Semiconductor Memory Interconnect Stability via Insulating Film Protrusions
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Solution Overview
Problem
Existing semiconductor memory devices face challenges in stabilizing interconnects due to the collapse of second interconnects in peripheral regions, leading to interconnect-interconnect shorts, particularly when using insulating films with softer materials like silicon oxide, which have a smaller Young's modulus compared to the metal compounds in the stacked films.
Innovation Solution
The implementation of a method where a second inter-layer insulating film with a lower etching rate than the first inter-layer insulating film is used in the peripheral region, with protrusions that have a protruding length less than the stacking height of the stacked films, to support the second interconnects and prevent collapse, thereby stabilizing the interconnects and reducing the aspect ratio of the protrusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a softer insulating film material like silicon oxide is used, then the etching rate is improved, but the structural stability deteriorates causing interconnect collapse
Solution Approach 1:
The patent changes the material parameter (Young's modulus) of the insulating film by selecting materials with different mechanical properties for different regions. The first inter-layer insulating film uses softer materials like silicon oxide for faster etching, while the second inter-layer insulating film uses harder materials with higher Young's modulus to provide structural support and prevent interconnect collapse.
2Strength
If the protruding length of support protrusions is increased, then the support strength is improved, but the aspect ratio increases causing manufacturing difficulty
Solution Approach 1:
The patent optimizes the geometric parameters of the support protrusions by controlling their protruding length to be within a specific range (0.5-2.0 times the thickness of the stacked film). This parameter optimization provides sufficient support strength while maintaining a manageable aspect ratio for manufacturing.
Solution Approach 2:
The patent creates a composite structure where the second inter-layer insulating film with higher Young's modulus works together with the optimized geometry of support protrusions. This combination provides enhanced support strength without requiring excessive protrusion height, thus maintaining acceptable aspect ratios.
3Device complexity
If the second inter-layer insulating film is not provided, then the device complexity is reduced, but interconnect-interconnect shorts occur due to collapse
Solution Approach 1:
The patent applies the second inter-layer insulating film with higher Young's modulus specifically in the peripheral region where interconnect collapse is most likely to occur. This localized approach provides targeted support to prevent shorts while minimizing the overall addition to device complexity.
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a plurality of first interconnects extending in a first direction, a plurality of second interconnects extending in a second direction, a plurality of stacked films respectively provided between the first interconnects and the second interconnects, each of the plurality of stacked films including a variable resistance film, a first inter-layer insulating film provided in a first region between the stacked films, and a second inter-layer insulating film provided in a second region having a wider width than the first region. The second inter-layer insulating film includes a plurality of protrusions configured to support one portion of the plurality of second interconnects on the second region. A protruding length of the protrusions is less than a stacking height of the stacked films.