Patent ID: 8924001

Claim:
An etching apparatus comprising an optical emission spectrometry for observing plasma optical emission in a chamber and a plurality of actuators for adjusting the plasma optical emission and carrying out a wafer etching process, the etching apparatus including a control function by which: when vales of the plurality of actuators are X and values of optical emission intensities at a plurality of wavelengths of the plasma optical emission monitored by the optical emission spectrometry are Y, a relation between set values (d 1 ) for the plurality of actuator values X applied to the etching process and actual values (d 2 ) for the optical emission intensity values Y at the plurality of wavelengths monitored by the optical emission spectrometry during the etching process is defined as a control model based on an algebraical expression expressing a relation between a variation ΔX of a value X and a variation ΔY of a value Y to each value X with the variation ΔX as input and the variation ΔY as output; the control model and a value of a parameter included in the control model are set in advance; and a target value (d 3 ) for the optical emission intensity values Y at the plurality of wavelengths is set in advance, wherein control of the etching process includes: a first process step (S 1 ) at which before start of the wafer etching process, values of differences (d 5 ) between the target value (d 3 ) for the value Y and a plurality of non-control optical emission intensity values (d 4 ) are determined to be a target controlled volume (d 6 ) for the value Y, and based on the control model, a controlled volume (d 7 ) for the plurality of actuator values X is calculated from the target controlled volume (d 6 ) for the value Y to apply the controlled volume (d 7 ) for the value X as the set value (d 1 ) to the plurality of actuators; a second process step (S 2 ) at which the wafer etching process is started, and is ended as the optical emission intensity values Y at the plurality of wavelengths of a spectrum of the plasma optical emission are monitored at given time intervals by the optical emission spectrometry; and a third step (S 3 ) at which the actual values (d 2 ) for the optical emission intensity values Y at the plurality of wavelengths based on data collected by the monitoring or obtained from the data under given time setting are used to calculate the plurality of non-control optical emission intensity values (d 4 ) to be used in a next wafer etching process, based on errors (d 8 ) between the actual values (d 2 ) for the values Y and the target value (d 3 ) and on the controlled volume (d 7 ) for the value X calculated at the first process step, and wherein the process steps 1 to 3 are executed repeatedly in each wafer etching process to adjust the plurality of actuator values X and control the optical emission intensity values Y at the plurality of wavelengths.