Contoured Microbump Arrays for High-Density Adhesion Reliability
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high-density electrical connections with reliable adhesion between microbumps and underlying structures, leading to potential delamination issues.
Innovation Solution
The implementation of microbumps with contoured bottom surfaces, including annular surface segments, to increase contact areas with dielectric passivation and capping dielectric layers, enhancing adhesion through strategic lateral offsets and material compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microbumps are used for high-density electrical connections, then connection density is improved, but adhesion reliability deteriorates due to potential delamination
Solution Approach 1:
The microbump bottom surface is formed with a contoured shape including an annular surface segment that curves along the sidewall of the opening. This curved geometry increases the contact area between the microbump and the dielectric passivation layer, thereby improving adhesion reliability while maintaining high connection density
Solution Approach 2:
The adhesion enhancement is achieved by transitioning from a planar contact interface to a three-dimensional contoured interface. The annular surface segment extends along the sidewall dimension, creating additional contact area in the vertical dimension and improving adhesion without increasing the horizontal footprint
2Ease of manufacture
If flat microbump surfaces are used, then manufacturing is simpler, but adhesion strength is insufficient leading to delamination
Solution Approach 1:
The contoured bottom surface with annular surface segment provides enhanced adhesion strength through increased contact area, while the curvature can be achieved through standard deposition and etching processes, maintaining reasonable manufacturing simplicity
3Reliability
If microbumps with increased contact area are formed, then adhesion is improved, but manufacturing complexity increases
Solution Approach 1:
The contoured geometry is formed through a systematic process sequence: depositing dielectric layers with openings, forming metal bump structures, and creating the annular surface segments through controlled deposition and etching. While the process has multiple steps, each step uses standard semiconductor manufacturing techniques
Solution Approach 2:
The microbump structure is divided into distinct functional segments: the annular surface segment for adhesion, the top surface for electrical connection, and the sidewall for structural support. This segmentation allows each portion to be optimized independently while maintaining overall manufacturability
Data Source
AI summary
A semiconductor die may include metal interconnect structures located within interconnect-level dielectric material layers, bonding pads located on a topmost interconnect-level dielectric material layer, a dielectric passivation layer located on the topmost interconnect-level dielectric material layer, and metal bump structures extending through the dielectric passivation layer and located on the bonding pads. Each of the metal bump structures comprises a contoured bottom surface including a bottommost surface segment in contact with a top surface of a respective one of the bonding pads, a tapered surface segment in contact with a tapered sidewall of a respective opening through the dielectric passivation layer, and an annular surface segment that overlies the dielectric passivation layer and having an inner periphery that is laterally offset inward from an outer periphery by a lateral offset distance that is at least 8% of a width of a respective underlying one of the bonding pads.