layer having the opposite conductive type, and said another diffusion layer having the opposite conductive type being further isolated using a diffusion layer for isolation having the first conductive type and which is earthed.

Abstract: A silicon oxide film as a dielectric film and a silicon nitride film or a polysilicon film as a protection film for the silicon oxide film are formed on a silicon substrate. After the two films are selectively etched to form contact holes of a bipolar transistor, a polysilicon film as a conductive film is laid on the entire substrate and selectively etched to form electrodes. In a MIS transistor, the protection film of the silicon nitride film serves as a gate insulator film and the protection film of the polysilicon film serves as a gate electrode. Accordingly, contamination to the gate insulator film at formation of contact holes of the bipolar transistor is prevented, and an excellent semiconductor with Bi-MOS structure is manufactured with low cost.

Abstract: A semiconductor device of this invention includes an N-type semiconductor region functioning as a collector of a bipolar transistor, a silicon dioxide film doped with boron and formed in contact with the surface of the N-type semiconductor region, a P-type semiconductor region formed in contact with the silicon dioxide film doped with boron in the N-type semiconductor region and functioning as a base of the bipolar transistor, and an N-type semiconductor region formed in the P-type semiconductor region and functioning as an emitter of the bipolar transistor.

Abstract: A semiconductor device of the present invention includes a bipolar transistor and MOS transistors which are formed on the same semiconductor substrate. The bipolar transistor is heterojunction transistor having a hetero junction. The hetero-bipolar transistor is a bipolar transistor of double-hetero structure in which a material used for forming the base region thereof has a band gap narrower than a material used for forming the emitter and collector regions thereof.

Abstract: A first process embodiment of the present invention comprises the steps of implanting a blanket low dose n-well implant before field oxidation. A blanket n-type punchthrough suppression implant precedes the field oxidation step. After field oxidation, an implantation masking step is used to adjust the doping for the p-well in its active and field regions.

Abstract: A logic circuit comprising an active-pull-down circuit in which electrodes of an active capacitor are formed of a conductive layer in common with one of contact electrodes of neighboring transistors is disclosed. The area for the capacitor is reduced, so that the element-occupied area is minimum even when the absorbing capability of the active-pull-down circuit is designed to be high for reducing a transient duration of an output signal. Besides, capacitor insulation film is used as a mask during a process, so that the process for fabrication of the integrated circuit is simplified.

Abstract: Disclosed is an improved bipolar-and-complementary MOS transistor coexisting semiconductor device and a method of making the same. A collector-and-base separator is formed on the site allotted to a bipolar transistor along with a source-and-drain separator on each site allotted to PMOS and NMOS transistors. The superficial collector-and-base separator coating causes no stress to the lattice of the underlying region in the epitaxy of the semiconductor substrate, and therefore there can be no lattice defect which may appear in a conventional composite type semiconductor device structure as a result of selective oxidization of the epitaxial layer to separate the base and collector region of the bipolar transistor. Such a superficial collector-and-base separator according to the present invention assures that the bipolar transistor each of such composite type semiconductor devices is free from the lowering of the breakdown voltage at its collector-and-base junction.

Abstract: A cell library for a semiconductor integrated circuit design, comprises a CMOS cell comprising two power source wires and a CMOS circuit placed between the two power source wires at a predetermined distance, and a BiCMOS cell comprising two power source wires which are placed at a distance equal to the distance between the power source wires in the CMOS cell, a CMOS circuit placed between the two power source wires in the BiCMOS cell, and bipolar transistor circuits placed at both outsides of the two power source wires in the BiCMOS cell.

Abstract: An adaptive photoreceptor semiconductor circuit for long-time-constant continuous learning having a low offset and insensitivity to light includes a photodiode in series with an MOS feedback transistor connected across a potential difference. An inverting amplifier comprises a first MOS amplifier transistor having its gate connected to a source of bias voltage potential in series with an cascode transistor having its gate connected to a source of cascode voltage potential and a second MOS amplifier transistor having its gate connected to the common connection between the photodiode and the MOS feedback transistor. An output node comprises the connection between the first MOS amplifier transistor and the cascode transistor. A light insensitive adaptive element has a driven node connected to the output node and an isolated node connected to the gate of the MOS feedback transistor. A capacitive voltage divider is connected between a first power supply rail, the adaptive element, and the output node.

