Specific Process Knowledge/Etch/DRIE-Pegasus/Parameters: Difference between revisions
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; Forward power versus Load power | ; Forward power versus Load power | ||
: In order for the RF power supplied by the generators to be absorped by the plasma, the impedance of the plasma must match the impedance of the RF network. The impedance of the plasma relies on the gas composition, the pressure and the power and is therefore beyond direct control of the instrument. Between the RF generators and the coil, two capacitors called Load and Tune form a matching network that enables us to change the impedance of the RF network. The tuning of Load and Tune is usually done automatically by the software. If the two impedances are not similar, the RF power will be absorped by the RF network (RF generator and capacitors) instead of the plasma - this power is labelled the Reflected power and it must be minimized. | : In order for the RF power supplied by the generators to be absorped by the plasma, the impedance of the plasma must match the impedance of the RF network. The impedance of the plasma relies on the gas composition, the pressure and the power and is therefore beyond direct control of the instrument. Between the RF generators and the coil, two capacitors called Load and Tune form a matching network that enables us to change the impedance of the RF network. The tuning of Load and Tune is usually done automatically by the software. If the two impedances are not similar, the RF power will be absorped by the RF network (RF generator and capacitors) instead of the plasma - this power is labelled the Reflected power and it must be minimized. The generators has two modes: | ||
*'''Forward power''' The generator delivers the power according to the recipe. If 10 % of the power is reflected, the real value of the power supplied to the plasma will be 10 % less. | |||
*'''Load power''' The RF power lost as reflected power is compensated for automatically. If 10 % of the forward power is lost, the input is automatically increased. | |||