Method for forming an inlaid via in a semiconductor device

摘要

A inlaid interconnect is formed in a semiconductor device (30). A first interlayer dielectric (ILD) 40 is deposited and etched to form a via opening (44). An etchstop layer (42) is deposited on ILD (40). A second ILD (45) is deposited on etchstop layer (42) in a manner so that a pinch-off region (46) is formed to prevent substantial deposition of the ILD material into via opening (44). While a small deposit (47) of ILD material may form within the via opening, this can be easily removed in a subsequent etch of ILD (45) which forms a trench opening (48) in ILD (45). A metal layer (50) is then deposited and polished to form a metal interconnect having a trench portion (52) and a via portion (54) in device (30). The present invention avoids the need for a substantial over-etch to clear the via, and avoids the need to form a thick resist mask to form the via opening, while maintaining a controlled via diameter.