Abstract: Disclosed herein is a Bi-CMOS IC which includes a semiconductor substrate of one conductivity type, a semiconductor layer of an opposite conductivity type formed on the substrate, a buried region of the opposite conductivity type formed between a first part of the semiconductor layer and the substrate and elongated under a second part of the semiconductor layer to form an elongated buried portion, a bipolar transistor formed in the first part by using the first part as a collector region thereof, a semiconductor region of the one conductivity type formed in the second part in contact with the elongated buried portion separately from the substrate, and an insulated gate transistor formed in the semiconductor region.

Abstract: A process and structure for resolving the divergent etching requirements of a relatively thick base oxide (62) and a relatively thin gate oxide (64) in a BiCMOS integrated circuit. The necessity of etching base oxide (62) is eliminated by extending nitride mask (58) over the extrinsic base region (86) so that the relatively thick base oxide (62) only covers intrinsic base region (60) and tab region (61). Base oxide (62) at tab region (61) is partially etched in the course of forming sidewall oxide filaments (78), resulting in the residual tab oxide (62'). An extrinsic base implant is performed in extrinsic base region (86) and tab region (61), with the presence of residual tab oxide (62') affecting the profile of the implant so that it is stepped. The resulting structure, after an anneal, is extrinsic base (87'), an intrinsic base (63) (formed prior to the extrinsic base implant), and an overlap region (88') common to both.

Abstract: A mixed-type semiconductor integrated circuit device of a type wherein a semiconductor layer is formed on the surface of a semiconductor substrate with an insulating layer interposed therebetween and each of bipolar transistors and MISFETs is formed in the semiconductor layer. In the semiconductor integrated circuit device, a base insulating layer for each bipolar transistor formed in said semiconductor layer is fabricated in the form of a thin film thickness and a base insulating layer for each MISFET formed in said semiconductor layer is fabricated in the form of a thick film thickness.

Abstract: Disclosed is an integrated transistor structure having increased conductance and operating speed including a complementary insulated gate field-effect transistor pair, each including a source and drain region with a gate contact positioned therebetween, ohmic contacts to the source and drain regions, and a p-n junction contact to each of the drain regions. The gates of the two transistors are interconnected and function as the input terminal, and the two p-n junction contacts are interconnected as the output of the device. The operation of the device is such that the lightly-doped drain regions act as bases of bipolar transistors, with the emitters formed by the p-n junction diodes. Minority carriers injected by the diodes modulate the channel regions, thereby lowering their resistivity and increasing the transconductance of the device without increasing the physical size or the capacitance of the device and thereby improving the speed of the device.

Abstract: A bipolar transistor Q.sub.1 having a collector formed of a substrate region SUB of a MOS transistor M.sub.1, a base formed of the drain region of the MOS transistor and an emitter formed on the base and connected to a bit line BL is connected between the bit line BL and a memory cell MC formed of the MOS transistor M.sub.1 and and a capacitor C.sub.1 and the current amplifying operation of a bipolar transistor is used for data readout.

Abstract: Insulator films (5) formed on an epitaxial layer (3) are opened such that external base regions (17) are not covered with the insulator films (5). Cross sections (14a) of the insulator films (5) are concavely sloped downward from the insulator films (5) toward an intrinsic base region (18) in the vicinity of the epitaxial layer (3). Base electrodes (15) which are in contact with the insulator films (5) along the cross sections (14a) are connected to the external base regions (17), so that coverage of the base electrodes (15) over the external base regions (17) is improved. The base resistance of a bipolar transistor (101) is reduced.

Abstract: An n.sup.- epitaxial layer 4 is formed on the top face of a p type semiconductor substrate 1. A p.sup.+ buried layer 20 is formed by implanting ions in the region extending over the p type semiconductor substrate 1 and the n.sup.- epitaxial layer 4. A p.sup.+ channel stop is formed in the upper layer of the p.sup.+ buried layer 20 by ion implantation. A p well is formed extending from the upper layer of the p.sup.+ channel stop to the top face of the n.sup.- epitaxial layer. An n channel MOS type field effect transistor 200 is formed in the p well 22. It is possible to reliably isolate an element from an adjacent element thereto because of the structure.

