Abstract: The present invention is drawn to a semiconductor integrated circuit device employing on the same silicon substrate a plurality of kinds of MOS transistors different in magnitude of tunnel current flowing either between the source and gate or between the drain and gate thereof. These MOS transistors include tunnel-current increased MOS transistors at least one of which is for use in constituting a main circuit of the device. The plurality of kinds of MOS transistors also include tunnel-current reduced or depleted MOS transistors at least one of which is for use with a control circuit. This control circuit is inserted between the main circuit and at least one of two power supply units.

Abstract: An n-channel type MIS field effect transistor is fabricated on a p-type well defined in a standard p-type silicon substrate, and is expected to respond to a high-frequency signal, wherein a heavily-doped p-type well contact region is formed outside of the p-type well for increasing the substrate resistance, and a capacitor is coupled to the heavily-doped p-type well contact region for increasing the impedance so that the insertion loss is reduced by virtue of the large impedance of the silicon substrate.

Abstract: The specification describes techniques for isolating noisy subcircuits in integrated analog/digital devices. Isolation is obtained using a modification of triple well isolation wherein the deep isolation implant is restricted to the digital circuits only to prevent noise from the digital circuits from propagating to the analog sections through the buried implant. Resistor sections are also separated from the buried isolation implant.

Abstract: A semiconductor device comprising a first transistor (40) and a second transistor (100), both formed in a semiconductor substrate (50). The first transistor comprises a gate conductor (56) and a gate insulator (54) separating the gate conductor from a semiconductor material and defining a channel area (66) in the semiconductor material opposite from the gate conductor. The first transistor further comprises a source (S2) comprising a first doped region (581) of a first conductivity type and adjacent the channel area. Further, the first transistor comprises a drain (D2). The drain comprises a first well (641) adjacent the channel area and having a first concentration of the first conductivity type and a first doped region portion and a second doped portion (68). The first doped portion has a second concentration of the first conductivity type. The second concentration is greater than the first concentration and the first doped region portion has a common interface with the first well.

Abstract: An object of the invention is to suppress degradation of the effective isolation width between a well and a diffusion layer caused by impurity ion implantation for forming the well performed at a predetermined incident angle. A well is formed by performing impurity ion implantation twice: first impurity ion implantation from a first direction at predetermined incident angle, acceleration voltage and dose; and second impurity ion implantation from a second direction different from the first direction by 180 degrees in a plan view at the same incident angle, acceleration voltage and dose as those in the first impurity ion implantation.

Abstract: A nonvolatile memory cell comprising a pair of spaced apart shallow trench isolation regions formed in a substrate and defining a substrate active region. A tunnel dielectric is formed on the substrate active region. A floating gate is formed on the tunnel dielectric and is self aligned between the spaced apart shallow trench isolation regions. A dielectric layer is formed on the floating gate and a control gate formed on the dielectric layer. A source region and a drain region are formed in the substrate active region on opposite sides of the floating gate.

Abstract: A semiconductor apparatus and method for making the same is disclosed herein in which the semiconductor apparatus includes a first active device formed in a mesa region of semiconductor material formed on one or more sidewalls of an isolation region, and a conductive path which extends from the active device in a linear direction of the mesa. An embodiment is disclosed in which a plurality of active devices are formed in the mesa region and electrically connected thereby.

Abstract: An integrated circuit CMOS structure and method for forming the structure provides gate sidewall spacers which are independently optimized for the n-channel and p-channel devices to improve hot-carrier lifetime while maintaining high drive currents. This is accomplished by providing polysilicon spacers for the n-channel devices and silicon nitride spacers for the p-channel devices.

Abstract: A first mask which is formed which exposes a cell array region and a peripheral circuit region of a semiconductor substrate. The cell array region and the peripheral circuit region are of a same conductive MOS type. Then, a preceding ion implantation process is implemented in both the cell array region and the peripheral circuit region utilizing the first mask. The preceding ion implantation process has ion implantation parameters corresponding to first implantation design specifications of one of the cell array region and the peripheral circuit region. Then, a second mask is formed which shields the one of the cell array region and the peripheral circuit region and which exposes the other of the cell array region and the peripheral circuit region. A subsequent ion implantation process is then implemented in the other of the cell array region and the peripheral circuit region utilizing the second mask.

