Patent ID: 7910014

Claim:
A method for controlling process stability in a processing bath used for processing semiconductor substrates, said method comprising: providing a processing bath; performing a plurality of successive processing runs in said processing bath, each said processing run removing at least part of at least one film that includes silicon and at least one further component; after each said processing run, calculating Si concentration in said processing bath based on a film thickness parameter of said film; summing each said Si concentration from each said processing run to determine an aggregate Si concentration; comparing said aggregate Si concentration to each of a plurality of control limits, each said control limit associated with a corresponding technology; terminating processing runs in said processing bath for each said technology in which said aggregate Si concentration is outside said associated control limit; determining a volume of a chemical to dispense into said processing bath based on said aggregate Si concentration to ensure that said aggregate Si concentration in said processing bath lies within each of said control limits; and automatically adding said volume of said chemical into said processing bath directly or indirectly.