Memory Hole Insulator Shaping to Prevent Electric Field Concentration
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Solution Overview
Problem
The formation of memory holes with undesired shapes, particularly convex portions on their side faces, leads to electric field concentration, which can cause erroneous writes and performance deterioration in semiconductor devices, such as NAND memory cells.
Innovation Solution
A method of manufacturing semiconductor devices involves forming a stacked film with alternating layers, creating a memory hole, and using selective slimming of insulators to correct the shape of the hole's side faces, ensuring uniform thickness and curvature, thereby preventing electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a memory hole is formed using conventional methods, then the manufacturing process is simple, but the side face shape becomes undesired with convex portions causing electric field concentration
Solution Approach 1:
The insulator formation process is segmented into multiple distinct steps: forming a first insulator, selectively removing it to expose the stacked film, and forming a second insulator on the exposed portions. This segmentation allows precise control over the final insulator shape to eliminate convex portions while maintaining manufacturing feasibility
Solution Approach 2:
The first insulator is formed in advance as a temporary structure that guides the subsequent selective removal process. This preliminary action enables precise definition of the exposed stacked film regions, which in turn determines the final shape of the second insulator, ensuring convex portions are prevented before they can cause electric field concentration
2Manufacturing precision
If the insulator is formed in a single step, then the manufacturing process is simple, but the thickness uniformity and shape control are insufficient
Solution Approach 1:
The insulator formation is divided into two separate formation steps with selective removal in between. The first insulator is formed with controlled thickness, selectively removed from specific regions, and the second insulator is formed to achieve the final uniform thickness. This segmentation enables precise thickness control that would be difficult to achieve in a single step
Solution Approach 2:
The selective removal of the first insulator creates different local conditions: exposed stacked film in some regions and covered regions in others. The second insulator is then formed with different local thicknesses corresponding to these regions, achieving overall uniformity while accommodating local variations in the underlying structure
Data Source
AI summary
In one embodiment, a method of manufacturing a semiconductor device includes forming a stacked film alternately including first layers and second layers in a first direction, forming a hole extending in the first direction in the stacked film, and forming a first insulator on a side face of the stacked film in the hole. The method further includes removing the first insulator in the hole to expose a first part of the side face of the stacked film at a predetermined height in the first direction of the hole and to expose a side face of the first insulator remaining on a second part of the side face of the stacked film at the predetermined height. The method further includes forming a second insulator on the first part of the side face of the stacked film and the side face of the remaining first insulator in the hole.