Methods for fabricating semiconductor devices with backside power delivery network using laser liftoff layer

A method for fabricating semiconductor devices, comprising:

• forming a stack on a first substrate;
• sequentially forming a laser liftoff layer and a dielectric layer on a second substrate;
• flipping the second substrate and attaching the dielectric layer to a first side of the stack;
• removing the first substrate from a second side of the stack, the second side being opposite to the first side;
• forming a plurality of device features using the stack;
• forming a plurality of first interconnect structures on the second side;
• removing the second substrate through the laser liftoff layer so as to expose the first side of the stack;
• and
• forming a plurality of second interconnect structures on the first side.

A method for fabricating semiconductor devices, comprising:

• forming a stack on a first substrate, wherein the stack comprises a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked on top of one another;
• sequentially forming a laser liftoff layer and a dielectric layer on a second substrate;
• flipping the second substrate and attaching the dielectric layer to a first side of the stack;
• removing the first substrate from a second side of the stack, the second side being opposite to the first side;
• forming a plurality of device features using the stack;
• forming a plurality of first interconnect structures over the plurality of device features;
• attaching a third substrate to the second side of the stack;
• flipping the third substrate together with the second substrate;
• removing the second substrate by applying radiation on the laser liftoff layer;
• and
• forming a plurality of second interconnect structures opposite the device features from the plurality of first interconnect structures.