Abstract: Provided is a technique for forming an indium field implant at the bottom of an STI trench to strengthen the p-well under field oxide, but to not weaken the n-well under the field oxide. The diffusivity of indium is an order of magnitude smaller than that of boron and the activation level of indium is high enough for well dopings. Thus, the implanted indium is able to keep the concentration of p-dopant at the p-n well junction under the field isolation and the oxide/silicon interface high, even with boron depletion, so that punchthrough is avoided.

Abstract: A semiconductor substrate has a main surface, a well, a plurality of memory cells, a first memory cell region, a second memory cell region, a border region, a well contact region, a first dummy element, a second dummy element, a first transistor and a second transistor. The first and second memory cell regions are located over the well. The memory cells are formed in the first and second memory cell regions. The border region is located over the well on a border between the first memory cell region and the second memory cell region. The well contact region is formed in the well in the border region and is electrically connected to a wiring layer for fixing the voltage of the well. The first and second dummy elements are formed in the border. The first transistor, that is a component of the memory cell, is formed in the first memory cell region and is located adjacent to the first dummy element.

Abstract: An RF circuit may be formed over a triple well that creates two reverse biased junctions. By adjusting the bias across the junctions, the capacitance across the junctions can be reduced, reducing the capacitive coupling from the RF circuits to the substrate, improving the self-resonance frequency of inductors and reducing the coupling of unwanted signals and noise from the underlying substrate to the active circuits and passive components such as the capacitors and inductors. As a result, radio frequency devices, such as radios, cellular telephones and transceivers such as Bluetooth transceivers, logic devices and Flash and SRAM memory devices may all be formed in the same integrated circuit die using CMOS fabrication is processes.

Abstract: A semiconductor device and a method of producing the semiconductor device, fabricated by forming a memory device and a logic device on a single semiconductor substrate, are provided. A side wall (9) and a silicide protection film (10) of a gate electrode (7e) are used instead of forming a silicide protection film in a logic device region (101), whereby the number of steps in forming a logic process consolidating device can be reduced. Further, high concentration impurity regions are formed using the silicide protection film (10) as a mask, whereby a degree of freedom of a condition of implanting ions becomes high.

Abstract: A semiconductor device has first and second active regions defined on the principal surface of a silicon substrate, a first n-channel MOS transistor formed in the first active region and having first extension regions and first pocket regions being deeper than the first extension regions and being doped with indium at a first concentration, and a second n-channel MOS transistor formed in the second active region and having second extension regions and second pocket regions being deeper than the second extension regions and being doped with indium at a second concentration lower than the first concentration. Boron ions may be implanted into the second pocket regions. The pocket regions can be formed by implanting indium ions and an increase in leak current to be caused by indium implantation can be reduced.

Abstract: A twin-well CMOS integrated circuit device includes an n-well region and a p-well region. Each of the n-well and p-well region includes spaced-apart regions which serve as drain and source regions, a channel region between the spaced-apart regions, a shallow trench isolation structure contiguous with one of the spaced-apart regions, and a doped diffused region extending from the surface of the well region, around and underneath the trench isolation structure, to a region beneath the contiguous spaced-apart region.

Abstract: In transistors with sub-micron channels, short-channel effects, such as a lowering of the threshold voltage, are usually suppressed by means of a halo (or pocket) implant in the source/drain regions, which operation is performed jointly with the LDD implantation. The halo implant, however, decreases the analog performance of transistors. To combine suppression of short-channel effects with a high analog performance, it is proposed to provide only transistors T1, which are not intended for analog functions with the halo implant (16), and to mask the analog transistors T2 with a mask (15) against the halo implant. To avoid short-channel effects in T2, this transistor is provided with a channel whose length is larger than that of transistor T1.

Abstract: A core section complementary transistor and a memory cell section complementary transistor are formed on a semiconductor substrate of a first conductivity type. The core section complementary transistor has a first well of a second conductivity type provided in the semiconductor substrate, a first core section MOS transistor provided on the first well of the second conductivity type, a second core section MOS transistor provided on the semiconductor substrate a device separation film which separates the first core section MOS transistor and the second core section MOS transistor from each other, and a well of the first conductivity type provided under a part of the device separation film which is closer to the second core section MOS transistor. The first core section MOS transistor has source-drain regions of the first conductivity type. The second core section MOS transistor has source-drain regions of the second conductivity type.

