Methods and apparatus for performing end point determination. A method includes receiving a wafer into an etch tool chamber for performing an RIE etch; beginning the RIE etch to form vias in the wafer; receiving in-situ measurements of one or more physical parameters of the etch tool chamber that are correlated to the RIE etch process; providing a virtual metrology model for the RIE etch in the chamber; inputting the received in-situ measurements to the virtual metrology model for the RIE etch in the chamber; executing the virtual metrology model to estimate the current via depth; comparing the estimated current via depth to a target depth; and when the comparing indicates the current via depth is within a predetermined threshold of the target depth; outputting a stop signal. An apparatus for use with the method embodiment is disclosed.