Taiwan Semiconductor Manufacturing Company Limited
Silicon photonics coupling structure using an etch stop layer and methods of forming the same

Abstract:

An optical structure may be provided by forming a silicon grating structure over a dielectric material layer, depositing at least one dielectric material layer over the silicon grating structure, and depositing at least one dielectric etch stop layer over the at least one dielectric material layer. The at least one dielectric etch stop layer includes at least one dielectric material selected from silicon nitride and silicon oxynitride. A passivation dielectric layer may be formed over the at least one dielectric etch stop layer, and a patterned etch mask layer may be formed over the passivation dielectric layer. An opening may be formed through an unmasked portion of the passivation dielectric layer by performing an anisotropic etch process that etches the dielectric material selective to a silicon nitride or silicon oxynitride using the patterned etch mask layer as a masking structure. The at least one etch mask layer minimizes overetching.