Movable Centering Members for Substrate Alignment
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Solution Overview
Problem
Current methods for centering semiconductor substrates in process chambers, such as those used in CVD or PECVD, face challenges in achieving accurate and cost-effective placement, particularly with shrinking device dimensions requiring narrower edge exclusion areas and more precise substrate alignment.
Innovation Solution
An apparatus and method utilizing movable centering members positioned along the periphery of a substrate support, which include weighted end portions to bias the centering fingers into contact with the substrate edge, allowing for radial displacement to center the substrate relative to a reference axis, and can be disengaged to prevent deposition at the edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shadow ring is used to achieve thickness uniformity with a 3.5 mm-wide edge exclusion area, then deposition uniformity is improved, but the device complexity increases and the substrate placement precision requirement becomes more stringent
Solution Approach 1:
The patent extracts the centering function from the shadow ring mechanism, separating it into independent movable centering members. This allows the shadow ring to focus solely on deposition control while the centering members handle substrate positioning, reducing overall system complexity and improving manufacturability
Solution Approach 2:
The shadow ring mechanism is segmented into multiple independent movable centering members that can be individually adjusted. This segmentation allows for simpler manufacturing of each component while achieving the same centering effect, reducing device complexity overall
2Productivity
If the edge exclusion area is reduced from 3.5 mm to 2 mm to meet shrinking device dimensions, then productivity is improved by utilizing more substrate area, but the substrate placement precision requirement increases significantly
Solution Approach 1:
The movable centering members are designed to automatically self-adjust and center the substrate through mechanical interaction without requiring high-precision manual placement. The substrate itself serves to trigger the centering action as it is placed on the support, reducing the precision requirement for initial placement while maintaining narrow edge exclusion
Solution Approach 2:
The centering members are made movable and adjustable rather than fixed, allowing the system to adapt to slight variations in substrate placement. This dynamic adjustment capability enables the use of narrower edge exclusion areas (2 mm) while compensating for placement variations, thereby improving substrate utilization efficiency
3Manufacturing precision
If movable centering members are introduced to center the substrate accurately, then substrate placement precision is improved, but the device complexity increases
Solution Approach 1:
The centering members are designed with movable joints and degrees of freedom that allow automatic adaptation to substrate position variations. This dynamic design achieves high centering accuracy without requiring complex control systems or multiple actuators, thereby limiting the increase in device complexity
Solution Approach 2:
The movable centering members serve multiple functions: they center the substrate, support the substrate weight, and can be retracted to avoid interference during deposition. This multi-functionality reduces the need for separate mechanisms, limiting the overall device complexity increase while achieving accurate centering
Data Source
AI summary
The present invention comprises an apparatus and method for centering a substrate in a process chamber. In one embodiment, the apparatus comprises a substrate support having a support surface adapted to receive the placement of a substrate and a reference axis substantially perpendicular to the support surface, and a plurality of centering members extending above the support surface. Each centering member is biased into a first position and is movable to a second position by interacting with an opposing member. A movement between the first position and the second position thereby causes each centering member to releasably engage with a peripheral edge of the substrate to push the substrate in a direction toward the reference axis.