Plasma processing method and plasma processing apparatus
View Patent ↗The invention provides a plasma processing apparatus and a dry etching method for etching a multilayered film structure having steps with high accuracy. The plasma processing apparatus comprises a vacuum reactor 107 , a lower electrode 113 placed within a processing chamber of the vacuum reactor and having a wafer 112 to be etched mounted on the upper surface thereof, bias supplying units 118 and 120 for supplying high frequency power for forming a bias potential to the lower electrode 113 , a gas supply means 111 for feeding reactive gas into the processing chamber, an electric field supplying means 101 through 103 for supplying a magnetic field for generating plasma in the processing chamber, and a control unit 127 for controlling the distribution of ion energy in the plasma being incident on the wafer 112 via the high frequency power.
1. A plasma processing method, the method comprising steps of:
placing on a lower electrode in a processing chamber inside a vacuum reactor, a wafer having on the surface thereof a multilayered structure including a metal material disposed on a high-k material and having a film structure with a step structure;
supplying an etching gas into the processing chamber;
controlling a processing pressure;
generating a plasma in the processing chamber;
supplying a bias power of a plurality of frequencies for forming a bias potential on the wafer, so as to process the film structure of the wafer via the plasma by varying an output of the bias power of the plurality of frequencies
detecting a time variation of an impedance of the plasma;
isolating a component of an impedance of a wall surface status and a component of an impedance above the wafer from the detected time variation of the impedance of the plasma;
detecting an end point of the plasma processing according to the detected time variation result of either the isolated impedance of the component of the wall surface status or the isolated impedance of the component above the wafer; and
independently controlling the ion energy being incident on the wafer and the distribution thereof by varying the bias output of the plurality of frequencies and the mixing ratio thereof after performing the end point detection.
2. The plasma processing method according to claim 1 , further comprising the steps of:
comparing the isolated component with a database or a fluctuation model; and
performing a wall surface cleaning or varying a wafer processing condition for a subsequent wafer processing according to the compared result.
3. The plasma processing method according to claim 1 , wherein
the plasma processing method sets the output ratio of the high frequency bias power to 30% or greater of the total bias power in the end point detection process of the plasma processing.
4. The plasma processing method according to claim 1 , further comprising the step of:
varying, by way of a monotone decrease or a monotone increase, the electron temperature, plasma density, gas species, ion energy, ion energy distribution and uniformities thereof across the wafer thereof during transition time from after the end point detection to a subsequent etching step.