Selective Etching of Reflowable Connectors in IC Packages
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Solution Overview
Problem
The semiconductor industry faces challenges in efficiently removing reflowable connectors from die connectors during the packaging process, leading to potential solder residue and reduced reliability of integrated circuit dies, especially when using conventional chemical mechanical planarization (CMP) methods which can be damaging and leave residue.
Innovation Solution
A wet etching process using a solution with an azole compound as a protective agent for die connectors and an oxidized metal ion as an etching agent for reflowable connectors, selectively removing the reflowable connectors while forming a protective layer on the die connectors to minimize etching damage and residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CMP methods are used to remove reflowable connectors, then the reflowable connectors can be removed, but solder residue is left and die connector dimensions are reduced
Solution Approach 1:
The patent applies parameter changes by transitioning from mechanical removal (CMP) to chemical etching with controlled parameters. The etching solution composition, temperature, and etching time are optimized to selectively remove reflowable connectors while preserving die connector dimensions, thereby resolving the contradiction between reliability improvement and manufacturing precision maintenance.
Solution Approach 2:
The patent introduces an intermediary protective layer (such as photoresist or specialized coating) on die connectors before the etching process. This intermediary protects the die connectors from etching damage while allowing selective removal of reflowable connectors, thus maintaining dimensional precision while improving reliability through complete residue removal.
2Reliability
If CMP methods are used to remove reflowable connectors, then the connectors can be removed, but significant etching damage occurs to die connectors
Solution Approach 1:
The patent introduces a protective layer as an intermediary between the etching solution and the die connector. This protective layer selectively shields the die connector from chemical etching damage while allowing the reflowable connector to be removed, thereby improving reliability without compromising connector integrity.
Solution Approach 2:
The patent applies local quality by creating different surface properties or protective treatments on different regions. The die connector regions receive protective treatment while reflowable connector regions remain exposed to etching, enabling selective removal that improves reliability while preserving die connector strength and integrity.
3Productivity
If reflowable connectors are not completely removed, then the packaging process can proceed faster, but solder residue reduces electrical performance
Solution Approach 1:
The patent replaces mechanical removal methods (CMP) with a chemical etching system that provides more complete and cleaner removal of reflowable connectors. This substitution enables thorough residue removal that improves electrical performance while maintaining efficient packaging process throughput.
Solution Approach 2:
The patent optimizes etching parameters (solution composition, temperature, time) to achieve complete removal of reflowable connectors without requiring excessive processing time. This parameter optimization ensures complete residue removal for improved electrical performance while maintaining high packaging productivity.
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 method effectively removes reflowable connectors with minimal reduction in die connector dimensions, reducing solder residue and enhancing the reliability and electrical performance of integrated circuit dies by using a selective etching process that protects the die connectors.
Implementation Method 1
etching the reflowable connector and the die connector with an etching solution
Implementation Method 2
a protective agent for the first conductive material... forming a protective layer on the die connectors
Implementation Method 3
an oxidized metal ion as an etching agent for reflowable connectors
Data Source
AI summary
In an embodiment, a device includes: a semiconductor substrate; a contact pad on the semiconductor substrate; a passivation layer on the contact pad and the semiconductor substrate; a die connector extending through the passivation layer, the die connector being physically and electrically coupled to the contact pad, the die connector including a first conductive material, the first conductive material being a Lewis acid having a first acid hardness/softness index; a dielectric layer on the die connector and the passivation layer; and a protective layer disposed between the dielectric layer and the die connector, the protective layer surrounding the die connector, the protective layer including a coordination complex of the first conductive material and an azole, the azole being a Lewis base having a first ligand hardness/softness index, where a product of the first acid hardness/softness index and the first ligand hardness/softness index is positive.