Bent Front Via Structure for Void-Free BSPDN Connections
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Solution Overview
Problem
The formation of high-aspect-ratio via structures in semiconductor devices is challenging due to difficulties in patterning and etching, often resulting in incomplete filling of via holes, which can lead to voids and deteriorate connection performance between front side and back side structures.
Innovation Solution
A semiconductor device design featuring a front via structure formed in a via hole with a bent connection surface, comprising a lower and upper via hole connected vertically, where the lower via hole has a higher aspect ratio than the upper via hole, and a sacrificial via structure is used to facilitate the formation of a stable connection between the front side and back side structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-aspect-ratio via hole is formed to connect front side and back side structures, then the connection between BSPDN and front side structure is achieved, but the via hole cannot be completely filled, generating voids that deteriorate connection performance
Solution Approach 1:
The via hole formation process is segmented into multiple steps: first forming an initial via hole through the isolation layer, then forming a second via hole through the via hole formation layer to reach the first via hole. This segmentation allows each via hole to have manageable aspect ratios, enabling complete filling without voids while maintaining reliable electrical connection between front side and back side structures.
Solution Approach 2:
The isolation layer is formed preliminarily before via hole formation, and the via hole formation layer is deposited conformally on the isolation layer. This preliminary action creates a structured foundation that guides the subsequent via hole formation process, ensuring proper alignment and facilitating complete material filling in the final via structure.
2Reliability
If a high-aspect-ratio via hole is formed to connect front side and back side structures, then the BSPDN connection is achieved, but patterning and etching become extremely difficult
Solution Approach 1:
The via connection structure is segmented into multiple via holes at different levels. The first via hole connects through the isolation layer, and the second via hole connects through the via hole formation layer to the first via hole. This segmentation reduces the aspect ratio of each individual via hole, making patterning and etching processes significantly easier while maintaining the overall connection functionality.
Solution Approach 2:
Different regions of the structure have different properties: the isolation layer provides electrical isolation in certain regions, while the via hole formation layer provides conductive pathways in other regions. This local differentiation allows optimized processing for each region, making the overall manufacturing process more manageable.
Data Source
AI summary
Provided is a semiconductor device that includes: at least one transistor, a front side structure, and a back side structure, the front side structure being disposed opposite to the back side structure with respect to the transistor; and a front via formed at a side of the transistor and connecting the front side structure to the back side structure, wherein the front via is formed in a via hole formed of a lower via hole and an upper via hole vertically connected to each other, and wherein the via hole has a bent structure at a side surface thereof where the lower via hole is connected to the upper via hole.