Through-Electrode Void Design for Thermal Expansion Management
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Solution Overview
Problem
Conventional semiconductor device manufacturing techniques using conformal plating for through-electrodes often result in voids within the metal embedded in through-holes, leading to potential damage during heating processes and electromigration issues due to the use of copper, which has low resistance to electromigration.
Innovation Solution
A semiconductor device design that incorporates a metal portion made of materials like nickel, gold, or tungsten within the through-hole, closer to the hole core, with a void to absorb thermal expansion forces and improve resistance to electromigration, thereby preventing substrate damage and enhancing conduction characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conformal plating is used to deposit metal in through-holes, then the embedding time is reduced, but voids are formed inside the metal due to electric field concentration at the opening end portion
Solution Approach 1:
The through-hole embedding is divided into two distinct stages: first, bottom-up plating is performed to deposit metal from the closed bottom toward the opening, ensuring void-free deposition; second, conformal plating is applied to complete the embedding. This segmentation allows each plating method to be used in its optimal condition, avoiding void formation while maintaining efficiency
Solution Approach 2:
The bottom-up plating is performed as a preliminary action before conformal plating. This preliminary deposition creates a foundation layer that prevents void formation, and only after this preliminary action is complete is the conformal plating applied to finish the embedding process
2Strength
If metal is embedded in through-holes without voids, then the structural integrity is improved, but the thermal expansion forces during heating processes cause substrate damage
Solution Approach 1:
The through-hole embedding structure is designed with non-uniform properties: the inner layer uses materials with different thermal expansion characteristics (such as tungsten, nickel, or palladium) compared to the outer copper layer. This local variation in material properties allows the structure to manage thermal expansion forces differently at different locations, preventing substrate damage during heating processes while maintaining overall structural integrity
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 design effectively reduces the risk of substrate damage during heating processes and improves the conduction characteristics of through-electrodes by using materials with higher resistance to electromigration, while also potentially reducing manufacturing costs by using less expensive metals.
Implementation Method 1
a metal portion made of a metal other than copper, formed closer to a hole core side of the through-hole than the copper layer is, and involving a void therein
Implementation Method 2
embedding of metal in a through-hole is performed by means of electrolytic plating
Implementation Method 3
electromigration issues due to the use of copper, which has low resistance to electromigration
Data Source
AI summary
According to an embodiment, a semiconductor device is provided. The semiconductor device includes a through-hole, a copper layer, and a metal portion. The through-hole penetrates a semiconductor substrate between front and rear sides. The copper layer is formed inside the through-hole. The metal portion is made of a metal other than copper, formed closer to a hole core side of the through-hole than the copper layer is, and involves a void therein.