Cup and Pillar Interconnect Containing Bond Material
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Solution Overview
Problem
Conventional interconnect structures in semiconductor die assemblies face challenges with electrical and thermal conductivity due to solder migration and intermetallic formation, which degrades performance and leads to voids and reduced thermal conductivity.
Innovation Solution
The interconnect structures feature a cup and pillar configuration with a bond material encapsulated within a depression, preventing solder spread and limiting intermetallic formation, enhancing electrical and thermal coupling by controlling the volume of bond material and using materials like copper and nickel for improved conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solder interconnects are used between stacked semiconductor dies, then electrical and thermal conduction is achieved, but solder migration and intermetallic formation occur which degrade conductivity and create voids
Solution Approach 1:
The interconnect structure is segmented into distinct functional zones: a cup portion with a depression that contains the bond material, and a pillar portion that extends to the second substrate. This segmentation prevents solder migration by confining the bond material within the depression, while the pillar provides a controlled path for electrical and thermal conduction without the harmful side effects of conventional solder joints.
Solution Approach 2:
The cup-pillar structure acts as an intermediary between the first and second substrates, replacing conventional solder interconnects. The bond material within the depression serves as a controlled mediator that provides electrical and thermal conduction while preventing the migration and intermetallic formation problems associated with traditional solder joints.
2Reliability
If bond material volume is increased to ensure complete coverage, then electrical and thermal coupling is improved, but intermetallic formation and voids increase
Solution Approach 1:
The depression in the cup portion creates a localized region with controlled bond material volume. This local quality control ensures adequate electrical and thermal coupling between substrates while preventing excessive bond material that would lead to intermetallic formation and voids. The depression confines the bond material to an optimal volume for performance.
3Ease of manufacture
If conventional flat interconnect surfaces are used, then manufacturing is simple, but solder spread causes reliability issues
Solution Approach 1:
The cup portion features a depression with curved surfaces that naturally contain the bond material. This curvature prevents solder spread while maintaining manufacturability through standard deposition and etching processes. The depression geometry provides inherent containment without requiring additional complex manufacturing steps.
Data Source
AI summary
Interconnect structures with improved conductive properties are disclosed herein. In one embodiment, an interconnect structure can include a first conductive member coupled to a first semiconductor die and a second conductive member coupled to second semiconductor die. The first conductive member includes a recessed surface defining a depression. The second conductive member extends at least partially into the depression of the first conductive member. A bond material within the depression can at least partially encapsulate the second conductive member and thereby bond the second conductive member to the first conductive member.