Time-Modulated Plasma Power for Vertical Etching Control
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Solution Overview
Problem
The existing plasma processing technologies face challenges in controlling plasma dissociation, particularly for microfabrication and three-dimensional device etching, where the etching area becomes smaller and the aspect ratio increases, leading to a limited process window for radical deposition control.
Innovation Solution
A plasma processing apparatus and method that utilize time-modulated radio frequency electric power with pulse waves of different amplitudes to generate and maintain plasma, allowing for the control of plasma dissociation and broadening the process window by alternating between high and low power periods for plasma generation and bias application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high electric power is supplied to generate highly dissociated plasma, then plasma generation efficiency is improved, but control over radical deposition becomes insufficient
Solution Approach 1:
The patent applies periodic action by alternating between high electric power periods (for plasma generation) and low electric power periods (for radical deposition control). During high power periods, highly dissociated plasma is generated to provide sufficient radical supply. During low power periods, the plasma dissociation degree is reduced to improve radical deposition control. This periodic switching resolves the contradiction by separating the functions of plasma generation and radical deposition control into different time periods.
2Productivity
If high density plasma is generated, then etching speed is improved, but process window for radical deposition control becomes limited
Solution Approach 1:
The patent uses periodic action to alternate between high density plasma periods (for fast etching) and low density plasma periods (for precise radical deposition control). During high density plasma periods, etching speed is maximized. During low density plasma periods, the process window for radical deposition control is expanded. This time-division approach allows both high productivity and broad process window to be achieved sequentially.
Solution Approach 2:
The patent applies dynamics by dynamically adjusting the electric power level between high and low states. The system transitions from a static high power state to a dynamic system that can switch between power levels. This dynamic adjustment allows the plasma density to be optimized for different process requirements, thereby expanding the process window while maintaining high etching speed capability.
3Duration of action of stationary object
If plasma is continuously generated, then etching continuity is improved, but vertical profile control deteriorates
Solution Approach 1:
The patent applies periodic action by introducing intentional interruptions in plasma generation through alternating high and low power periods. The low power periods create intervals where plasma dissociation is reduced, allowing better control over radical deposition and vertical profile formation. Despite these periodic interruptions, the overall etching process maintains continuity through the cumulative effect of multiple cycles, resolving the contradiction between etching continuity and vertical profile 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 enables more precise control over plasma dissociation, allowing for vertical etching with a broader process window, even when the etching surface has differences between isolation and dense patterns, and maintains a stable after-glow state for effective microfabrication.
Implementation Method 1
a power supply for plasma generation that supplies radio frequency electric power for generating the plasma
Implementation Method 2
the pulse wave of the second period supplies radio frequency electric power of second amplitude smaller than the first amplitude capable of maintaining after-glow of the plasma
Implementation Method 3
supplying bias power for entering ion of the after-glow state into the sample while the second radio frequency electric power value is supplied
Data Source
AI summary
The plasma processing apparatus has a plasma processing chamber where plasma processing of the sample is performed, and plasma power supply that supplies radio frequency electric power for generating plasma. The radio frequency electric power is time modulated by a pulse wave having a first period and a second period that are repeated periodically. The pulse wave of the first period has first amplitude and the pulse wave of the second period has second amplitude which is a limited value smaller than the first amplitude. The extinction of the plasma, which is generated during the first period having the first amplitude, is maintained during the second period having the second amplitude with a predetermined dissociation.