Electrostatic Chuck Layout for Leakage Suppression at Wafer Edges
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Solution Overview
Problem
Existing electrostatic chuck devices face challenges in reducing leakage current and achieving uniform plasma distribution during high-temperature plasma processing, particularly near the edges of substrates, due to the limitations of previous designs that focus on resistance and electrode geometry.
Innovation Solution
The introduction of a high-resistance ring-shaped portion with increased volume resistivity, made from materials like aluminum nitride, surrounding the substrate attachment area to suppress leakage current and improve plasma uniformity by enhancing the resistance against the substrate contact area, combined with a larger diameter ESC electrode and optional RF electrode configurations for plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an attraction electrode with smaller diameter than the wafer and an auxiliary electrode are used to reduce leakage current, then leakage current is reduced, but plasma uniformity deteriorates especially near the edge of the wafer
Solution Approach 1:
The patent applies local quality by creating a high-resistance ring-shaped portion with different resistance properties than the main stage body. This localized high-resistance region specifically addresses leakage current at the periphery while leaving the central substrate attachment area unaffected, thus reducing leakage current without compromising plasma uniformity over the entire wafer surface.
Solution Approach 2:
The stage is segmented into two distinct resistance regions: a high-resistance ring-shaped portion at the periphery and a lower-resistance central region for substrate attachment. This segmentation allows independent optimization of leakage current suppression at the edges while maintaining proper plasma distribution across the wafer surface.
2Reliability
If the distance from the stage surface to the attraction electrode and to the auxiliary electrode are made different, then leakage current is reduced, but manufacturing precision deteriorates due to deformation during sintering
Solution Approach 1:
Instead of using multiple electrodes at different distances, the patent uses a single attraction electrode combined with a high-resistance ring-shaped portion. This approach achieves leakage current reduction through local resistance modification rather than complex multi-electrode geometry, significantly simplifying manufacturing and improving positioning accuracy.
3Reliability
If the stage resistance is increased to reduce leakage current, then leakage current is reduced, but electrostatic attraction force deteriorates
Solution Approach 1:
The patent applies local quality by creating a high-resistance ring-shaped portion at the periphery while keeping the central substrate attachment area with lower resistance. This localized approach suppresses leakage current at the edges where it occurs, while maintaining sufficient conductivity in the center to preserve strong electrostatic attraction force for substrate holding.
Solution Approach 2:
The stage is segmented into high-resistance and low-resistance regions, allowing the high-resistance portion to suppress leakage current while the low-resistance central region maintains proper electrostatic attraction for substrate chucking.
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 effectively reduces leakage current and enhances plasma uniformity near the substrate edges, maintaining strong electrostatic attraction and stable processing conditions by increasing the resistance of the ring-shaped portion and optimizing the ESC electrode diameter and RF electrode placement.
Implementation Method 1
The substrate to be processed is electrostatically attached to the substrate attached area of the stage by the Johnsen-Rahbek force by applying a DC voltage to the ESC electrode
Implementation Method 2
the stage includes a high-resistance ring-shaped portion in an outer portion arranged outside the substrate attached area in plan view, which is configured to suppress current leaking from the outer portion to the plasma space when the DC voltage is applied
Data Source
AI summary
An electrostatic chuck device of the present disclosure includes a stage having on its upper surface a circular substrate attached area (where DS is the diameter of the area) to which a circular substrate to be processed is electrostatically attached; and an ESC electrode embedded in the stage, having a diameter DE1 larger than the diameter DS of the substrate attached area, and arranged concentrically with the center of the substrate attached area in plan view; wherein the substrate to be processed is electrostatically attached to the upper surface of the stage by the Johnsen-Rahbek force by applying a DC voltage to the ESC electrode, and the stage includes a high-resistance ring-shaped portion in an outer portion arranged outside the substrate attached area in plan view, which is configured to suppress current leaking from the outer portion to the plasma space when the DC voltage is applied.