Scanning Capacitance Microscopy (SCM) Applications in Failure Analysis

摘要

In semiconductor device manufacturing and development, dopant-related failure analysis (FA) has been a great challenge, especially with ever-sophisticated chip circuitry and reduced device dimensions that are well below 100 ran. Due to the small active area and the nature of planar device structures in most technologies, conventional one-dimensional dopant profiling techniques, such as secondary ion mass spectroscopy (SIMS) and spread-resistance probe, are often not applicable. Traditionally, selective chemical etch (stain) is widely used. Although staining procedures are quick and simple and can produce good results in certain circumstances, they can be destructive and inconsistent. In the last decade, scanning probe microscopy (SPM)-related techniques, such as scanning capacitance microscopy (SCM),] scanning spreading-resistance microscopy,] and scanning microwave microscopy, have become available, along with other novel techniques-such as off-axis electron holography and local electric-field atom probe. Many of those techniques have demonstrated their capabilities for two-dimensional (2-D) dopant profiling with high spatial resolution and dynamic range. However, the results are largely achieved in lab settings. Practical challenges in production chips still exist, due to difficulties in accessing the target (electrically and physically) under multiple backend layers and sophisticated interconnects. Among all the techniques, SCM is most extensively developed and applied in FA due to its relatively easier sample preparation and short turnaround time. Although the junction location determined by SCM can be subject to surface quality and sample bias, the problem can be mitigated by using a good sample as reference.