Self-Aligned Pad Protection in Semiconductor Devices
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Solution Overview
Problem
The existing methods for processing semiconductor devices often result in contamination and corrosion of metal bonding pads during the transition from frontend to backend processing, leading to fluctuations in bonding quality and potential non-stick issues, which can compromise the reliability of the finished semiconductor device.
Innovation Solution
A method involving the formation of a final metal layer, followed by the deposition and structuring of a passivation layer using atomic layer deposition (ALD) to create a self-aligned pad protection, where the passivation layer is formed over the metal layer and structured together with it, ensuring that the passivation layer remains in regions where the metal layer is not removed, thereby protecting the bonding pads from corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the passivation layer is opened by etching using halogens to create open bonding pads, then the metal layer becomes accessible for bonding, but the opened pads become contaminated and corroded during processing
Solution Approach 1:
The patent segments the passivation layer into two distinct regions: a first passivation layer that is opened to expose bonding pads, and a second passivation layer that remains intact to protect the metal layer. This segmentation allows the bonding pads to be accessible for bonding while the protected region prevents corrosion and contamination, resolving the contradiction between accessibility and reliability.
2Ease of operation
If the passivation layer is completely removed to expose bonding pads, then bonding can be performed, but the metal layer becomes vulnerable to corrosion during backend processing
Solution Approach 1:
The patent applies local quality by creating different passivation states in different regions of the device. The first passivation layer is locally removed at bonding pad locations to enable bonding, while the second passivation layer remains in other regions to provide corrosion protection. This localized differentiation resolves the contradiction between needing exposed pads for bonding and needing protection to prevent corrosion.
3Reliability
If a protective layer is added over the metal layer to prevent corrosion, then the metal layer is protected, but the structure complexity increases
Solution Approach 1:
The patent merges the protective function into the existing passivation layer structure by adding a second passivation layer that works in conjunction with the first passivation layer. Rather than introducing a completely separate protective system, the solution integrates protection into the passivation architecture, reducing overall structural complexity while maintaining corrosion resistance.
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 effectively prevents corrosion and contamination of the metal bonding pads, ensuring consistent bonding quality and enhancing the reliability of the semiconductor device by maintaining a protective interface between the metallization layer and the passivation layer, reducing the complexity of the structure and minimizing issues at interfaces.
Implementation Method 1
depositing a passivation layer over the final metal layer by means of atomic layer deposition
Implementation Method 2
at least partially polymerizing the first passivation layer
Data Source
AI summary
According to one embodiment, a method for processing a semiconductor device is provided including forming a final metal layer forming a passivation layer over the final metal layer and structuring the passivation layer and the final metal layer to form a patterned metal layer and a patterned passivation layer, wherein the patterned metal layer includes a pad region covered by the patterned passivation layer.