Retuning for impedance matching network control
A physical vapor deposition system may include an RF generator configured to transmit an AC process signal to a physical vapor deposition chamber via an RF matching network. A controller of the RF matching network receives the DC magnitude and phase error signals and varies an impedance of the RF matching network in response to the DC magnitude and phase error signals. The matching network operates in a first mode until a tuning dead-zone is determined. Once a tuning dead-zone is determined, the matching network operates in additional modes until the network is tuned. The controller uses a composite value of magnitude and phase error to drive the variable tuning and load capacitors. In some cases, a blended mode (representing multiple tuning algorithms concurrently) may be implemented as a single mode that weights across what would have been multiple modes and thereby tunes the network using a weighted blended mode.
1. A matching network system, comprising:
an input sensor that, in operation, senses a current value, a voltage value, and a phase value between the current value and the voltage value of an RF input signal;
a controller coupled to the input sensor, the controller programmed to:
determine a phase error value and a magnitude error value;
perform tuning of the matching network, the tuning comprising:
performing a first tuning algorithm wherein:
a first adjustment for a position of a first variable capacitor is determined based on the magnitude error value; and
a second adjustment for a position of a second variable capacitor is determined based on the phase error value;
performing a second tuning algorithm wherein:
a third adjustment for the position of the first variable capacitor is determined based on a first composite value of the magnitude error value and the phase error value; and
a fourth adjustment for the position of the second variable capacitor is determined based on a second composite value of the magnitude error value and the phase error value;
using a blended mode tuning that provides a scaling factor influence to reduce an influence of composite error signals as the matching network converges on a tuning point, the blended mode tuning to apply one or more adjustments by:
applying a first weighting factor to the first adjustment and a second weighting factor to the third adjustment to create a blended first adjustment;
applying a third weighting factor to the second adjustment and a fourth weighting factor to the fourth adjustment to create a blended second adjustment;
adjusting the first variable capacitor based on the blended first adjustment; and
adjusting the second variable capacitor based on the blended second adjustment;
determining whether a dead-zone has occurred; and
if a dead-zone has occurred, then changing at least the first weighting factor and the second weighting factor or the third weighting factor and the fourth weighting factor prior to repeating the using the blended mode tuning to apply one or more adjustments.
2. The matching network system of claim 1 , the tuning further comprising:
performing a third tuning algorithm;
creating the blended first adjustment using a fifth weighting factor based on the third tuning algorithm; and
creating the blended second adjustment using a sixth weighting factor based on the third tuning algorithm.
3. The matching network system of claim 2 , wherein a sum of the first weighting factor plus the second weighting factor plus the fifth weighting factor is equal to 1.
4. The matching network system of claim 2 , wherein a sum of the third weighting factor plus the fourth weighting factor plus the sixth weighting factor is equal to 1.
5. The matching network system of claim 1 , the tuning further comprising:
determining whether the matching network has reached a tuned state based on convergence on the tuning point; and
if the matching network has reached a tuned state, then resetting each of the first weighting factor, the second weighting factor, the third weighting factor, and the fourth weighting factor to a respective initial pre-defined default value.
6. The matching network system of claim 1 , wherein the first weighting factor plus the second weighting factor is equal to 1 and the third weighting factor plus the fourth weighting factor is equal to 1.
7. The matching network system of claim 1 , wherein the scaling factor is based on gamma with gamma representing a reflection coefficient.
8. A radio frequency plasma processing device comprising:
a reaction chamber;
a radio frequency generator to supply radio frequency power to a plasma in the reaction chamber; and
a matching network system comprising:
an input sensor that, in operation, senses a current value, a voltage value, and a phase value between the current value and the voltage value of an RF input signal;
a controller coupled to the input sensor and programmed to:
determine a phase error value and a magnitude error value;
perform tuning of the matching network, the tuning comprising:
performing a first tuning algorithm wherein:
a first adjustment for a position of a first variable capacitor is determined based on the magnitude error value; and
a second adjustment for a position of a second variable capacitor is determined based on the phase error value;
performing a second tuning algorithm wherein:
a third adjustment for the position of the first variable capacitor is determined based on a first composite value of the magnitude error value and the phase error value; and
a fourth adjustment for the position of the second variable capacitor is determined based on a second composite value of the magnitude error value and the phase error value;
using a blended mode tuning that provides a scaling factor influence to reduce an influence of composite error signals as the matching network converges on a tuning point, the blended mode tuning to apply one or more adjustments by:
applying a first weighting factor to the first adjustment and a second weighting factor to the third adjustment to create a blended first adjustment;
applying a third weighting factor to the second adjustment and a fourth weighting factor to the fourth adjustment to create a blended second adjustment;
adjusting the first variable capacitor based on the blended first adjustment; and
adjusting the second variable capacitor based on the blended second adjustment;
determining whether a dead-zone has occurred; and
if a dead-zone has occurred, then changing at least the first weighting factor and the second weighting factor or the third weighting factor and the fourth weighting factor prior to repeating the using the blended mode tuning to apply one or more adjustments.
9. The radio frequency plasma processing device of claim 8 , the tuning further comprising:
performing a third tuning algorithm;
creating the blended first adjustment using a fifth weighting factor based on the third tuning algorithm; and
creating the blended second adjustment using a sixth weighting factor based on the third tuning algorithm.
10. The radio frequency plasma processing device of claim 9 , wherein a sum of the first weighting factor plus the second weighting factor plus the fifth weighting factor is equal to 1.
11. The radio frequency plasma processing device of claim 8 , the tuning further comprising:
determining whether the matching network has reached a tuned state based on convergence on the tuning point; and
if the matching network has reached a tuned state, then resetting each of the first weighting factor, the second weighting factor, the third weighting factor, and the fourth weighting factor to a respective initial pre-defined default value.
12. The radio frequency plasma processing device of claim 8 , wherein the first weighting factor plus the second weighting factor is equal to 1 and the third weighting factor plus the fourth weighting factor is equal to 1.
13. The radio frequency plasma processing device of claim 8 , wherein the scaling factor is based on gamma with gamma representing a reflection coefficient.