Method of controlling plasma processing apparatus and plasma processing apparatus
The present disclosure relates to a method of controlling a plasma processing apparatus, and a plasma processing apparatus for performing the method. According to one embodiment of the present disclosure, a method of controlling a plasma processing apparatus includes supplying power having a sine wave from a high-frequency power source to a lower electrode to generate a plasma; and supplying power from the high-frequency power source to the lower electrode, to control an ion in the generated plasma, and when a voltage of a wafer disposed on the lower electrode has a negative peak value in a phase region, inputting a negative DC voltage to a focusing ring by a DC power source.
1 . A method of controlling a plasma processing apparatus including a reaction chamber provided with a plasma treatment space; a support unit including a stage disposed in the reaction chamber and configured to support a wafer; the wafer; a lower electrode disposed below the wafer in the reaction chamber to form plasma; an upper electrode disposed above the wafer and opposite to the lower electrode in the reaction chamber; a power source connected to the support unit and including a high frequency (HF) power source configured to generate plasma and a low frequency (LF) power source configured to control ions in the plasma; a focusing ring disposed around an edge region of the wafer; and a DC power source connected to the focusing ring to supply a DC voltage, wherein the method comprises:
supplying power having a sine wave from the HF power source to the lower electrode to generate the plasma;
supplying power from the LF power source to the lower electrode, to control the ions in the generated plasma, and when a voltage of the wafer has a negative peak value in a phase region, a controller is configured to input a negative DC voltage to the focusing ring by the DC power source;
measuring an ion current flowing in the focusing ring through a sensor unit connected to the focusing ring by a lower support unit;
acquiring capacitance of the focusing ring calculated through focusing ring information including at least one of an area, a thickness, a structure, or a material of the focusing ring; and
inputting a negative DC voltage using the ion current and the capacitance and having a magnitude equal to or lower than a negative voltage of the voltage of the wafer disposed on the lower electrode, to the focusing ring,
wherein, in the inputting the negative DC voltage to the focusing ring by the DC power source, a negative DC voltage having a magnitude equal to or lower than a negative voltage of the voltage of the wafer is input to the focusing ring.
2 . The method of claim 1 , further comprising:
periodically repeating a first voltage state in which the DC voltage supplies a first voltage value and a second voltage state having at least one voltage value, lower than the first voltage value; and
maintaining the second voltage state in a section in which potential of the wafer becomes a negative peak according to supply of a power source of the HF power source, and maintaining the first voltage state in a different section.
3 . The method of claim 1 , wherein the phase region is a region in which potential of the wafer disposed on the lower electrode is 3π/2.
4 . The method of claim 3 , further comprising determining a time during which the DC voltage maintains a second state in a 3π/2 region of the potential of the wafer according to a type of the wafer, a type of an etching process to be performed, a type of gas to be injected, and potential corresponding to a degree of ion tilting of an edge region of the wafer.
5 . The method of claim 1 , further comprising, when the HF and LF power sources supply pulsed power having different magnitudes of voltage according to a duty cycle to the lower electrode, applying a preset minimum DC voltage during a duty cycle in which the pulsed power is supplied less than a preset magnitude.
6 . The method of claim 5 , wherein the minimum DC voltage is a value corresponding to when the DC power source stops supplying a power source or when the DC power source supplies a power source having a certain threshold value or lower.
7 . The method of claim 1 , wherein, in the inputting a negative DC voltage to the focusing ring by the DC power source,
a magnitude of an absolute value of the negative DC voltage increases constantly, and the negative DC voltage is 0 outside the phase region.
8 . The method of claim 1 , wherein the power source comprises a high frequency (HF) power source generating plasma and a low frequency (LF) power source controlling ion energy of the plasma, and
the method further comprises, before the inputting a negative DC voltage to the focusing ring by the DC power source:
synchronizing the LF power source based on a phase of the HF power source;
synchronizing a phase of the DC power source based on a phase of the LF power source; and
acquiring a voltage or current waveform supplied to the lower electrode by the LF power source through a sensor connected to the power source.
9 . The method of claim 1 , wherein, when the focusing ring is etched by an etching process, potential corresponding to a step difference between the focusing ring and the wafer is additionally supplied.
10 . A computer recording medium recording a computer program for executing the method of claim 1 on a computer.