Industry Collaboration and SEMI Standards to enable IC manufacturing for advanced nodes

Ultrapure water (UPW) is extensively used for cleaning and dilution purposes in fabs. A problem in UPW can have a fatal effect on wafer defectivity so that the final die yield. Therefore, it is crucial to characterize the risk of on-wafer defectivity of UPW at different stages of purification. The current 12-inch wafer testing methods are capital intensive requiring special equipment for both sample preparation and on-wafer particle scanning. Therefore, extensive application of on-wafer analysis of UPW is not a financially viable solution. This presentation will introduce a practical and economically feasible methodology to analyze the on-wafer defectivity of UPW using small wafers (2-inch or 4-inch). The method is based on applying the spin-drying process successively on the same wafer, increasing the particle density to a level higher than the existing particle baseline of the wafer.

Roundtable handout from February Community Event

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

This article provides an overview of the biggest challenge of UPW technology – particle control. The latest semiconductor technologies require near particle-free water, where the “killer” particle size is far below the size that UPW metrology can effectively detect. Also, current advanced treatment methods cannot guarantee reliable removal of killer-sized particles. The quality of the high-purity materials used downstream of the final filters has not typically been tested for shedding of the “killer” particles. Consequently, the semiconductor industry requires a comprehensive approach for the particle control. A new approach should include mitigating particle occurrence and continuously improving the technologies used in UPW polish and distribution systems. Such an approach should also include extensive use of SEMI standards to improve the quality of the materials used; a new way to engineer solutions related to system-configuration and system design; improved process control; and a careful review of critical operational decisions. Collaboration throughout the industry via IRDS and SEMI Standards is key to enabling such systematic improvement, and overcoming the metrology and other constraints. This article was originally published in the Ultrapure Micro Journal in November 2017.

Particles in ultrapure water (UPW), used during the manufacture of microcircuits on semiconductor wafers, can deposit onto the wafer surface thereby causing decreased yield and reliability of the microcircuits. As microcircuit future sizes continue to decrease, understanding the ability of a filter to capture and retain these particles becomes increasingly important and challenging. In 2013, SEMI C79-0113, “Guide to Evaluate the Efficacy of Sub-15 nm Filters used in Ultrapure Water (UPW) Distribution System” was published. This document provides a SEMI recommended method for evaluating the efficacy of filter elements used to remove particles in UPW fluid streams. Since the release of this guide, the method has been enhanced to allow quantification of particle retention over a broad size range. This was accomplished by adding larger silica particles to the Ludox® SM30 silica specified by SEMI C79 resulting in a poly-dispersed silica challenge. A particle size distribution (PSD) slope of -2 (log-log) was selected so the challenge would more closely mimic a PSD typically found in UPW, yet still have sufficient large particles to measure a log retention value of 2 or 99% retention. This silica challenge has been designated as an “area-weighted challenge”. The use of this enhanced method has resulted in some interesting observations including indication of a most penetrating particle size similar to what is observed in gas filtration. The presence of a most penetrating particle size would indicate that retention mechanisms other than sieving are active, particularly for particles smaller than 30 nm. This paper will review the enhancements made to the test method, review the retention data from a number of filter types and manufacturers, and discuss the implications for filters used in UPW. This article was originally published in the Ultrapure Micro Journal in November 2017.

In recent years, with the development of the semiconductor manufacturing process, ultrapure water (UPW) used to wash semiconductor devices have required high purity. In particular, particles in UPW are strictly controlled. Our 10 nm SEM analysis can measure 10 nm particles, which was previously impossible. This article presents the results of measuring 10 nm particles in the existing ultrapure water system. We clarified the behaviour (including generation sources and compositions) of 10 nm particles in ultrapure water systems in order to optimize and enhance. This article was originally published in the Ultrapure Micro Journal in November 2017.

The ability to conduct current through a liquid is measured by conductivity and can be related to the concentrations of ions in the solution. In this work, a patented analytical technique is used to quantify the contaminant level of specific chemicals in an on-line ultrapure water (UPW) system. The method uses a resistivity system with additional mathematical techniques to exploit the physical relationship between temperature and resistivity. This method utilises the slope between resistivity/temperature curves and not the absolute resistivity. The theoretical conductance of chemicals is compared with experimentally-measured values from 1 parts-per-trillion (ppt) to 10 parts-per-billion (ppb). This work helps establish the characteristics of compounds that can be measured with this technique and determines the limits of detection, and therefore has a potential commercial application. High conductance compounds like sodium chloride and potassium hydrogen phthalate are measurable at the 100 ppt level while low conductance compounds like boric acid cannot be discerned from the background. As the method matures into a product the limits of detection should be lowered. This article was originally published in the Ultrapure Micro Journal in March 2019.

This Q&A session took place at the 2020 Ultrapure Micro annual conference. It was a part of the Ultrapure Water Production track, and and included speakers from the UPW and Liquid Chemicals System Improvements session.

This presentation was given at the Ultrapure Micro 2019 annual conference. It was presented during the Learning Series, as part of the Ultrapure Water Production track.

This presentation was given at the Ultrapure Micro 2018 annual conference. It was presented during the Learning Series, as part of the Ultrapure Water Production track.