Measuring device and method of obtaining thickness of sheath
A measuring device includes a substrate disposed on a substrate support of a plasma processing apparatus, a transmission circuit, a transmitting antenna, a receiving antenna, a reception demodulation circuit, and a calculator which are provided in the substrate. The transmission circuit generates a microwave. The transmitting antenna transmits the microwave generated by the transmission circuit as a transmission wave. The receiving antenna receives a reflected wave of the transmission wave by plasma above the substrate support as at least one reception wave. The reception demodulation circuit generates a signal that reflects a thickness of a sheath between the substrate and the plasma, from the reception wave. The calculator obtains the thickness of the sheath from the signal generated by the reception demodulation circuit.
1. A measuring device comprising:
a substrate disposed on a substrate support of a plasma processing apparatus;
a transmission circuit provided in the substrate, and configured to generate a microwave;
a transmitting antenna provided in the substrate, and configured to transmit the microwave generated by the transmission circuit as a transmission wave;
at least one receiving antenna provided in the substrate, and configured to receive a reflected wave of the transmission wave by plasma above the substrate support as at least one reception wave;
a reception demodulation circuit provided in the substrate, and configured to generate at least one signal that reflects a thickness of a sheath between the substrate and the plasma, from the at least one reception wave; and
a calculator provided in the substrate, and configured to obtain the thickness from the at least one signal.
2. The measuring device according to claim 1 , wherein a plurality of receiving antennas is provided as the at least one receiving antenna,
the plurality of receiving antennas are arranged along a direction component of a transmission direction of the transmission wave which is parallel to the substrate,
the reception demodulation circuit is configured to generate a plurality of signals that represents intensities of a plurality of reception waves received by the plurality of receiving antennas, respectively, and
the calculator is configured to obtain the thickness from the plurality of signals.
3. The measuring device according to claim 1 , wherein the transmitting antenna transmits a pulse of the microwave output from the transmission circuit as the transmission wave,
the reception demodulation circuit is configured to generate the at least one signal that represents an intensity of the at least one reception wave, and
the calculator is configured to obtain a delay time of the at least one reception wave with respect to the transmission wave from the at least one signal, and obtain the thickness from the delay time.
4. The measuring device according to claim 3 , wherein a plurality of receiving antennas is provided as the at least one receiving antenna,
the plurality of receiving antennas are arranged along a direction component of a transmission direction of the transmission wave which is parallel to the substrate,
the reception demodulation circuit is configured to generate a plurality of signals that represents intensities of the plurality of reception waves received by the plurality of receiving antennas, respectively,
the calculator is configured to obtain a plurality of delay times of the plurality of reception waves, respectively, with respect to the transmission wave from the plurality of signals, and obtain the thickness from the plurality of delay times.
5. The measuring device according to claim 1 , wherein the reception demodulation circuit is configured to generate the at least one signal that represents a phase difference between the transmission wave and the at least one reception wave.
6. The measuring device according to claim 1 , wherein the transmission circuit is configured to cause a frequency of the transmission wave to alternately and monotonically increase and decrease, and
the reception demodulation circuit is configured to mix the transmission wave and the at least one reception wave, thereby generating an intermediate frequency signal having a beat frequency that reflects the thickness of the sheath as the at least one signal.
7. The measuring device according to claim 1 , wherein the transmission circuit is configured to scan a transmission direction of the transmission wave to increase and decrease an angle formed by the transmission direction of the transmission wave with respect to the substrate in synchronization with a reference signal having a predetermined frequency which is lower than a frequency of the transmission wave,
the reception demodulation circuit is configured to generate a signal of a predetermined frequency component that is included in the at least one reception wave, as the at least one signal, and
the calculator is configured to obtain the thickness from a phase difference between the reference signal and the at least one signal.
8. The measuring device according to claim 1 , wherein the transmission wave is a millimeter wave.
9. The measuring device according to claim 1 , wherein a plurality of receiving antennas is provided as the at least one receiving antenna,
the plurality of receiving antennas are arranged along a direction component of a transmission direction of the transmission wave which is parallel to the substrate,
the reception demodulation circuit is configured to generate a plurality of signals that represents intensities of a plurality of reception waves received by the plurality of receiving antennas, respectively,
the calculator is configured to obtain the thickness from the plurality of signals, and
the transmission wave is a millimeter wave.
10. The measuring device according to claim 1 , wherein the transmitting antenna transmits a pulse of the microwave output from the transmission circuit as the transmission wave,
the reception demodulation circuit is configured to generate the at least one signal that represents an intensity of the at least one reception wave,
the calculator is configured to obtain a delay time of the at least one reception wave with respect to the transmission wave from the at least one signal, and obtain the thickness from the delay time, and
the transmission wave is a millimeter wave.
11. The measuring device according to claim 3 , wherein a plurality of receiving antennas is provided as the at least one receiving antenna,
the plurality of receiving antennas are arranged along a direction component of a transmission direction of the transmission wave which is parallel to the substrate,
the reception demodulation circuit is configured to generate a plurality of signals that represents intensities of the plurality of reception waves received by the plurality of receiving antennas, respectively,
the calculator is configured to obtain a plurality of delay times of the plurality of reception waves, respectively, with respect to the transmission wave from the plurality of signals, and obtain the thickness from the plurality of delay times, and
the transmission wave is a millimeter wave.
12. The measuring device according to claim 1 , wherein the reception demodulation circuit is configured to generate the at least one signal that represents a phase difference between the transmission wave and the at least one reception wave, and
the transmission wave is a millimeter wave.
13. The measuring device according to claim 1 , wherein the transmission circuit is configured to cause a frequency of the transmission wave to alternately and monotonically increase and decrease,
the reception demodulation circuit is configured to mix the transmission wave and the at least one reception wave, thereby generating an intermediate frequency signal having a beat frequency that reflects the thickness of the sheath as the at least one signal, and
the transmission wave is a millimeter wave.
14. The measuring device according to claim 1 , wherein the transmission circuit is configured to scan a transmission direction of the transmission wave to increase and decrease an angle formed by the transmission direction of the transmission wave with respect to the substrate in synchronization with a reference signal having a predetermined frequency which is lower than a frequency of the transmission wave,
the reception demodulation circuit is configured to generate a signal of a predetermined frequency component that is included in the at least one reception wave, as the at least one signal,
the calculator is configured to obtain the thickness from a phase difference between the reference signal and the at least one signal, and
the transmission wave is a millimeter wave.
15. A method of obtaining a thickness of a sheath, the method comprising:
(a) placing a measuring device on a substrate support in a chamber of a plasma processing apparatus, the measuring device including:
a substrate disposed on the substrate support of the plasma processing apparatus,
a transmission circuit provided in the substrate, and configured to generate a microwave,
a transmitting antenna provided in the substrate, and configured to transmit the microwave generated by the transmission circuit as a transmission wave,
at least one receiving antenna provided in the substrate, and configured to receive a reflected wave of the transmission wave by plasma above the substrate support as at least one reception wave,
a reception demodulation circuit provided in the substrate, and configured to generate at least one signal that reflects the thickness of the sheath between the substrate and the plasma, from the at least one reception wave, and
a calculator provided in the substrate, and configured to obtain the thickness from the at least one signal;
(b) generating plasma in the chamber of the plasma processing apparatus; and
(c) while the plasma is generated in the chamber, obtaining the thickness from the at least one signal in the calculator of the measuring device placed on the substrate support.