Connector Site Spacing to Prevent Passivation Cracks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The stresses between different materials in semiconductor die packaging, such as underbump metallization, passivation layers, and contact pads, can cause cracks during manufacturing or usage, leading to damage or destruction of the semiconductor device.
Innovation Solution
The solution involves controlling the spacing and dimensions of the contact pad, passivation layer openings, and underbump metallization to reduce stress, specifically by maintaining a certain relationship between the diameters and distances of these components, such as keeping the third distance greater than 10 μm and the fifth distance greater than 5 μm, to minimize crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different materials (underbump metallization, passivation layer, contact pad) are stacked to form external connections, then electrical and physical connections are achieved, but stresses cause cracks to form in the passivation layer
Solution Approach 1:
The patent applies parameter changes by optimizing the dimensions and spacing relationships between the contact pad, passivation layer opening, and underbump metallization. Specifically, it defines that the contact pad diameter should be greater than the opening diameter by a first distance of about 10 μm, and the opening diameter should be greater than the underbump metallization diameter by a second distance of about 5 μm. These parameter adjustments reduce stress concentration and prevent crack formation in the passivation layer while maintaining reliable electrical connections.
2Area of stationary object
If the contact pad and underbump metallization are closely spaced to reduce device size, then area is reduced, but stress increases causing cracks
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter relationships: the contact pad diameter exceeds the opening diameter by about 10 μm, and the opening diameter exceeds the underbump metallization diameter by about 5 μm. These controlled dimensional parameters allow compact device design while maintaining sufficient spacing to reduce stress concentration and preserve passivation layer strength.
Solution Approach 2:
The patent addresses the area-strength contradiction by transitioning from a two-dimensional close-spaced layout to a three-dimensional hierarchical structure with controlled vertical spacing. The layered arrangement with specific diameter relationships creates stress relief zones that prevent cracks while maintaining compact footprint.
3Productivity
If the passivation layer is made thinner to reduce processing time, then manufacturing speed increases, but crack resistance decreases
Solution Approach 1:
The patent compensates for reduced passivation layer thickness by optimizing the horizontal spacing parameters. The contact pad diameter is greater than the opening by about 10 μm, and the opening is greater than the underbump metallization by about 5 μm. These parameter adjustments create stress distribution patterns that enhance crack resistance even in thinner passivation layers, maintaining reliability while enabling faster processing.
Data Source
AI summary
A system and method for preventing cracks in a passivation layer is provided. In an embodiment a contact pad has a first diameter and an opening through the passivation layer has a second diameter, wherein the first diameter is greater than the second diameter by a first distance of about 10 μm. In another embodiment, an underbump metallization is formed through the opening, and the underbump metallization has a third diameter that is greater than the first diameter by a second distance of about 5 μm. In yet another embodiment, a sum of the first distance and the second distance is greater than about 15 μm. In another embodiment the underbump metallization has a first dimension that is less than a dimension of the contact pad and a second dimension that is greater than a dimension of the contact pad.