Nanometrology for size and chemical analysis of semiconductor process impurity

The semiconductor yield is closely related to the number of process steps, as well as the quality of process gases and liquids. Impurities in gases and liquids can remain on the wafer surface during processing, and impurities increase in size and quantity with the number of process steps, ultimately leading to wafer defects and semiconductor device failures. Therefore, controlling impurity concentrations in process gases and liquids is a critical factor in semiconductor yield.
As semiconductor process nodes continue to shrink, the specifications for impurity size and concentration in process gases and liquids have become increasingly stringent. The impurity size specification must be smaller than 2.5 nm, and the particle concentration must be less than 3 particles per milliliter. With the rapid advancement of the semiconductor industry, the development of nanometrology must also keep pace to maintain measurement standards and traceability in the semiconductor field. This project aims to develop nanometrologies for nanoparticle measurement and composition analysis. For nanopaticle size measurement, electrospray-differental mobility analyzer (ES-DMA-CPC) was selected. Nanoparticle standards, commercial nanoparticles, and biological proteins were used for the optimization of sample treatment and instrument parameters, and the measurement capabilities for nanoparticle size less than 5 nm was achieved. For the composition analysis, inductively coupled plasma mass spectrometry (ICP-MS) was selected for metal analysis, and ion chromatography (IC) was selected for inorganic analysis. The metal and inorganic standards were used for establishing database and calibration curves. With the optimization of experimental parameters, the detection limit for both metal and inorganic analysis less than 10 ppt was achieved.
The research outcomes of this project have been successfully applied to impurity detection in semiconductor process liquids, assisting semiconductor manufacturers in distinguishing sample quality and fulfilling the vision of metrology applications in the industry.