Control system and method for ion energy distribution in plasma process chambers using tailored waveform generators
AssigneeInspiring Atoms Pte Ltd
InventorYang Pan
Life of this patent
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Abstract
Disclosed herein is a real-time control and optimization system for a plasma process system, specifically focusing on a tailored waveform generator coupled to a chuck. The system employs a system controller that divides the process recipe into a setting phase and a processing phase. The setting phase is used to determine optimized slopes for voltage waveforms during plasma processing. This innovation enhances the precision and consistency of ion energy and current during plasma etching and related processes.
Claims15
A process system, comprising:
- a vacuum chamber configured for processing of a wafer;
- a chuck configured to sustain the wafer;
- a bias unit coupled to the chuck, the bias unit comprising an SMPC, a current source designed to produce varied currents;
- a current sensor positioned at an output terminal of the bias unit,
- wherein the bias unit is configured to generate a waveform that includes a positive voltage step, a negative voltage bias setting point, and a linear descent slope towards a voltage more negative than the negative bias setting point;
- wherein a system controller is configured to manage the waveform during a setting phase by initiating a pulse train comprising multiple groups of pulses, each group having a consistent slope, with different groups having varied slopes;
- wherein an output current of the bias unit is detected by the current sensor within each group, and the system controller is further configured to average output currents measured within each group to mitigate noise interference and determine an optimized slope by identifying the slope corresponding to the minimum change in the output current as a function of the varied slope;
- and
- wherein, during a processing phase, the system controller directs the bias unit to apply a pulse train with the optimized slope.
A method for generating a voltage bias for accelerating ions in a plasma process chamber, comprising:
- receiving a process recipe by a system controller;
- generating a first pulse train by a bias unit, the first pulse train comprising a plurality of pulses, each represented by a waveform exhibiting a positive voltage step, a negative voltage setting point, and a linear ramp step towards a voltage more negative than the setting point, wherein varied slopes are assigned to the ramp steps, wherein the system controller is configured to manage the waveform during a setting phase by initiating the first pulse train comprising multiple groups of pulses, each group having a consistent slope, with different groups having varied slopes;
- measuring an output current of the bias unit by a current sensor within each group, wherein the system controller is further configured to average output currents measured within the group to mitigate noise interference;
- determining an optimized slope by identifying the slope corresponding to the minimum change in the output current as a function of the varied slope;
- and
- generating, by the bias unit, a second pulse train comprising multiple pulses, wherein the ramp steps adopt the optimized slope.
Dependencies are inferred from the claim text.