Scanning Capacitance Microscopy: A Valuable Tool to Diagnose Current Paths in 3D-Capacitors Process

Some process abnormalities can be very difficult to detect with conventional FA techniques. Scanning Capacitance Microscopy (SCM) has been shown to be a reliable and versatile tool and the case analysis presented in this work illustrates its significant role. In this paper, a 3D-PICS capacitor used as an element of a band pass filter of a cardiac detection chain was studied. As the electrical and physical diode current signature of this device did not satisfy the targeted needs, a complete failure analysis flow was performed, including OBIRCH and Scanning Capacitance Microscopy characterizations. SCM accumulated measurements allowed extracting and validating a trend according to electrical performance variations from the center to the edge of the wafer. As a result, the root cause of the level of this diode reverse current was identified and corrective actions could be introduced in the process to meet the application requirements.