Pillar-Type Microbump Formation via Slanted Passivation Openings
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Solution Overview
Problem
In semiconductor packaging, particularly for high-performance applications, pillar-type microbumps with small pitches face issues due to undesirable topographies from underlying structures, leading to yield loss and reliability degradation.
Innovation Solution
The method involves forming pillar-type microbumps by creating a plurality of small, slanted openings in a passivation layer over a metallization layer, allowing for the deposition of a metal contact pad and subsequent microbump formation, which increases shear strength and minimizes topography transfer to the microbump surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the pitch and dimensions of microbumps are decreased to increase the number of I/O, then the number of microbumps increases, but undesirable topographies on the microbump surfaces worsen due to underlying structure topographies
Solution Approach 1:
The contact opening is divided into multiple smaller openings arranged in an array. This segmentation allows the microbump to contact the metallization layer through multiple small contact points rather than a single large opening, distributing the stress and preventing topography transfer to the microbump surface while maintaining electrical connection.
Solution Approach 2:
The openings are configured with specific local characteristics including slanted sidewalls at angles between 50°-85°, specific diameter ratios, and arranged in regular patterns. These localized geometric features ensure that the microbump forms a flat upper surface while maintaining strong adhesion to the underlying metallization layer through the slanted opening walls.
2Length of moving object
If the microbump diameter is reduced to achieve smaller pitches, then the pitch decreases, but the bump adhesion and underlying structures introduce undesirable topographies
Solution Approach 1:
The openings are designed with slanted sidewalls forming a curved or tapered profile rather than vertical walls. This curvature allows the microbump material to conform to the opening shape during formation, creating enhanced adhesion through the slanted walls while the top portion of the microbump maintains a flat upper surface free from topography transfer.
Solution Approach 2:
The array of small openings is formed in the passivation layer before the microbump deposition process. This preliminary structuring of the contact interface ensures that when the microbump is subsequently formed, it automatically conforms to the pre-defined opening geometry, achieving both strong adhesion through the slanted walls and a flat upper surface.
3Ease of manufacture
If conventional single opening contact structures are used, then the process is simple, but topography from contact openings is transferred to microbump surfaces causing yield loss
Solution Approach 1:
The single contact opening is segmented into multiple smaller openings arranged in a regular array pattern. This segmentation can be achieved through standard lithography and etching processes by defining the opening pattern before deposition, maintaining process simplicity while dramatically improving yield by preventing topography transfer to the microbump upper surface.
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 production of microbumps with improved shear strength and flat surfaces, reducing yield loss and reliability issues associated with small pitch microbump packaging.
Implementation Method 1
a metal contact layer is conformally deposited on the passivation layer and in the openings
Implementation Method 2
a metal contact layer is conformally deposited on the passivation layer and in the openings
Implementation Method 3
the microbump is formed by electroplating
Data Source
AI summary
The disclosed technology relates to pillar-type microbumps formed on a semiconductor component, such as an integrated circuit chip or an interposer substrate, and a method of forming the pillar-type microbumps. In one aspect, a method of forming the pillar-type microbump on a semiconductor component includes providing the semiconductor component, where the semiconductor component has an upper metallization layer, and the metallization layer has a contact area. The method additionally includes forming a passivation layer over the metallization layer. The method additionally includes forming a plurality of openings through the passivation layer such that the contact area is exposed at a bottom of the openings. The method further includes forming the microbump over the contact area, where the microbump forms an electrical connection with the contact area through the openings.