Segmented Electrode Plasma Uniformity Control
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Solution Overview
Problem
Conventional plasma processing apparatuses with capacitive coupling face challenges in achieving high planar uniformity of plasma potential and ion energy distribution, leading to poor etching uniformity and charge-up damage, especially at lower pressures and ion energies.
Innovation Solution
The apparatus features a process chamber with a second electrode comprising conductive segments separated from each other, allowing for the application of a DC voltage to create a uniform electric potential distribution, which in turn ensures uniform ion and electron energy distribution, improving etching uniformity and reducing charge-up damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a lower pressure and lower ion energy are used to improve dimensional accuracy and selectivity, then etching precision is improved, but planar uniformity of plasma potential deteriorates
Solution Approach 1:
The upper electrode is divided into multiple independent conductive segments that can be independently controlled. This segmentation allows different regions of the electrode to be biased at different potentials, enabling compensation for non-uniform plasma distribution and improving planar uniformity while maintaining low pressure and ion energy conditions
Solution Approach 2:
By applying appropriate DC bias voltages to the segmented electrode, the plasma potential is made more uniform across the substrate surface. This creates equipotential regions that ensure consistent ion energy distribution and prevent charge-up damage, thereby improving reliability without sacrificing etching precision
2Device complexity
If conventional single-electrode configuration is used, then device complexity is low, but planar uniformity of plasma potential is poor
Solution Approach 1:
The upper electrode is divided into multiple independent conductive segments that can be independently controlled. This segmentation allows different regions of the electrode to be biased at different potentials, enabling compensation for non-uniform plasma distribution and improving planar uniformity while maintaining low pressure and ion energy conditions
Solution Approach 2:
DC bias voltages are superimposed on the RF voltage applied to the segmented electrode. By independently adjusting the DC bias on each segment, the plasma potential distribution is optimized to improve planar uniformity. This parameter change enables better control over ion energy and plasma density distribution across the substrate
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 planar uniformity of the etching process, reduces charge-up damage such as dielectric breakdown, and maintains the structural simplicity of the apparatus by using existing materials and components.
Implementation Method 1
an RF power is applied to the first electrode to form an RF electric field within a plasma generation region between the first and second electrodes, so as to turn the process gas into plasma by the RF electric field
Implementation Method 2
a DC voltage is applied to at least one of the segments of the second electrode, thereby ensuring a uniform ion and electron energy distribution
Data Source
AI summary
A capacitive coupling plasma processing apparatus includes a process chamber configured to have a vacuum atmosphere, and a process gas supply section configured to supply a process gas into the chamber. In the chamber, a first electrode and a second electrode are disposed opposite each other. The second electrode includes a plurality of conductive segments separated from each other and facing the first electrode. An RF power supply is configured to apply an RF power to the first electrode to form an RF electric field within a plasma generation region between the first and second electrodes, so as to turn the process gas into plasma by the RF electric field. A DC power supply is configured to apply a DC voltage to at least one of the segments of the second electrode.