Wafer Placement Table Electrode Layout for Plasma and Attraction Balance
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Solution Overview
Problem
The efficiency of plasma generation in wafer placement tables is reduced due to increased thickness of the dielectric layer, which decreases capacitance and obstructs the attraction of wafers and focus rings, leading to suboptimal plasma generation.
Innovation Solution
The focus-ring-side radio-frequency bias electrode is positioned at the same height as the focus ring attraction electrode, and the wafer-side radio-frequency bias electrode is positioned at the same height as the wafer attraction electrode, reducing the distance and increasing capacitance, thereby enhancing plasma generation efficiency without obstructing the attraction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bias electrode is disposed below the attraction electrode, then the attraction of the target (wafer or focus ring) is ensured, but the thickness of the dielectric layer increases and the capacitance reduces, leading to reduced plasma generation efficiency
Solution Approach 1:
The patent transitions from a vertical stacking arrangement (bias electrode below attraction electrode) to a lateral arrangement where both electrodes are embedded at the same height in the ceramic substrate. This dimensional change allows the bias electrode to be positioned adjacent to rather than beneath the attraction electrode, reducing the dielectric layer thickness while maintaining attraction functionality.
Solution Approach 2:
The patent changes the spatial parameters of electrode positioning by embedding both the attraction electrode and bias electrode at the same depth in the ceramic substrate. This parameter modification reduces the effective dielectric layer thickness from a multi-layer vertical stack to a single-layer configuration, thereby increasing capacitance and plasma generation efficiency.
2Ease of operation
If the dielectric layer thickness is increased to ensure proper electrode arrangement, then the attraction electrode can be properly positioned, but the capacitance between the bias electrode and placement surface reduces
Solution Approach 1:
The patent employs a lateral positioning strategy where the bias electrode is placed adjacent to the attraction electrode at the same depth, rather than stacking it vertically below. This dimensional reconfiguration reduces the dielectric layer thickness while maintaining proper electrode arrangement, thereby achieving both ease of operation and manufacturing precision.
3Productivity
If the bias electrode is positioned closer to the placement surface, then the capacitance and plasma generation efficiency increase, but the attraction of the target may be obstructed
Solution Approach 1:
The patent applies local quality by assigning different functional zones to different electrodes at the same depth level. The attraction electrode maintains its electrostatic attraction function while the bias electrode, positioned adjacent to it, provides the radio frequency bias for plasma generation. This localized functional separation allows both attraction and high-efficiency plasma generation to coexist.
Solution Approach 2:
By positioning both electrodes at the same depth and arranging them laterally adjacent to each other rather than vertically stacked, the patent enables the bias electrode to be closer to the placement surface without interfering with the attraction electrode's function. This spatial reconfiguration resolves the contradiction between plasma generation efficiency and target attraction.
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 increases plasma generation efficiency above both the wafer and focus ring surfaces without compromising their attraction, ensuring balanced attraction and plasma generation.
Implementation Method 1
A wafer placed on the wafer placement surface is electrostatically attracted to the wafer placement surface when a direct-current voltage is applied to a wafer attraction electrode embedded in the central portion of the ceramic substrate
Implementation Method 2
a source radio frequency power source that generates a source radio frequency for producing plasma above the wafer or above the focus ring
Implementation Method 3
a wafer-side bias electrode that is a radio frequency electrode for pulling ions into the wafer, and a focus-ring-side bias electrode that is a radio frequency electrode for pulling ions into the focus ring
Data Source
AI summary
The wafer placement table includes a ceramic plate and a conductive substrate. The ceramic plate includes a plate annular portion at an outer circumference of a plate central portion having a wafer placement surface. The plate annular portion has an annular focus ring placement surface. The conductive substrate is provided on a lower surface of the ceramic plate and used as a radio-frequency source electrode. At the same height from the focus ring placement surface in the plate annular portion, a focus ring attraction electrode and a focus-ring-side radio-frequency bias electrode to which a bias radio frequency is supplied are embedded.