Abstract:

As semiconductor device geometries continue to shrink, with critical particle sizes approaching 2 nm for next-generation devices, traditional contamination control methods face significant challenges. Sub-10 nm particles can present retention difficulties for conventional filtration systems, while particle precursors—dissolved molecular compounds that form particles when dried on wafer surfaces—remain largely unmanaged by current filtration media due to their molecular nature. Further, this type of contamination is invisible to traditional optical particle counting techniques.

The semiconductor industry has responded through collaborative efforts between the International Roadmap for Devices and Systems (IRDS) and SEMI International, resulting in three relevant specifications: SEMI C93 for determining ion exchange resin quality, SEMI C79 for evaluating sub-15 nm filter retention efficacy, and the newly published SEMI F121 guide for particle precursor metrology evaluation. These standards address the proactive contamination management required as killer particle sizes decrease below the capability of traditional measurement techniques.

IRDS UPW and Critical Components Task Forces have conducted extensive testing programs correlating particle and particle precursor concentrations in process liquids such as ultrapure water (UPW) and isopropyl alcohol (IPA) with on-wafer particle deposition. These studies have established critical correlations between particle and particle precursors in liquids and particles deposited on the wafer, providing quantitative risk assessment capabilities for manufacturing yield protection.

This presentation will provide an overview of the SEMI specifications and IRDS collaborative research related to sub-10 nm particles and particle precursor measurement and control. Details to be covered include advanced metrology techniques utilizing nebulization and aerosol particle counting technologies, specifically Liquid Nanoparticle Sizing (LNS) and Scanning Threshold Particle Counting (STPC), capable of measuring contaminants as small as 1.8 nm. The presentation also examines on-wafer particle measurement capabilities to 8 nm using surface-enhanced particle sizing (SEPS) technology, demonstrating the critical correlation between liquid-phase contamination and wafer-level defectivity.

The integration of these advanced metrology approaches enables proactive contamination management strategies essential for maintaining manufacturing yields as the industry progresses toward increasingly stringent cleanliness requirements driven by Moore's Law scaling challenges.