Abstract: An integrated circuit structures such as an SRAM construction wherein the soft error rate is reduced comprises an integrated circuit structure formed in a semiconductor substrate, wherein at least one N channel transistor is built in a P well adjacent to one or more deep N wells connected to the high voltage supply and the deep N wells extend from the surface of the substrate down into the substrate to a depth at least equal to that depth at which alpha particle-generated electron-hole pairs can effectively cause a soft error in the SRAM cell. For a 0.25 &mgr;m SRAM design having one or more N wells of a conventional depth not exceeding about 0.5 &mgr;m, the depth at which alpha particle-generated electron-hole pairs can effectively cause a soft error in the SRAM cell is from 1 to 3 &mgr;m. The deep N well of the 0.25 &mgr;m SRAM design, therefore, extends down from the substrate surface a distance of at least about 1 &mgr;m, and preferably at least about 2 &mgr;m.

Abstract: A first silicon layer (Si layer), a second silicon layer (Si1Cy layer) containing carbon and a third silicon layer not containing carbon are stacked in this order on a silicon substrate. Since the lattice constant of the Si1-yCy layer is smaller than that of the Si layer, the conduction band and the valence band of the second silicon layer receive a tensile strain to be split. Electrons having a smaller effective mass, which have been induced by an electric field applied to a gate electrode, are confined in the second silicon layer, and move in the channel direction. Thus, an n-MOSFET having extremely high mobility can be obtained. Furthermore, if the second silicon layer is made of Sil-x-yGexCy, a structure suitable for a high-performance CMOS device can be formed. A high-performance field effect transistor can be provided at lower costs by using a heterojunction structure mainly composed of silicon.

Abstract: A shallow P well and a deep P well are formed in the surface of a P type semiconductor substrate so as to partially overlap each other and these wells are surrounded by an N well, a deep bottom N type well and a connection N well. The impurity concentration of this overlapping region is higher than the impurity concentration of the P well or of the deep P well and a P+ type region is formed in the surface of the overlapping region. A potential (VBB) different from the ground potential is applied to the P+ type region. The P+ type region is formed in overlapping region and, thereby, the layout of the semiconductor device can be scaled down.

Abstract: A semiconductor device improved to suppress a leakage current of a transistor is provided. A gate electrode is disposed on a semiconductor substrate. A pair of p type source/drain layers are provided on the surface of the semiconductor substrate, on both sides of the gate electrode in the gate length direction Y. An n type gate width determining layer is provided on the surface of the semiconductor substrate to sandwich the source/drain layers in the width direction X of the gate electrode, which determines a gate width of the gate electrode. The source/drain layers and the gate width determining layer are isolated by PN junction.

Abstract: A configuration for voltage buffering in dynamic memories based on CMOS technology uses the capacitance of a well structure for buffering the amplified word line voltage or the negative word line reverse voltage.

Abstract: A Vss-side off transistor is often used in an electrostatic breakdown prevention circuit having an NMOS transistor. In such a circuit, the state of connection of the transistor ensures that off-leak current has a significant influence on the standby current, which is particularly noticeable when the circuit is used in a semiconductor device running at low power consumption. In such case, since the threshold voltage of a MOS transistor forming the semiconductor device is made as low as possible, the sub-threshold leak current in the electrostatic breakdown prevention circuit is large. To prevent this, the NMOS transistor forming the electrostatic breakdown prevention circuit is formed with a P type gate electrode for the purpose of increasing its threshold voltage by about 1.1 V as compared with that if the gate electrode of the NMOS transistor were to have an N type gate electrode.

Abstract: A semiconductor memory device has a semiconductor substrate, a peripheral circuit region and a memory cell region on the principal surface of the semiconductor substrate. The semiconductor memory device has a first well formed in the peripheral circuit region, a second well of first conductivity type and a third well of second conductivity type formed in the memory cell region having substantially the same depth, and a device element isolator formed in the memory cell region for isolating a device element formed in the second well from a device element formed in the third well. The second and third wells extend to an area under the device element isolator. The second and third wells extend to a level under the device element isolator. The second and third wells may include a first layer having a depth shallower than the first well, and a second layer having substantially the same depth as the first well.

Abstract: A semiconductor device is provided with an SRAM memory cell. The semiconductor device includes a first gate-gate electrode layer, a second gate-gate electrode layer, a first drain-drain wiring layer, a second drain-drain wiring layer, a first drain-gate wiring layer and a second drain-gate wiring layer. The first drain-gate wiring layer and an upper layer and a lower layer of the second drain-gate wiring layer are located in different layers, respectively. The upper layer is provided above either an n-type well region or a p-type well region.

