Flash Memory Wordline Air Gap Etch for Data Retention
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Solution Overview
Problem
Flash memory devices experience data retention issues due to charge loss caused by wordline coupling and contamination, which existing techniques have not adequately addressed.
Innovation Solution
An etch process is employed post-wordline definition to increase data retention by forming a larger air gap between wordline structures, reducing capacitive coupling and contamination, and using an electrically insulative layer to protect the memory device from oxidation and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication processes are used without post-wordline etching, then manufacturing simplicity is maintained, but data retention is poor due to charge loss from wordline coupling and contamination
Solution Approach 1:
An etch process is performed after wordline definition to proactively remove contamination and create air gaps before subsequent processing steps. This preliminary cleaning action prevents charge loss mechanisms from developing, thereby improving data retention without compromising manufacturing feasibility
Solution Approach 2:
An air gap is introduced as an intermediary structure between wordline structures. This air gap acts as a physical barrier that reduces capacitive coupling between adjacent wordlines, thereby reducing charge loss and improving data retention while maintaining manufacturing simplicity
2Quantity of substance
If wordline structures are placed close together to increase storage density, then storage capacity is improved, but charge loss increases due to stronger capacitive coupling between adjacent wordlines
Solution Approach 1:
An air gap is introduced as an intermediary structure between closely-spaced wordline structures. This air gap acts as a physical barrier that reduces capacitive coupling between adjacent wordlines, thereby reducing charge loss and improving data retention while maintaining manufacturing simplicity
Solution Approach 2:
The etch process removes material to create air gaps between wordline structures, extracting the harmful capacitive coupling effect from the system. By removing the dielectric material between adjacent wordlines, the patent eliminates the charge loss pathway while maintaining close spacing for high density
3Reliability
If no air gap is formed between wordline structures, then manufacturing simplicity is maintained, but charge loss occurs due to capacitive coupling, reducing data retention
Solution Approach 1:
An etch process is performed after wordline definition to proactively remove contamination and create air gaps before subsequent processing steps. This preliminary cleaning action prevents charge loss mechanisms from developing, thereby improving data retention without compromising manufacturing feasibility
Solution Approach 2:
An air gap is introduced as an intermediary structure between wordline structures. This air gap acts as a physical barrier that reduces capacitive coupling between adjacent wordlines, thereby reducing charge loss and improving data retention while maintaining manufacturing simplicity
4Reliability
If active areas are not protected during fabrication, then manufacturing simplicity is maintained, but contamination causes shorts and charge loss, degrading device performance
Solution Approach 1:
An etch process is performed after wordline definition to proactively remove contamination and create air gaps before subsequent processing steps. This preliminary cleaning action prevents charge loss mechanisms from developing, thereby improving data retention without compromising manufacturing feasibility
Solution Approach 2:
An air gap is introduced as an intermediary structure between wordline structures. This air gap acts as a physical barrier that reduces capacitive coupling between adjacent wordlines, thereby reducing charge loss and improving data retention while maintaining manufacturing simplicity
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 solution effectively reduces charge loss and increases data retention by decoupling wordline structures and protecting the memory device from contamination, enhancing the breakdown voltage and overall performance of the flash memory device.
Implementation Method 1
reducing capacitive coupling and contamination
Implementation Method 2
protect the memory device from oxidation and contamination
Data Source
AI summary
Embodiments of the present disclosure are directed towards use of an etch process post wordline definition to improve data retention in a flash memory device. In one embodiment, a method includes forming a plurality of wordline structures on a substrate, wherein individual wordline structures of the plurality of wordline structures include a control gate having an electrically conductive material and a cap having an electrically insulative material formed on the control gate, depositing an electrically insulative material to form a liner on a surface of the individual wordline structures, and etching the liner to remove at least a portion of the liner. Other embodiments may be described and/or claimed.