Nonvolatile Memory Device Electrode Pad Buffering
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Solution Overview
Problem
The strength below the electrode pad in nonvolatile semiconductor memory devices is insufficient, leading to potential destruction from bonding tools and limiting the downsizing of these devices due to the need to prevent damage to underlying wiring and device elements.
Innovation Solution
A nonvolatile semiconductor memory device design featuring a stacked body with a thickness of 1.5 μm or more beneath the electrode pad, including vias and conductive layers that act as a buffer to absorb the impact of bonding tools, allowing wiring layers to be routed below the electrode pad without risking damage, and ensuring electrical insulation to shield against electrical noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirings and device elements are not placed below the electrode pad to prevent destruction, then reliability is improved, but device area increases limiting downsizing
Solution Approach 1:
The patent transitions from a planar wiring layout to a three-dimensional stacked architecture where memory cells are arranged vertically above the electrode pad rather than laterally beside it. This vertical stacking enables wirings and device elements to be positioned below the electrode pad in the depth dimension, allowing downsizing in the planar area while maintaining reliability through the protective stacked structure.
Solution Approach 2:
The patent employs a composite stacked body structure consisting of multiple alternating layers of insulating material and electrode layers. This composite architecture provides both mechanical strength to protect underlying wirings and electrical insulation properties, enabling reliable placement of wirings below the electrode pad while maintaining device integrity.
2Reliability
If a thick stacked body is placed below the electrode pad to absorb bonding impact, then reliability is improved, but device complexity increases
Solution Approach 1:
The stacked body structure serves multiple functions simultaneously: it acts as a mechanical buffer to absorb bonding tool impact, provides electrical insulation to shield underlying wirings, and forms part of the functional memory device architecture with alternating insulating and electrode layers. This multi-functionality reduces overall device complexity despite the thick stacked structure.
Solution Approach 2:
The alternating layers of insulating material and electrode layers create a composite structure where each material contributes specific properties - insulating layers provide mechanical cushioning and electrical isolation, while electrode layers provide electrical connectivity. This composite approach achieves impact resistance without requiring additional protective layers, simplifying the overall structure.
Data Source
AI summary
According to one embodiment, a nonvolatile semiconductor memory device includes a memory cell region provided with a plurality of memory cells, and a peripheral region provided around the memory cell region. The device includes: a foundation layer provided in the memory cell region and in the peripheral region, the foundation layer including a plurality of wiring layers and a plurality of device elements; and a stacked body provided on the foundation layer, the stacked body including a plurality of electrode layers and a plurality of intermediate layers alternately stacked. The peripheral region includes an interlayer insulating film provided on the stacked body; and an electrode pad provided on the interlayer insulating film and electrically connected to one of the plurality of wiring layers.