Abstract: A process for forming a first transistor of a first conductivity type and a second transistor of a second conductivity type in a semiconductor substrate is disclosed. The substrate has a first well of the first conductivity type and a second well of the second conductivity type. A gate dielectric is formed over the wells. A first metal layer is then formed over the gate dielectric. A portion of the first metal layer located over the second well is then removed. A second metal layer different from said first metal is then formed over the wells and a gate mask is formed over the second metal. The metal layers are then patterned to leave a first gate over the first well and a second gate over the second well. Source/drains are then formed in the first and second wells to form the first and second transistor.

Abstract: A shallow P well and a deep P well are formed in the surface of a P type semiconductor substrate so as to partially overlap each other and these wells are surrounded by an N well, a deep bottom N type well and a connection N well. The impurity concentration of this overlapping region is higher than the impurity concentration of the P well or of the deep P well and a P+ type region is formed in the surface of the overlapping region. A potential (VBB) different from the ground potential is applied to the P+ type region. The P+ type region is formed in overlapping region and, thereby, the layout of the semiconductor device can be scaled down.

Abstract: A semiconductor integrated circuit has a logic circuit operated at a small power supply voltage of about 0.5V, wherein a noise margin of the logic circuit can be set at a larger value even if characteristics of the circuit vary depending upon manufacturing process conditions. Satisfactory speed can be ensured during an operation and power consumption can be reduced during a stand-by time. This is attained by controlling individual potentials of first and second conductivity type wells in which a logic circuit is formed. For this purpose, two voltage supply circuits for controlling voltages of the wells and a logic threshold voltage generator are provided.

Abstract: An improved semiconductor device, such as a MOSFET with raised source/drain extensions on a substrate with isolation trenches etched into the surface of the substrate . The device has thin first dielectric spacers on the side of a gate and gate oxide and extend from the top of the gate to the surface of the substrate. Raised source/drain extensions are placed on the surface of a substrate, which extend from the first dielectric spacers to the isolation trenches. Thicker second dielectric spacers are placed adjacent to the first dielectric spacers and extend from the top of the first dielectric spacers to the raised source/drain extensions. Raised source/drain regions are placed on the raised source/drain extensions, and extend from the isolation trenches to the second dielectric spacers. The semiconductor device has very shallow source drain extensions which result in a reduced short channel effect.

Abstract: An RF circuit may be formed over a triple well that creates two reverse biased junctions. By adjusting the bias across the junctions, the capacitance across the junctions can be reduced, reducing the capacitive coupling from the RF circuits to the substrate, improving the self-resonance frequency of inductors and reducing the coupling of unwanted signals and noise from the underlying substrate to the active circuits and passive components such as the capacitors and inductors. As a result, radio frequency devices, such as radios, cellular telephones and transceivers such as Bluetooth transceivers, logic devices and Flash and SRAM memory devices may all be formed in the same integrated circuit die using CMOS fabrication processes.

Abstract: The present invention provides an embedded type flash memory structure and a method for operating the same. The memory structure of the present invention comprises a first deep doped-region formed on the surface of a semiconductor substrate. A second doped-region is implanted in the first deep doped-region. A plurality of first shallow doped-regions are respectively formed in the second doped-region and the first deep doped-region to be used as drains and sources. A dielectric insulating layer and a poly-silicon gate are stacked above the first deep doped-region between the source and the drain. The present invention also proposes programming, erasing, and reading processes corresponding to the flash memory cell structure.

Abstract: The present invention provides an embedded type flash memory structure and a method for operating the same. The memory structure of the present invention comprises a first deep doped-region formed on the surface of a semiconductor substrate. A second doped-region is implanted in the first deep doped-region. A plurality of first shallow doped-regions are respectively formed in the second doped-region and the first deep doped-region to be used as drains and sources. A dielectric insulating layer and a poly-silicon gate are stacked above the first deep doped-region between the source and the drain. The present invention also proposes programming, erasing, and reading processes corresponding to the flash memory cell structure.

Abstract: A signal output circuit includes a first NMOS transistor that supplies the potential of its drain as output data to an output terminal that has been pulled up to a high power source voltage. This signal output circuit includes a second NMOS transistor having input to its gate a control signal that becomes a high logical level when there is no power supplied, and having its drain connected to the gate of the first NMOS transistor.

Abstract: A capacitive element C1 having a small leakage current is formed by utilizing a gate oxide film 9B thicker than that of a MISFET of a logic section incorporated in a CMOS gate array, without increasing the number of steps of manufacturing the CMOS gate array. The capacitive element C1has a gate electrode 10E. A part of the gate electrode 10E is made of a polycrystalline silicon film. The polycrystalline silicon film is doped with n-type impurities, so that the capacitive element may reliably operate even at a low power-supply voltage.

