3D Memory String Selection Gate Fill for Word Line Resistance
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Solution Overview
Problem
As the number of channel structures in three-dimensional semiconductor memory devices increases, the resistance characteristics of components deteriorate due to unfilled regions in the word lines.
Innovation Solution
The semiconductor memory device incorporates a cell unit with a stack structure and channel structures penetrating through it, featuring a higher ratio of conductive material occupation in the string selection gates compared to the cell gates, particularly in defined regions, to maintain resistance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of channel structures is increased to improve integration density, then the degree of integration is improved, but the resistance characteristics of components deteriorate due to unfilled regions in the word line
Solution Approach 1:
The patent applies local quality by making the string selection gate have a higher ratio of conductive material occupation compared to cell gates in regions where channel structures are densely packed. This localized adjustment ensures that critical selection gates maintain low resistance even when overall integration density increases and unfilled regions expand
Solution Approach 2:
The patent changes the parameter of conductive material occupation ratio specifically for string selection gates, increasing it from the standard ratio used in cell gates. This parameter change compensates for the increased resistance caused by unfilled regions, maintaining reliable electrical characteristics while preserving high integration density
Data Source
AI summary
A semiconductor memory device includes a cell unit including a stack structure and a channel structure penetrating through the stack structure, the stack structure including at least one string selection gate and a plurality of cell gates, cell separation structures separating the cell unit in a first direction, and gate cutting structures defining regions within the cell unit between adjacent cell separation structures. The cell unit includes a first region defined between a first cell separation structure and a first gate cutting structure and a second region defined between the first gate cutting structure and a second gate cutting structure. A ratio of a region of the at least one string selection gate that is occupied by a conductive material in the second region is greater than a ratio of a region of at least one cell gate that is occupied by the conductive material in the second region.