Plasma Processing Apparatus RF Power Pulsing
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Solution Overview
Problem
Current plasma processing apparatuses face challenges in suppressing re-dissociation of reaction products and excessive gas dissociation during plasma etching, leading to substrate contamination and reduced etching efficiency.
Innovation Solution
The apparatus employs a radio frequency power source that generates pulses with increasing power levels in one period and stops power supply during periods with pulsed negative direct-current voltage, maintaining low electron temperature to prevent re-dissociation and overshoot, while using a bias power source to control ion acceleration and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio frequency power is continuously supplied to generate plasma, then plasma generation is maintained, but electron temperature increases causing excessive gas dissociation and re-dissociation of reaction products
Solution Approach 1:
The radio frequency power source supplies power in periodic pulses rather than continuously. During each pulse period, power is supplied to generate plasma; during the off period, power is stopped to allow electron temperature to decrease. This periodic on-off cycling prevents excessive electron temperature while maintaining plasma generation stability.
2Productivity
If high radio frequency power is supplied to maintain plasma, then etching continues, but reaction products re-dissociate and deposit on substrate causing contamination
Solution Approach 1:
By periodically interrupting radio frequency power supply, the system allows electron temperature to drop during off periods, preventing re-dissociation of reaction products. During on periods, plasma is generated to maintain etching. This periodic cycling eliminates substrate contamination while preserving etching productivity.
Solution Approach 2:
The patent converts the harmful effect of continuous high electron temperature into a beneficial periodic process. The off periods, which might seem to reduce productivity, actually prevent contamination that would otherwise require substrate cleaning, thereby maintaining long-term etching efficiency and quality.
3Productivity
If radio frequency power pulses have abrupt rise to peak power, then plasma generation is efficient, but electron temperature overshoot occurs causing gas dissociation
Solution Approach 1:
The radio frequency power pulses employ a dynamic rise profile rather than an abrupt step change. The power level gradually increases from zero to peak over a controlled rise time, preventing electron temperature overshoot while still achieving efficient plasma generation. This dynamic power modulation optimizes both productivity and temperature control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses re-dissociation and excessive gas dissociation, maintaining high etching rates and preventing substrate contamination, thereby improving plasma processing efficiency.
Implementation Method 1
The radio frequency power source is configured to generate radio frequency power to generate a plasma from a gas in the chamber
Implementation Method 2
The bias power source is electrically connected to the lower electrode and configured to generate bias power for drawing ions into the substrate support
Data Source
AI summary
In a plasma processing apparatus of an exemplary embodiment, a radio frequency power source generates radio frequency power for plasma generation. A bias power source periodically applies a pulsed negative direct-current voltage to a lower electrode to draw ions into a substrate support. The radio frequency power source supplies the radio frequency power as one or more pulses in a period in which the pulsed negative direct-current voltage is not applied to the lower electrode. The radio frequency power source stops supply of the radio frequency power in a period in which the pulsed negative direct-current voltage is applied to the lower electrode. Each of the one or more pulses has a power level that gradually increases from a point in time of start thereof to a point in time when a peak thereof appears.