Dielectric Window with Tapered Recess for Plasma Symmetry
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Solution Overview
Problem
Conventional plasma processing apparatuses with flat dielectric windows fail to achieve a wide range of process margin and high axial symmetry of plasma, leading to non-uniform processing on semiconductor substrates, requiring frequent changes in slot antenna plates and increasing costs.
Innovation Solution
A dielectric window with a ring-shaped recess tapered inwardly and multiple second recesses arranged symmetrically around the center, allowing for continuous thickness variation and mode locking, enhancing plasma stability and symmetry across varying processing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat dielectric window is used, then the structure is simple and manufacturing is easy, but the process margin is narrow and plasma axial symmetry is poor
Solution Approach 1:
The dielectric window has different thicknesses in different regions: a first thickness in the center region and a second thickness (different from the first) in the peripheral region. This local variation in thickness allows different parts of the window to serve different functions, improving plasma axial symmetry and process margin while maintaining overall structural simplicity
Solution Approach 2:
The invention transitions from a flat, two-dimensional dielectric window to a three-dimensional structure with varying thickness. By introducing thickness variation as an additional dimensional parameter, the window can control microwave propagation and plasma generation more effectively, achieving better axial symmetry and wider process margin
2Ease of manufacture
If a flat dielectric window is used, then manufacturing is easy, but processing uniformity is poor
Solution Approach 1:
The dielectric window has different thicknesses in different regions: a first thickness in the center region and a second thickness (different from the first) in the peripheral region. This local variation in thickness allows different parts of the window to serve different functions, improving plasma axial symmetry and process margin while maintaining overall structural simplicity
Solution Approach 2:
The invention transitions from a flat, two-dimensional dielectric window to a three-dimensional structure with varying thickness. By introducing thickness variation as an additional dimensional parameter, the window can control microwave propagation and plasma generation more effectively, achieving better axial symmetry and wider process margin
3Adaptability or versatility
If slot antenna plates are changed frequently to adapt to different processing conditions, then processing adaptability is improved, but operation complexity and cost increase
Solution Approach 1:
The dielectric window with its specific thickness configuration (first thickness in center, second thickness in periphery) can maintain stable plasma generation and good axial symmetry across a wide range of processing conditions. This multi-functional capability allows a single window design to handle various etching processes without requiring frequent changes to slot antenna plates
Solution Approach 2:
The invention changes the physical parameter of the dielectric window (thickness distribution) to achieve adaptability. By having different thicknesses in different regions, the window can adjust microwave propagation characteristics to maintain stable plasma generation under varying processing conditions, reducing the need for frequent component changes
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 dielectric window configuration provides a wide process margin and high axial symmetry of plasma, improving processing uniformity and reducing the need for frequent slot antenna plate changes, while maintaining cost-effectiveness.
Implementation Method 1
a dielectric window for use in a plasma processing apparatus, having a substantially circular plate shape and allowing passage of microwave
Implementation Method 2
a recess is formed on a surface of the ceiling plate (dielectric window) at the side where plasma is generated. The recess resonantly absorbs the microwave at side surfaces thereof and allows the microwave to propagate therein in a single mode
Implementation Method 3
a plasma processing apparatus using microwave as a plasma source
Data Source
AI summary
In a dielectric window 41 for a plasma processing apparatus, a first dielectric window recess 47 is formed on an outer region of a surface of the dielectric window 41 in a diametrical direction of the dielectric window 41 at a side where plasma is generated, and the first dielectric window recess 47 is extended in a ring shape and has a tapered shape inwardly in a thickness direction of the dielectric window 41. A multiple number of second dielectric window recesses 53a to 53g are formed between the center of the dielectric window 41 and the first dielectric window recess 47, and each of the second dielectric window recesses 53a to 53g is recessed inwardly in the thickness direction of the dielectric window 41 from the surface of the dielectric window 41.