Abstract: The present invention provides a BiCMOS integrated circuit with bipolar, NMOS and PMOS transistors. In a bipolar transistor, an emitter buffer is provided to minimize a hot carrier effect. The emitter buffer is implanted using the same mask used for a base link. However, the n-type dopant is implant using a large angle, while the p-type dopant is implanted using a normal implant. A "base" oxide is grown over the implant region. This oxide ultimate isolates the emitter buffer from the polysilicon emitter contact section. Local interconnects are formed using a "dual-gate" technique, in which a tungsten silicide cap layer is formed over polysilicon to short pn junctions in the interconnect.

Abstract: A bipolar junction transistor (BJT) which exhibits a suppressed Kirk Effect comprises a lightly-doped n-type collector region formed above a more heavily-doped n+ layer. Directly above the collector is a p-type base which has an extrinsic region disposed laterally about an intrinsic region. An n+ emitter is positioned directly above the intrinsic base region. The BJT also includes a localized n+ region disposed directly beneath the intrinsic base region which significantly increases the current handling capabilities of the transistor.

Abstract: A process for manufacturing an integrated circuit having both field effect and bipolar transistors provides, in one embodiment, a polycide film over the gate and field oxides. The polycide film is patterned such that a protective structure of gate material is formed on top the base region while the gate of the FET is formed, in a single process step. Ionic species are implanted to form the source and drain and the collector contact. The protective structure of gate material in the active region of the bipolar transistor is removed just before the base region is implanted to form the base. In a second embodiment, a silicon nitride oxidation mask for field oxide regions is formed over the bipolar transistor and the field effect transistor active regions. The portion of the nitride oxidation mask is removed only from the FET active regions after field oxide regions are formed.

Abstract: A dielectric isolation substrate comprises a first semiconductor wafer, a second semiconductor wafer bonded on the first semiconductor wafer with a first insulating layer interposed therebetween, a semiconductor layer formed on the second semiconductor wafer, a first groove formed in the semiconductor layer and the second semiconductor wafer so as to reach the first insulating layer, thereby isolating the semiconductor layer and the second semiconductor wafer, and a second insulating layer formed on the side face of the first groove or embedded in the first groove. In this dielectric isolation substrate, a high breakdown voltage element and a low breakdown voltage element are formed in a region isolated by the first groove.

Abstract: P-channel MOSFETs in a fully CMOS-type memory cell are formed by a thin film (polysilicon), and portions that serve as source and drain regions of the thin-film p-channel MOSFETs are thickened by a conductor layer having a small resistance value. Further, the thin film and the conductor layer having a small resistance value are formed in common with a base lead-out layer of an npn bipolar transistor constituting a peripheral circuit.

Abstract: There is disclosed a C-BiCMOS semiconductor device in which a base electrode (300) of an NPN bipolar transistor and a drain electrode (360) of a PMOS transistor are formed of the same polycrystalline semiconductor, in which a base electrode (310) of a PNP bipolar transistor and a drain electrode (350) of an NMOS transistor are formed of the same polycrystalline semiconductor, and in which a source electrode (530) of the PMOS transistor and a source electrode (520) of the NMOS transistor are formed of aluminium wiring. The C-BiCMOS semiconductor device achieves preferable electric conductivity in the source electrodes, size reduction in the drain electrodes, and simplified process steps in the formation of the base electrodes of the bipolar transistors, so that the size of the devices is reduced in simple process steps without deterioration of the electric conductivity.

Abstract: A composite semiconductor element includes a semiconductor substrate having a single crystal region projecting in the form of an island, an epitaxial growth layer formed on the semiconductor substrate so as to surround the single crystal region, an insulating isolation layer formed in predetermined regions of the epitaxial growth layer, of the single crystal region, and of the semiconductor substrate so as to insulate/isolate the epitaxial growth layer and the single crystal region from each other and to form a plurality of island-like element regions in the epitaxial growth layer and in the single crystal region, an n-channel MOS transistor and a CCD element respectively formed in element regions in the single crystal region, and a p-channel MOS transistor and a bipolar element respectively formed in element regions in the epitaxial growth layer.

