Semiconductor Memory Device With Varying Electrode Film Thickness
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Solution Overview
Problem
The increasing number of electrode films in three-dimensional semiconductor memory devices makes it difficult to form memory holes, leading to substrate warping and accuracy issues in manufacturing, as well as potential short circuits due to low etching selectivity and high aspect ratios of memory holes.
Innovation Solution
The semiconductor memory device design features electrode films with varying thicknesses, where upper layers have thicker films and voids, and lower layers have thinner films without voids, reducing the aspect ratio of memory holes and preventing substrate warping, while maintaining consistent resistance values across layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of electrode films is increased to increase memory cell density, then the number of memory cells increases, but substrate warping occurs and manufacturing accuracy deteriorates
Solution Approach 1:
The patent applies local quality by varying the thickness of electrode films at different positions. Specifically, the first electrode film has a first thickness in a first region and a second thickness in a second region, with the first thickness being greater than the second thickness. This non-uniform thickness distribution compensates for stress variations across the substrate, preventing warping while maintaining high memory cell density.
Solution Approach 2:
The patent changes the physical parameter of electrode film thickness to resolve the contradiction. By adjusting the thickness parameter of the first electrode film across different regions, the patent optimizes stress distribution in the stacked body, thereby preventing substrate warping that would otherwise occur with increased numbers of electrode films.
2Productivity
If the number of electrode films is increased to increase memory cell density, then the number of memory cells increases, but etching selectivity decreases leading to short circuits
Solution Approach 1:
The patent applies local quality by making the first electrode film thicker in the first region where memory holes are formed. This increased thickness in the critical region enhances etching selectivity and prevents short circuits between adjacent memory holes, while the overall structure maintains high memory cell density through the stacked configuration.
3Productivity
If the number of electrode films is increased to increase memory cell density, then the number of memory cells increases, but the aspect ratio of memory holes increases making formation difficult
Solution Approach 1:
The patent applies local quality by concentrating the thickness increase in the first electrode film specifically in the first region where memory holes are formed. This localized thickening reduces the effective aspect ratio of memory holes in critical areas, making them easier to form and fill, while maintaining high overall memory cell density through the stacked electrode film structure.
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a substrate, a stacked body, and a plurality of columnar parts. The stacked body is provided on the substrate. The stacked body includes a plurality of electrode films stacked separately from each other. The plurality of columnar parts is provided in the stacked body. Each of the plurality of columnar parts includes a semiconductor pillar extending in a stacking direction of the stacked body, and a charge storage film provided between the semiconductor pillar and the stacked body. The plurality of electrode films includes a first electrode film provided in upper layers of the stacked body and a second electrode film provided in lower layers of the stacked body. A thickness of the first electrode film is thicker than a thickness of the second electrode film. The first electrode film is provided with a void.