Semiconductor Floating Gate Insulating Film Thickness
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Solution Overview
Problem
The narrowing of floating gate electrodes in flash memory devices leads to increased electric field concentration, which results in leakage current and difficulties in forming control gate electrodes, impacting programming properties and product yield.
Innovation Solution
A semiconductor device with a multilayered interelectrode insulating film structure, where the silicon nitride film is thicker above the floating gate electrode and thinner along its sidewall and on the element isolation insulating film, reducing electric field concentration and facilitating control gate electrode formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the width of floating gate electrodes is narrowed to increase storage capacity, then storage capacity is improved, but electric field concentration increases causing leakage current and degraded programming properties
Solution Approach 1:
The interelectrode insulating film is designed with spatially varying thickness: thinner regions above floating gate electrodes to reduce electric field concentration and leakage current, and thicker regions in other areas to maintain charge storage capability. This local differentiation resolves the contradiction by optimizing the film structure for different functional requirements in different locations.
Solution Approach 2:
The thickness parameter of the interelectrode insulating film is changed from uniform to non-uniform distribution. By controlling the film thickness to be smaller above the floating gate electrodes, the electric field concentration is reduced, thereby improving programming properties while maintaining narrow electrode widths for high storage capacity.
2Quantity of substance
If the width of floating gate electrodes is narrowed to increase storage capacity, then storage capacity is improved, but control gate electrode formation becomes difficult due to narrowed gaps
Solution Approach 1:
The interelectrode insulating film thickness is locally optimized: thinner above floating gate electrodes to facilitate control gate filling, and thicker in lateral regions to maintain charge storage. This local differentiation enables control gate electrode formation in narrowed gaps while preserving storage capacity.
3Ease of manufacture
If the interelectrode insulating film is thinned to facilitate control gate electrode formation, then ease of manufacture is improved, but charge storage capability may be compromised
Solution Approach 1:
The interelectrode insulating film is designed with different thicknesses in different regions: thinner above floating gate electrodes to enable control gate filling, and thicker in lateral regions to maintain charge storage capability. This spatial differentiation resolves the contradiction between manufacturability and charge storage.
Solution Approach 2:
The interelectrode insulating film is segmented into functionally distinct regions with different thicknesses: one region optimized for control gate formation and another region optimized for charge storage. This segmentation allows each region to perform its specific function effectively without compromising the other.
Data Source
AI summary
A semiconductor device includes a multilayered interelectrode insulating film formed between a charge storage layer and a control electrode layer. The interelectrode insulating film is formed in a first region above an upper surface portion of the element isolation insulating film, a second region along a sidewall portion of the charge storage layer, and a third region above an upper surface portion of the charge storage layer. The interelectrode insulating film includes a stack of first silicon oxide film, a silicon nitride film, and a second silicon oxide film. The silicon nitride film is relatively thicker in the third region compared to the first region and compared to at least a portion of the second region.