Portable Continuous TOC Monitoring In A Semiconductor Water System

By Doug Bender and Anthony C. Bevilacqua, Ph.D. Thornton Inc.

Introduction

The primary requirements of water systems are (or ought to be) driven by the required quality of the finished products. In the microelectronics industry, this often translates into "cleaner water for smaller linewidth devices". While the most common on-line measurement in any semiconductor water system may be flow rate, the most common on-line measurement of the quality of the water is resistivity[1]. Throughout the 1980's and early 1990's, resistivity measurements have become effective early-warning detection systems for ionic contaminants[2]. The ability of resistivity instrumentation to measure low-level ionic impurities results in a water system specification with ionic impurity specifications. The effectiveness of resistivity measurements is due in part to its sensitivity at ppb levels[3], ability to operate on-line and in-line without harm to the water system, speed of response, and relatively low cost ($900 to 1500) for a complete system.

In this paper, we review the current TOC devices in terms of their oxidation and measurement technologies. Then, a new TOC analyzer technology is described. Finally, a few applications of advantages afforded by this new technology are presented. To address the need for rapid, on-line data processing, the discussion in this paper is constrained to on-line analyzers only.