Wafer thinning method in wafer treating system

A wafer thinning method for treating wafers each having at least a circuit-forming surface thereof protected, by immersing the wafers in a treating solution, comprising the steps of:

• sorting the wafers into groups according to predetermined ranges of thickness;
• storing the wafers sorted into the groups in containers;
• a plurality of wafers in each of the groups being stored in one container;
• transporting the containers successively to a treating tank storing the treating solution, and determining an immersion time for each group from a target thickness of the wafers, an average thickness in each group, and a treating rate by the treating solution;
• and
• immersing the containers in the treating tank, with the immersion time changed for each group, such that the immersion time is made the longer for the groups having the thicker wafers.