Void-Free Electroplated Redistribution Layer for Semiconductor Packages
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Solution Overview
Problem
Existing electroplating processes for forming redistribution layers (RDLs) in integrated fan-out packages are inadequate due to defects such as voids, which degrade the mechanical and electrical reliability of RDLs.
Innovation Solution
An electroplating process using an additive-free plating solution and a specialized electroplating apparatus that ensures a void-free plated conductive layer with larger copper crystal grains and reduced impurity concentration, formed by immersing the seed material in a copper sulfate-based solution without organic additives, and using a carbon filter to maintain solution cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing electroplating processes are used to form redistribution layers, then the plating can be performed with standard equipment and procedures, but voids and defects are formed in the RDLs which degrade mechanical and electrical reliability
Solution Approach 1:
The patent applies parameter changes by modifying the electroplating process conditions, specifically using a pulsed current regime with specific duty cycles and frequencies, adjusting plating solution composition and temperature, and controlling plating speed to optimize crystal grain growth and eliminate void formation, thereby improving both reliability and manufacturing precision
Solution Approach 2:
The patent implements periodic action through the use of pulsed electroplating current with specific on/off duty cycles and frequency ranges, which creates periodic deposition patterns that promote uniform crystal grain growth and prevent void formation, directly addressing the contradiction between reliability and manufacturing precision
2Manufacturing precision
If electroplating is performed to form conductive layers, then copper crystal grains can be deposited on the seed material, but impurities are incorporated into the plated layer reducing its quality
Solution Approach 1:
The patent uses parameter changes by optimizing plating solution composition (specific copper concentration, pH levels, temperature ranges), current density, and plating speed to control impurity incorporation during copper crystal grain formation, achieving high manufacturing precision while maintaining plated layer quality and reliability
Solution Approach 2:
The patent implements feedback mechanisms through real-time monitoring of plating solution conditions, current parameters, and deposition rate, with automatic adjustments to maintain optimal crystallization conditions and minimize impurity incorporation, ensuring both manufacturing precision and long-term reliability
3Ease of manufacture
If conventional plating solutions with organic additives are used, then plating can proceed with standard chemistry, but the plating bath degrades over time requiring frequent replacement
Solution Approach 1:
The patent applies parameter changes by eliminating organic additives from the plating solution and using pure copper sulfate electrolyte with controlled pH and temperature, which simplifies the chemistry while extending plating bath life, and uses pulsed current parameters to maintain deposit quality without requiring traditional organic brighteners or levelers
Solution Approach 2:
The patent extracts and removes organic additives from the conventional plating solution, using only inorganic copper sulfate electrolyte, which eliminates the source of bath degradation while maintaining effective copper deposition through optimized electroplating parameters, thereby extending plating bath longevity while preserving ease of manufacture
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 solution results in a redistribution layer with improved mechanical strength, reduced impurity concentration, and enhanced electrical performance, minimizing voids and defects, thereby increasing the reliability and longevity of the plating bath.
Implementation Method 1
formation of a plated conductive layer in an electroplating process
Implementation Method 2
using a carbon filter to maintain solution cleanliness
Implementation Method 3
An electrochemical reaction is performed on the plating solution to form a redistribution circuitry on the work piece
Data Source
AI summary
A semiconductor package, a redistribution structure and a method for forming the same are provided. The redistribution structure for coupling an encapsulated die is provided, the redistribution structure includes a conductive pattern disposed over and electrically coupled to the encapsulated die. The conductive pattern extends beyond an edge of the encapsulated die along a first extending direction which intersects a second extending direction of the edge of the encapsulated die by an angle in a top view, and an impurity concentration of sulfur in the conductive pattern is less than about 0.1 ppm.