Semiconductor device structure and methods of forming the same

A memory comprising at least an oxide-semiconductor complementary field-effect transistor (OSCFET), the OSCFET comprising:

• an n-type oxide-semiconductor field-effect transistor (OSFET);
• and
• a p-type OSFET stacked with the n-type OSFET in a vertical direction;
• wherein the OSCFET is sandwiched between two of a plurality of metallization layers formed in a back-end-of-the-line (BEOL) process after a device layer is formed in a front-end-of-the-line (FEOL) process.

A method, comprising:

• forming one or more active devices;
• forming a first set of metallization layers each comprising a plurality of conductive features;
• forming a first oxide-semiconductor device over the first set of metallization layers;
• forming a second oxide-semiconductor device stacking over the first oxide-semiconductor device;
• forming a second set of metallization layers over the second oxide-semiconductor device, each of the second set of metallization layers comprising a plurality of conductive features.