A method to form a 3D semiconductor device, the method including: providing a first level including first circuits, the first circuits including first transistors and first interconnection; preparing a second level including a silicon layer; forming second circuits over the second level, the second circuits including second transistors and second interconnection; transferring with bonding the second level on top of the first level; and then thinning the second level to a thickness of less than thirty microns, where the bonding includes oxide to oxide bonds, where the bonding includes metal to metal bonds, and where at least one of the metal to metal bond structures has a pitch of less than 1 micron from another of the metal to metal bond structures.

A method to form a 3D semiconductor device, the method including: providing a first level including first circuits, the first circuits including first transistors and first interconnection; preparing a second level including a silicon layer; performing growth of an epitaxial layer on top of the silicon layer, the epitaxial layer including non-silicon atoms; forming second circuits over the second level, the second circuits including second transistors and second interconnection; transferring and then bonding the second level on top of the first level; and then thinning the second level to a thickness of less than ten microns, where the bonding includes oxide to oxide bonds.

The present disclosure provides a die assembly. The die assembly includes a first die, a second die and a third die stacked together. The first die includes a plurality of first metal lines facing a plurality of second metal lines of the second die, and a second substrate beneath the second metal lines faces a plurality of third metal lines of the third die. The die assembly further includes at least one first plug, a first redistribution layer and a second redistribution layer. The first plug penetrates through the second substrate to connect to at least one of the second metal lines. A first redistribution layer physically connects at least one of the first metal lines to at least one of the second metal lines, and a second redistribution layer physically connects at least one of the third metal lines to the first plug.

The present disclosure provides a die assembly. The die assembly includes a first die, a second die and a third die stacked together. The first die includes a plurality of first metal lines facing a plurality of second metal lines of the second die, and a second substrate beneath the second metal lines faces a plurality of third metal lines of the third die. The die assembly further includes at least one first plug, a first redistribution layer and a second redistribution layer. The first plug penetrates through the second substrate to connect to at least one of the second metal lines. A first redistribution layer physically connects at least one of the first metal lines to at least one of the second metal lines, and a second redistribution layer physically connects at least one of the third metal lines to the first plug.

A method to form a 3D semiconductor device, the method including: providing a first level including first circuits, the first circuits including first transistors and first interconnection; preparing a second level including a silicon layer; forming second circuits over the second level, the second circuits including second transistors and second interconnection; transferring with bonding the second level on top of the first level; and then thinning the second level to a thickness of less than ten microns, where the bonding includes oxide to oxide bonds, and where the bonding includes metal to metal bonds.

A method to form a 3D semiconductor device, the method including: providing a first level including first circuits, the first circuits including first transistors and first interconnection; preparing a second level including a silicon layer; forming second circuits over the second level, the second circuits including second transistors and second interconnection; transferring with bonding the second level on top of the first level; and then thinning the second level to a thickness of less than ten microns, where the bonding includes oxide to oxide bonds, and where the bonding includes metal to metal bonds.

A method to form a 3D semiconductor device, the method including: providing a first level including first circuits, the first circuits including first transistors and first interconnection; preparing a second level including a silicon layer; performing growth of an epitaxial layer on top of the silicon layer, the epitaxial layer including non-silicon atoms; forming second circuits over the second level, the second circuits including second transistors and second interconnection; transferring and then bonding the second level on top of the first level; and then thinning the second level to a thickness of less than ten microns, where the bonding includes oxide to oxide bonds.

A method to form a 3D semiconductor device, the method including: providing a first wafer including first circuits including transistors and interconnection; preparing a second wafer including a silicon layer; performing growth of an epitaxial layer on top of the silicon layer, the epitaxial layer including non-silicon atoms, forming second circuits over the second wafer, the second circuits including transistors and interconnection; transferring and then bonding the second wafer on top of the first wafer; and then thinning the second wafer to a thickness of less than ten microns.

A method to form a 3D semiconductor device, the method including: providing a first wafer including first circuits including transistors and interconnection; preparing a second wafer including a silicon layer; performing growth of an epitaxial layer on top of the silicon layer, the epitaxial layer including non-silicon atoms, forming second circuits over the second wafer, the second circuits including transistors and interconnection; transferring and then bonding the second wafer on top of the first wafer; and then thinning the second wafer to a thickness of less than ten microns.

A 3D semiconductor device, the device including: a first single crystal layer; at least one first metal layer above the first single crystal layer; a second metal layer above the first metal layer; a plurality of first transistors atop the second metal layer; a plurality of second transistors atop the second transistors; a plurality of third transistors atop the second transistors; a third metal layer above the plurality of third transistors: a fourth metal layer above the third metal layer; and a second single crystal layer above the fourth metal layer; and a plurality of connecting metal paths from the fourth metal layer to the second metal layer, where at least one of the plurality of third transistors is aligned to at least one of the plurality of first transistors with less than 40 nm alignment error, where the fourth metal layer is providing global power distribution to the device.