Capacitive sensor for detecting bubbles in SOG

摘要

A spin-on-glass delivery system has the invention's capacitive sensor to detect gas bubbles in a SOG tube. A SOG bottle is provided. The SOG bottle contains SOG. A N2 gas supply is connected to the pressure tank by a pressure tube wherein the N2 gas supply pressurizes the inside of the SOG bottle with N2 gas. The SOG bottle is connected to SOG tube. In a key feature, a capacitive sensor is mounted on the SOG tube. The capacitive sensor detects gas bubbles in the SOG flowing through the SOG tube. The SOG tube is connected to a nozzle in a SOG tool. The SOG flows through the nozzle over to a wafer. A key point of the invention is to use a capacitive sensor to detect gas bubbles in spin-on-glass flowing through a SOG tube. This is a new, unsuggested use for the capacitive sensor. The prior art bubble sensors are optical sensors.