Plasma Processing Apparatus Phase Control for Etching Uniformity
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in achieving uniform etching rates across the wafer due to insufficient voltage difference between inner and outer electrodes, requiring high-rated radio frequency bias power sources and experiencing phase discrepancies.
Innovation Solution
A plasma processing apparatus with a sample stage divided into electrically distinct regions, utilizing separate radio frequency power sources and an inter-electrode circuit to control the phase difference between the power applied to the inner and outer electrodes, allowing for a predetermined voltage difference, thereby improving etching uniformity without needing high-rated power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the outputs of two radio frequency bias power sources are supplied to the inner stage and outer stage of the electrode table with the same phase to create a VPP difference, then a difference in peak-to-peak voltage can be achieved, but a radio frequency bias power source having a large rated output is required
Solution Approach 1:
The patent changes the phase parameter of the radio frequency power supplied to the inner and outer stages. By setting a phase difference (e.g., 180 degrees) between the two stages, the patent creates constructive and destructive interference patterns that produce the desired VPP difference without requiring one power source to have a much larger rated output than the other.
2Reliability
If external phase control is used to make the outputs of two radio frequency bias power sources the same, then phase alignment can be achieved, but differences in phase rotation in each bias power source cause the actually applied radio frequency power to not become the same phase
Solution Approach 1:
Instead of trying to make the phases the same and accepting the inherent differences in phase rotation, the patent inverts the approach by deliberately setting a specific phase difference (such as 180 degrees) between the inner and outer stages. This intentional phase opposition accounts for and compensates for the inherent phase rotation differences in each power source, ensuring consistent and reliable phase relationships in the actually applied power.
3Manufacturing precision
If the inter-electrode circuits causing the voltage difference are insufficient, then circuit complexity is reduced, but it is impossible to make a sufficient difference in VPP between the electrodes
Solution Approach 1:
The patent achieves sufficient VPP difference by changing the phase parameter of the supplied power rather than by adding complex inter-electrode circuits. By controlling the phase difference between the radio frequency power sources for the inner and outer stages, the patent creates the necessary voltage difference through electromagnetic interference effects, thereby achieving the desired precision without increasing circuit complexity.
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 configuration enhances the uniformity of the etching rate from the center to the peripheral regions of the wafer while reducing the cost by using radio frequency bias power sources with smaller rated outputs.
Implementation Method 1
a plasma processing apparatus including a processing chamber in which a sample is subject to plasma processing
Implementation Method 2
an inter-electrode circuit portion that is disposed between a first transmission path for supplying the first radio frequency power to the first region and a second transmission path for supplying the second radio frequency power to the second region
Data Source
AI summary
According to one embodiment, a plasma processing apparatus includes a processing chamber, a sample stage that is disposed inside the processing chamber and electrically divided into a plurality of regions on which a sample is placed, an electromagnetic wave introduction unit that introduces electromagnetic waves into the processing chamber, and a bias power applying unit that applies bias power to the sample stage, in which the bias power applying unit is configured to include a first radio frequency power applying unit that applies first radio frequency power to a first region out of the plurality of electrically divided regions of the sample stage, a second radio frequency power applying unit that applies second radio frequency power to a second region out of the plurality of electrically divided regions of the sample stage, and a phase adjuster that controls the first radio frequency power applying unit and the second radio frequency power applying unit to shift the phases of the first radio frequency power and the second radio frequency power by a predetermined amount.