Nonlinear Control Gate Electrodes for 3D NAND Stress Management
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Solution Overview
Problem
Existing three-dimensional NAND memory devices face challenges in achieving high density and minimizing substrate warpage due to compressive or tensile stress from control gate electrodes, which can lead to mechanical instability and manufacturing issues.
Innovation Solution
The implementation of nonlinear control gate electrodes and slit trenches to redistribute stress, combined with a method of forming memory devices with alternating layers and etching techniques to create memory openings and backside openings, reduces substrate warpage and enhances mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If control gate electrodes are added to increase storage density, then storage density is improved, but substrate warpage and mechanical instability worsen due to compressive or tensile stress
Solution Approach 1:
The control gate electrode is segmented into multiple sections along the vertical channel, with insulating layers separating adjacent conductive sections. This segmentation distributes the stress along the electrode structure rather than concentrating it, reducing substrate warpage while maintaining the electrode's control function over the channel
Solution Approach 2:
Different sections of the control gate electrode have different electrical properties (conductive vs. insulating), allowing local optimization where conductive sections provide control functionality and insulating sections reduce stress transmission to the substrate
2Quantity of substance
If more control gate electrodes are stacked vertically, then storage density is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Multiple control gate electrodes are merged into a single continuous electrode structure that extends vertically through multiple memory cell layers, with insulating layers integrated within the same structure. This combining approach achieves high density without proportionally increasing manufacturing steps
3Device complexity
If control gate electrodes are made continuous to simplify structure, then device complexity is reduced, but substrate warpage increases due to accumulated stress
Solution Approach 1:
The continuous control gate electrode is divided into discrete conductive sections separated by insulating layers, maintaining structural simplicity while eliminating stress accumulation that would occur in a fully continuous electrode
Data Source
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AI summary
A monolithic three dimensional NAND string includes a plurality of control gate electrodes extending substantially parallel to a major surface of a substrate in at least one active region, a plurality of semiconductor channels having at least one end portion of each of the plurality of semiconductor channels extending substantially perpendicular to the major surface of the substrate, at least one memory film located between each of the plurality of control gate electrodes and each respective semiconductor channel of the plurality of semiconductor channels, and at least one first slit trench extending substantially perpendicular to the major surface of the substrate. Each of the plurality of control gate electrodes has a nonlinear side wall adjacent to the at least one first slit trench in the at least one active region.