A 3D integrated circuit, the circuit including: a first wafer including a first crystalline substrate, a plurality of first transistors, and first copper interconnecting layers, where the first copper interconnecting layers at least interconnect the plurality of first transistors; and a second wafer including a second crystalline substrate, a plurality of second transistors, and second copper interconnecting layers, where the second copper interconnecting layers at least interconnect the plurality of second transistors; where the second wafer is bonded face-to-face on top of the first wafer, where the bonded includes copper to copper bonding; and where the second crystalline substrate has been thinned to a thickness of less than 5 micro-meters.

A 3D integrated circuit, the circuit including: a first level including a first wafer, the first wafer including a first crystalline substrate, a plurality of first transistors, and first copper interconnecting layers, where the first copper interconnecting layers at least interconnect the plurality of first transistors; and a second level including a second wafer, the second wafer including a second crystalline substrate, a plurality of second transistors, and second copper interconnecting layers, where the second copper interconnecting layers at least interconnect the plurality of second transistors, where the second level is bonded to the first level, where the bonded includes metal to metal bonding, where the bonded includes oxide to oxide bonding, and where at least one of the second transistors include a replacement gate.

A 3D device including: a first level including first single crystal transistors overlaid by a second level including second single crystal transistors; a third level including third single crystal transistors, the second level is overlaid by the third level; a fourth level including fourth single crystal transistors, the third level is overlaid by the fourth level; first bond regions including first oxide to oxide bonds, where the first bond regions are between the first level and the second level; second bond regions including second oxide to oxide bonds, where the second bond regions are between the second level and the third level; and third bond regions including third oxide to oxide bonds, where the third bond regions are between the third level and the fourth level, where the second level, third level, and fourth level each include one array of memory cells, and where the one array of memory cells is a DRAM type memory.

A 3D integrated circuit, the circuit including: a first wafer including a first crystalline substrate, a plurality of first transistors, and first copper interconnecting layers, where the first copper interconnecting layers at least interconnect the plurality of first transistors; and a second wafer including a second crystalline substrate, a plurality of second transistors, and second copper interconnecting layers, where the second copper interconnecting layers at least interconnect the plurality of second transistors, where the second wafer is bonded face-to-face on top of the first wafer, where the bonded includes copper to copper bonding, and where the second crystalline substrate has been thinned to a thickness of less than 5 micro-meters.

A 3D integrated circuit, the circuit including: a first wafer including a first crystalline substrate, a plurality of first transistors, and first copper interconnecting layers, where the first copper interconnecting layers at least interconnect the plurality of first transistors; and a second wafer including a second crystalline substrate, a plurality of second transistors, and second copper interconnecting layers, where the second copper interconnecting layers at least interconnect the plurality of second transistors; where the second wafer is bonded face-to-face on top of the first wafer, where the bonded includes copper to copper bonding; and where the second crystalline substrate has been thinned to a thickness of less than 5 micro-meters.

A method to form a 3D integrated circuit, the method including: providing a first wafer including a first crystalline substrate, a plurality of first transistors, and first copper interconnecting layers, where the first copper interconnecting layers at least interconnect the plurality of first transistors; providing a second wafer including a second crystalline substrate, a plurality of second transistors, and second copper interconnecting layers, where the second copper interconnecting layers at least interconnect the plurality of second transistors; and then performing a face-to-face bonding of the second wafer on top of the first wafer, where the face-to-face bonding includes copper to copper bonding; and thinning the second crystalline substrate to a thickness of less than 5 micro-meters.

A semiconductor device includes: a semiconductor substrate; a semiconductor layer on the semiconductor substrate; a source electrode and a drain electrode spaced apart from each other on the semiconductor layer; a gate electrode on the semiconductor layer between the source electrode and the drain electrode; and an insulating film covering the semiconductor layer, the source electrode, the drain electrode and the gate electrode, the gate electrode has an eaves structure including a lower electrode joined to the semiconductor layer and an upper electrode provided on the lower electrode and wider than the lower electrode, a principal ingredient of the insulating film is an oxide film where atomic layers are alternately arrayed for each monolayer, and a film thickness of the insulating film that covers the lower electrode of the gate electrode is equal to a film thickness of the insulating film that covers the upper electrode.

A tunable breakdown voltage RF MESFET and/or MOSFET and methods of manufacture are disclosed. The method includes forming a first line and a second line on an underlying gate dielectric material. The second line has a width tuned to a breakdown voltage. The method further includes forming sidewall spacers on sidewalls of the first and second line such that the space between first and second line is pinched-off by the dielectric spacers. The method further includes forming source and drain regions adjacent outer edges of the first line and the second line, and removing at least the second line to form an opening between the sidewall spacers of the second line and to expose the underlying gate dielectric material. The method further includes depositing a layer of material on the underlying gate dielectric material within the opening, and forming contacts to a gate structure and the source and drain regions.

A tunable breakdown voltage RF MESFET and/or MOSFET and methods of manufacture are disclosed. The method includes forming a first line and a second line on an underlying gate dielectric material. The second line has a width tuned to a breakdown voltage. The method further includes forming sidewall spacers on sidewalls of the first and second line such that the space between first and second line is pinched-off by the dielectric spacers. The method further includes forming source and drain regions adjacent outer edges of the first line and the second line, and removing at least the second line to form an opening between the sidewall spacers of the second line and to expose the underlying gate dielectric material. The method further includes depositing a layer of material on the underlying gate dielectric material within the opening, and forming contacts to a gate structure and the source and drain regions.

A tunable breakdown voltage RF MESFET and/or MOSFET and methods of manufacture are disclosed. The method includes forming a first line and a second line on an underlying gate dielectric material. The second line has a width tuned to a breakdown voltage. The method further includes forming sidewall spacers on sidewalls of the first and second line such that the space between first and second line is pinched-off by the dielectric spacers. The method further includes forming source and drain regions adjacent outer edges of the first line and the second line, and removing at least the second line to form an opening between the sidewall spacers of the second line and to expose the underlying gate dielectric material. The method further includes depositing a layer of material on the underlying gate dielectric material within the opening, and forming contacts to a gate structure and the source and drain regions.