Three or more states for achieving high aspect ratio dielectric etch

A system comprising:

• a plasma chamber having a first electrode and a second electrode;
• an impedance matching circuit coupled to the plasma chamber;
• a bias radio frequency (RF) generator coupled to the impedance matching circuit, wherein the bias RF generator is configured to supply a bias radio frequency (RF) signal to the impedance matching circuit, wherein the bias RF signal includes a first plurality of parameter levels during a repeating time period, wherein the first plurality of parameter levels include a first parameter level during a first state, a second parameter level during a second state, and a third parameter level during a third state;
• and
• a source RF generator coupled to the impedance matching circuit, wherein the source RF generator is configured to supply a source RF signal to the impedance matching circuit, wherein the source RF signal includes a second plurality of parameter levels during the repeating time period, wherein the second plurality of parameter levels include a first parameter level during the first state, a second parameter level during the second state, and a third parameter level during the third state,
• wherein the first, second and third parameter levels of the bias RF signal are different from each other,
• wherein the first, second and third parameter levels of the source RF signal are different from each other.