3D Semiconductor Package with Silicon Interposer for Warpage Control
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Solution Overview
Problem
In semiconductor packaging, thermal stress caused by CTE mismatch between semiconductor chips and substrates leads to cracking of conductive bumps and warpage, limiting miniaturization and increasing fabrication costs due to the need for larger substrate areas and longer fabrication times.
Innovation Solution
A semiconductor package using a silicon interposer with through-silicon vias and a Redistribution Layer (RDL) structure, allowing for 3D stacking of semiconductor elements and reducing substrate area requirements, while maintaining chip reliability and preventing warpage by matching CTE with the chip and using encapsulants to connect elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a plurality of chips are disposed on a packaging substrate in a 2D manner to increase circuit density, then the number of chips increases, but the area of the packaging substrate must be increased
Solution Approach 1:
The patent transitions from 2D planar arrangement to 3D vertical stacking by introducing an interposer layer. Multiple semiconductor chips are stacked vertically on the interposer, enabling increased chip quantity without increasing substrate area. The interposer provides through-silicon vias that enable electrical connections between stacked chips and the substrate.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers: packaging substrate, interposer (with through-silicon vias), and multiple semiconductor chips. This composite architecture enables high-density integration by combining different functional layers vertically, allowing more chips to be integrated within a compact footprint.
2Quantity of substance
If conventional flip-chip packaging is used to achieve high integration, then circuit density increases, but conductive bumps crack easily under thermal stresses from CTE mismatch
Solution Approach 1:
The interposer serves as a thermal expansion buffer between the semiconductor chip and the packaging substrate. By selecting an interposer material with appropriate CTE properties, the patent reduces the CTE mismatch stress transmitted to the conductive bumps, preventing cracking while maintaining high circuit density.
3Quantity of substance
If CTE mismatch between chips and packaging substrates increases to achieve higher integration, then circuit density increases, but thermal stresses induce more serious warpages
Solution Approach 1:
The interposer acts as a stress buffer that decouples the thermal expansion mismatch between the chip and substrate. The interposer's material properties and structure are designed to absorb and distribute thermal stresses, preventing warpage while enabling higher circuit density through vertical stacking.
Data Source
AI summary
A fabrication method of a semiconductor package is disclosed, which includes the steps of: disposing a plurality of first semiconductor elements on an interposer; forming a first encapsulant on the interposer for encapsulating the first semiconductor elements; disposing a plurality of second semiconductor elements on the first semiconductor elements; forming a second encapsulant on the first semiconductor elements and the first encapsulant for encapsulating the second semiconductor elements; and thinning the interposer, thereby reducing the overall stack thickness and preventing warpage of the interposer.