Multi-Length-Scale Dopants Analysis of an Image Sensor via Focused Ion Beam-Secondary Ion Mass Spectrometry and Atom Probe Tomography

TL;DR

This paper introduces a multi-scale characterization workflow combining FIB-SIMS and atom probe tomography to analyze doping chemistry and distribution in complex CMOS image sensors, addressing limitations of conventional techniques.

Contribution

It presents an integrated approach using complementary methods for detailed dopant analysis at nano- and micro-scales in advanced semiconductor devices.

Findings

FIB-SIMS provides sub-20 nm compositional maps.

Atom probe tomography yields atomic-scale dopant profiles.

The workflow effectively resolves dopant distributions across multiple scales.

Abstract

The following article presents a multi-length-scale characterization approach for investigating doping chemistry and spatial distributions within semiconductors, as demonstrated using a state-of-the-art CMOS image sensor. With an intricate structural layout and varying doping types/concentration levels, this device is representative of the current challenges faced in measuring dopants within confined volumes using conventional techniques. Focused ion beam-secondary ion mass spectrometry is applied to produce large-area compositional maps with a sub-20 nm resolution, while atom probe tomography is used to extract atomic-scale quantitative dopant profiles. Leveraging the complementary capabilities of the two methods, this workflow is shown to be an effective approach for resolving nano- and micro- scale dopant information, crucial for optimizing the performance and reliability of advanced semiconductor devices.