Electrostatic Chuck Through-Hole Layout to Prevent Dielectric Breakdown
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Solution Overview
Problem
Existing electrostatic chucks face challenges in preventing dielectric breakdown during the holding of semiconductor wafers, particularly due to the proximity of plasma to the support structure, which can lead to short-circuits and reduced thermal conductivity.
Innovation Solution
The electrostatic chuck design incorporates a ceramic substrate with through-holes and a porous member, where the second through-hole has a larger diameter opening than the first, and the electrodes are positioned to maintain a clearance, reducing the likelihood of plasma reaching the support and minimizing dielectric breakdown. Additionally, a sleeve and recess structures are used to further prevent plasma discharge and enhance thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the support structure is placed close to the plasma during electrostatic chuck operation, then structural support and thermal conduction are improved, but dielectric breakdown and short-circuits occur
Solution Approach 1:
The patent introduces an intermediary structure (insulating layer or plasma shield) between the support and the plasma environment. This intermediary element protects the support from direct plasma exposure, preventing dielectric breakdown while maintaining the support's structural and thermal functions. The intermediary acts as a barrier that blocks harmful plasma particles and energy from reaching the support structure.
2Productivity
If the through-hole diameter is increased to improve plasma exhaust, then plasma removal efficiency is improved, but the risk of plasma reaching the support and causing short-circuits increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform through-hole structure with varying diameters along its length. The hole has a smaller diameter at the plasma-facing end and a larger diameter at the exhaust end. This gradual expansion allows efficient plasma exhaust while maintaining a narrow opening that limits direct plasma contact with the support, thus preventing short-circuits.
Solution Approach 2:
The through-hole structure exhibits asymmetry in its diameter distribution. Rather than a uniform cylindrical hole, the design features an asymmetric profile where the opening at the plasma interface is smaller than the opening at the exhaust side. This asymmetric geometry optimizes both plasma removal efficiency and electrical insulation by controlling plasma flow paths.
3Force
If the electrode is positioned closer to the substrate surface to improve electrostatic attraction, then holding force is improved, but the risk of dielectric breakdown increases
Solution Approach 1:
The patent modifies the physical parameters of the system by introducing intermediate layers or adjusting the geometry of the electrode and substrate interface. These parameter changes increase the effective insulation distance or alter the electric field distribution, allowing the electrode to maintain strong electrostatic attraction while operating at safer voltage levels that reduce dielectric breakdown risk.
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 reduces dielectric breakdown and maintains efficient heat transfer by keeping plasma away from the support, ensuring stable electrostatic attraction and uniform thermal conductivity during semiconductor processing.
Implementation Method 1
an electrode for electrostatic attraction located inside the substrate
Implementation Method 2
a porous member located in the second through-hole and fixed to the second main surface
Data Source
AI summary
An insulating substrate has a sample holding surface. A support is bonded to the insulating substrate. A first through-hole in the insulating substrate and a second through-hole in the support are continuous with each other to serve as a gas inlet. A porous member is located in the second through-hole. The second through-hole has, at its opening adjacent to the insulating substrate (opening adjacent to the substrate), a larger diameter than the first through-hole. The opening of the second through-hole and an electrostatic attraction electrode are at different positions in a direction parallel to the sample holding surface. The electrostatic attraction electrode and the second through-hole avoid overlapping each other as viewed from above.