Semiconductor Contact Pads With Liner Undercuts
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Solution Overview
Problem
The manufacturing of three-dimensional non-volatile memory devices is complicated by the need for contact plugs to be formed at various depths, which can lead to bridging issues when passing through word lines, making it difficult to achieve a stable and integrated structure.
Innovation Solution
A semiconductor device with a stacked structure featuring conductive layers and insulating layers, where undercuts are formed under the conductive layers, and contact pads are coupled to the conductive layers with a liner layer filling the undercuts, preventing bridging and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If contact plugs are formed at various depths to connect to stacked word lines, then the degree of integration is increased, but the manufacturing process becomes difficult and bridges may form
Solution Approach 1:
The contact structure is segmented into multiple pads at different depths, each pad connecting to a specific word line level. This segmentation allows independent formation and control of each contact point, simplifying the manufacturing process while maintaining high degree of integration through the stacked three-dimensional structure
Solution Approach 2:
The patent transitions from planar contact formation to three-dimensional stacked structure with pads arranged vertically at different depths. This dimensional change enables connection to multiple word line levels without requiring complex lateral routing, thereby increasing integration while maintaining manufacturing simplicity
2Reliability
If contact plugs pass through word lines to reach deeper levels, then connection to stacked structures is achieved, but bridging issues occur
Solution Approach 1:
Insulating layers are formed beforehand between adjacent pads and around the periphery of each pad before the conductive material is deposited. This preliminary insulation prevents bridging between contact plugs and between pads and word lines, ensuring reliable connections without short circuits
Solution Approach 2:
Insulating layers serve as intermediary barriers between conductive elements (pads and word lines). These intermediary layers physically separate conductive paths that would otherwise be in close proximity, preventing harmful bridging while allowing the structure to achieve high integration
Data Source
AI summary
A semiconductor device includes a stacked structure having first conductive layers stacked stepwise and first insulating layers interposed between the first conductive layers, wherein undercuts are formed under the first conductive layers and each of the first conductive layers includes a first region covered by the first conductive layer and a second region extending from the first region, contact pads coupled to the second regions of the respective first conductive layers, and a liner layer formed on the contact pads and filling the undercuts.