SiC Wafer Backside Auxiliary Structure for Thinning Stability
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Solution Overview
Problem
The challenge lies in manufacturing semiconductor devices with thinner silicon carbide wafers, as they are brittle and prone to mechanical damage during handling, while existing methods for reducing wafer thickness complicate handling and increase costs due to the need for auxiliary carriers and complex dicing processes.
Innovation Solution
A method involving a silicon carbide substrate with a front side metallization and a backside metallization, where an auxiliary structure with laterally separated metal portions is used to stabilize the substrate during processing, allowing for thinner wafer thickness without compromising mechanical stability or increasing dicing complexity, and a metal disc is structurally connected to the backside metallization for additional stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of silicon carbide wafer is reduced to improve device characteristics, then on-state resistance decreases, but mechanical stability deteriorates and the wafer becomes prone to damage during handling
Solution Approach 1:
A metal auxiliary structure is introduced as an intermediary element between the thin silicon carbide wafer and the handling system. This auxiliary structure provides mechanical support during processing and handling, enabling the wafer to be handled safely despite its reduced thickness. The auxiliary structure can be attached to the wafer背面 and provides the necessary rigidity without affecting the electrical performance of the thinned wafer.
2Ease of manufacture
If wafer split methods are used to reduce wafer thickness, then cost is reduced, but handling complexity increases and mechanical stability is compromised
Solution Approach 1:
The support function is segmented from the wafer itself - instead of relying on the wafer's own structural integrity, a separate auxiliary structure is provided that can be attached to and removed from the wafer. This segmentation allows the thinning process to proceed independently while the support function is handled separately by the auxiliary structure, simplifying each individual process step.
3Strength
If auxiliary carriers are used to improve mechanical stability of thin wafers, then handling stability improves, but dicing complexity increases
Solution Approach 1:
Instead of providing uniform support across the entire wafer surface, the auxiliary structure provides localized support at specific regions where it is most needed during handling and dicing. The metal auxiliary structure can be configured to provide support at the wafer edges or at specific device regions, optimizing the support-to-complexity ratio by providing support only where mechanically necessary.
Data Source
AI summary
According to an embodiment of a method described herein, a silicon carbide substrate is provided that includes a plurality of device regions. A front side metallization may be provided at a front side of the silicon carbide substrate. The method may further comprise providing an auxiliary structure at a backside of the silicon carbide substrate. The auxiliary structure includes a plurality of laterally separated metal portions. Each metal portion is in contact with one device region of the plurality of device regions.