Multi-station plasma reactor with RF balancing
Methods and apparatus for multi-station semiconductor deposition operations with RF power frequency tuning are disclosed. The RF power frequency may be tuned according to a measured impedance of a plasma during the semiconductor deposition operation. In certain implementations of the methods and apparatus, a RF power parameter may be adjusted during or prior to the deposition operation. Certain other implementations of the semiconductor deposition operations may include multiple different deposition processes with corresponding different recipes. The recipes may include different RF power parameters for each respective recipe. The respective recipes may adjust the RF power parameter prior to each deposition process. RF power frequency tuning may be utilized during each deposition process.
1. An apparatus for cyclic plasma-assisted semiconductor deposition processing, the apparatus comprising:
multiple deposition stations, wherein each of the deposition stations includes at least one wafer support and is configured to receive at least one substrate, and wherein the multiple deposition stations are within a chamber;
a power source configured to provide RF power to the chamber to generate and maintain a plasma;
an impedance sensor configured to measure plasma impedance;
a RF frequency tuner configured to tune the RF power's frequency;
one or more RF power adjusters configured to adjust the RF power distributed to the multiple deposition stations and thereby reduce station to station variations; and
one or more controllers, wherein the one or more controllers, the power source, the impedance sensor, the RF frequency tuner, and the RF power adjusters are communicatively connected and the controller is configured to:
tune the RF power frequency, wherein tuning the RF power frequency includes:
i) determining the impedance of the plasma via the plasma impedance measured by the impedance sensor;
ii) determining, according to the impedance measured in (i), a change to the frequency of the RF power; and
iii) adjusting the frequency of the RF power via the RF frequency tuner,
instruct the one or more RF power adjusters to adjust the RF power distributed to each station to reduce station-to-station variations, and
control the distribution of RF power repeatedly to multiple stations to thereby repeatedly generate plasma in the stations, control the deposition of a thin film on the substrate at each station during a single ALD cycle of semiconductor deposition processing, and tune the RF power frequency, each time during a new ALD cycle of the semiconductor deposition processing, wherein:
the apparatus is configured to ignite the plasma and temporarily deliver one or more process gases to the chamber during each ALD cycle and configured to maintain station-to-station distribution of the RF power parameter unchanged over multiple ALD cycles, and
the controller is configured such that tuning the RF power frequency produces a first RF power frequency in one ALD cycle and a second RF power frequency in another ALD cycle, wherein the first and second RF power frequencies are different.
2. The apparatus of claim 1 , wherein ii) comprises determining a change to the frequency of the RF power such that the change to the frequency would result in a phase of the impedance having zero value.
3. The apparatus of claim 1 , wherein the RF adjuster is selected from the group consisting of: variable capacitors and variable coil inductors.
4. The apparatus of claim 1 , wherein the impedance sensor is configured to measure impedance as seen by the power source and ii) comprises determining a change to the frequency of the RF power such that the change to the frequency would result in a phase of the impedance as seen by the power source having zero value.
5. The apparatus of claim 1 , wherein the RF power provided is at a fixed frequency.
6. The apparatus of claim 5 , wherein the impedance sensor is configured to measure impedance as seen by the power source and the fixed frequency is a frequency calculated to result in a magnitude of the impedance as seen by the power source having a value of about 50 ohms.
7. The apparatus of claim 5 , wherein the fixed frequency is a frequency of about 13.56 MHz.
8. The apparatus of claim 1 , wherein tuning the frequency of the RF power is performed over a duration of 10 seconds or less.