Wafer wet cleaning system

A method, comprising:

• performing a cleaning process comprising dispensing, from an external tank, a chemical solution on a wafer and removing the chemical solution from the wafer, wherein the cleaning process removes contaminants from the wafer;
• intermittently sampling, directly after the contaminants are removed from the wafer, a portion of the chemical solution in a drain collector at a sampling interval;
• analyzing the portion of the chemical solution sampled in the drain collector to determine a contaminant concentration of the portion of the chemical solution, wherein the contaminant concentration of the portion of the chemical solution is substantially the same as another contaminant concentration of the chemical solution when the chemical solution is removed from the wafer, and wherein analyzing the chemical solution comprises determining a concentration of metal ions in the chemical solution;
• adjusting the sampling interval based on a time for analyzing the portion of the chemical solution;
• comparing the contaminant concentration to a baseline value;
• after adjusting the sampling interval and based on the comparison of the contaminant concentration to the baseline value, terminating the cleaning process;
• and
• increasing a temperature of the chemical solution to be dispensed onto the wafer in response to the concentration of metal ions exceeding the baseline value.

A method, comprising:

• dispensing, from an external tank, a chemical solution to remove contaminants on a wafer on a cleaning station via a cleaning process;
• diverting, directly after removing the chemical solution from the wafer, a portion of the chemical solution to a drain collector;
• collecting, from the drain collector, samples of the portion of the chemical solution at sampling intervals;
• analyzing the samples of the portion of the chemical solution stored in the drain collector to determine a concentration of metal ions in the chemical solution, wherein the concentration of the metal ions in the chemical solution is unchanged since the chemical solution is removed from the wafer;
• adjusting the sampling intervals based on a time for analyzing the samples;
• comparing the concentration of metal ions to a baseline value;
• after adjusting the sampling intervals and in response to the concentration of metal ions being equal to or less than the baseline value, terminating the cleaning process and removing the wafer from the wafer cleaning station;
• and
• in response to the concentration of metal ions being greater than the baseline value, adjusting a parameter of the cleaning process, wherein adjusting the parameter comprises adjusting one or more of a temperature of the chemical solution to be dispensed onto the wafer and decreasing a water content of the chemical solution.