Mosaic Composite Oxide Semiconductor for Low Off-State TFTs
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Solution Overview
Problem
Current oxide semiconductor transistors, particularly those using a dual-layer stack of indium zinc oxide and IGZO, suffer from high subthreshold swing (S value) and threshold voltage (Vth) issues, leading to suboptimal electrical characteristics and reliability.
Innovation Solution
A composite oxide semiconductor with a mosaic pattern structure is introduced, comprising regions of indium oxide, gallium oxide, and zinc oxide with specific atomic ratios and sizes, enhancing the electrical properties and reliability of the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indium content is increased to improve field-effect mobility, then electrical conductivity is enhanced, but off-state current increases and device reliability deteriorates
Solution Approach 1:
The patent distributes indium-rich regions alongside regions with other metal elements (Ga, Al, Hf, Sn) in a mosaic pattern. This local variation ensures that high indium content areas provide mobility while adjacent areas with different compositions suppress off-state current, achieving both goals simultaneously through spatial differentiation.
Solution Approach 2:
The patent changes the compositional parameters by varying the metal element ratios (In:M:Zn where M is Ga, Al, Hf, or Sn) across different regions of the active layer. This parameter variation allows optimization of local electrical properties to balance mobility enhancement with off-state current suppression.
Data Source
AI summary
A novel material is provided. A composite oxide semiconductor includes a first region and a second region. The first region contains indium. The second region contains an element M (the element M is one or more of Ga, Al, Hf, Y, and Sn). The first region and the second region are arranged in a mosaic pattern. The composite oxide semiconductor further includes a third region. The element M is gallium. The first region contains indium oxide or indium zinc oxide. The second region contains gallium oxide or gallium zinc oxide. The third region contains zinc oxide.