A 3D semiconductor device, the device including: a first level including a first single crystal layer and including first transistors which each includes a single crystal channel; a first metal layer; a second metal layer overlaying the first metal layer; a second level including second transistors, first memory cells including at least one second transistor, and overlaying the second metal layer; a third level including third transistors and overlaying the second level; a fourth level including fourth transistors, second memory cells including at least one fourth transistor, and overlaying the third level, where at least one of the second transistors includes a metal gate, where the first level includes memory control circuits which control writing to the second memory cells, and at least one Phase-Lock-Loop (PLL) circuit or at least one Digital-Lock-Loop (DLL) circuit.

A semiconductor device including: a first silicon level including a first single crystal silicon layer and a plurality of first transistors; a first metal layer disposed over the first silicon level; a second metal layer disposed over the first metal layer; a third metal layer disposed over the second metal layer; a second level including a plurality of second transistors, disposed over the third metal layer; a third level including a plurality of third transistors, disposed over the second level; a via disposed through the second and third levels; a fourth metal layer disposed over the third level; a fifth metal layer disposed over the fourth metal layer; and a fourth level including a second single crystal silicon layer and is disposed over the fifth metal layer, where each of the plurality of second transistors includes a metal gate, and the via has a diameter of less than 450 nm.

A 3D semiconductor device including: a first level including a first single crystal layer and first transistors, which each include a single crystal channel; a first metal layer with an overlaying second metal layer; a second level including second transistors, overlaying the first level; a third level including third transistors, overlaying the second level; a fourth level including fourth transistors, overlaying the third level, where the second level includes first memory cells, where each of the first memory cells includes at least one of the second transistors, where the fourth level includes second memory cells, where each of the second memory cells includes at least one of the fourth transistors, where the first level includes memory control circuits, where second memory cells include at least four memory arrays, each of the four memory arrays are independently controlled, and at least one of the second transistors includes a metal gate.

A JFET structure may be formed such that the channel region is isolated from the substrate to reduce parasitic capacitance. For example, instead of using a deep well as part of a gate structure for the JFET, the deep well may be used as an isolation region from the surrounding substrate. As a result, the channel in the JFET may be pinched laterally between doped regions located between the source and the drain of the JFET. In other example embodiments, the channel may be pinched vertically and the isolation between the JFET structure and the substrate is maintained. A JFET structure with improved isolation from the substrate may be employed in some embodiments as a low-noise amplifier. In particular, the low-noise amplifier may be coupled to small signal devices, such as microelectromechanical systems (MEMS)-based microphones.

The disclosed technology relates to semiconductors, and more particularly to a junction field effect transistor (JFET). In one aspect, a method of fabricating a JFET includes forming a well of a first dopant type in a substrate, wherein the well is isolated from the substrate by an isolation region of a second dopant type. The method additionally includes implanting a dopant of the second dopant type at a surface of the well to form a source, a drain and a channel of the JFET, and implanting a dopant of the first dopant type at the surface of the well to form a gate of the JFET. The method additionally includes, prior to implanting the dopant of the first type and the dopant of the second type, forming a pre-metal dielectric (PMD) layer on the well and forming contact openings in the PMD layer above the source, the drain and the gate. The PMD layer has a thickness such that the channel is formed by implanting the dopant of the first type and the dopant of the second type through the PMD layer. The method further includes, after implanting the dopant of the first type and the dopant of the second type, siliciding the source, the drain and the gate, and forming metal contacts in the contact openings.

A solid source-diffused junction is described for fin-based electronics. In one example, a fin is formed on a substrate. A glass of a first dopant type is deposited over the substrate and over a lower portion of the fin. A glass of a second dopant type is deposited over the substrate and the fin. The glass is annealed to drive the dopants into the fin and the substrate. The glass is removed and a first and a second contact are formed over the fin without contacting the lower portion of the fin.

A power integrated circuit includes a double-diffused metal-oxide-semiconductor (LDMOS) transistor formed in a first portion of the semiconductor layer with a channel being formed in a first body region. The power integrated circuit includes a first deep diffusion region formed in the first deep well under the first body region and in electrical contact with the first body region and a second deep diffusion region formed in the first deep well under the drain drift region and in electrical contact with the first body region. The first deep diffusion region and the second deep diffusion region together form a reduced surface field (RESURF) structure in the LDMOS transistor.

The method comprises implanting a deep well of a first type of electrical conductivity provided for a drift region in a substrate of semiconductor material, the deep well of the first type comprising a periphery, implanting a deep well or a plurality of deep wells of a second type of electrical conductivity opposite to the first type of electrical conductivity at the periphery of the deep well of the first type, implanting shallow wells of the first type of electrical conductivity at the periphery of the deep well of the first type, the shallow wells of the first type extending into the deep well of the first type; and implanting shallow wells of the second type of electrical conductivity adjacent to the deep well of the first type between the shallow wells of the first type of electrical conductivity.

A device includes a buried well region and a first HVW region of the first conductivity, and an insulation region over the first HVW region. A drain region of the first conductivity type is disposed on a first side of the insulation region and in a top surface region of the first HVW region. A first well region and a second well region of a second conductivity type opposite the first conductivity type are on the second side of the insulation region. A second HVW region of the first conductivity type is disposed between the first and the second well regions, wherein the second HVW region is connected to the buried well region. A source region of the first conductivity type is in a top surface region of the second HVW region, wherein the source region, the drain region, and the buried well region form a JFET.

A method of forming a double-gated junction field effect transistors (JFET) and a tri-gated metal-oxide-semiconductor field effect transistor (MOSFET) on a common substrate is provided. The double-gated JFET is formed in a first region of a substrate by forming a semiconductor gate electrode contacting sidewall surfaces of a first channel region of a first semiconductor fin and a top surface of a portion of a first fin cap atop the first channel region. The tri-gated MOSFET is formed in a second region of the substrate by forming a metal gate stack contacting a top surface and sidewall surfaces of a second channel region of a second semiconductor fin.