Tsuyoshi Matsumura

Analysis of Low Metallic Contamination on Silicon Wafer Surfaces by Vapor-Phase Treatment and Total Reflection X-ray Fluorescence Analysis

We have developed a new practical method for quantifying metallic contaminants with concentrations as low as 109 atoms/cm2 on silicon wafer surfaces. It is named VPT-TXRF and uses vapor-phase treatment (VPT) with a total reflection X-ray fluorescence analysis (TXRF) system. VPT can change the form of metallic impurities on the surface from thin-film type to particulate type and thus the detected X-ray intensity is increased because of the inherent nature of TXRF, namely, the angular dependence of fluorescence yield. By this method, high sensitivity was achieved within a practical measuring time of 500 s, while maintaining the original surface contamination distribution of the wafers. We are convinced that this method will become the most useful monitoring method for the critical process contamination of the future ultra-large-scale-integration (ULSI) manufacturing line.

Development of an Eco-friendly Copper Interconnect Cleaning Process

This paper reports the development of an eco-friendly, low-cost and clean wet cleaning process in forming copper interconnections, especially on a copper surface at the bottom of the via. From analysis and electrical data, the components of post-etch residues are mainly formed by copper fluorides, copper oxides and silicon oxides. Therefore, diluted inorganic acid solutions are used to remove these polymers and a diluted amine solution is used to stabilize the copper surface after cleaning. These chemicals are treated by an effluent treatment facility, and are very cheap and clean. In the results of post-cleaning, the analysis data shows that the residues are removed, and the electrical data such as via chain yield, electro migration, etc., shows good performance.

Analysis of low metallic contamination on silicon wafer surfaces by VPT-TXRF - quantification of 10/sup 9/ atoms/cm/sup 2/ level contamination

Total reflection X-ray fluorescence (TXRF) spectroscopy is well known as on-line monitoring system for ULSI manufacturing line, but it is not useful for quantifying less than 10/sup 10/ atoms/cm/sup 2/ metallic contamination because of its insufficient sensitivity. We developed a practical method named VPT-TXRF using vapor phase treatment (VPT) for quantifying metallic contaminants as low as 10/sup 9/ atoms/cm/sup 2/ on silicon wafer surface with TXRF system. One important aspect of this method is that high sensitivity was achieved within a practical measuring time of 500 seconds while maintaining the original surface conditions of the wafers. We are convinced that this method will become the most useful monitoring method for critical process contamination of the coming ULSI manufacturing line.