Multi-Segment Wire-Bond Heel Structure to Prevent Cracking
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Solution Overview
Problem
Semiconductor manufacturing faces issues with heel cracks in wire-bonds, which affect electrical performance and device reliability, particularly due to the mechanical weakness of the heel portion and the formation of gaps between the wire and substrate during the bonding process.
Innovation Solution
A multi-segment wire-bond profile is introduced, featuring a heel portion with multiple segments of varying thicknesses and cross-sectional profiles, combined with a multifaceted capillary for wire-bonding machines that applies a continuous force to eliminate gaps and enhance bonding strength, using a capillary with distinct face profiles to shape the wire-bond and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional single-segment wire-bond is used, then the manufacturing process is simple, but the heel portion is mechanically weak and prone to cracking
Solution Approach 1:
The wire-bond heel portion is divided into multiple segments with different cross-sectional profiles. Each segment has a specific thickness profile designed to optimize mechanical strength and stress distribution. This segmentation allows the heel to better withstand bonding forces and reduces the likelihood of cracking while maintaining manufacturability through controlled wire formation processes.
2Ease of manufacture
If a traditional single-segment wire-bond is used, then the manufacturing process is simple, but gaps form between the wire and substrate during bonding
Solution Approach 1:
The multi-segment heel structure creates multiple contact zones between the wire and substrate. Each segment provides a distinct bonding interface, ensuring continuous electrical and mechanical connection. This segmentation prevents gap formation by distributing the bonding force across multiple zones, improving bond reliability without complicating the manufacturing process.
3Reliability
If a multi-segment wire-bond profile is used, then heel crack resistance is improved, but the device complexity increases
Solution Approach 1:
The wire-bond structure implements local quality by applying different cross-sectional profiles to different segments of the heel portion. Each segment has optimized local characteristics (thickness, curvature, contact area) tailored to its specific functional requirements. This localized optimization improves crack resistance while maintaining overall structural simplicity and manufacturability.
Data Source
AI summary
A multifaceted capillary that can be used in a wire-bonding machine to create a multi-segment wire-bond is disclosed. The multifaceted capillary is shaped to apply added pressure and thickness to an outer segment of the multi-segment wire-bond that is closest to the wire loop. The added pressure eliminates a gap under a heel portion of the multi-segment wire-bond and the added thickness increases a mechanical strength of the heel portion. As a result, a pull test of the multi-segment wire-bond may be higher than a single-segment wire-bond and the multi-segment wire-bond may resist cracking, lifting, or breaking.