Top Oxide Regrowth for Memory Cell Leakage
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Solution Overview
Problem
As semiconductor memory devices are scaled down, the quality of the top oxide layer deteriorates, leading to charge leakage, which affects the reliability and efficiency of memory cell operations.
Innovation Solution
The method involves removing the first poly and top oxide from a memory cell and reforming a second top oxide around the charge storage element, potentially using a sacrificial layer and oxidation processes to improve the quality and thickness of the top oxide, thereby reducing charge leakage paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device dimensions are scaled down to achieve higher circuit density, then circuit density is improved, but top oxide quality deteriorates leading to charge leakage
Solution Approach 1:
The patent segments the top oxide formation process into multiple stages: initial top oxide formation, charge storage layer deposition, and secondary top oxide regrowth. This segmentation allows each layer to be optimized independently, with the secondary regrowth specifically targeting quality improvement in the scaled-down device environment where charge leakage is problematic.
Solution Approach 2:
The patent performs preliminary actions by forming the first top oxide and charge storage layer before finalizing the top oxide structure. This preliminary structure enables subsequent regrowth processes to focus specifically on improving top oxide quality without compromising the already-established charge storage architecture, thereby addressing charge leakage issues in high-density devices.
2Reliability
If top oxide quality is improved through replacement and regrowth, then charge leakage is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into the secondary top oxide regrowth process: it simultaneously restores top oxide quality, provides electrical isolation, and protects the charge storage layer. This consolidation achieves multiple objectives in a single process step, reducing the need for additional separate manufacturing steps despite the initial complexity of the replacement approach.
Solution Approach 2:
The charge storage layer acts as an intermediary element between the first and second top oxide layers. This intermediary structure enables the replacement process by providing a foundation for secondary regrowth while maintaining device functionality, thereby managing manufacturing complexity through a structured intermediate state.
3Quantity of substance
If charges are trapped in the charge storage layer for data storage, then memory function is achieved, but charge leakage through top oxide increases
Solution Approach 1:
The patent applies local quality by ensuring that the charge storage layer maintains its charge-trapping capability in specific regions while the top oxide is locally improved through secondary regrowth to prevent leakage. This localized approach allows charge storage functionality to be preserved in areas where it is needed while addressing leakage paths in the top oxide structure.
Solution Approach 2:
The patent converts the potential harm of charge leakage into a benefit by using the charge storage layer itself as a platform for secondary top oxide regrowth. The regrowth process leverages the existing charge storage structure to create a higher quality top oxide that prevents leakage, thereby transforming the charge storage architecture from a potential leakage source into a foundation for improved isolation.
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 quality of the top oxide layer, reducing charge leakage and improving the performance and reliability of memory cells, particularly in high-density memory devices.
Implementation Method 1
forming a second top oxide around the charge storage element
Data Source
AI summary
Methods of replacing/reforming a top oxide around a charge storage element of a memory cell and methods of improving quality of a top oxide around a charge storage element of a memory cell are provided. The method can involve removing a first poly over a first top oxide from the memory cell; removing the first top oxide from the memory cell; and forming a second top oxide around the charge storage element. The second top oxide can be formed by oxidizing a portion of the charge storage element or by forming a sacrificial layer over the charge storage element and oxidizing the sacrificial layer to a second top oxide.