UV Light Shielding Films in Non-Volatile Memory Devices
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Solution Overview
Problem
Conventional non-volatile semiconductor memory devices face challenges in regulating threshold voltage due to excessive electron trapping caused by UV light during the fabrication process, leading to increased threshold voltage and reduced reliability in write and erase operations.
Innovation Solution
A non-volatile semiconductor memory device configuration that includes a first UV light shielding film covering the bit line isolation portion and a second UV light shielding film covering the memory cell region, effectively blocking UV light and reducing electron trapping, thereby minimizing threshold voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If UV light shielding film is provided to cover the memory cell region, then UV light entering the memory cell region is reduced, but bit lines may be short-circuited via the UV light shielding film
Solution Approach 1:
The UV light shielding film is divided into two separate films: a first UV light shielding film covering the bit line isolation portion and a second UV light shielding film covering the memory cell region. This segmentation allows each film to perform its specific function independently, preventing bit line short circuits while effectively blocking UV light from the memory cell region.
Solution Approach 2:
Different regions are provided with different UV light shielding configurations: the bit line isolation portion has a first UV light shielding film, while the memory cell region has a second UV light shielding film. This local differentiation ensures that UV light is blocked where needed without creating short circuit risks in the bit line area.
2Object-affected harmful factors
If a single UV light shielding film covers the entire region, then UV light is blocked, but manufacturing complexity increases and bit line contacts cannot be properly formed
Solution Approach 1:
The UV light shielding function is segmented into two separate films positioned at different locations and formed at different stages of the manufacturing process. This reduces the complexity of forming a single comprehensive shielding film while achieving the same UV protection effect.
Solution Approach 2:
The first UV light shielding film is formed on the bit line isolation portion before forming bit line contacts, preventing UV light from affecting the isolation regions during subsequent processing. The second UV light shielding film is then formed to protect the memory cell region, creating a staged approach that simplifies manufacturing.
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 achieves reduced local variations in threshold voltage and enhanced reliability by effectively blocking UV light, ensuring stable write and erase operations in non-volatile semiconductor memory devices.
Implementation Method 1
a first UV light shielding film formed on the semiconductor substrate and covering at least a portion of the bit line isolation portion or a portion of the semiconductor substrate in the bit line contact region
Data Source
AI summary
A non-volatile semiconductor memory device includes a plurality of memory cell regions including a plurality of bit lines, a plurality of word lines intersecting the plurality of bit lines, and a first insulating film formed in a region between any two adjacent bit lines, a bit line contact region including bit line contacts connected to the plurality of bit lines, a first UV light shielding film covering at least a portion of the semiconductor substrate in the bit line contact region, an interlayer insulating film, and a second UV light shielding film covering the plurality of memory cell regions. The first UV light shielding film effectively reduces or blocks UV light generated during a fabrication step.