3D Memory Array Isolation Structure for Low-Hydrogen TFT Stability
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Solution Overview
Problem
Existing semiconductor memories, particularly volatile memories like SRAM and DRAM, lose stored data when powered off, and non-volatile memories like FeRAM face challenges in maintaining data stability and efficiency due to hydrogen diffusion affecting transistor stability.
Innovation Solution
A 3D memory array with vertically stacked memory cells using thin film transistors (TFTs) and a low-hydrogen dielectric material to reduce hydrogen diffusion, combined with a ferroelectric memory film for polarization-based data storage, enhancing transistor stability and data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric materials are used in FeRAM, then manufacturing is easier, but hydrogen diffusion occurs affecting transistor stability and data retention
Solution Approach 1:
The patent changes the chemical composition parameters of the dielectric material by using silicon oxide with controlled hydrogen content (less than 5 atomic percent) instead of conventional dielectric materials. This parameter change reduces hydrogen diffusion into the transistor channel, improving transistor stability and data retention without requiring complex structural modifications.
Solution Approach 2:
The patent employs a composite structure combining a silicon oxide dielectric layer with specific hydrogen content control. This composite approach integrates material composition control with structural design to simultaneously achieve low hydrogen diffusion and maintain dielectric functionality for capacitor operation.
2Duration of action of stationary object
If FeRAM is used for non-volatile memory, then data retention is improved, but hydrogen diffusion reduces transistor stability
Solution Approach 1:
The patent controls the hydrogen concentration parameter in the silicon oxide dielectric material to be less than 5 atomic percent. This parameter control prevents hydrogen diffusion that would otherwise degrade transistor stability, thereby maintaining both data retention capability and transistor reliability in FeRAM devices.
3Productivity
If hydrogen-comprising precursors are used at high flowrate, then dielectric material deposition is faster, but hydrogen concentration increases causing transistor defects
Solution Approach 1:
The patent optimizes the hydrogen-comprising precursor flowrate parameter to achieve the desired hydrogen concentration (less than 5 atomic percent) in the silicon oxide dielectric material. This parameter optimization balances deposition speed with hydrogen concentration control, preventing transistor defects while maintaining manufacturing efficiency.
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 improves data retention and reduces errors in reading/writing operations by stabilizing TFTs through reduced hydrogen concentration, allowing for efficient and reliable data storage in non-volatile memory arrays.
Implementation Method 1
a ferroelectric memory film for polarization-based data storage
Implementation Method 2
a low-hydrogen dielectric material to reduce hydrogen diffusion
Data Source
AI summary
A memory cell includes a thin film transistor over a semiconductor substrate. The thin film transistor includes a memory film contacting a word line; and an oxide semiconductor (OS) layer contacting a source line and a bit line, wherein the memory film is disposed between the OS layer and the word line; and a dielectric material separating the source line and the bit line. The dielectric material forms an interface with the OS layer. The dielectric material comprises hydrogen, and a hydrogen concentration at the interface between the dielectric material and the OS layer is no more than 3 atomic percent (at %).