Shallow trench isolation process using chemical-mechanical polish with self-aligned nitride mask on HDP-oxide
 A method of planarizing a non-conformal oxide layer 40 forming shallow trench isolation between active areas 12 in a substrate. The invention uses a first chemical-mechanical polish (CMP) step to form openings 50 only over wide active areas. An etch is used to remove oxide 40 from only over the wide active areas 12A. A second CMP step is used to planarized the oxide layer 40. The invention begins by forming spaced trenches 30 in said substrate 10 defining active areas 12. A first insulating layer 40 composed of a non-conformal silicon oxide is formed by a HDPCVD process over the substrate and fills the trenches 30. A etch barrier layer 44 is formed over the first insulating layer 40. In a first chemical-mechanical polish (CMP) step, the conformal etch barrier layer 44 over only the wide raised portions 12A is polished to form a self-aligned first openings 50. The chemical-mechanical polishing of the conformal etch barrier layer forms a self-aligned etch mask. The first insulating layer 40 is then etched through at least the first opening 50 to expose a first barrier layer 24 over the wide active areas 12A. In a second CMP step, the etch barrier layer 44 is removed and the first insulating layer 40 is planarized to fill the shallow trenches 30. 
Taiwan Semiconductor Manufacturing Company
H H
H01L H01L
inventional inventional
Chung-Te Chin-Hsiun
Lin Ho