Electrostatic Chuck Protrusion Structure for Uniform Plasma
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Solution Overview
Problem
Existing electrostatic chucks face issues with plasma uniformity and wafer degradation due to the degradation of the joining layer exposed to plasma, leading to non-uniform etching processes and potential scattering of wafer edges.
Innovation Solution
The electrostatic chuck design includes a dielectric substrate with a protrusion section and an RF electrode within the substrate, ensuring plasma uniformity by sandwiching the entire space above the substrate between a pair of electrodes, including the RF electrode, and reducing the influence of the joining layer on the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the outer circumferential edge of the dielectric substrate protrudes outward beyond the joined surface of the base plate, then the joining layer is protected from plasma exposure and wafer degradation is reduced, but plasma uniformity deteriorates due to the absence of RF electrode coverage in the protrusion region
Solution Approach 1:
The RF electrode is extended into the protrusion section of the dielectric substrate, adding electrode coverage in the previously uncovered dimensional space. This ensures that the space above the protrusion section is also sandwiched between electrode pairs, maintaining plasma uniformity while preserving the protective protrusion structure
Solution Approach 2:
The RF electrode and the protrusion section are integrated such that the RF electrode is provided within the protrusion section. This merging allows the electrode to extend into the protruding region, ensuring continuous plasma generation coverage across the entire dielectric substrate surface including the protrusion area
2Strength
If a cured silicone adhesive is used as a joining layer to join the dielectric substrate and base plate, then the components are securely joined, but the joining layer degrades through plasma exposure and scatters, adversely affecting the wafer
Solution Approach 1:
The harmful joining layer is extracted or removed from the plasma exposure zone by designing the dielectric substrate with an outer circumferential edge that protrudes beyond the joined surface. This physical extraction prevents the joining layer from being exposed to plasma, eliminating the source of degradation and scattering while maintaining the joining function
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 maintains plasma uniformity and reduces wafer degradation by minimizing the impact of the joining layer, enhancing process uniformity and temperature control on the wafer.
Implementation Method 1
When a voltage is applied to the attraction electrode, an electrostatic force is generated, and the wafer placed on the dielectric substrate is attracted and held
Implementation Method 2
a part of the RF electrode is provided in the protrusion section. Since a part of the RF electrode is provided in the protrusion section, almost the whole of a space immediately above the dielectric substrate (including a space immediately above the protrusion section) is sandwiched between a pair of electrodes including the RF electrode. Accordingly, plasma uniformity on an upper side of the dielectric substrate can be ensured
Data Source
AI summary
An electrostatic chuck includes a dielectric substrate, an RF electrode provided inside the dielectric substrate, and a base plate made of metal and joined to the dielectric substrate. The dielectric substrate includes a protrusion section protruding outward beyond a surface of the base plate in top view, and a part of the RF electrode is provided in the protrusion section.