Plasma Etching Intermittent Power Switching
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Solution Overview
Problem
In plasma etching methods using continuous plasma, switching between etching processes leads to unstable plasma conditions due to high-frequency reflected waves, causing unintended etching and difficulty in maintaining uniformity.
Innovation Solution
A plasma etching method that stabilizes plasma by intermittently supplying high-frequency power with a duty ratio during the switching process from one etching condition to another, ensuring the effective power in the switching phase is equal to or lower than the second etching process, thereby reducing high-frequency reflected waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If high frequency power is continuously supplied during process switching to maintain plasma, then plasma continuity is maintained, but high-frequency reflected waves are generated causing plasma instability
Solution Approach 1:
The patent applies periodic action by intermittently supplying high frequency power during the switching process between etching processes. Instead of continuous power supply, the power is supplied in pulses with specific duty ratios, which prevents the generation of high-frequency reflected waves while maintaining plasma continuity. This periodic power supply approach resolves the contradiction by eliminating the instability caused by continuous power during gas switching.
2Adaptability or versatility
If different gases are switched during etching processes, then process flexibility is improved, but a period of gas mixing is generated causing undesired etching
Solution Approach 1:
The patent applies preliminary anti-action by suppressing the plasma reaction during the gas switching period through intermittent power supply with reduced effective power. This preliminary suppression prevents the undesired etching that would occur during the gas mixing phase, allowing flexible gas switching while maintaining etching uniformity. The low power state acts as a preventive measure against off-specification etching during the transition.
3Reliability
If high frequency power with high effective power is supplied during switching, then plasma stability is improved, but etching progresses during switching causing non-conformance to process conditions
Solution Approach 1:
The patent uses periodic action with duty ratio control to supply high frequency power intermittently during switching. The effective power is kept at or below the level of the second etching process by adjusting the duty ratio, which stabilizes plasma without causing excessive etching during the switching period. This periodic supply method allows plasma stability and etching control to coexist.
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 high-frequency reflected waves and stabilizes the plasma, improving processing accuracy and yield by maintaining plasma stability during the switching process.
Implementation Method 1
switching a process from one etching process to another etching process while maintaining plasma
Implementation Method 2
supplying high frequency power having first effective power
Data Source
AI summary
A plasma etching method is provided to perform a desired etching by switching a process condition while maintaining plasma by supplying high frequency power. A first plasma etching process is performed based on a first process condition. A second plasma etching process different from the first process conditions is performed based on a second process condition while supplying first high frequency power having first effective power. Second high frequency power having second effective power is intermittently supplied between the first plasma etching process and the second plasma etching process during a switch from the first plasma etching process to the second plasma etching process. The second effective power of the second high frequency power is equal to or lower than the first effective power of the first high frequency power in the second plasma etching process.