Silicon Nitride Charge Trapping Layer Oxidation Prevention
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Solution Overview
Problem
The silicon nitride layer in charge trapping type non-volatile memory devices is deteriorated during successive thermal processes, leading to reduced charge trapping sites and compromised electrical characteristics due to partial oxidation, which affects the programming and erasing operations.
Innovation Solution
A method involving the formation of a thin silicon oxide layer on one area of the substrate using a radical oxidation process, while preventing oxidation of the silicon nitride layer on another area by using a blocking layer, ensuring sufficient charge trapping sites without forming an oxide layer between the nitride and dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon nitride layer is formed as a charge trapping layer in successive thermal processes, then the memory device can store data, but the silicon nitride layer undergoes partial oxidation which reduces charge trapping sites and deteriorates electrical characteristics
Solution Approach 1:
A thin oxide layer is formed on the substrate surface before forming the silicon nitride layer. This preliminary oxide layer acts as a barrier that prevents oxygen from diffusing into and oxidizing the silicon nitride layer during subsequent thermal processes, thereby preserving the charge trapping sites and electrical characteristics of the memory device
Solution Approach 2:
The thin oxide layer serves as an intermediary barrier layer between the substrate and the silicon nitride charge trapping layer. This intermediary layer blocks the harmful oxidation effect while allowing the silicon nitride layer to maintain its charge trapping functionality, thus resolving the contradiction between reliability and compositional stability
2Object-affected harmful factors
If the silicon nitride layer thickness is reduced due to partial oxidation, then the oxidation effect is minimized, but the bond strength between silicon and nitride increases which further reduces charge trapping sites
Solution Approach 1:
The thin oxide layer is formed in advance before the silicon nitride layer deposition, creating a protective barrier that prevents oxygen penetration. This preliminary protective action ensures that the silicon nitride layer maintains its original thickness and composition throughout the thermal processing steps, preserving both the charge trapping sites and the bonding characteristics necessary for reliable programming and erasing operations
3Reliability
If a thick dielectric layer is used to compensate for the reduced dielectric constant caused by oxidation, then the electrical insulation is maintained, but the overall device complexity and manufacturing difficulty increase
Solution Approach 1:
By forming the thin oxide protective layer at the beginning, the silicon nitride layer is protected from oxidation throughout the manufacturing process. This prevents the dielectric constant reduction that would otherwise occur, eliminating the need to increase dielectric layer thickness for compensation. The layer structure remains simple and manageable while maintaining adequate electrical insulation properties
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 maintains the thickness and charge trapping sites of the silicon nitride layer, improving the electrical characteristics of the charge trapping type non-volatile memory device by preventing oxidation and enhancing programming and erasing operations.
Implementation Method 1
a blocking layer in the first area of the substrate. The oxide layer may be formed by a radical oxidation process in which oxygen radicals react with the second area of the substrate
Data Source
AI summary
In a method of forming a thin layer (e.g., a charge trapping nitride layer) of a semiconductor device (e.g. a charge trapping type non-volatile memory device), the nitride layer may be formed on a first area of a substrate. A blocking layer may be formed on the nitride layer. An oxide layer may be formed on a second area of the substrate while preventing or reducing an oxidation of the nitride layer by a radical oxidation process in which oxygen radicals react with the second area of the substrate and the blocking layer in the first area of the substrate. The nitride layer may ensure sufficient charge trapping sites and may have a uniform thickness without oxidation thereof in the radical oxidation process.