Abstract: P type well regions 31 and 32 are formed in N type well regions 21 and 22 respectively. The N type well regions 21 and 22 are formed separately each other. Charge transfer MOS transistors M2 and M3 are formed in the P type well regions 31 and 32 respectively. Thus, parasitic thyristor causing latch-up is nor formed.

Abstract: An insulated gate field effect transistor or a CMOS pair of transistors of a family of logic circuits includable in any type of integrated circuit, including microprocessors, memories and logic macros, and any or all functional portions thereof preferably forms an asymmetrical conduction device junction integrally with the gate structure to provide hysteresis that yields increased noise immunity and reduced power consumption and dissipation by asymmetric alteration of switching thresholds for positive and negative input signal transitions such that the turn-ON transition time or speed is slowed relative to the turn-OFF transition time or speed. The asymmetric conduction function is preferably provided by a polysilicon diode junction which is exposed and allowed to function as such by masking prior to application of a conductive material to the gate structure.

Abstract: A semiconductor device according to the present invention includes a semiconductor substrate; device isolation regions provided in the semiconductor substrate; a first conductivity type semiconductor layer provided between the device isolation regions; a gate insulating layer provided on an active region of the first conductivity type semiconductor layer; a gate electrode provided on the gate insulating layer; gate electrode side wall insulating layers provided on side walls of the gate electrode; and second conductivity type semiconductor layers provided adjacent to the gate electrode side wall insulating layers so as to cover a portion of the corresponding device isolation region, the second conductivity type semiconductor layers acting as a source region and/or a drain region. The gate electrode and the first conductivity type semiconductor layer are electrically connected to each other.

Abstract: In an integrated circuit device, there are various optimum gate lengths, thickness of gate oxide films, and threshold voltages according to the characteristics of circuits. In a semiconductor integrated circuit device in which the circuits are integrated on the same substrate, the manufacturing process is complicated in order to set the circuits to the optimum values. As a result, in association with deterioration in the yield and increase in the number of manufacturing days, the manufacturing cost increases. In order to solve the problems, according to the invention, transistors of high and low thresholds are used in a logic circuit, a memory cell uses a transistor of the same high threshold voltage and a low threshold voltage transistor, and an input/output circuit uses a transistor having the same high threshold voltage and the same concentration in a channel, and a thicker gate oxide film.

Abstract: The present invention provides a CMOS process, wherein a halo structure can be fabricated without employing an additional lithographic mask for protecting the transistors of the opposite conductivity during a halo implant. The halo implant has a projected range or depth that lies in the range of an LIP implant or a counter-doping implant in the well containing the transistors of the opposite conductivity. The LIP or counter-doping implant effectively cancels the halo impurities.

Abstract: In a semiconductor device having MOS transistors, protective elements are connected to gate electrodes 5-b and 5-c each of which is an independent gate electrode through the first aluminum layers 7-a and 7-d. The first aluminum layers 7-a and 7-d are the wiring layers of the lowest layer. The protective elements are constituted by a junction of N well 1 and P+ diffused layer 3-f and a junction of P well 2 and N+ diffused layer 4-f, and a junction of N well 1 and P+ diffused layer 3-g and a junction of P well 2 and N+ diffused layer 4-g.

Abstract: The present invention is related to a method of processing a high voltage p++/n-well junction on a substrate comprising at least one n-well region and at least one p-well region. The method comprises performing a p-type implantation in a zone surrounding said high voltage p++/n-well junction independently from other implantation.

Abstract: In a bipolar transistor block, a base layer (20a) of SiGe single crystals and an emitter layer (26) of almost 100% of Si single crystals are stacked in this order over a collector diffused layer (9). Over both edges of the base layer (20a), a base undercoat insulating film (5a) and base extended electrodes (22) made of polysilicon are provided. The base layer (20a) has a peripheral portion with a thickness equal to that of the base undercoat insulating film (5a) and a center portion thicker than the peripheral portion. The base undercoat insulating film (5a) and gate insulating films (5b and 5c) for a CMOS block are made of the same oxide film. A stress resulting from a difference in thermal expansion coefficient between the SiGe layer as the base layer and the base undercoat insulating film 5a can be reduced, and a highly reliable BiCMOS device is realized.

