Template Layer Conductive Pillar Formation
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Solution Overview
Problem
Current metal-to-metal bonding methods, such as direct bonding and solder bonding, face challenges in achieving precise and contamination-free formation of conductive pillars, particularly in reducing lateral dimensions and avoiding mechanical damage and contamination during the plating process.
Innovation Solution
The use of a template layer as a plating template allows for the formation of conductive pillars without the need for photo resist, eliminating the requirement for a seed layer and enabling reduced lateral dimensions, improved protection from contamination, and enhanced mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photo resist is used as a plating template to form conductive pillars, then the plating process can be performed, but the lateral dimensions of the conductive pillars cannot be significantly reduced and the process becomes more complex
Solution Approach 1:
The patent removes the photo resist template from the plating process entirely. Instead, a dielectric layer with a patterned opening is used as the template, which is formed through etching processes rather than photo lithography. This extraction of the photo resist step simplifies the overall process and enables reduced lateral dimensions of the conductive pillars.
Solution Approach 2:
The patent introduces a dielectric layer as an intermediary template structure. This dielectric layer with a patterned opening serves as the mediating element that defines the shape and dimensions of the conductive pillar during plating, replacing the traditional photo resist approach and enabling better dimensional control.
2Ease of manufacture
If a seed layer is required for the plating process, then electroplating can be performed, but the process steps increase and mechanical damage risk increases during seed layer removal
Solution Approach 1:
The patent extracts and eliminates the seed layer step from the plating process. By using a dielectric layer with a patterned opening as the template, the conductive material can be directly plated without requiring a separate seed layer, thereby reducing process steps and eliminating the risk of mechanical damage associated with seed layer removal.
Solution Approach 2:
The dielectric layer with its patterned opening serves the dual function of both template and release mechanism. The conductive pillar is formed directly in the opening and can be released cleanly without requiring separate seed layer removal steps, making the process self-sufficient and reducing mechanical intervention.
3Reliability
If traditional bonding methods are used without template protection, then the bonding process can proceed, but the conductive pillars are exposed to contamination and mechanical damage
Solution Approach 1:
The patent uses a thin dielectric layer with a patterned opening as a protective shell during the bonding process. This dielectric structure protects the conductive pillar from contamination and mechanical damage while allowing the bonding process to proceed, integrating protection into the bonding structure itself rather than adding separate protective elements.
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 approach enables the formation of conductive pillars with significantly reduced lateral dimensions, improved protection from contamination and mechanical damage, and simplifies the plating process, enhancing the reliability and precision of metal-to-metal bonding.
Implementation Method 1
A conductive pillar is formed in the second opening
Implementation Method 2
A conductive pillar is formed in the second opening
Implementation Method 3
During the bonding process, the device die and the package substrate are also heated. With the pressure and the elevated temperature, the surface portions of the metal bumps of the device die and the package substrate inter-diffuse, so that bonds are formed.
Implementation Method 4
A pressure is applied to press the device die and the package substrate against each other. With the pressure and the elevated temperature, the surface portions of the metal bumps of the device die and the package substrate inter-diffuse, so that bonds are formed.
Data Source
AI summary
A method includes forming a first dielectric layer over a conductive pad, forming a second dielectric layer over the first dielectric layer, and etching the second dielectric layer to form a first opening, with a top surface of the first dielectric layer exposed to the first opening. A template layer is formed to fill the first opening. A second opening is then formed in the template layer and the first dielectric layer, with a top surface of the conductive pad exposed to the second opening. A conductive pillar is formed in the second opening.