CORRELATION BETWEEN CONDUCTIVITY AND PH MEASUREMENTS FOR KOH TEXTURING SOLUTIONS AND ADDITIVES

摘要

The variability of an etchant concentration in an immersion processes for treatment of semiconductor devices can be significantly lowered by continuously measuring the conductivity of an etchant solution and comparing against predetermined thresholds. The etchant concentration can be maintained by a feed and bleed process based on conductivity measurements of the etchant solution and the conductivity measurements being correlated with premeasured pH values of an etchant solution.

主权项

1. A method of etching material from at least one substrate, the method comprising:
a) immersing the at least one substrate in an etchant solution within a process chamber, the process chamber operably coupled to a recirculation line to form a closed-loop circulation system; b) circulating a circulation volume of the etchant solution through the closed-loop circulation system; c) repetitively measuring conductivity of the circulation volume of the etchant solution that is circulating through the closed-loop circulation system with a conductivity sensor; and d) upon detecting that the circulation volume of the etchant solution has an average measured conductivity over a predetermined period of time that is at or below a lower threshold of conductivity, automatically performing a feed-and-bleed event that comprises: (i) bleeding a volume of contaminated etchant solution from the circulation volume of the etchant solution; and (ii) adding fresh etchant solution to the circulation volume of the etchant solution to increase the conductivity of the circulation volume of the etchant solution to a value that is greater than the lower threshold of conductivity but less than or equal to an upper threshold of conductivity.