Self-Aligned Channel Cap Structure for 3D Memory Openings
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in forming self-aligned channel cap structures efficiently, which are crucial for enhancing memory density and performance, due to limitations in existing fabrication methods.
Innovation Solution
A semiconductor structure and method involving an alternating stack of insulating and electrically conductive layers, where memory openings are formed with a semiconductor core and annular cap structures, allowing for the formation of vertical semiconductor channels and source layers with precise control over p-n junctions, reducing the need for additional processing steps and thermal budgets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication methods are used to form channel cap structures, then additional processing steps and thermal budgets are required, but this increases fabrication complexity and adversely affects copper interconnects and bonding pads
Solution Approach 1:
The semiconductor cap structure is formed preliminarily during the memory opening formation process, before the vertical semiconductor channels are created. This preliminary formation of the cap structure on the memory opening sidewalls eliminates the need for subsequent separate processing steps to form channel cap structures, thereby reducing fabrication complexity while maintaining precise control over p-n junctions
Solution Approach 2:
The semiconductor cap structure is nested within the memory opening, forming an integrated structure that combines the cap formation with the memory opening formation process. This nesting approach allows the cap structure to be formed as part of the existing process sequence without requiring additional thermal budgets or separate fabrication steps
2Manufacturing precision
If additional processing steps are added to form self-aligned channel cap structures, then p-n junction control is improved, but fabrication time and thermal budget increase
Solution Approach 1:
The formation of the semiconductor cap structure is merged with the memory opening formation process. The cap structure is formed as an integrated part of the memory opening fabrication sequence, combining multiple functions into a single process flow that achieves self-alignment without requiring additional time-consuming steps
Solution Approach 2:
The cap structure is formed preliminarily during the memory opening formation process, establishing the self-aligned configuration before vertical semiconductor channels are created. This preliminary action ensures precise p-n junction alignment while avoiding the need for subsequent alignment-critical processing steps
Data Source
AI summary
A semiconductor structure includes an alternating stack of insulating layers and electrically conductive layers, a memory opening vertically extending through the alternating stack, a memory opening fill structure located in the memory opening and comprising a memory film, a vertical semiconductor channel, and a semiconductor cap structure that includes a semiconductor core structure contacting a bottom end of the vertical semiconductor channel and an annular semiconductor structure laterally surrounding the semiconductor core structure and having a lesser vertical extent than the semiconductor core structure, and a source layer contacting a bottom surface of the semiconductor core structure.