Semiconductor Underfill Cure Gradient for Chip Stack Alignment
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Solution Overview
Problem
The excessive lateral extension of underfill in semiconductor packages causes various problems during high integration of semiconductor chips, leading to inefficiencies and potential issues.
Innovation Solution
A semiconductor package design with a first underfill having a first portion adjacent to the center region and a second portion adjacent to the edge region, where the second portion has a higher degree of cure than the first, and inner connection terminals extending into the underfill, controlled through a laser bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the underfill is applied between multiple semiconductor chips for high integration, then the mounting capacity and integration level are improved, but the underfill protrudes outside the chips and causes excessive lateral extension leading to various problems
Solution Approach 1:
The underfill is designed with different degrees of cure in different regions: a first degree of cure in the lateral extension region and a second degree of cure in the center region, where the first degree is higher than the second degree. This local quality differentiation allows the underfill to have different properties in different areas, preventing excessive lateral extension while maintaining proper bonding in the center region.
Solution Approach 2:
The patent changes the physical and chemical parameters of the underfill by controlling the degree of cure through selective heating. By applying heat to specific regions (lateral extension region vs center region), the underfill's curing state is modified locally, changing its flowability and bonding characteristics to achieve the desired effect of preventing lateral extension while maintaining integration capability.
2Ease of manufacture
If the underfill protrudes outside the semiconductor chips, then the chips can be mounted, but the lateral extension causes various problems that need to be controlled
Solution Approach 1:
Different regions of the underfill are given different degrees of cure: the lateral extension region receives a higher degree of cure to control protrusion, while the center region maintains a lower degree of cure for proper bonding. This local differentiation enables precise control over underfill behavior during and after chip mounting.
Solution Approach 2:
The underfill is pre-heated or pre-cured in the lateral extension region before final chip mounting to prevent excessive protrusion during the mounting process. This preliminary action counteracts the potential harmful effect of lateral extension before it occurs, ensuring manufacturing precision while maintaining ease of chip mounting.
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 design effectively prevents excessive lateral extension of the underfill, ensuring precise alignment and minimizing distance between stacked semiconductor chips, thereby enhancing the integrity and efficiency of the semiconductor package.
Implementation Method 1
The preliminary underfill is cured using a laser bonding process, thereby forming a first underfill
Implementation Method 2
The plurality of inner connection terminals reflows during the formation of the first underfill through the curing of the preliminary underfill
Data Source
AI summary
A semiconductor package includes a first semiconductor chip on a lower structure. A first underfill is between the first semiconductor chip and the lower structure. The first underfill includes a first portion adjacent to a center region of the first semiconductor chip, and a second portion adjacent to an edge region of the first semiconductor chip. The second portion has a higher degree of cure than the first portion. A plurality of inner connection terminals is between the first semiconductor chip and the lower structure. The plurality of inner connection terminals extends in the first underfill.