Variable-Thickness Conductive Traces for RDL Crosstalk Shielding
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Solution Overview
Problem
Conventional semiconductor packaging technologies face challenges in reducing crosstalk between conductive lines and enhancing signal integrity, particularly in wafer level packaging where redistribution layers are used to increase the number of input/output pads.
Innovation Solution
The implementation of conductive lines with varying thicknesses, where thicker lines act as electromagnetic shields for thinner lines, reducing crosstalk and improving signal integrity by forming a shielding effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional uniform thickness conductive lines are used in redistribution layers, then manufacturing is simpler, but crosstalk between adjacent lines increases and signal integrity deteriorates
Solution Approach 1:
The patent applies local quality by varying the thickness of conductive lines based on their specific function and position. Thicker lines are used for power/ground connections requiring higher current capacity and shielding, while thinner lines are used for signal lines where crosstalk reduction is critical. This localized differentiation optimizes both signal integrity and manufacturing feasibility.
Solution Approach 2:
The patent changes the physical parameter of conductive line thickness to resolve the contradiction. By adjusting the thickness parameter of different conductive lines according to their functional requirements, the patent achieves reduced crosstalk and improved signal integrity while maintaining manufacturing practicality through controlled parameter variation.
2Reliability
If thicker conductive lines are used throughout, then electromagnetic shielding and signal integrity improve, but material usage and manufacturing cost increase
Solution Approach 1:
The patent applies local quality by providing electromagnetic shielding only where needed through selective placement of thicker conductive lines. Power and ground lines are made thicker to provide shielding for adjacent signal lines, while signal lines themselves use optimized thinner dimensions. This localized approach achieves necessary electromagnetic shielding without excessive material consumption.
Solution Approach 2:
The patent changes the thickness parameter of conductive lines based on functional requirements. By optimizing the thickness parameter for each line type (thicker for power/ground shielding, thinner for signals), the patent achieves effective electromagnetic shielding while minimizing conductive material usage and associated manufacturing costs.
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 effectively reduces near-end and far-end crosstalk by up to 3.2 dB and 7.7 dB, respectively, thereby enhancing signal integrity in semiconductor devices.
Implementation Method 1
thicker lines act as electromagnetic shields for thinner lines, reducing crosstalk and improving signal integrity by forming a shielding effect
Data Source
AI summary
A method includes forming a dielectric layer over a contact pad of a device, forming a first polymer layer over the dielectric layer, forming a first conductive line and a first portion of a second conductive line over the first polymer layer, patterning a photoresist to form an opening over the first portion of the second conductive feature, wherein after patterning the photoresist the first conductive line remains covered by photoresist, forming a second portion of the second conductive line in the opening, wherein the second portion of the second conductive line physically contacts the first portion of the second conductive line, and forming a second polymer layer extending completely over the first conductive line and the second portion of the second conductive line.