Light Dependent Compensation of TOC Measurement and its Relationship with Dissolved Oxygen Concentrations in Ultrapure Rinse Waters for Semiconductor Manufacturing

摘要

The presence of dissolved oxygen in ultra pure rinse water affects the rate of oxidation on wafer surfaces. Native oxides' presence on silicon wafers negatively impacts film growth in the highly selective ion-etching and film deposition processes. According to the Semiconductor Industry Association (SIA) Roadmap a dissolved oxygen (DO) concentration of 10 ppb (parts per billion) or less is required to minimize silicon wafer oxidation. Therefore, concerted efforts toward maintaining the lowest possible oxygen concentration in Semiconductor ultra pure rinse waters have been undertaken. The primary method for minimizing the concentration of dissolved oxygen in commercial semiconductor ultrapure water systems is via vacuum degassification. A less common method, and one generally utilized for small scale, and or research applications is to reduce the dissolved oxygen concentration by means of sparging with an inert gas, such as helium or nitrogen. Recently developed technology related to TOC measurement at ultra low levels of TOC utilizes a novel measurement approach associated with light dependant compensation of TOC. It is now possible to accurately measure TOC in high purity, ultra low TOC containing Semiconductor process waters whose dissolved oxygen (DO) concentrations approach 1 part per billion (ppb). Issues relating light dependent compensation of TOC concentrations in Semiconductor ultrapure rinse waters will be discussed in this paper.