Stacked Memory Device Stress Compensation
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Solution Overview
Problem
High-density nonvolatile memory devices with stacked cells face substrate warpage issues due to compressive and tensile stresses from multiple films, leading to manufacturing accuracy problems and equipment instability.
Innovation Solution
A nonvolatile memory device design where dielectric and electrode films are alternately stacked with films generating compressive and tensile stresses, with semiconductor pillars and a charge storage layer, to cancel out stress and reduce substrate warpage, and a method for manufacturing this device by alternating the formation of stress-generating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large number of dielectric films and electrode films are stacked alternately on the substrate to achieve high-density memory, then the memory density is improved, but the substrate warpage increases due to accumulated compressive and tensile stresses from the films
Solution Approach 1:
The patent uses composite material structure by alternating dielectric films and electrode films with different stress characteristics. Specifically, it combines films generating compressive stress (such as polycrystalline silicon films) with films generating tensile stress (such as TEOS films) in a stacked configuration. This composite stacking approach allows the stresses from different materials to counterbalance each other, reducing overall substrate warpage while maintaining high memory density through multiple stacked layers.
2Quantity of substance
If multiple films generating compressive or tensile stress are stacked on one surface of the substrate, then the memory capacity is increased, but the manufacturing process accuracy deteriorates due to substrate distortion
Solution Approach 1:
The patent implements composite material stacking where dielectric films and electrode films with opposing stress characteristics are alternately deposited. This creates a self-balancing stress system where compressive stress from one film type counteracts tensile stress from another, keeping the substrate flat and within acceptable warpage specifications (e.g., maintaining warpage below 100 μm even with 32 stacked layers), thereby preserving manufacturing process accuracy.
3Quantity of substance
If films generating compressive or tensile stress are stacked to increase memory density, then the storage capacity is improved, but the equipment stability decreases due to large substrate warpage
Solution Approach 1:
The patent employs composite material architecture with alternating dielectric and electrode films that have complementary stress properties. This composite structure creates internal stress compensation mechanisms that maintain substrate flatness, preventing equipment instability issues such as wafer breaking or manufacturing equipment malfunction, while enabling high storage capacity through increased stacking layers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively minimizes substrate warpage, improving manufacturing accuracy and stability, and allows for a large number of stacked films without significant distortion, enhancing the reliability of high-density memory devices.
Implementation Method 1
at least one of the dielectric films including a film generating one of a compressive stress and a tensile stress, and at least one of the electrode films including a film generating the other of the compressive stress and a tensile stress
Data Source
AI summary
A nonvolatile memory device includes: a substrate; a stacked structure member including a plurality of dielectric films and a plurality of electrode films alternately stacked on the substrate and including a through-hole penetrating through the plurality of the dielectric films and the plurality of the electrode films in a stacking direction of the plurality of the dielectric films and the plurality of the electrode films; a semiconductor pillar provided in the through-hole; and a charge storage layer provided between the semiconductor pillar and each of the plurality of the electrode films. At least one of the dielectric films includes a film generating one of a compressive stress and a tensile stress, and at least one of the electrode films includes a film generating the other of the compressive stress and the tensile stress.