Flip-Chip Bump Barrier Openings to Prevent Solder Bridging
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Solution Overview
Problem
During the flip-chip soldering process, package substrates can deform, leading to flatness differences and compression in semiconductor chip structures, resulting in solder overflow and bridging between bumps due to the lack of effective control over solder flow.
Innovation Solution
A semiconductor structure and manufacturing method that include a semiconductor substrate, a metal pad, a bump, and a metal barrier layer with a storage cavity and openings on its sidewalls, where the solder layer is placed within the cavity, allowing controlled diversion of solder overflow through the openings to prevent bridging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the package substrate is heated during the flip-chip soldering process, then the soldering process can be completed, but the package substrate deforms causing flatness differences and compression in the semiconductor chip structure
Solution Approach 1:
The patent segments the soldering process into two distinct stages: a first soldering process that completes the electrical connection, and a second soldering process that addresses flatness issues. This segmentation allows each process to be optimized independently, resolving the contradiction between completing the soldering and maintaining substrate flatness.
Solution Approach 2:
The patent applies preliminary action by performing the first soldering process before the substrate deformation becomes problematic, and then applying a compression layer in advance before the second soldering process to pre-compensate for the expected substrate deformation and compression during heating.
2Stress or pressure
If compression occurs in the semiconductor chip structure due to substrate deformation, then the substrate can accommodate thermal stress, but solder overflow and bridging between bumps occurs
Solution Approach 1:
The patent changes the physical state and properties of the solder material by introducing a phase change layer containing phase change particles. These particles undergo phase change at specific temperatures during the soldering process, altering the solder's viscosity and flow characteristics to prevent overflow and bridging while still accommodating thermal stress.
Solution Approach 2:
The phase change layer acts as an intermediary between the compressed solder and the substrate. It mediates the interaction by controlling solder flow through phase change, preventing direct contact and potential bridging between adjacent bumps while still allowing the structure to accommodate thermal stress.
3Ease of manufacture
If traditional soldering methods are used without compression control, then the process is simple, but solder bridging between bumps occurs reducing yield
Solution Approach 1:
The patent embeds the phase change layer within the solder structure itself, creating a nested configuration where the phase change particles are contained within the solder material. This nested design adds functionality for preventing bridging without requiring separate external control systems, maintaining ease of manufacture while improving yield.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The controlled diversion of solder through the openings in the metal barrier layer mitigates solder bridging between bumps, improving yield and reducing convexity caused by substrate warping during heating, enabling more precise and reliable interconnection.
Implementation Method 1
a phase change layer comprising phase change particles, wherein the phase change particles undergo phase change at specific temperature so as to adjust the viscosity of the solder material
Implementation Method 2
During the flip-chip soldering process, the package substrate can be deformed when it is heated
Data Source
AI summary
A semiconductor structure and a manufacturing method thereof are disclosed. The semiconductor structure includes a semiconductor substrate, a metal pad, a bump, a metal barrier layer, and a solder layer. The metal pad is arranged on the semiconductor substrate; the bump is arranged on the metal pad; the metal barrier layer is arranged on the side of the bump away from the metal pad; the metal barrier layer contains a storage cavity; the sidewall of the metal barrier layer is configured with an opening connecting to the storage cavity; the solder layer is arranged inside the storage cavity, and the top side of the solder layer protrudes from the upper side of storage cavity. During the flip-chip soldering process, solder is heated to overflow, the opening allows the solder flow out through the opening. The openings achieve good solder diversion in overflow, thus mitigating the problem of solder bridging between bumps.