Bond Pad Trench for Aluminum Splash Containment
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Solution Overview
Problem
During the wire bonding process in semiconductor devices, the deformation of aluminum bond pads leads to conductive splashes that can cause passivation cracking, resulting in reliability failures due to the lack of effective containment mechanisms for the splashes.
Innovation Solution
Forming trenches in the passivation layer underlying the bond pads, which are sized and positioned to capture at least a portion of the conductive splash that occurs during the attachment of wire bonds, thereby reducing passivation cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum bond pads are used for wire bonding, then electrical connectivity is achieved, but aluminum splash causes passivation cracking reducing reliability
Solution Approach 1:
The patent converts the harmful aluminum splash into a beneficial feature by designing a trench structure that captures and contains the splash material. The trench transforms the harmful splashing action into a controlled containment mechanism, where the splash material fills the trench and creates an integrated structure that prevents passivation cracking while maintaining electrical connectivity
Solution Approach 2:
The bond pad structure is segmented into distinct regions: a flat bonding area for wire attachment and a trench region for splash containment. This segmentation separates the bonding function from the splash management function, allowing each region to optimize its specific purpose without interfering with the other
2Reliability
If passivation layer is placed between bond pads, then electrical isolation is achieved, but passivation cracking occurs due to aluminum splash
Solution Approach 1:
The trench structure serves as a pre-positioned cushioning mechanism that absorbs and contains the aluminum splash before it can reach and crack the passivation layer. By placing the trench between the bond pad and passivation, the system creates a buffer zone that protects the passivation from the harmful effects of splash material
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 trenches effectively contain a significant portion of the conductive splash, reducing passivation cracking and enhancing the reliability and yield of semiconductor devices by providing a controlled area for splash containment.
Implementation Method 1
the aluminum pad deforms resulting in an aluminum splash which extends from under the ball bond
Data Source
AI summary
A conductive structure is formed in a last metal layer of an integrated circuit. Passivation material is patterned over a portion of the conductive structure. A first trench is patterned around a selected portion of the passivation material. The selected portion represents a bond region of a wire bond to be formed above the passivation material. A portion of the passivation material completely covers a bottom of the trench. A layer of conductive material is conformally deposited over the passivation material. The conformal depositing resulting in a second trench forming in the conductive material over the first trench in the passivation material. The second trench is positioned to contain at least a portion of a splash of the conductive material when the wire bond is subsequently formed.