Two-Layer Electrostatic Chuck with Focus Ring
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Solution Overview
Problem
Conventional substrate mounting tables in plasma processing apparatuses face issues with plasma-induced wear of adhesive layers and abnormal discharge due to exposure of base portion surfaces, leading to reduced lifespan and increased complexity with additional components and assembly steps.
Innovation Solution
A substrate mounting table design featuring a two-layer electrostatic chuck structure with a larger lower circular part and a focus ring that covers the peripheral portions, hiding gaps and preventing plasma exposure to the base portion and adhesive layer, thereby preventing arcing and wear without increasing component count or assembly steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional substrate mounting table with a single-layer electrostatic chuck is used, then the structure is simple, but the adhesive layer and base portion surface are exposed to plasma causing wear and abnormal discharge
Solution Approach 1:
The electrostatic chuck is divided into two layers: an upper electrostatic chuck layer and a lower electrostatic chuck layer. This segmentation allows the lower layer to extend beyond the upper layer's peripheral surface, creating an overlapping configuration that shields the adhesive layer and base portion from plasma exposure while maintaining structural simplicity
Solution Approach 2:
The solution extends the protection in the radial dimension by having the lower electrostatic chuck layer protrude beyond the upper layer's peripheral surface. This dimensional extension creates an overlapping region that blocks plasma pathways without adding vertical complexity or requiring additional protective components
2Reliability
If a protective coating is added to cover the adhesive layer, then plasma-induced wear and arcing are prevented, but the number of components and assembly steps increases
Solution Approach 1:
The protective function is merged into the electrostatic chuck structure itself by designing the lower layer to extend beyond the upper layer's peripheral surface. This integration eliminates the need for separate protective coatings or additional components, as the two-layer configuration inherently shields the adhesive layer and base portion from plasma exposure
Solution Approach 2:
The electrostatic chuck structure provides its own protection against plasma-induced wear and arcing through the overlapping configuration of its two layers. The lower layer automatically shields the adhesive layer and base portion without requiring external protective measures, making the system self-protecting
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 design effectively prevents plasma-induced wear and arcing on the substrate mounting table, extending its lifespan by shielding the base portion and adhesive layer from plasma exposure, while maintaining assembly efficiency and component simplicity.
Implementation Method 1
A DC voltage is applied to the electrostatic electrode plate while an etching process is performed on the wafer, so that the wafer is attracted and held on the electrostatic chuck by Coulomb force or Johnsen-Rahbek force generated by the DC voltage.
Implementation Method 2
A DC voltage is applied to the electrostatic electrode plate while an etching process is performed on the wafer, so that the wafer is attracted and held on the electrostatic chuck by Coulomb force or Johnsen-Rahbek force generated by the DC voltage.
Implementation Method 3
The substrate processing apparatus generates a plasma in the chamber and performs an etching process on the wafer mounted on the substrate mounting table by the plasma.
Data Source
Figure 1
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Figure 4~5
AI summary
A substrate mounting table of a substrate processing apparatus includes a base portion and a circular plate-shaped electrostatic chuck adhered to an upper surface of the base portion by an adhesive layer. The electrostatic chuck has a circular attracting surface to support a substrate. The substrate mounting table further includes an annular focus ring arranged around the electrostatic chuck to surround the substrate and to cover an outer peripheral portion of the upper surface of the base portion. The electrostatic chuck has a two-layer structure including an upper circular part and a lower circular part having a diameter larger than that of the upper circular part. An outer peripheral portion of the lower circular part and an outer peripheral portion of the adhesive layer adhering the lower circular part to the base portion are covered with the focus ring.