3D Semiconductor Contact Pad Stacking for Integration Density
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Solution Overview
Problem
Conventional semiconductor devices face challenges in achieving high integration density and reliability due to the limitations of two-dimensional (2D) memory devices, which require expensive equipment for fine pattern formation and are economically and technically constrained.
Innovation Solution
The semiconductor device design includes a substrate with a device isolation layer, word lines, interconnections, contact pads, and plugs that are strategically positioned and sized to enhance integration density and reliability, allowing for improved electrical connections and increased process margins, enabling higher integration density without the need for expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional two-dimensional memory device techniques are used to increase integration density, then the area occupied by unit memory cells is reduced, but expensive equipment is required for fine pattern formation and technical constraints limit further improvement
Solution Approach 1:
The patent transitions from conventional two-dimensional planar memory structures to three-dimensional vertical structures. Memory cells are stacked vertically with multiple active regions arranged in layers, allowing integration density to increase without requiring finer lateral patterning. This vertical stacking approach eliminates the need for expensive fine pattern formation equipment while achieving higher integration density.
2Reliability
If contact pad size is increased to improve connection reliability, then process margins are increased, but device area is consumed
Solution Approach 1:
The contact pad structure extends in the vertical dimension rather than requiring large lateral area. Multiple contact pads are stacked vertically to connect to different active regions, allowing reliable electrical connections with process margins while consuming minimal planar device area. The vertical stacking enables large effective contact area without increasing footprint.
Solution Approach 2:
Contact pads are nested vertically within the three-dimensional structure, with lower contact pads positioned beneath upper contact pads. This nesting arrangement allows multiple contact pads to occupy the same lateral footprint at different heights, providing reliable connections to multiple active regions without consuming additional device area.
3Adaptability or versatility
If more interconnections are added to increase functionality, then device capability is enhanced, but device complexity increases
Solution Approach 1:
Interconnections are arranged in three-dimensional space with multiple layers stacked vertically. This vertical stacking allows numerous interconnections to be packed into a compact volume without increasing lateral complexity. The three-dimensional arrangement enables enhanced device capability while maintaining manageable structural complexity through systematic layering.
Solution Approach 2:
The three-dimensional interconnection structure serves multiple functions simultaneously: providing electrical connections, enabling signal routing between stacked active regions, and supporting the vertical memory cell architecture. This multi-functionality reduces the need for separate dedicated structures, thereby enhancing device capability without proportionally increasing complexity.
Data Source
AI summary
A semiconductor device includes a substrate with an active region defined by a device isolation layer. A word line extends over the active region in a first direction, and a plurality of interconnections extends over the word line in a second direction perpendicular to the first direction. A contact pad is disposed between and spaced apart from the word line and the plurality of interconnections, extending in the first direction to overlap the plurality of interconnections and the active region when viewed from a plan view. A lower contact plug electrically connects the contact pad to the active region. An upper contact plug electrically connects the contact pad to one of the plurality of interconnections.