Semiconductor Package Routing Via With Dual-Side Seed-Barrier Coverage
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Solution Overview
Problem
The integration of multiple semiconductor devices in wafer-level packaging poses challenges due to the complexity of forming efficient redistribution structures across the substrate, particularly in achieving adequate coverage and preventing material diffusion in high-aspect-ratio through holes.
Innovation Solution
A method involving dual-side sputtering to form a composite seed-barrier layer along the sidewalls of through holes, using a backside film to mask the holes and enable asymmetrical redistribution structure formation, and integrating semiconductor dies with conductive blocks and through insulator vias for efficient electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-side sputtering is used to form seed-barrier layers in through holes, then the manufacturing process is simple, but the coverage is insufficient and material diffusion occurs in high-aspect-ratio holes
Solution Approach 1:
The sputtering process is segmented into two separate operations: first sputtering from the front side to form an initial seed layer, then sputtering from the back side to complete the seed-barrier layer formation. This segmentation allows each sputtering operation to target specific regions, ensuring complete coverage of high-aspect-ratio through holes while preventing material diffusion through the composite layer structure
Solution Approach 2:
The process transitions from single-side (one-dimensional) sputtering to dual-side (two-dimensional) sputtering by accessing the substrate from both front and back surfaces. This dimensional change enables complete infiltration of conductive material into high-aspect-ratio through holes and formation of a composite seed-barrier layer that prevents material diffusion
2Reliability
If through holes are made deeper to achieve better connectivity, then electrical connectivity improves, but material diffusion increases and coverage becomes difficult
Solution Approach 1:
The first sputtering operation performs preliminary action by depositing an initial seed layer from the front side before the main back-side sputtering. This preliminary layer acts as a foundation that prevents material diffusion during subsequent processing, enabling deeper through holes to be filled with conductive material while maintaining manufacturing precision and controlling material diffusion
Solution Approach 2:
A composite seed-barrier layer is formed by combining materials deposited from both front and back sides. This composite structure integrates the benefits of both sputtering directions: the front-side deposition provides initial coverage and adhesion, while the back-side deposition completes the layer and prevents diffusion, achieving both deep connectivity and material control
3Productivity
If asymmetric redistribution structures are formed using backside masking, then device integration efficiency improves, but process steps increase
Solution Approach 1:
A backside film is applied as a preliminary masking layer before the second sputtering operation. This preliminary action enables selective deposition on specific regions of the substrate, allowing formation of asymmetric redistribution structures that improve device integration efficiency by enabling complex interconnect patterns to be formed in a controlled manner
Solution Approach 2:
The backside film serves as an intermediary masking element that controls material deposition during the second sputtering operation. This intermediary layer enables precise formation of asymmetric redistribution structures by blocking deposition in certain areas while allowing it in others, improving device integration efficiency despite adding a process step
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 allows for effective seeding of conductive material deposition, enhancing adhesion and reducing material diffusion, enabling the formation of efficient redistribution structures and facilitating the integration of semiconductor devices with reduced manufacturing complexity and cost.
Implementation Method 1
a sputtering process is performed from the side of the backside surface (700b) to form a barrier layer (720) and a seed layer (740)
Data Source
AI summary
A semiconductor package includes a substrate, a composite seed-barrier layer, a routing via, and a semiconductor die. The substrate has a through hole formed therethrough. The composite seed-barrier layer extends on sidewalls of the through hole and includes a first barrier layer, a seed layer, and a second barrier layer sequentially stacked on the sidewalls of the through hole. The routing via fills the through hole and is separated from the substrate by the composite seed-barrier layer. The semiconductor die is electrically connected to the routing via. Along the sidewalls of the through holes, at a level height corresponding to half of a total thickness of the substrate, the seed layer is present as inclusions of seed material surrounded by barrier material of the first barrier layer and the second barrier layer.