Copper Bonding Pad Layout for Oxidation-Resistant Chip Packaging
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Solution Overview
Problem
Current chip packaging technologies face limitations in miniaturization and performance due to inadequate packaging methods, leading to issues with adhesion, oxidation, and process margins, resulting in reduced yield and reliability.
Innovation Solution
A die and chip packaging structure featuring an aluminum bonding pad with a passivation layer and a copper layer that is partially exposed, spaced apart from the passivation layer, which enhances adhesion and prevents oxidation, and a manufacturing method involving laser drilling to form through holes in the plastic encapsulation layer, ensuring the copper layer is protected and maintaining electrical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the copper layer is formed to cover the entire aluminum bonding pad, then the adhesion between copper and passivation layer is improved, but the copper layer may detach due to poor adhesion and the aluminum bonding pad may be exposed to oxidation
Solution Approach 1:
The copper layer is selectively formed only in the central region of the aluminum bonding pad, leaving a spacing around the perimeter. This local quality approach ensures the copper layer has sufficient adhesion in its formed region while the aluminum bonding pad remains protected from oxidation through the passivation layer's first opening. The selective positioning resolves the contradiction by optimizing both adhesion and oxidation protection in different spatial zones.
Solution Approach 2:
The passivation layer serves as an intermediary structure between the copper layer and the aluminum bonding pad. The first opening in the passivation layer allows the copper layer to be formed while maintaining a protective barrier that prevents oxidation of the aluminum bonding pad. This intermediary structure enables both good adhesion and oxidation protection simultaneously.
2Productivity
If laser drilling is used to form through holes in the plastic encapsulation layer, then the manufacturing efficiency is improved, but the aluminum bonding pad may be perforated due to excessive laser energy
Solution Approach 1:
The copper layer is formed in advance before the laser drilling process. This preliminary action creates a protective barrier that prevents the laser from directly contacting and perforating the aluminum bonding pad during the through hole formation process. The copper layer absorbs or deflects the laser energy, allowing efficient drilling while maintaining the integrity of the underlying aluminum structure.
Solution Approach 2:
The copper layer acts as a cushioning layer that absorbs excess laser energy before it can reach the aluminum bonding pad. This beforehand cushioning prevents potential damage from excessive laser energy while still allowing the laser drilling process to efficiently form through holes in the plastic encapsulation layer.
3Reliability
If the copper layer is formed extending to the boundary of the passivation layer, then the electrical conductivity is maximized, but the process margin is reduced and yield decreases
Solution Approach 1:
The spatial parameters of the copper layer are optimized by defining its extent relative to the passivation layer boundary. By setting the copper layer to extend to but not beyond the first opening's boundary, the design achieves optimal electrical conductivity while maintaining sufficient process margin. This parameter optimization resolves the contradiction between maximizing conductivity and maintaining manufacturing yield.
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 solution improves the yield and reliability of chip packaging by preventing copper layer detachment, oxidation, and perforation, thereby enhancing the electrical performance and process margins of the packaging structures.
Implementation Method 1
forming a through hole, in which the copper layer is exposed, in the plastic encapsulation layer by laser drilling
Data Source
AI summary
The present disclosure provides a die, a manufacturing method of the die, a chip packaging structure and a manufacturing method of the chip packing structure. The die includes an aluminum bonding pad, a passivation layer and a copper layer. The aluminum bonding pad and the passivation layer are both on an active surface of the die, and the passivation layer has a first opening in which the aluminum bonding pad is partially exposed. The copper layer is on the aluminum bonding pad and covers a part of the aluminum bonding pad. A boundary of the copper layer is spaced apart from the passivation layer at a boundary of the first opening by a distance. Since the copper layer covers a part of the aluminum bonding pad, and the boundary of the copper layer is spaced apart from the passivation layer by a distance, the copper layer is completely received in the opening in the passivation layer.