Abstract: An integrated circuit is provided wherein bipolar, CMOS and DMOS devices are merged together on one chip with fabrication taking place from a CMOS point of view rather than from a bipolar point of view as in the prior art and p-type epitaxial silicon is used as opposed to n-type epitaxial silicon in the prior art. The integrated circuit uses a P+ substrate upon which a P- epitaxial layer is formed. N+ buried regions isolate the DMOS, PMOS and NPN bipolar devices from the P-epitaxial layer. Each of the devices is formed in a N-well with a first level of polysilicon gate layer providing both the gate and masking for the backgate diffusion of the DMOS device and a sidewall oxide later formed on the first level gate layer to control the diffusion of the source and drain regions of the DMOS device to control channel length. A second level of polysilicon layer provides the gate structures for the CMOS devices as well as one plate of a capacitor.

Abstract: A voltage reduction circuit is electrically inserted between between a first power supply pad and a power source voltage supplying portion of a bipolar circuit part. Receiving a control signal from a CMOS circuit part, the voltage reduction circuit reduces a power source voltage given thereto via the power supply pad, thereby producing a reduced power source voltage and outputting the reduced power source voltage to the power source voltage supplying portion of the bipolar circuit part. Hence, even though the same power source voltage is commonly supplied to the power supply pads of the bipolar circuit part and the CMOS circuit part via the same external power source pin, one of the bipolar circuit part and the CMOS circuit part receives the reduced power source voltage from the voltage reduction circuit. Thus, it is possible that a power source voltage to the CMOS circuit part and a power source voltage to the bipolar circuit part are different without increasing the number of external power source pins.

Abstract: In order to obtain a logic circuit capable of performing a high-speed operation, respective gates of a P-channel MOSFET (1) and an N-channel MOSFET (2) are connected to an input node (6) in common, and ends of resistors (12, 13) are connected to respective drains thereof. Respective emitters of an NPN transistor (3) and a PNP transistor (4) are connected to an output node (9) with an end of a resistor (5) in common, and ends of the resistors (12, 13) are connected to respective bases thereof. A source of the P-channel MOSFET (1) and a collector of the NPN transistor (3) are connected to a high potential point (8) in common while a source of the N-channel MOSFET (2) and a collector of the PNP transistor (4) are connected to a low potential point (40) in common respectively. Respective other ends of the resistors (5, 12, 13) are connected at a node (7) in common. Thus, the potential of an output terminal quickly fluctuates when a bipolar transistor is in an ON state.

Abstract: In a semiconductor device having an element isolation region including a LOCOS type field oxide film formed in a surface of a silicon substrate and a U-trench isolation region provided in the silicon substrate, the U-trench isolation region is constituted with a U-trench provided such that it penetrates the field oxide film, a channel stopper provided in a portion of the silicon substrate exposed on a bottom face of the U-trench, a first film in a form of a silicon oxide film formed by thermal oxidation of an exposed portion of the silicon substrate in the U-trench, a second film comprising a buried layer having thermal reflow characteristics and burying the U-trench, a third film having non-thermal reflow characteristics and having a top face substantially coplanar with a top face of the field oxide film and a bottom face connected to a top face of the second films and a fourth film in a form of an insulating film connected to the top face of the third film at an upper end of said U-trench and covering the U

Abstract: This invention is an SOI BICMOS process which uses oxygen implanted wafers as the starting substrate. The bipolar transistor is constructed in two stacked epitaxial layers on the surface of the oxygen implanted substrate. A buried collector is formed in the first epitaxial layer that is also used for the CMOS transistors. The buried collector minimizes the collector resistance. Selective epitaxial silicon is then grown over the first epitaxial layer and is used to form the tanks for the bipolar transistors. An oxide layer is formed over the base to serve as an insulator between the emitter poly and the extrinsic base, and also as an etch stop for the emitter etch. The emitter is formed of a polysilicon layer which is deposited through an opening in the oxide layer such that the polysilicon layer contacts the epitaxial layer and overlaps the oxide layer.

