An ion collector includes a plurality of segments and a plurality of integrators. The plurality of segments are physically separated from one another and spaced around a substrate support. Each of the segments includes a conductive element that is designed to conduct a current based on ions received from a plasma. Each of the plurality of integrators is coupled to a corresponding conductive element. Each of the plurality of integrators is designed to determine an ion distribution for a corresponding conductive element based, at least in part, on the current conducted at the corresponding conductive element. An example benefit of this embodiment includes the ability to determine how uniform the ion distribution is across a wafer being processed by the plasma.

A plasma processing apparatus includes a chamber; a substrate support having a lower electrode, an electrostatic chuck, and a heater; a radio frequency power supply; a DC power supply; a first controller; and a second controller. The first controller controls the radio frequency power supply to supply a pulsed radio frequency power to the lower electrode periodically with a cycle defined by a first frequency, and controls the DC power supply to apply a pulsed negative voltage to the edge ring periodically with the cycle. The second controller includes a heater controller that controls the power by obtaining a resistance value of the heater from sample values of a current and a voltage supplied to the heater. The first frequency is different from a second frequency that is a sampling frequency of the sample value of the current and the sample value of the voltage in the second controller.

A RF generator includes a RF power source and a RF control module coupled to the RF power source. The RF control module is configured to generate at least one control signal to vary a respective at least one of an RF output signal from the RF power source or an impedance between the RF power source and a load. The RF output signal includes a RF signal modulated by a pulse signal, and the RF control module is further configured to adjust the at least one control signal to vary at least one of an amplitude or a frequency of the RF output signal or the impedance between the RF power source and the load to control a shape of the pulse signal. The at least one of the amplitude, the frequency, or the impedance is adjusted in accordance with respective feedforward adjustments that vary in accordance with a respective sensed pulse parameter detected between a matching network and the load.

For a first period of time, a higher radiofrequency power is applied to generate a plasma in exposure to a substrate, while applying low bias voltage at the substrate level. For a second period of time, a lower radiofrequency power is applied to generate the plasma, while applying high bias voltage at the substrate level. The first and second periods of time are repeated in an alternating and successive manner for an overall period of time necessary to produce a desired effect on the substrate. In some embodiments, the first period of time is shorter than the second period of time such that on a time-averaged basis the plasma has a greater ion density than radical density. In some embodiments, the first period of time is greater than the second period of time such that on a time-averaged basis the plasma has a lower ion density than radical density.

At a time point T.sub.0 when starting a process, a duty ratio of a high frequency power RF1 to which power modulation is performed is set to be an initial value (about 90%) which allows plasma to be ignited securely under any power modulating conditions. At the substantially same time of starting the process, the duty ratio of the high frequency power RF1 is gradually reduced from the initial value (about 90%) in a regular negative gradient or in a ramp waveform. At a time point t.sub.2 after a lapse of a preset time T.sub.d, the duty ratio has an originally set value D.sub.s for an etching process. After the time point t.sub.2, the duty ratio is fixed or maintained at the set value D.sub.s until the end (time point T.sub.4) of the process.

Systems and methods for multi-level pulsing of a parameter and multi-level pulsing of a frequency of a radio frequency (RF) signal are described. The parameter is pulsed from a low level to a high level while the frequency is pulsed from a low level to a high level. The parameter and the frequency are simultaneously pulsed to increase a rate of processing a wafer, to increase mask selectivity, and to reduce angular spread of ions within a plasma chamber.

A method for multi-state pulsing to achieve a balance between bow control and mask selectivity is described. The method includes generating a primary radio frequency (RF) signal. The primary RF signal pulses among three states including a first state, a second state, and a third state. The method further includes generating a secondary RF signal. The secondary RF signal pulses among the three states. During the first state, the primary RF signal has a power level that is greater than a power level of the secondary RF signal. Also, during the second state, the secondary RF signal has a power level that is greater than a power level of the primary RF signal. During the third state, power levels of the primary and secondary RF signals are approximately equal.

Bias supplies and plasma processing systems are disclosed. One bias supply comprises an output node, a return node, and a switch network and at least one power supply coupled to the output node and the return node. The switch network and the at least one power supply configured, in combination, to apply an asymmetric periodic voltage waveform and provide a corresponding current waveform at the output node relative to the return node. A timing parameter estimator receives a digital representation of a full cycle of the voltage and current waveforms, and generates a pulse width control signal based on a crossing time that the current waveform crosses a threshold current value after falling from a positive peak current value to control the switch network.

Systems and methods for increasing peak ion energy with a low angular spread of ions are described. In one of the systems, multiple radio frequency (RF) generators that are coupled to an upper electrode associated with a plasma chamber are operated in two different states, such as two different frequency levels, for pulsing of the RF generators. The pulsing of the RF generators facilitates a transfer of ion energy during one of the states to another one of the states for increasing ion energy during the other state to further increase a rate of processing a substrate.

A control circuit for outputting a direct current (DC) signal in the form of a pulsed signal includes a switch circuit having a first terminal, a second terminal, a third terminal, a fourth terminal, a first control terminal, and a second control terminal, wherein the first terminal and the second terminal are input terminals of the DC signal, the third terminal and the fourth terminal are output terminals of the pulsed signal, the first control terminal and the second control terminal receive a first signal or a second signal to control outputting the pulsed signal, in response to the first control terminal and the second control terminal receiving the first signal, the third terminal and the fourth terminal output the pulsed signal, and in response to the first control terminal and the second control terminal receiving the second signal, the third terminal and the fourth terminal stop outputting the pulsed signal; and an energy storage circuit having two terminals connected to the first terminal and the second terminal of the switch circuit to store residual electric energy of the switch circuit when the switch circuit does not output the pulsed signal. The control circuit reduces the oscillation the voltage of occurred at the end of each pulse, and improving the accuracy of controlling the plasma energy and density used in the semiconductor processes.