Stacked Semiconductor Memory Electrode Stability
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Solution Overview
Problem
Stability in characteristics of stacked-type semiconductor memory devices is a challenge due to issues with electrode film formation and memory cell transistor performance, particularly in forming high aspect ratio memory holes and maintaining uniformity and resistance of electrode films.
Innovation Solution
The method involves alternately stacking silicon nitride and silicon oxide films, using etching gases containing bromine and fluorine to form memory holes with a protective tungsten bromide film, and embedding tungsten in spaces to form electrode films with reduced resistance and improved stability, while avoiding bowing shapes in memory holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form memory holes, then the manufacturing process is simple, but the memory holes develop bowing shapes and non-uniform diameters
Solution Approach 1:
A protective film is introduced as an intermediary layer during the etching process. This protective film prevents direct contact between the etching gas and the memory hole walls, thereby preventing bowing shapes and maintaining uniform diameter throughout the high aspect ratio memory holes.
Solution Approach 2:
The protective film is formed in advance before the etching process begins. This preliminary action ensures that the memory holes are protected from etching-induced deformation throughout the entire etching process, resulting in uniform diameter and improved manufacturing precision.
2Reliability
If electrode films are formed without metal-containing layers, then the manufacturing process is simpler, but the resistance of electrode films is high and stability is poor
Solution Approach 1:
The electrode film is constructed as a composite structure with multiple layers including metal-containing layers and other conductive materials. This composite structure reduces the overall resistance of the electrode film while maintaining structural stability and improving reliability of the stacked-type semiconductor memory device.
Solution Approach 2:
Metal-containing layers are strategically positioned at specific locations within the electrode film structure where high conductivity and stability are most needed. This local enhancement of material quality optimizes the electrode film performance without unnecessarily increasing overall device complexity.
3Productivity
If high aspect ratio memory holes are formed, then the device can achieve higher integration, but the electrode film uniformity and resistance characteristics deteriorate
Solution Approach 1:
The protective film serves as a mediator that enables the formation of high aspect ratio memory holes while maintaining electrode film uniformity. By preventing etching-induced bowing, the protective film ensures that even in high aspect ratio structures, the electrode films remain uniform in diameter and maintain stable resistance characteristics.
Solution Approach 2:
The use of protective film etching changes the etching parameters and process characteristics, allowing for the formation of high aspect ratio memory holes with controlled and uniform dimensions. This parameter change enables higher integration while maintaining manufacturing precision of the electrode films.
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
This approach enhances the stability and performance of select gate and memory cell transistors by maintaining uniform electrode film diameters and reducing resistance, improving switching and operating characteristics of the semiconductor memory device.
Implementation Method 1
When an etching gas containing bromine is used, a protective film is formed on an inner surface of the memory hole
Implementation Method 2
using etching gases containing bromine and fluorine to form memory holes with a protective tungsten bromide film
Data Source
AI summary
A semiconductor memory device according to one embodiment includes a plurality of lower electrode films stacked separated from each other, an upper electrode film provided above the plurality of lower electrode films, a semiconductor pillar extending in an arrangement direction of the plurality of lower electrode films and the upper electrode film, a memory film provided between the semiconductor pillar and one of the plurality of lower electrode films and between the semiconductor pillar and the upper electrode film, and a metal-containing layer provided at least one of on a lower surface and an upper surface of the one of the plurality of lower electrode films and between the one of the plurality of lower electrode films and the memory film, the metal-containing layer having a composition different from a composition of the plurality of lower electrode films. The upper electrode film is in contact with the memory film.