Dielectric Member Recesses for Plasma Etching Uniformity
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Solution Overview
Problem
Existing plasma etching apparatuses face challenges in generating uniform, vigorous plasma over a wide area while maintaining a low-cost, high-durability chamber-sealed structure using a high-withstand-pressure dielectric member, and they struggle with deposition prevention of reaction products, leading to decreased plasma density and uniformity.
Innovation Solution
A plasma etching apparatus with a high-withstand-pressure dielectric member featuring independent recess portions and large-thickness portions, combined with a second electrode for capacitive coupling, reduces radio frequency induction magnetic field loss and enhances applied power efficiency, allowing for uniform plasma generation and deposition prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metallic beam or frame body is used to support the dielectric, then enough pressure strength can be secured, but the structure becomes complex and metal contaminations occur
Solution Approach 1:
The invention extracts and eliminates the metallic beam or frame body from the structure. The dielectric member is designed to support itself without external metallic support structures, thereby removing the source of metal contaminations and simplifying the overall structure while maintaining pressure strength through optimized dielectric geometry.
Solution Approach 2:
The invention replaces expensive and complex metallic support structures with a simpler dielectric member design. The dielectric member, while potentially having limited lifetime due to plasma exposure, eliminates the need for separate metallic support components, reducing overall system complexity and potential contamination sources.
2Loss of energy
If the dielectric thickness is reduced to reduce dielectric loss, then electrical efficiency improves, but pressure strength decreases
Solution Approach 1:
The dielectric member is segmented into multiple functional regions: thinner regions (first thickness) positioned near the coil for reduced dielectric loss and enhanced RF field transmission, and thicker regions (second thickness) positioned at support points for maintaining pressure strength. This segmentation allows simultaneous optimization of electrical efficiency and mechanical strength.
Solution Approach 2:
Different thicknesses of the dielectric member are applied locally to different functional requirements: thinner sections where RF field transmission is critical and thicker sections where structural support is critical. This local quality variation optimizes both electrical performance and mechanical strength without compromise.
3Quantity of substance
If a recess portion is formed in the dielectric to enhance radio frequency wave directivity, then plasma density improves, but mechanical strength decreases
Solution Approach 1:
The dielectric member is segmented into recess portions (with first thickness) and large-thickness portions (with second thickness). The recess portions enhance RF wave directivity and plasma density, while the surrounding large-thickness portions provide the necessary mechanical strength and pressure resistance, compensating for the material removed in the recess areas.
Solution Approach 2:
The dielectric member features asymmetric thickness distribution with recess portions strategically positioned to optimize RF field distribution and plasma generation, while maintaining asymmetric thicker regions for structural integrity. This asymmetric design allows functional optimization without compromising overall strength.
4Productivity
If reaction products are deposited on the dielectric member, then plasma generation continues, but plasma density and uniformity decrease
Solution Approach 1:
The second electrode, positioned between the dielectric member and the object to be treated, serves a dual function: it maintains the plasma generation process while simultaneously preventing reaction product deposition on the dielectric member through capacitive coupling. This self-service mechanism keeps the dielectric surface clean, maintaining plasma density and uniformity throughout continuous processing.
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
The solution enables efficient, uniform, and vigorous plasma generation over a wide area with reduced maintenance needs and improved durability, while preventing deposition of reaction products, thus enhancing processing speed and cost-effectiveness.
Implementation Method 1
a first electrode which is placed so as to face an upper opening of the chamber and to which AC power is applied to transform a reactant gas within the chamber into a plasma by inductive coupling
Implementation Method 2
loss of the radio frequency induction magnetic field or inductive coupling power corresponding to the distribution density from the first electrode can be reduced by an extent of thickness difference
Implementation Method 3
a second electrode which is placed between the first electrode and the dielectric member and in which radio frequency transmission portions are formed... allowing for uniform plasma generation and deposition prevention
Data Source
AI summary
A plasma etching apparatus includes a pressure-reducible chamber 1, a placement section 3 for supporting an object to be treated within the chamber 1, a dielectric member 5 for sealing an upper opening of the chamber 1, and a coil 4 provided outside the dielectric member 5. The coil 4 generates a plasma 6 in the chamber 1 by inductive coupling so that the object 2 is subjected to etching. The dielectric member 5 has recess portions 5c discontinuous to one another. Portions of the dielectric member 5 form large-thickness portions 5b. A thickness of the dielectric member 5 in the recess portions 5c is smaller than a thickness of the large-thickness portions 5b. The recess portions 5c are placed according to distribution densities of conductors constituting the coil 4.