Abstract: In a semiconductor device, a charge transfer device, a bipolar transistor, and a MOSFET are formed on a single chip, and the peripheral portion of the charge transfer device is surrounded by an N.sup.+ -type region. Since the charge transfer device block is surrounded by the N.sup.+ -type region and the N.sup.+ -type buried layer, leaked charge of clocks from the charge transfer device is absorbed by the N.sup.+ -type region and the N.sup.+ -type buried layer.

Abstract: The invention provides an improved BiCMOS device and a method of fabricating such a BiCMOS device which requires fewer process steps than known fabrication methods. In one embodiment, the invention provides a method of forming an interpoly capacitor in a BiCMOS device which maintains the thickness of the interpoly dielectric in the capacitor while a window is etched for the emitter in a bipolar transistor. The method includes the use of a thin polysilicon layer overlying the oxide layer, which protects the oxide from etching while the emitter window is etched.

Abstract: A semiconductor device includes a bipolar transistor and an IIL element fabricated on a single wafer. The emitter region of the bipolar transistor is formed by diffusing the impurity of an impurity layer formed in contact with the base region therein. The impurity layer is formed of a polycide layer formed of a polysilicon layer doped with an impurity and a metal silicide layer laminated on the polysilicon layer, a laminated layer of a polysilicon layer and a refractory metal layer, or a metal silicide layer.

Abstract: Disclosed is an improved Bi-CMOS gate array for increasing integration density. The gate array includes a predetermined region for forming PMOS transistors, a predetermined region for forming bipolar transistors, a predetermined region for forming resistance elements, and a predetermined region for forming NMOS transistors. The resistance element region is formed adjacent to the bipolar transistor region, and, therefore, it is not necessary to provide any interconnection for forming a logic circuit including the resistance element connected to the bipolar transistor. An area occupied by interconnections on the semiconductor substrate is thus reduced, and, therefore the integration density is increased.

Abstract: A bipolar transistor/insulated gate transistor hybrid semiconductor device comprises a well region formed on a semiconductor substrate to serve as a first active region of a bipolar transistor, an insulated gate transistor having source and drain regions formed in the well region, which acts as a back gate of the insulated gate transistor, and second and third active regions of the bipolar transistor formed in the well region. At least one of the second and third active regions is used in common to one of the source and drain regions of the insulated gate transistor. A plurality of well regions is regularly arranged to constitute a gate array.

Abstract: A dielectrically isolated island architecture in which the island is contoured inwardly to form one or more projections that penetrate a well separating two regions in the island to assure that the two regions will be electrically isolated without additional processing steps.

Abstract: A BiMOS integrated circuit device comprises a bipolar transistor and at least one MOSFET. The collector and emitter of the bipolar transistor are connected to a high potential source and a low potential source, respectively. The MOSFET has two gate electrodes, a source, and a drain. The source is connected to the high potential source, and the drain is the base of the bipolar transistor by a diffusion layer. The diffusion layer is located between the gate electrodes, and serves as both the base of the bipolar transistor and the drain of the MOSFET. Therefore, the MOSFET has a great channel width, and a large current can be supplied to the base of the bipolar transistor. In other words, the MOSFET has a great driving capability, and the bipolar transistor has a high amplification factor.

Abstract: The impurity concentration of an n.sup.+ buried layer 51a in the region for forming a p channel MOS transistor 23 is higher than the impurity concentration of an n.sup.+ buried layer 3a in the region for forming an npn bipolar transistor 21. N.sup.+ buried layers 3a and 51a are formed on a p type silicon substrate 1. An n.sup.- well region 10 is formed as a region for forming npn bipolar transistor 21 on n.sup.+ buried layer 3a. An n well region 12 is formed as a region for forming p channel MOS transistor 23 on n.sup.+ buried layer 51a. While the performance of npn bipolar transistor 21 is maintained, the performance of a CMOS transistor formed of an n channel MOS transistor 22 and p channel MOS transistor 23 is improved. In a Bi-CMOS semiconductor device, the performance of a bipolar transistor portion is maintained, while preventing the formation of a punch through and improving the latch up tolerance of a CMOS transistor portion.

