Recessed Active Region Memory Layout With Protruding Drain Contacts
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Solution Overview
Problem
The semiconductor industry faces challenges in manufacturing complex and densely packed memory devices with reduced geometry sizes, which increases power dissipation and complicates the manufacturing process due to the need for advanced processing techniques.
Innovation Solution
The method involves forming metal-oxide-nitride-oxide-silicon (MONOS) memory devices with protruding drains, where recesses are created in the substrate to position sources and drains at different levels, allowing for a dense layout and reduced channel length, while maintaining manufacturing efficiency by using specific etching and deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If geometry size is decreased to increase functional density, then production efficiency is improved and costs are lowered, but power dissipation increases
Solution Approach 1:
The patent transitions from planar 2D device layout to 3D vertical structures by forming protruding drain regions that extend upward from the substrate. This dimensional change allows increased functional density without further reducing the planar footprint, thereby maintaining lower power dissipation while achieving higher production efficiency.
Solution Approach 2:
The device structure is segmented into distinct vertical regions including the substrate, protruding drain regions, gate structures, and interlayer dielectric layers. This segmentation enables independent optimization of each region's dimensions and properties, allowing density increase through vertical stacking rather than horizontal compression that would increase power dissipation.
2Productivity
If geometry size is decreased to increase functional density, then the number of interconnected devices per chip area increases, but manufacturing complexity increases
Solution Approach 1:
By forming protruding drain regions that extend vertically from the substrate surface, the patent achieves higher functional density in the vertical dimension rather than compressing devices horizontally. This approach maintains simpler manufacturing processes compared to advanced node planar fabrication, as it uses conventional etching and deposition techniques to create the three-dimensional structure.
Solution Approach 2:
The protruding drain regions are formed prior to gate structure fabrication. This preliminary action simplifies subsequent manufacturing steps by providing pre-defined contact regions, eliminating the need for complex alignment and patterning processes that would be required if drains were formed at later stages with smaller geometries.
3Productivity
If protruding drain structures are formed to reduce pitch, then layout density increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves pitch reduction primarily in the vertical dimension through protruding drain formation, rather than requiring ultra-precise lateral etching at advanced nodes. The horizontal pitch between devices can be maintained at larger dimensions while achieving high density through vertical stacking, thereby reducing the stringency of lateral manufacturing precision requirements.
Solution Approach 2:
Mandrel structures are used as intermediary elements to define the pattern of protruding drain regions. These mandrels serve as self-aligned masks during etching processes, automatically defining the precise locations and dimensions of drain regions without requiring complex multi-step lithography alignment, thus reducing the effective precision requirements.
Data Source
AI summary
A device includes an active region, a select gate, a control gate, a first metal alloy layer, and a second metal alloy layer. The active region has a source region and a drain region. The select gate is over the active region and between the source region and the drain region. The control gate is over the active region and between the source region and the select gate. The first metal alloy layer is in contact with the source region. The second metal alloy layer is in contact with the drain region and higher than a top surface of the control gate.