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AssigneeLam Research Corporation
InventorsMichael S. Barnes, Brett Richardson, Tuan Ngo, John Patrick Holland
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A gas in a vacuum plasma processing chamber is ignited to a plasma by subjecting the gas to an r.f. field derived from an r.f. source having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma. The r.f. field is supplied to the gas by a reactive impedance element connected via a matching network to the r.f. source. The matching network includes first and second variable reactances that control loading of the source and tuning a load, including the reactive impedance element and the plasma, to the source. The value of only one of the reactances is varied until a local maximum of a function of power coupled between the source and the load is reached. The value of only the other reactance is varied until a local maximum of the function is reached. The two varying steps are then repeated as necessary.
A method of igniting a gas to a plasma in a vacuum plasma chamber for processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate, comprising
A memory usable with a computer, the computer being in combination with an apparatus for igniting a gas to a plasma in a vacuum plasma chamber for processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate, the gas in the chamber being coupled with a reactive impedance element for coupling an r.f. field to the gas, the r.f. field being derived from a source having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the reactive impedance element being connected via a matching network to an r.f. source that can generate the r.f. field, the matching network including first and second variable reactances for respectively controlling loading of the source and tuning a load including the reactive impedance element and the plasma processing the workpiece to the source, the memory comprising a structure that stores signals to control the computer so the computer can derive signals to control the values of the first and second reactances prior to plasma ignition so (1) the value of the only one of the reactances is varied until a function of power coupled between the source and the load is locally maximized, (2) then the value of only the other reactance is varied until the function of power coupled between the source and the load is locally maximized, and (3) operations of steps (1) and (2) are repeated if the plasma is not ignited.
Apparatus for igniting a gas to a plasma in a vacuum plasma chamber for processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate, comprising a reactive impedance element, the reactive impedance element being positioned for electrical coupling with the gas in the chamber, an r.f. electric source, a matching network connected between the source and the reactive impedance, the matching network including first and second variable reactances for respectively controlling loading of the source and tuning the source with a load including the reactive impedance element and the plasma processing the workpiece, the r.f. source having a frequency and power level for causing the reactive impedance element to supply an electromagnetic field to the gas to ignite the gas to the plasma, the plasma when ignited causing at least one of (a) material to be etched from the workpiece and (b) material to be deposited on the workpiece, and a controller for controlling the values of the first and second variable reactances, the controller being responsive to a function of power coupled between the source and load, the controller being arranged so that prior to ignition, the controller:
Apparatus for igniting a gas to a plasma in a vacuum plasma chamber for processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate comprising a reactive impedance element, the reactive impedance element being positioned for electrical coupling with the gas in the chamber, an r.f. electric source, a matching network connected between the source and the reactive impedance element, the matching network including first and second variable reactances for respectively controlling loading of the source and tuning the source to a load including the reactive impedance element and the plasma for processing the workpiece, the r.f. source having a frequency and power level for causing the reactive impedance element to supply an electromagnetic field to the gas to ignite the gas to the plasma, the plasma when ignited causing at least one of (a) material to be etched from the workpiece and (b) material to be deposited on the workpiece, an amplitude detector for r.f. current amplitude flowing between the r.f. source and the reactive impedance element, a plasma detector for detecting plasma ignition in the chamber, a controller responsive to the amplitude detector for controlling the values of the first and second variable reactances, the controller being arranged so that prior to plasma ignition the controller (1) varies the value of only one of the reactances until the r.f. current amplitude detected by the amplitude detector has a local maximum value, (2) then varies the value of only the other reactance until the r.f. current amplitude detected by the amplitude detector has a local maximum value, then repeats operations (1) and (2) until the plasma detector indicates ignition of the plasma in the chamber.
Apparatus for igniting a gas to a plasma in a vacuum plasma chamber for processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate comprising a reactive impedance element, the reactive impedance element being positioned for electrical coupling with the gas in the chamber, an r.f. electric source, a matching network connected between the source and the reactive impedance element, the matching network including first and second variable reactances for respectively controlling loading of the source and tuning the source to a load including the reactive impedance element and the plasma for processing the workpiece, the r.f. source having a frequency and power level for causing the reactive impedance element to supply an electromagnetic field to the gas to ignite the gas to the plasma, the plasma when ignited causing at least one of (a) material to be etched from the workpiece and (b) material to be deposited on the workpiece, first detectors for detecting the amplitude of r.f. forward current and r.f. forward voltage coupled by the source to the matching network, and second detectors for detecting the amplitude of r.f. reflected current and r.f. reflected voltage coupled from the matching network to the source, a plasma detector for detecting plasma ignition in the chamber, a controller responsive to the first and second detectors for controlling the values of the first and second variable reactances, the controller being arranged so that prior to plasma detector detecting plasma ignition the controller (1) varies the value of only one of the reactances until a function of reflected and forward power has a local maximum value, (2) then varies the value of only the other reactance until a function of reflected and forward power has a local maximum value, then repeats operations (1) and (2) until the plasma detector indicates ignition of the plasma in the chamber.
A method of detecting whether or not gaseous ions in a vacuum plasma processing chamber that is processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate have been excited to an r.f plasma, the gaseous ions in the chamber being responsive to an r.f. field derived by a reactive impedance element responsive to r.f. electric energy derived an r.f. source and coupled to the reactive impedance element via a matching network including a pair of reactances, the method comprising detecting the value of an electric parameter determined by the amount of power reflected from the reactive impedance plasma excitation element back toward the source, comparing the detected value of the parameter with a threshold value of said parameter, signalling that the gaseous ions are excited to the r.f. plasma in response to the comparing step indicating the detected value lies on a first side of the threshold value of said parameter, and signalling that the gaseous ions are not excited into the r.f. plasma in response to the comparing step indicating the detected value lies on a second side of the threshold value of said parameter.
Apparatus for detecting whether or not gaseous ions that are not initially in a plasma state in a vacuum plasma chamber for processing a workpiece including any of a metal substrate, semiconductor substrate or dielectric substrate have been ignited into a plasma discharge by an r.f. source connected to a reactive impedance plasma excitation element of the chamber, comprising
Dependencies are inferred from the claim text.