Non-volatile Memory Coating for Mobile Ion Diffusion Control
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Solution Overview
Problem
Data retention in non-volatile semiconductor memory devices is compromised due to shifts in threshold voltage distributions, primarily affecting higher programmed states, caused by mobile ion diffusion during the assembly process, which can lead to data corruption.
Innovation Solution
Applying a coating, such as an acrylic resin, to the substrate or leader frame before attaching the memory chip, or using a patterned barrier material to reduce mobile ion diffusion, effectively minimizing threshold voltage shifts and enhancing data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mobile ions are allowed to diffuse during assembly, then manufacturing is easier and faster, but threshold voltage shifts occur causing data retention problems
Solution Approach 1:
A barrier layer is introduced as an intermediary substance between the copper trace and the floating gate to prevent mobile ion diffusion. This barrier layer acts as a mediator that blocks the harmful interaction between copper ions and the memory structure, allowing fast assembly while maintaining data retention reliability.
Solution Approach 2:
The harmful mobile ions are extracted or blocked from reaching the floating gate by introducing a barrier layer. This removes the harmful factor (mobile ion diffusion) from the system while maintaining the beneficial aspects of the assembly process.
2Device complexity
If no barrier material is used, then device complexity is reduced, but threshold voltage distributions shift affecting data accuracy
Solution Approach 1:
A barrier layer is introduced as an intermediary substance between the copper trace and the floating gate to prevent mobile ion diffusion. This barrier layer acts as a mediator that blocks the harmful interaction between copper ions and the memory structure, allowing fast assembly while maintaining data retention reliability.
3Reliability
If barrier coating is applied to prevent mobile ion diffusion, then data retention is improved, but manufacturing process becomes more complex
Solution Approach 1:
A barrier layer is introduced as an intermediary substance between the copper trace and the floating gate to prevent mobile ion diffusion. This barrier layer acts as a mediator that blocks the harmful interaction between copper ions and the memory structure, allowing fast assembly while maintaining data retention reliability.
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 proposed solution significantly reduces threshold voltage variations in programmed blocks, thereby improving data retention and preventing data corruption, especially in multi-state memory devices.
Implementation Method 1
mobile ion diffusion during the assembly process
Data Source
AI summary
Mobile ion diffusion causes a shift in the threshold voltage of non-volatile storage elements in a memory chip, such as during an assembly process of the memory chip. To reduce or avoid such shifts, a coating can be applied to a printed circuit board substrate or a leader frame to which the memory chip is surface mounted. An acrylic resin coating having a thickness of about 10 μm may be used. A memory chip is attached to the coating using an adhesive film. Stacked chips may be used as well. Another approach provides metal barrier traces over copper traces of the printed circuit board, within a solder mask layer. The metal barrier traces are fabricated in the same pattern as the copper traces but are wider so that they at least partially envelop and surround the copper traces. Corresponding apparatuses and fabrication processes are provided.