Substrate Carrier Composite Design for Stress Reduction
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Solution Overview
Problem
Existing substrate carriers, such as silicon wafer carriers, tend to break during processing, cleaning, or refurbishment due to stress, while silicon carbide carriers are heavier and can damage substrate supports or break under stress from pocket formation.
Innovation Solution
A substrate carrier with a substantially planar body and a plurality of holding elements arranged on its surface, which can be formed from materials like silicon, silicon carbide, or molybdenum, and may include a two-layer configuration with holes and protrusions to reduce stress and prevent substrate movement, and pockets with support surfaces or tabs to securely hold substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon wafer carriers are used, then substrates can be carried, but the carriers tend to break during processing, cleaning, and refurbishment due to stress
Solution Approach 1:
The substrate carrier uses a composite structure combining silicon carbide layer and molybdenum layer. The silicon carbide provides high strength and stress resistance, while the molybdenum layer reduces overall weight. This composite material approach resolves the contradiction between durability and strength by leveraging the complementary properties of both materials.
Solution Approach 2:
The carrier is divided into functional layers: a silicon carbide layer for structural strength and stress resistance, and a molybdenum layer for weight reduction. The pockets are also segmented into rounded-bottom pockets for substrate support and flat-bottom pockets for specific substrate types, allowing each segment to optimize its function without compromising overall integrity.
2Strength
If silicon carbide wafer carriers are used, then carrier strength is improved, but the carriers are heavier and can damage substrate supports
Solution Approach 1:
The dual-layer composite structure combines heavy silicon carbide (for strength) with lighter molybdenum (for weight reduction). The molybdenum layer specifically addresses the weight issue while the silicon carbide layer maintains the necessary strength, resolving the contradiction between these two properties.
Solution Approach 2:
The silicon carbide material is applied locally where maximum strength is needed (in the structural framework and pocket regions), while the molybdenum material is used in areas where weight reduction is prioritized. This localized material distribution optimizes the strength-to-weight ratio throughout the carrier structure.
3Ease of operation
If pockets are formed in the carrier, then substrates can be held, but stresses in the carrier result from the pocket formation causing breakage
Solution Approach 1:
The pockets are designed with specific geometric characteristics: rounded bottoms for general substrates and flat bottoms for specific types. The pocket walls are optimized for thickness and curvature radius to distribute stresses evenly. This localized geometric optimization allows effective substrate holding while minimizing stress concentration that would cause breakage.
Solution Approach 2:
The pocket geometry parameters (curvature radius, wall thickness, bottom shape) are specifically optimized to reduce stress during formation and use. The rounded-bottom design with controlled curvature radius distributes mechanical stresses more evenly compared to sharp-cornered pockets, preventing crack initiation and propagation.
4Reliability
If holding elements are arranged on the surface with at least three elements around each substrate position, then substrate holding security is improved, but device complexity increases
Solution Approach 1:
The holding function is segmented into multiple discrete holding elements distributed around each substrate position. Each holding element independently contributes to substrate retention, and the minimum of three elements per position provides redundant security. This segmentation approach achieves reliable substrate holding through simple, repeatable geometric patterns rather than complex mechanisms.
Data Source
AI summary
Embodiments of substrate carriers and method of making the same are provided herein. In some embodiments, a substrate carrier includes a substantially planar body formed of an upper layer stacked on a lower layer; and a plurality of pockets formed in the substantially planar body each of which includes a support surface surrounding the pocket for supporting a substrate.