Oxide TFT Diffusion Barrier Structure for Anneal Stability
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Solution Overview
Problem
Existing thin film transistors (TFTs) made of oxide semiconductors face challenges in preventing the diffusion of metallic elements during anneal processes, which can alter the material composition and degrade transistor characteristics.
Innovation Solution
Incorporation of a dielectric diffusion barrier liner between the bottom gate dielectric and active layer, and optionally a capping dielectric diffusion barrier liner, to prevent the out-diffusion of metallic elements, thereby maintaining the integrity of the active layer composition and transistor properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anneal process is performed to improve transistor characteristics, then electrical properties are enhanced, but metallic elements diffuse and alter material composition
Solution Approach 1:
A dielectric diffusion barrier liner is introduced as an intermediary layer between the active layer and surrounding structures. This liner selectively blocks metallic element diffusion while permitting anneal process benefits to reach the active layer, thus mediating between composition stability and electrical property enhancement
Solution Approach 2:
The diffusion barrier liner is applied locally at specific interfaces where metallic element diffusion occurs, rather than uniformly throughout the entire structure. This targeted approach prevents composition alteration only where needed, maintaining local material stability during annealing
2Stability of the object's composition
If dielectric diffusion barrier liner is added to prevent metallic element diffusion, then material composition is preserved, but device structure becomes more complex
Solution Approach 1:
The diffusion barrier protection is segmented into discrete liner layers positioned only at critical interfaces where metallic element diffusion is problematic. This segmentation avoids adding complexity to the entire device structure while providing targeted protection where needed
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 dielectric diffusion barrier effectively blocks metallic element diffusion, preserving the material composition and enhancing the electrical properties of the thin film transistors, ensuring stable performance.
Implementation Method 1
a dielectric diffusion barrier liner between the bottom gate dielectric and active layer, and optionally a capping dielectric diffusion barrier liner, to prevent the out-diffusion of metallic elements
Data Source
AI summary
A semiconductor device includes an insulating layer having formed therein a gate electrode and overlying a substrate, a stack of a gate dielectric including a gate dielectric material, a dielectric diffusion barrier liner including a dielectric diffusion barrier material, and an active layer overlying a top surface of the gate electrode, and a source electrode and a drain electrode contacting a respective portion of a top surface of the active layer. The dielectric diffusion barrier material is different from the gate dielectric material and is selected from a dielectric metal oxide material and a dielectric compound of silicon, and suppresses loss of metallic elements during subsequent anneal processes.