Provided is a semiconductor device including: a channel structure; a gate structure on the channel structure; a backside isolation structure on the gate structure; an alignment spacer layer on a lower side surface of the backside isolation structure, the alignment spacer layer comprising a material different from the backside isolation structure; a source/drain pattern on the channel structure; and a backside contact structure on the source/drain pattern.

A method includes forming a transistor over a front side of a substrate, in which the transistor comprises a channel region, a gate region over the channel region, and source/drain regions on opposite sides of the gate region; forming a front-side interconnect structure over the transistor, wherein the front-side interconnect structure includes a dielectric layer and conductive features; and bonding the front-side interconnect structure to a carrier substrate via a bonding layer, in which the bonding layer is between the front-side interconnect structure and the carrier substrate, and the bonding layer has a higher thermal conductivity than the dielectric layer of the front-side interconnect structure.

Various implementations of backside and topside routing of bitlines and wordlines in memory arrays are disclosed. Bitlines in backside and topside metal layers may be alternated between adjacent bit cells in a memory array. Alternating the location of the bitlines between bit cells in the memory array may reduce bitline capacitance in a memory array. Placing wordlines in backside metal layers may allow dual wordlines to be implemented across a span of bit cells in a memory array. The dual wordlines may be alternately connected to adjacent bit cells, thereby allowing selective toggling of bit cells based on the wordline transmitting a control signal.