3D Memory Source Layer Air-Gap Structure for Defect-Free Conductive Paths
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Solution Overview
Problem
Existing three-dimensional semiconductor memory devices face challenges in improving operational reliability due to defects such as seams or voids within the conductive layers in contact with the channel structure, which affect electrical characteristics.
Innovation Solution
The semiconductor memory device incorporates a second source layer with an air gap surrounded by a conductive layer, and a method of manufacturing that includes forming a source structure, a stack, and a channel structure, followed by the creation of a trench, cavity, and conductive layer with an air gap to enhance electrical characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional conductive layer is formed without air gaps, then the manufacturing process is simpler, but seams or voids appear inside the conductive layer causing poor electrical characteristics
Solution Approach 1:
The conductive layer is segmented into multiple parts separated by air gaps. Instead of forming a continuous conductive layer that develops seams and voids, the layer is divided into discrete segments that are positioned apart from each other, eliminating the harmful connections while maintaining electrical functionality through controlled pathways.
Solution Approach 2:
The air gaps are strategically positioned at specific locations within the conductive layer structure where seams and voids would otherwise form. This local modification creates regions of different properties - solid conductive material where needed for electrical connection and air gaps where needed to prevent defect formation - thereby improving overall electrical characteristics.
2Manufacturing precision
If the source sacrificial structure is completely removed to form air gaps, then defects are reduced, but additional manufacturing steps are required
Solution Approach 1:
The source sacrificial structure is formed in advance during the standard manufacturing process, and air gaps are pre-positioned around it. This preliminary arrangement ensures that when the sacrificial structure is later removed, the air gaps remain in optimal positions to prevent seam and void formation, achieving defect reduction without requiring complex post-processing steps.
Solution Approach 2:
The source sacrificial structure serves as an intermediary element that facilitates the creation of air gaps. By using this temporary structure as a mold or template during manufacturing, the air gaps can be formed indirectly through a series of standard processing steps, avoiding the need for direct and complex air gap formation techniques.
Data Source
AI summary
A semiconductor memory device, and a method of manufacturing the semiconductor memory device, includes a first source layer, a second source layer on the first source layer, a stack on the second source layer, a channel structure passing through the stack and the second source layer, and a common source line passing through the stack and the second source layer. The second source layer includes an air gap and a conductive layer surrounding the air gap.