US Patent 11784228 Process and structure for source/drain contacts

A method includes providing a structure having source/drain electrodes and a first dielectric layer over the source/drain electrodes; forming a first etch mask covering a first area of the first dielectric layer; performing a first etching process to the first dielectric layer, resulting in first trenches over the source/drain electrodes; filling the first trenches with a second dielectric layer that has a different material than the first dielectric layer; removing the first etch mask; performing a second etching process including isotropic etching to the first area of the first dielectric layer, resulting in a second trench above a first one of the source/drain electrodes; depositing a metal layer into at least the second trench; and performing a chemical mechanical planarization (CMP) process to the metal layer.