A Novel Etch Scheme to Form Sloped Profile by Standard Anisotropic CMOS Process.

In this work, electrical short problem was found for sensing material resistor device, which was defined by thin metal electrode layer pattern. FIB and X-SEM was done for failure analysis (FA), and thin metal layer residue was found on the sidewall bottom of the sensing material pattern edge which had induced the short problem. Mechanism of the residue problem was investigated, and it was because that metal layer thickness on the sidewall of sensing material pattern edge was much larger than thin metal layer thickness on top surface which had induced that metal layer residue on sidewall during anisotropic etch process. Novel etch scheme was proposed and implemented to realize sloped profile with large angle and solve this problem. Physical profile and electrical test was done to evaluate the performance of the new process. From the measured data, the new process scheme can well solve the short problem.