Analyzing sub-20 nm defects and ultrathin (~1 nm thick) residues in semiconductor processes

With shrinking semiconductor device sizes and modern advanced packaging processes, it is crucial to eliminate sub-20 nm defects and surface contaminants. To do so effectively, one must be able to discern the molecular identity of a defect/contaminant. While the presence of defects as small as 20 nm can be detected with survey tools, the traditional suite of analytical tools—such as XPS, ToF-SIMS, or SEM/TEM EDX—have difficulty in clearly identifying the contaminating source of defects, especially if they are organic.

Organics are difficult to identify at this scale because traditional analytical tools either lack the spatial resolution required, or they only provide elemental information. Infrared photo-induced force microscopy (IR PiFM) can fill this gap by offering the ability to identify or name chemical compounds with nanometer-scale resolution. It does this by combining a non-contact AFM with IR spectroscopy to acquire topographical and chemical information concurrently at the nanoscale [1]. Since PiF-IR spectra match FTIR spectra for a given material, existing IR libraries can be used to identify defects analyzed with IR PiFM.

Given PiFM’s sub-5 nm spatial resolution, even a multi-component defect can be de-composed into pure components via multivariate data analysis of PiF-IR spectra from different regions of a defect.