Dopant and ultra-low concentration elemental analysis using Scanning Transmission Electron Microscopy (STEM) imaging and Electron Energy Loss Spectroscopy (EELS)

EELS analysis of gate and channel is performed on fin field-effect transistors (finFETs). Scanning transmission electron microscopy (STEM) imaging coupled with EELS mapping reveals information like intermixing between layers, the integrity of the interfaces, and atomic density measurements crucial for device performance. The high sensitivity of EELS helps overcome the structural challenges of these transistors. EELS provides a reliable way to measure layer thicknesses and low atomic number dopant distributions. 

Below is an example (Fig. 1) where an FEI Titan is operated at 200 kV in STEM mode coupled with an EELS detector. STEM imaging and EELS mapping is performed across the channel normal to the finFET plane. The elemental map overlapped on the STEM image accurately depicts the gate layers (Fig 1a). The elemental measurements from a selected region (black box) from the image are shown (Fig 1b).

Fig. 1. (a). STEM image and corresponding EELS map at the location data was collected. (b). A plot of the EELS measurements taken at the location indicated by the black box in Fig(a). Reference [1]

The decrease in critical dimensions in next-generation semiconductor devices requires advanced analysis techniques to analyze state-of-the-art finFETs. Infinita Lab’s vast network of materials testing labs and experts enables us to produce reliable, reproducible, and high precision measurements in these smaller technology nodes using cutting-edge techniques.

[1] Martin, Andrew & Wei, Yong & Scholze, Andreas. (2017). Analyzing the channel dopant profile in next-generation FinFETs via atom probe tomography. Ultramicroscopy. 186. 10.1016/j.ultramic.2017.12.013.