Abstract: Provided with a semiconductor device including: a semiconductor substrate having a first conductivity type; a first well having a second conductivity type formed in a first region in a major surface of the semiconductor substrate; a second well having the first conductivity type formed in a second region in the major surface of the semiconductor substrate; a first MOS transistor having the first conductivity type and a first contact region having the second conductivity type formed in the first well; a second MOS transistor having the second conductivity type and a second contact region having the second conductivity type formed in the second well; a heavily doped region of buried layer having the second conductivity type formed at a portion corresponding to the first contact region in the first well; and a heavily doped region of buried layer having the first conductivity type formed at a portion corresponding to the second contact region in the second well.

Abstract: A semiconductor device having an SRAM section in which a p-well, a first n-well, and a second n-well are formed in a semiconductor substrate. Two n-type access transistors and two n-type driver transistors are formed in the p-well. Two p-type load transistors are formed in the first n-well. The second n-well is located under the p-well and the first n-well and also is connected to the first n-well. The potential of the first n-well is supplied from the second n-well. According to the present invention, the SRAM section can be reduced in size.

Abstract: A new design for a high voltage bipolar transistor is disclosed. Instead of a buried subcollector (which would be N+ in an NPN device), a buried P+ layer is used. The presence of this P+ layer results in pinch-off between itself and the bipolar base. This allows much higher breakdown voltages to be achieved. In particular, the device will not break down at the bottom of the base-collector junction which is the weak spot for conventional devices. A process for manufacturing this device is described. A particular feature of this new process is that the N type epitaxial layer that is grown over the P+ layer is only about half the thickness of its counterpart in the conventional device. The process is fully compatible with conventional BiCMOS processes and has lower cost.

Abstract: An efficient method for fabricating dual well type structures uses the same number of masks used in single well type structure fabrication. In a preferred embodiment, the current invention allows low voltage and high voltage n-channel transistors and low voltage and high voltage p-channel transistors to be formed in a single substrate. One mask is used for forming a diffusion well, a second mask for both forming a retrograde well and doping the well to achieve an intermediate threshold voltage in that well, and a third mask for both differentiating the gate oxides for the low voltage devices and doping the threshold voltages to achieve the final threshold voltages.

Abstract: The present invention provides a low-voltage-triggered electrostatic discharge (LVTESD) protection circuit coupled to a pad of an integrated circuit (IC) to protect core circuits of the IC from ESD. The ESD protection circuit comprises a semiconductor substrate having the first conductivity type, a well region having the second conductivity type is formed in the semiconductor substrate, and an anode-doped region having the first conductivity type and formed in the well region to become an anode of a semiconductor control rectifier (SCR). A gate structure is formed in the semiconductor substrate outside the well region. A first doped region having the second conductivity type is formed between the well region and the gate structure in the semiconductor substrate. A second doped region having the second conductivity type is formed adjacent to the second side of the gate structure in the semiconductor substrate.

Abstract: A pad oxide layer is formed on a substrate, wherein the thickness of the pad oxide layer is about greater than 250 Å. The alignment photo-resist layer is selectively patterned by a conventional lithography method to define the N-well region. The pad oxide layer is partially etched by using etch method with the alignment photo-resist pattern as a mask until the thickness of the pad oxide layer is about 100 Å to form an alignment mark. The N-type ion-implant is performed by the alignment photo-resist pattern as a mask to form an N-doped region in the substrate. Then, the alignment photo-resist pattern is removed. The P-well photo-resist is defined and formed on the pad oxide layer, then performing a P-type ion-implant through the pad oxide layer into the substrate by means of the P-well photo-resist as a mask to form a P-doped region. Then remove the P-well photo-resist and proceed with the drive-in process to form the N-well region and P-well region.

Abstract: A densely integrated pixel, fabricated by CMOS technology, comprises a photodiode formed by a n-well, with cathode, surrounded by a p-well; a reset MOS transistor formed such that its polysilicon gate is positioned, for diode control, across the junction formed by p-well and n-well regions, and its source is merged with the photodiode cathode; and a sensing MOS transistor formed such that its source is combined with the drain of the reset transistor and its gate is electrically connected to the source of the reset transistor. In the pixel of the invention, the photodiode leakage current is greatly reduced, because no n+/p-well junction is connected to the photodiode, and the fill factor is improved, because the pixel size is much reduced.

Abstract: The semiconductor device has a triple well structure. The triple well and other wells have impurity concentration distributions in the depth direction, which are determined in accordance with required function. Thereby, the required performances such as suppression of a leak current can be achieved even in a miniaturized structure.