Conductive Bump Mold with Vacuum Adsorption and Groove Cavity
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Solution Overview
Problem
Conventional methods for forming conductive bumps in semiconductor devices, such as solder ball placement, electroplating, and stencil printing, face limitations in manufacturing speed, material limitations, and quality control, especially as wafer size and integration density increase, and are prone to damage during the process.
Innovation Solution
A mold comprising a first substrate with grooves and a second substrate with through-holes, along with a mask layer, is used to form conductive bumps, allowing for precise formation and repeated use without damage, enabling the use of various materials and overcoming material limitations of traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solder ball placement method is used, then uniformity of bump heights is improved, but manufacturing speed deteriorates and distance between bumps must be wide
Solution Approach 1:
The patent replaces the mechanical solder ball placement system with a chemical/electrochemical system using electroplating to form bumps. This substitution enables continuous processing without the speed limitations of mechanical placement, while maintaining height uniformity through controlled electrochemical deposition.
Solution Approach 2:
The patent uses a mold with cavity patterns to replicate bump structures across the wafer surface. The mold copies the desired bump geometry and arrangement, enabling high-speed formation of uniformly spaced bumps without mechanical placement limitations.
2Productivity
If electroplating method or evaporation method is used, then manufacturing speed is improved, but material variety is limited
Solution Approach 1:
The patent introduces a mold as an intermediary that decouples the formation process from material limitations. The mold cavity structure enables precise bump formation while the material selection is freed from process constraints, allowing use of various materials including organic compounds, metals, and alloys.
3Ease of manufacture
If stencil printing method is used, then facility cost is reduced, but bump quality deteriorates with increased integration density
Solution Approach 1:
The patent uses a precision mold that copies bump patterns at high density. The mold cavity array enables replication of fine-pitch bump structures with high fidelity, achieving the precision needed for high integration density that stencil printing cannot provide.
4Adaptability or versatility
If intermediate formation processes are used, then bump formation flexibility is improved, but substrate durability deteriorates due to damage and wear
Solution Approach 1:
The patent performs preliminary formation of bump structures within protected mold cavities before transfer to the wafer. This preliminary action within the mold protects the substrate from damage during subsequent handling and transfer operations, improving durability while maintaining formation flexibility.
Solution Approach 2:
The patent replaces mechanical substrate handling and cleaning processes with a mold-based formation system. Bumps are formed within the mold cavities and transferred as integrated structures, eliminating mechanical stress and cleaning-related damage to the substrate.
Data Source
AI summary
A mold for forming a conductive bump, a method of fabricating the mold, and a method of forming a bump on a wafer using the mold are provided. The bump can be formed by employing various materials, the mold can be repeatedly used several times because the mold is not damaged, and due to a high precision, the pitch of the bumps is not limited. The mold for forming a conductive bump comprises a first substrate having a groove to form a bump; a second substrate for vacuum adsorption formed below the first substrate, and having a through-hole in communication with the groove; and a mask layer formed on the first substrate, and used to form the groove.