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 semiconductor device includes a semiconductor layer having a first surface and a second surface at an opposite side thereto, a bottom gate region of a first conductivity type that is formed in the semiconductor layer, and a top gate region of the first conductivity type that is formed in a surface layer portion of the first surface of the semiconductor layer and faces the bottom gate region in a thickness direction of the semiconductor layer, the bottom gate region includes a first bottom gate region at the source region side and a second bottom gate region at the drain region side, and an interval in the thickness direction between the second bottom gate region and the top gate region is greater than an interval in the thickness direction between the first bottom gate region and the top gate region.

Junction field effect transistors (JFETs) and related manufacturing methods are disclosed herein. A disclosed JFET includes a vertical channel region located in a mesa and a first channel control region located on a first side of the mesa. The first channel control region is at least one of a gate region and a first base region. The JEFT also includes a second base region located on a second side of the mesa and extending through the mesa to contact the vertical channel region. The vertical channel can be an implanted vertical channel. The vertical channel can be asymmetrically located in the mesa towards the first side of the mesa.

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 transistor device includes: a first source region and a first drain region spaced apart from each other in a first direction of a semiconductor body; at least two gate regions arranged between the first source region and the first drain region and spaced apart from each other in a second direction of the semiconductor body; at least one drift region adjoining the first source region and electrically coupled to the first drain region; at least one compensation region adjoining the at least one drift region and the at least two gate regions; a MOSFET including a drain node connected to the first source region, a source node connected to the at least two gate region, and a gate node. Active regions of the MOSFET are integrated in the semiconductor body in a device region that is spaced apart from the at least two gate regions.

A complementary metal oxide semiconductor (CMOS)-integrated junction field effect transistor (JFET) has reduced scale and reduced noise. An exemplary JFET has a substrate layer of one dopant type with a gate layer of that dopant type disposed on the substrate, a depletion channel of a second dopant type disposed on the first gate layer, and a second gate layer of the first dopant type disposed on the depletion channel and proximate a surface of the transistor. The second gate layer can separate the depletion channel from the surface, and the depletion channel separates the first gate layer from the second gate layer.