Methods For Checking And Calibrating Concentration Sensors In A Semiconductor Processing Chamber

A process for calibrating one or more concentration sensors of a liquid distribution system having a first chemical distribution line, including a first chemical supply source that houses a first chemical and a first flow control device, a second chemical distribution line, including a second chemical supply source that houses a second chemical that differs from the first chemical and a second flow control device, the second chemical distribution line coming together with said first chemical distribution line to form a first blended chemical distribution line;

• and a first concentration sensor disposed along the first blended chemical distribution line, the process comprising the steps of:
• a) flowing a baseline fluid through the first concentration sensor via the first chemical distribution line or the second chemical distribution line or an alternative line specifically for the baseline fluid into the first concentration sensor in order to establish a baseline calibration value in the first concentration sensor;
• b) flowing a calibration solution having a known concentration value through the first concentration sensor via the first chemical distribution line, the second chemical distribution line or an alternative line specifically for the baseline fluid into the first concentration sensor in order to obtain a concentration sensor value for the first concentration sensor;
• c) comparing the known concentration sensor value of the calibration fluid as established by a model with the concentration sensor value obtained for the first concentration sensor in step b) either manually or using a programmable logic controller;
• and
• d) based on the comparison of step c), adjusting the value of the concentration sensor if necessary;
• with the proviso that if the calibration solution utilized differs in composition from the first and second chemicals, the process will further comprise the additional steps of flushing the first chemical distribution line with the first chemical, flushing the second chemical distribution line with the second chemical, and flushing the first blended chemical distribution line with a blend of the first chemical and the second chemical.

A process for calibrating one or more concentration sensors of a liquid distribution system having a first chemical distribution line, including a first chemical supply source that houses a first chemical, and a first flow control device, a second chemical distribution line, including a second chemical supply source that houses a second chemical that differs from the first chemical and, a second flow control device, the second chemical distribution line coming together with said first chemical distribution line to form a first blended chemical distribution line;

• and a first concentration sensor disposed along the first blended chemical distribution line, the process comprising the steps of:
• a) flowing a baseline fluid through the first concentration sensor via the first chemical distribution line or the second chemical distribution line or an alternative line specifically for the baseline fluid into the first concentration sensor in order to establish a baseline calibration value in the first concentration sensor;
• b) setting an initial flow rate for each of the first flow control device and the second flow control device and flowing a calibration solution through either the first or second chemical distribution line at the initial flow rate, and deionized water through the remaining chemical distribution line at the initial flow rate, the calibration solution and deionized water coming together to form a first calibration blend that flows along the first chemical blend distribution line and through the first concentration sensor in order to obtain a first concentration sensor value for the first concentration sensor;
• c) holding the flow rate of the calibration solution steady while steadily adjusting the flow rate of the deionized water while at the same time continuing to measure the concentration sensor value for the first concentration sensor at the varying flow rates until a minimum, maximum or inflection point is established;
• d) comparing either manually or using a programmable logic controller the concentration sensor value obtained in step c) to the known concentration sensor value of the chemical blend as established by a model;
• and
• e) based on the comparisons of step d), adjusting the value of the conductivity sensor if necessary;
• with the proviso that if the calibration solution utilized differs in composition from the first and second chemicals, the process will further comprise the additional steps of flushing the first chemical distribution line with the first chemical, flushing the second chemical distribution line with the second chemical, and flushing the first blended chemical distribution line with a blend of the first chemical and the second chemical.

A process for calibrating one or more concentration sensors of a liquid distribution system having a first chemical distribution line, including a first chemical supply source that houses a first chemical and a first flow control device, a second chemical distribution line, including a second chemical supply source that houses a second chemical that differs from the first chemical and a second flow control device, the second chemical distribution line coming together with the first chemical distribution line to form a first blended chemical distribution line, and a first concentration sensor disposed along the first blended chemical distribution line, the process comprising the steps of:

• a) flowing a baseline fluid through the first concentration sensor via the first chemical distribution line, the second chemical distribution line or an alternative line specifically for the baseline fluid in order to establish a baseline calibration value for the first concentration sensor;
• b) allowing the first chemical from the first chemical supply source and the second chemical from the second chemical supply source to flow along their respective chemical distribution lines and to come together to form a first chemical blend that flows along the first chemical blend distribution line;
• c) passing the first chemical blend through the first chemical blend distribution line and through the first concentration sensor in order to obtain a concentration sensor value for the first chemical blend;
• d) withdrawing a sample of the first chemical blend after the concentration value of the chemical blend is obtained;
• e) measuring the concentration sensor value of the withdrawn sample using either:
• i) an external concentration sensor that is known to be properly calibrated and that is the same or different from the concentration sensor used in the liquid distribution system with the proviso that when the external sensors are the same, a direct comparison can be made between the sensor values achieved for both the external concentration sensor and the concentration sensor being checked and calibrated and when the external sensor is different, the concentration sensor value of the external concentration sensor is determined using established models for the chemical blend;
• or
• ii) a titration method in which the concentration sensor value of the titration method is determined using established models for the chemical blend;
• f) comparing the concentration sensor value obtained in step c) with the concentration sensor value obtained in step e) and adjusting the value of the first concentration sensor if necessary.