Abstract: A base resistance controlled thyristor with integrated single-polarity gate control includes a thyristor having an anode region, a first base region, a second base region on the first base region and a cathode region contacting the second base region and defining a P-N junction therewith. For providing gated turn-off control, a depletion-mode field effect transistor is provided on the second base region and is separated therefrom by an insulating region. In particular, an insulating region, such as a buried dielectric layer, is provided on the second base region and the depletion-mode field effect transistor is formed thereon. The depletion-mode field effect transistor is electrically connected between the cathode contact and the second base region and provides a direct electrical connection therebetween in response to a turn-off bias signal which is preferably a zero or near zero bias.

Abstract: A process and resultant devices is described for forming MOSFET, CMOS and BICMOS devices of Group IV alloys, in particular Si.sub.x Ge.sub.1-x wherein 0<x<1, using ion beam oxidation (IBO) or ion beam nitridation (IBN) by CIMD to form insulators of the Group IV alloys.

Abstract: A semiconductor device, comprises a semiconductor substrate, a digital element part as a pair of MOS transistors formed on the semiconductor substrate; and an analog element part as a pair of MOS transistors formed on the semiconductor substrate, wherein a gate insulator film of the analogue element part comprises at least a first silicon oxide film and a silicon nitride film, a gate insulator film of the digital element part comprises a second silicon oxide, and the gate insulation film of the analogue element part is thicker than the gate insulation film of the digital element part. A fabrication method of the semiconductor device also is described.

Abstract: In a semiconductor integrated circuit, a digital circuit section and an analog circuit section are formed on a substrate. A pair of first power source lines connects a circuit element in the digital circuit section to a power source, while a pair of second power source lines connects a substrate region in the digital circuit section to the power source. The pair of second power source lines is formed separately from the pair of first power source lines in the digital circuit section. The substrate region in the digital circuit section is surrounded by a guard ring well, to which one of the pair of second power source lines is connected.

Abstract: At least part of a low impurity concentration collector region which lies between the emitter and collector regions of a bipolar transistor in a Bi-CMOS device is formed to have a low impurity concentration. Therefore, a high emitter-collector withstanding voltage can be obtained. Further, at least part of the low impurity concentration collector region which lies between the base region and an opposite conductivity type region is formed to have a high impurity concentration. Therefore, the punch-through withstanding voltage of a parasitic transistor formed of the base, collector and, opposite conductivity type region can be enhanced, and, at the same time, the collector resistance can be reduced.

Abstract: Emitter-base protection for a first bipolar transistor formed as part of a BiCMOS circuit. A second bipolar transistor is formed in the same well as the first bipolar transistor with both transistors using the well as their collectors. A current path through the collector-emitter of the second transistor provides current to the base of the first transistor maintaining the emitter-to-base voltage of the first transistor at a relatively low reverse potential.

Abstract: A semiconductor device according to the present invention has a semiconductor body of a first conductivity type, three islands of a second conductivity type, formed in the surface of the semiconductor body. Two wells of the first conductivity are formed in the first and second islands. The device further has a charge transfer device which back gate is formed of the first well, an insulated-gate FET of the first conductivity type which back gate is formed of the second island, an insulated-gate FET of the second conductivity type which back gate is formed of the second well, and a bipolar transistor which collector is formed of the third island. The first island surrounds the first well which serves as back gate of the charge transfer device, and blocks the noise generated in the first well. Hence, the other islands are free from the influence of the noise.

Abstract: Buried layers of a second conductivity type are formed in a plurality of portions of a surface region of a semiconductor substrate of a first conductivity type, and an epitaxial layer of the first conductivity type is formed on the buried layers and the semiconductor substrate. A plurality of well regions of the second conductivity type are formed in the epitaxial layer in contact with the buried layers, and a region of the second conductivity type with a high impurity concentration is formed in one of the well regions in contact with the buried layers. A field insulating layer is formed on a surface region of the semiconductor substrate between the well regions. An impurity is ion-implanted in a portion substantially immediately below the field insulating film a plurality of times to form inversion preventing layers of the first conductivity type having a plurality of impurity concentration peaks. Active elements are formed in the epitaxial layer of the first conductivity type and the well regions.