Copper Surface Roughening for Polymer Adhesion
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Solution Overview
Problem
Structural delamination between adjacent polymer and copper layers in wafer level packaging poses a challenge in semiconductor chip production, affecting the reliability and performance of multilayer polymer/copper architectures.
Innovation Solution
A method involving a substrate processing sequence that includes immersing a substrate in acid-based baths with copper-containing compounds and electric currents to deposit and etch conductive and barrier layers, resulting in a roughened surface that enhances polymer adhesion to copper, specifically using copper sulfate, sulfuric acid, and hydrogen chloride with or without additives in sequential plating and de-plating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wafer level packaging with multilayer polymer/copper architecture is used, then high performance and low cost are achieved, but structural delamination occurs between adjacent polymer and copper layers
Solution Approach 1:
The patent applies preliminary action by performing surface treatment on the copper layer before polymer deposition. The copper surface undergoes electroplating with additives to create a roughened morphology, followed by electroless copper deposition. This preliminary surface modification ensures that when the polymer is subsequently deposited, it adheres strongly to the roughened copper surface, preventing delamination during later processing steps.
Solution Approach 2:
The patent creates a porous or roughened copper surface structure through controlled electroplating with specific additives. The copper surface is intentionally made non-smooth with increased surface area and porosity, which provides mechanical interlocking for the polymer layer. This porous structure allows the polymer to penetrate and anchor into the copper surface features, significantly enhancing adhesion and preventing delamination.
2Reliability
If electroplating with additives is used to roughen copper surface, then polymer adhesion is enhanced, but process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single electroplating step. The electroplating process simultaneously deposits copper material, roughens the surface morphology, and incorporates adhesive promoters through the use of specific additives in the plating solution. This consolidation of surface preparation, material deposition, and adhesion enhancement into one step reduces the number of separate process steps needed, thereby managing process complexity while achieving the desired roughened surface for enhanced polymer adhesion.
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 method effectively reduces structural delamination, improving the adhesion between polymer and copper layers, thereby enhancing the reliability and performance of semiconductor chip packaging, and can be applied to various metals used in semiconductor manufacturing.
Implementation Method 1
providing a first electric current between the conductive seed layer and a first anode disposed in electrical contact with the first bath to deposit a conductive material within the opening
Implementation Method 2
providing a second electric current that is a reverse of the first electric current between the conductive seed layer plus the conductive material and a second anode disposed in electrical contact with the second bath; etching the conductive seed layer from atop a field region of the barrier layer
Data Source
AI summary
A method of processing a semiconductor substrate includes: immersing a substrate in a first bath, wherein the substrate comprises a barrier layer, a conductive seed layer, and a patterned photoresist layer defining an opening; providing a first electric current between the conductive seed layer and a first anode disposed in electrical contact with the first bath to deposit a conductive material within the opening; stripping the patterned photoresist layer; immersing the substrate in a second bath; providing a second electric current that is a reverse of the first electric current between the conductive seed layer plus the conductive material and a second anode disposed in electrical contact with the second bath; etching the conductive seed layer from atop a field region of the barrier layer; and etching the barrier layer from atop a field region of the substrate.