Pulsed RF Bevel Plasma Processing to Reduce Wafer Edge Arcing
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Solution Overview
Problem
Arcing damage caused by charge build-up during bevel edge plasma processing in semiconductor wafers leads to defects and reduced yield, primarily due to the use of continuous wave RF generators.
Innovation Solution
Implementing a pulsed mode operation for the RF generator with a duty cycle and adjusting power settings to maintain effective power delivery, combined with increasing pulsing frequency to reduce charge build-up and arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If continuous wave RF generator is used to deliver power for bevel edge processing, then sufficient power is delivered to achieve adequate deposition efficiency and etch rates, but significant charge build-up occurs causing electrical arcing damage
Solution Approach 1:
The patent applies periodic action by switching the RF generator from continuous wave mode to pulsed mode operation. The RF power is delivered in periodic pulses with controlled duty cycles (e.g., 10-90% duty cycle), creating intervals of power delivery followed by intervals of reduced or zero power delivery. This periodic interruption allows charge to dissipate during the off-periods while maintaining sufficient average power for processing during the on-periods, thereby resolving the contradiction between power delivery and charge build-up prevention
Solution Approach 2:
The patent implements dynamics by making the RF power delivery dynamic rather than static. The system dynamically adjusts the RF power delivery by modulating the duty cycle and pulse width, allowing the power delivery characteristics to change over time. This dynamic control enables the system to deliver high power when needed for processing while periodically reducing power to prevent charge accumulation, thus resolving the contradiction between maintaining power delivery and preventing arcing damage
2Object-affected harmful factors
If pulsed mode operation is implemented to reduce charge build-up, then arcing damage is reduced, but power delivery efficiency decreases
Solution Approach 1:
The patent applies parameter changes by systematically adjusting key parameters of the pulsed RF power delivery including duty cycle (ratio of on-time to total cycle time), pulse width, and frequency. By optimizing these parameters, the system maintains sufficient average power delivery for effective bevel edge processing while preventing charge build-up. For example, a duty cycle of 50-90% ensures that enough power is delivered on average to maintain processing efficiency while the periodic off-periods allow charge dissipation, thus resolving the contradiction between reducing arcing and maintaining power efficiency
Solution Approach 2:
The patent implements feedback mechanisms to monitor and adjust the RF power delivery parameters in real-time. Sensors detect charge build-up conditions and process outcomes, and this information feeds back to the RF generator control system which adjusts the duty cycle and pulse parameters accordingly. This closed-loop feedback ensures that the system automatically optimizes the balance between power delivery efficiency and charge prevention, resolving the contradiction by adapting power delivery to actual process conditions
3Productivity
If higher power levels are used to maintain throughput in pulsed mode, then processing efficiency is maintained, but charge build-up increases
Solution Approach 1:
The patent applies periodic action with carefully controlled duty cycles to balance throughput and charge prevention. By setting the duty cycle appropriately (e.g., 50-90%), the system delivers high power during the on-periods to maintain processing throughput while the off-periods provide sufficient time for charge dissipation. The periodic nature ensures that charge does not accumulate to dangerous levels while the average power delivery remains high enough to maintain productivity, thus resolving the contradiction between throughput and charge build-up
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that the pulsed RF power delivery continues throughout the processing cycle without interruption. The pulsed mode maintains continuous plasma presence and processing activity, with only the power level being modulated. This continuous useful action ensures that processing throughput is maintained while the periodic power modulation prevents charge build-up, resolving the contradiction between productivity and charge prevention
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
Substantially reduces arcing damage and maintains processing throughput by effectively dissipating charge during off-cycles, achieving similar etch rates as continuous wave modes while minimizing arcing.
Implementation Method 1
radio frequency (RF) power is supplied to create plasma
Implementation Method 2
gases are introduced, and radio frequency (RF) power is supplied to create plasma
Implementation Method 3
delivering power using CW RF generators is causing significant charge build-up in the wafer edge, which tends to accumulate
Implementation Method 4
calculating or accessing a compensation factor to an input power setting of the generator. The compensation factor is configured to add an incremental amount of power to the input power setting to account for a loss in power attributed to the duty cycle
Data Source
AI summary
Methods and systems for processing a bevel edge of a wafer in a bevel plasma chamber. The method includes receiving a pulsed mode setting for a RF generator of the bevel plasma chamber. The method includes identifying a duty cycle for the pulsed mode, the duty cycle defining an ON time and an OFF time during each cycle of power delivered by the generator. The method includes calculating or accessing a compensation factor to an input RF power setting of the generator. The compensation factor is configured to add an incremental amount of power to the input power setting to account for a loss in power attributed to the duty cycle to be run in the pulsed mode. The method is configured to run the generator in the pulse mode with the duty cycle and the pulsing frequency. The generator is configured to generate the input power in pulsing mode that includes incremental amount of power to achieve an effective power in the bevel plasma chamber to achieve a target bevel processing throughput, while reducing charge build-up that causes arcing damage.