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 quasi-lateral diffusion transistor is formed in a semiconductor-on-insulator (SOI) wafer by forming a gate region, a body region, a drift region, and a source region and bonding a handle wafer to the SOI wafer at a first side (e.g., top side) of the SOI wafer; and removing a semiconductor substrate of the SOI wafer, forming a hole in a buried insulator layer of the SOI wafer, and forming a drain region for the transistor at a second side (e.g., bottom side) of the SOI wafer. The body region and the drift region physically contact the buried insulator layer. The drain region is formed in a bottom portion of the drift region exposed by the hole and is laterally offset from the source region. In operation of the quasi-lateral diffusion transistor, a current flow direction through the semiconductor layer is diagonal between the source region and the drain region.

A semiconductor structure that includes at least one lateral diffusion field effect transistor is described. The structure includes a source contact and a gate shield that enables the line width of an ohmic region that electrically connects the source/body region to the gate shield to be smaller than the minimum contact feature size. The gate shield defines a bottom recess for forming a narrower bottom portion of the source contact, and a section that flares outward with distance from the ohmic region to extend above and laterally beyond the ohmic region. By providing a wider area for the source contact, the flared portion of the gate shield allows the portion of the gate shield that contacts the ohmic region to be narrower than the minimum contact feature size. As a result, the cell pitch of the lateral diffusion field effect transistor can be reduced.

A semiconductor device including: a first level including a first single crystal silicon layer, a plurality of first transistors, and input/output circuits; a first metal layer; a second metal layer which includes a power delivery network; where interconnection of the plurality of first transistors includes the first and second metal layers; a second level including a plurality of metal gate second transistors and first array of memory cells, disposed over the first level; a third level including a plurality of metal gate third transistors and a second array of memory cells, disposed over the second level; a via disposed through the second and third levels; a third metal layer disposed over the third level; a fourth metal layer disposed over the third metal layer; and a fourth level disposed over the fourth metal layer and including a second single crystal silicon layer.

A semiconductor device including: a first level including a first single crystal silicon layer, a plurality of first transistors, and input/output circuits; a first metal layer; a second metal layer which includes a power delivery network; where interconnection of the plurality of first transistors includes the first and second metal layers; a second level including a plurality of metal gate second transistors and first array of memory cells, disposed over the first level; a third level including a plurality of metal gate third transistors and a second array of memory cells, disposed over the second level; a via disposed through the second and third levels; a third metal layer disposed over the third level; a fourth metal layer disposed over the third metal layer; and a fourth level disposed over the fourth metal layer and including a second single crystal silicon layer.

A method to process a semiconductor device: processing the substrate forming a first level with a first single-crystal silicon-layer, first transistors, input-and-output (IO) circuits; forming a first metal-layer; forming a second metal-layer including a power-delivery network, where interconnection of the first transistors includes the first metal-layer and the second metal-layer; processing a second level including second transistors with metal gates and a first array of memory-cells; processing a third level including a plurality of third transistors with metal gates and a second array of memory-cells; third level disposed over the second level; forming a fourth metal-layer over a third metal-layer over the third-level; processing a fourth level including a second single-crystal silicon-layer, fourth level is disposed over the fourth metal-layer; forming a via disposed through the second and third levels, connections of the device to external devices includes the IO-circuits; the second level is disposed over the first level.