Semiconductor Structure with OSP and UBM Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional flip chip packages using Ni/Au protection layers for inductors result in increased resistance and reduced quality factor due to the skin effect, necessitating a solution that enhances the Q factor without degrading the inductor's performance.
Innovation Solution
A semiconductor structure incorporating an organic solderability preservative (OSP) film and an under bump metallurgy (UBM) layer that wraps the passive device, preventing the skin effect and allowing for a thicker, more robust passive device with reduced resistance and increased quality factor, while avoiding contact with the passivation layer to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ni/Au protection layer is used for the inductor, then the inductor is protected from oxidation, but the skin effect increases resistance and degrades the quality factor
Solution Approach 1:
The patent removes the Ni/Au protection layer from the inductor surface and replaces it with an OSP film applied only to the passive device portions. This extraction eliminates the source of the skin effect while maintaining oxidation protection where needed.
Solution Approach 2:
The patent applies different protection strategies to different areas: the OSP film is applied only to portions of the passive device that require protection, while leaving the inductor windings exposed to avoid the skin effect. This localized approach optimizes both protection and electrical performance.
2Reliability
If thick Ni/Au protection layer is applied to the inductor surface, then oxidation protection is enhanced, but the quality factor and resistance performance deteriorate due to skin effect
Solution Approach 1:
The patent extracts the protection layer from the inductor windings entirely, applying it only to the passive device portions. This eliminates the harmful skin effect on the inductor while maintaining protection where structurally necessary.
Solution Approach 2:
The patent changes the material parameter from metallic Ni/Au layers to an organic OSP film, and controls the thickness parameter by applying the OSP film only to specific portions rather than as a uniform thick layer across the entire inductor surface.
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 OSP film and UBM layer combination effectively prevent the skin effect, enabling passive devices like inductors to achieve higher quality factors and reduced resistance without the need for additional metal layers, allowing for thicker designs and improved mechanical strength.
Implementation Method 1
the Ni/Au protection layer will cause the skin effect in the inductor
Data Source
AI summary
The invention provides a semiconductor structure. The semiconductor structure includes a substrate. A first passivation layer is disposed on the substrate. A conductive pad is disposed on the first passivation layer. A second passivation layer is disposed on the first passivation layer. A conductive structure is disposed on the conductive pad, and a passive device is also disposed on the conductive pad, wherein the passive device has a first portion located above the second passivation layer and a second portion passing through the second passivation layer. A solderability preservative film covers the first portion of the passive device, and an under bump metallurgy (UBM) layer covers the second portion of the passive device and a portion of the conductive structure.