Rotatable Multi-Layer Focus Ring for Plasma Edge Uniformity
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Solution Overview
Problem
Plasma non-uniformity during semiconductor processing leads to defects in integrated circuit dies, particularly at the edge of the substrate, due to structural differences and electromagnetic field variations between the center and edge, resulting in reduced yield.
Innovation Solution
A multi-layer focus ring with adjustable height, achieved through rotational movement of its layers, is used to encircle the substrate, allowing for controlled plasma sheath and electromagnetic field uniformity by adjusting the height of the focus ring to mitigate plasma non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-layer focus ring is used, then the device complexity is low, but plasma uniformity across the substrate deteriorates due to edge effects and electromagnetic field variations
Solution Approach 1:
The focus ring is divided into multiple independent layers (first ring layer and second ring layer) that can rotate relative to each other. This segmentation allows each layer to be optimized for specific functions: the first layer provides structural support while the second layer controls plasma uniformity through rotational adjustment, thereby improving plasma uniformity without excessive complexity
Solution Approach 2:
The second ring layer is made rotatable relative to the first ring layer, introducing dynamic adjustability to the focus ring structure. This rotational movement enables real-time optimization of plasma uniformity across the substrate by adjusting the relative position of the layers, transforming a static structure into a dynamically可调 system that adapts to processing requirements
2Adaptability or versatility
If the focus ring height is fixed, then the device complexity is low, but adaptability to different processing conditions deteriorates
Solution Approach 1:
The focus ring incorporates a dynamic height adjustment mechanism where the second ring layer can rotate relative to the first ring layer. This rotation changes the effective height of the focus ring, enabling adaptation to different processing conditions such as varying plasma power, pressure, or substrate materials without requiring complete redesign of the focus ring
Solution Approach 2:
The invention changes the height parameter of the focus ring through rotational movement of the second layer. By adjusting the relative rotation angle between layers, the effective height is varied continuously, allowing optimization of plasma uniformity and ion bombardment angles for different processing scenarios without mechanical height adjustment mechanisms
3Manufacturing precision
If plasma processing is performed without height adjustment, then the productivity is high, but manufacturing precision deteriorates due to plasma non-uniformity at substrate edges
Solution Approach 1:
The rotatable second ring layer provides rapid height adjustment capability that can be implemented during or between processing cycles. This dynamic adjustment allows quick optimization of plasma uniformity without significantly extending processing time, thereby improving edge-to-center uniformity while maintaining acceptable productivity levels
Solution Approach 2:
The focus ring height can be pre-adjusted before substrate processing begins, optimizing plasma uniformity in advance. This preliminary adjustment ensures that when processing starts, the optimal configuration is already in place, minimizing the time penalty for achieving uniform plasma distribution across the substrate
Data Source
AI summary
The present disclosure relates to plasma semiconductor processes and related components and tools. In one embodiment, a focus ring includes first and second ring layers. An upper surface of the second ring layer is configured to support the first ring layer by a lower surface of the first ring layer contacting the upper surface. The lower and upper surfaces are periodic circumferentially and have a same period length. At least one of the lower and upper surfaces includes a first protrusion radial line (PRL), a second PRL, and a recess radial line (RRL) disposed between the first and second PRLs. The period length is from the first PRL to the second PRL. The lower and/or upper surface from the first PRL to the RRL is continuous and from the RRL to the second PRL is continuous. The second ring layer is rotatably movable relative to the first ring layer.