Under-Bump Metallization Adhesion via Laser-Roughened Trench
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Solution Overview
Problem
Semiconductor device packaging faces challenges in accommodating sophisticated features and applications while maintaining reliability and minimizing performance and cost impacts, particularly due to susceptibility to stress-induced delamination in under-bump metallization structures.
Innovation Solution
A semiconductor device with an under-bump metallization (UBM) structure is developed, where a non-conductive layer is formed over a semiconductor die, an opening is created to expose a bond pad, and a laser-ablated trench with a roughened bottom surface is formed near the perimeter of the opening, allowing for superior adhesion of the UBM structure through low-energy laser processing and subsequent copper plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UBM structures are used, then manufacturing is simpler, but stress-induced delamination occurs reducing reliability
Solution Approach 1:
The patent applies preliminary action by forming a roughened surface on the UBM structure before final assembly. The low-energy laser processing creates surface roughness in advance, which then provides enhanced adhesion sites for subsequent bonding operations, preventing stress-induced delamination during device operation.
Solution Approach 2:
The patent changes the surface parameter of the UBM structure by using low-energy laser processing to transform a smooth surface into a roughened surface. This parameter change increases the surface area and creates micro-structures that enhance mechanical interlocking and adhesion, thereby improving reliability without requiring fundamentally different materials or structures.
2Reliability
If low-energy laser processing is used to roughen the trench, then adhesion is improved, but processing time increases
Solution Approach 1:
The patent applies partial action by using low-energy laser processing that removes only enough material to create the necessary surface roughness for adhesion, rather than completely removing or heavily processing the surface. This partial action achieves the minimum required effect (sufficient roughness for adhesion) while minimizing processing time and energy consumption.
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
This approach minimizes stress-induced delamination, enhancing the overall reliability of the semiconductor device by improving adhesion and reducing potential failures in the UBM structure.
Implementation Method 1
a laser ablated trench is formed at the surface of the non-conductive layer near a perimeter of the opening. By using a low energy laser to form the trench, a bottom surface of the trench is roughened
Implementation Method 2
The UBM structure is formed by plating over the trench and exposed pad region
Data Source
AI summary
A method of manufacturing a semiconductor device is provided. The method includes forming a non-conductive layer over an active side of a semiconductor die partially encapsulated with an encapsulant. An opening in the non-conductive layer is formed exposing a portion of a bond pad of the semiconductor die. A laser ablated trench is formed at a surface of the non-conductive layer proximate to a perimeter of the opening. A bottom surface of the laser ablated trench is substantially roughened. An under-bump metallization (UBM) structure is formed over the bond pad and laser ablated trench.