Specific Process Knowledge/Etch/DRIE-Pegasus/System-description: Difference between revisions
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The matching unit consists of two tunable capacitors and an impedance matching network. The network measures the impedance of the circuit and automatically adjusts the capacitances of the two capacitors (called Load and Tune, one connected in serial, the other in parallel) in order to match the 50 ohm impedance. The adjustment of the capacitance is accomplished by changing of the active area inside the capacitor - the shaft rotates one part of the capacitor as illustrated above. In all recipes, one has to provide setpoints for the Load and Tune. If chosen correctly, then once the plasma ignites the matching network will then adjust automatically to achieve RF matching. | The matching unit consists of two tunable capacitors and an impedance matching network. The network measures the impedance of the circuit and automatically adjusts the capacitances of the two capacitors (called Load and Tune, one connected in serial, the other in parallel) in order to match the 50 ohm impedance. The adjustment of the capacitance is accomplished by changing of the active area inside the capacitor - the shaft rotates one part of the capacitor as illustrated above. In all recipes, one has to provide setpoints for the Load and Tune. If chosen correctly, then once the plasma ignites the matching network will then adjust automatically to achieve RF matching. | ||
It is unrealistic to achieve perfect matching (zero reflected power) so some minimum value (always less than 10 % of the input power) is found. This is, however, by no means a simple matter and the setpoints of Load and Tune (always measured as percentages of full capacitance) must be chosen wisely or the RF matching will fail. Therefore, if the setpoints for Load and Tune in a recipe are wrong - the process will fail and most likely abort. | It is unrealistic to achieve perfect matching (zero reflected power) so some minimum value (always less than 10 % of the input power) is found. This is, however, by no means a simple matter and the setpoints of Load and Tune (always measured as percentages of full capacitance) must be chosen wisely or the RF matching will fail. Therefore, if the setpoints for Load and Tune in a recipe are wrong - the process will fail and most likely abort. | ||