Method of measuring the amount of capacitive coupling of RF power in an inductively coupled plasma
AssigneeApplied Materials, Inc.
InventorsArthur Sato, Xue-Yu Qian
Life of this patent
Estimating the term…
Abstract
The amount of capacitive coupling of RF power to a semiconductor substrate or wafer in an inductively coupled RF plasma reactor is quantitatively measured by separating the RF current from the plasma through the wafer pedestal into the Fourier components including the fundamental frequency (F) of the RF power and the second harmonic (2F) of the frequency of the RF power and then measuring the current or power of the fundamental component. As an additional feature, the amount of inductive coupling is measured by measuring the current or power of the second harmonic.
Claims20
A plasma reactor having an inductive antenna adapted to be connected to an RF source of power operating at a desired frequency, a reactor chamber and a wafer support pedestal inside the chamber, said reactor comprising:
- a frequency discriminator having as its input a signal representative of plasma current flow and capable of separating such a signal into a fundamental frequency component output and a second harmonic frequency component output;
- whereby a measurement of the fundamental component output and the second harmonic output provides an indication of the apportionment of RF power between capacitive coupling and inductive coupling.
In an inductively coupled plasma reactor having an inductive antenna connected to an RF source of a frequency F, a reactor chamber and a wafer pedestal inside the chamber, a method of measuring capacitive coupling of RF energy to the wafer pedestal, comprising:
- measuring a signal representative of plasma current flow;
- separating said representative signal into respective frequency components including a first component at said frequency F and a second component at twice said frequency F;
- and
- sensing the amplitude of said first component.
An inductively coupled plasma reactor, comprising:
- a reactor chamber with means for introducing a processing gas into said chamber and a pedestal for supporting a semiconductor substrate inside said chamber;
- an inductively coupled antenna adjacent said chamber for producing a plasma from said gas by inductive coupling of RF power;
- a plasma source power RF generator coupled to the antenna and having a fundamental RF frequency F;
- means for quantitatively measuring a capacitively coupled component of said inductively coupled RF power.
In an inductively coupled plasma reactor having an inductive antenna connected to an RF source of a frequency F, a reactor chamber and a wafer pedestal inside the chamber, a method of measuring capacitive coupling of RF energy to the wafer pedestal relative to inductive coupling, comprising:
- measuring current from said plasma to said wafer pedestal to provide a current measurement;
- separating said current measurement into respective frequency components including a first component corresponding to capacitive coupling and a second component corresponding to inductive coupling;
- and
- sensing the respective amplitudes of said first and second components and providing a measurement of said capacitive coupling as a fraction of a whole equal to said first component divided by the sum of said first and second components.
Dependencies are inferred from the claim text.