Plasma Sheath Adjustment for Uniform Etching With Focus Ring Wear
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Solution Overview
Problem
In plasma etching processes, the wear down of focus rings leads to a mismatch in the vertical position of the plasma sheath, causing uneven etching rates between the edge and the center of the substrate, which existing technologies struggle to adjust effectively.
Innovation Solution
A plasma processing apparatus with a sheath adjuster, radio frequency power source, and bias power source that controls the vertical position of the plasma sheath and power levels to synchronize etching rates by varying the potential of the substrate and adjusting the sheath position, ensuring consistent etching across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching is performed using conventional apparatus, then etching process can be completed, but the focus ring wears down causing mismatch in sheath position between edge and center of substrate
Solution Approach 1:
The patent applies dynamics by making the sheath adjuster movable to dynamically compensate for focus ring wear. The sheath adjuster can move in the vertical direction to adjust the position of the sheath above the focus ring, allowing the system to adapt to changing conditions during operation and maintain etching uniformity despite focus ring degradation.
Solution Approach 2:
The patent changes physical parameters by adjusting the position of the sheath in the vertical direction. The sheath adjuster modifies the vertical position parameter to compensate for focus ring wear, thereby maintaining the correct sheath position relative to the substrate edge and ensuring uniform etching rates across the substrate surface.
2Manufacturing precision
If direct current voltage is applied to focus ring to adjust sheath position, then vertical position of sheath can be adjusted, but device complexity increases
Solution Approach 1:
The patent introduces a sheath adjuster as an intermediary component between the focus ring and the plasma sheath. This sheath adjuster serves as a mechanical mediator that physically adjusts the sheath position without requiring direct electrical control of the focus ring, thereby simplifying the overall system architecture while maintaining precision sheath position control.
3Productivity
If focus ring thickness is reduced due to wear, then etching process continues, but sheath position mismatch causes uneven etching rates
Solution Approach 1:
The patent implements feedback control through the sheath adjuster, which continuously monitors and compensates for focus ring wear. By detecting changes in focus ring thickness and adjusting the sheath position accordingly, the system maintains optimal etching conditions throughout the focus ring's service life, ensuring both productivity and etching uniformity.
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 solution effectively reduces the difference in etching rates between the edge and the center of the substrate, maintaining uniformity and efficiency in the plasma etching process even when focus rings wear down.
Implementation Method 1
The radio frequency power source is configured to generate radio frequency power which is supplied to generate a plasma from a gas in the chamber
Implementation Method 2
The substrate is etched by chemical species such as ions and radicals from the plasma
Implementation Method 3
The bias power source is configured to generate bias power. The bias power is set to vary a potential of the substrate placed on the electrostatic chuck within a cycle which is defined at a second frequency
Implementation Method 4
The electrostatic chuck supports a substrate disposed in a region surrounded by the focus ring
Data Source
AI summary
In an apparatus for plasma processing according to an exemplary embodiment, a radio frequency power source generates radio frequency power which is supplied for generation of a plasma. A bias power source supplies bias power to a lower electrode of a substrate support. The bias power varies a potential of a substrate within a cycle thereof. The radio frequency power is supplied in at least a part of a first period in the cycle, in which the potential of the substrate is relatively high. A power level of the radio frequency power is lowered in a second period in the cycle, in which the potential of the substrate is relatively low. In the first period and the second period, the sheath adjuster adjusts a position in a vertical direction of an upper end of a sheath above an edge ring.