Non-Volatile Memory Trench Formation via Segmented Etching
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Solution Overview
Problem
The formation of trenches for isolation in non-volatile memory devices using dry etch processes generates by-products that stagnate, leading to increased manufacturing time and potential defects due to tension between cleaning solutions and stack layers, causing inclination and reduced yield.
Innovation Solution
A method involving repeated dry etch and cleaning processes to form trenches, including a primary dry etch process followed by a wet cleaning process, and a secondary dry etch process with a final dry cleaning step to prevent residue stagnation and maintain trench depth, thereby preventing stack layer inclination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single dry etch process is used to form trenches, then the etching speed is fast, but by-products stagnate and cause manufacturing time increase and defects
Solution Approach 1:
The single dry etch process is segmented into multiple alternating dry etch and cleaning processes. This segmentation allows residues to be removed at intermediate stages, preventing stagnation and enabling faster overall manufacturing without compromising cleanliness.
Solution Approach 2:
The manufacturing process uses periodic alternation between dry etching and cleaning steps. This periodic action maintains etching efficiency by removing residues that would otherwise slow down subsequent etching operations, thereby reducing total manufacturing time.
2Reliability
If a cleaning process is performed after trench formation, then residues are removed, but the cleaning solution creates tension with stack layers causing inclination
Solution Approach 1:
Cleaning actions are performed preliminarily during the trench formation process itself, rather than as a final step after complete trench formation. This preliminary cleaning prevents residue accumulation that would cause inclination, while the shallow trench depth at cleaning stages minimizes tension effects on stack layers.
Solution Approach 2:
The process dynamically adjusts the depth of trenches during different stages. Shallow trenches are formed and cleaned alternately, and only after final cleaning is the trench deepened to target depth. This dynamic approach ensures cleanliness without exposing stack layers to excessive cleaning solution tension.
3Manufacturing precision
If multiple dry etch and cleaning processes are repeated, then residues are effectively removed and inclination is prevented, but manufacturing time increases
Solution Approach 1:
The trench formation is segmented into multiple shallow etching stages with intermediate cleaning, rather than one deep etching stage. This segmentation achieves complete residue removal and prevents inclination, while the cumulative time is optimized by performing cleaning only when trenches are shallow.
Solution Approach 2:
The process maintains continuous useful action by alternating etching and cleaning without idle periods. Each cleaning step is immediately followed by another etching step, ensuring that the trenches reach target depth with complete cleanliness and no inclination, optimizing the balance between precision and time.
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 reduces manufacturing time, increases yield, and enhances the reliability of non-volatile memory devices by effectively removing residues and maintaining trench integrity.
Implementation Method 1
An etch process for forming the trenches for isolation is performed using a dry etch process
Implementation Method 2
a wet cleaning process for removing residues generated in the primary dry etch process
Implementation Method 3
performing a dry cleaning process for removing residues generated in the secondary dry etch process
Data Source
AI summary
A method of manufacturing non-volatile memory devices includes forming a gate insulating layer and a first conductive layer over a semiconductor substrate, etching the first conductive layer and the gate insulating layer to expose part of the semiconductor substrate, forming trenches at a target depth of the semiconductor substrate by repeatedly performing a dry etch process for etching the exposed semiconductor substrate and a cleaning process for removing residues generated in the dry etch process, forming isolation layers within the trenches, forming a dielectric layer on a surface of the entire structure in which the isolation layers are formed, and forming a second conductive layer on the dielectric layer.