CAAC Oxide Semiconductor Transistor with Graded Dopant Regions
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Solution Overview
Problem
Transistors with oxide semiconductors face challenges in miniaturization due to fluctuations in electric characteristics, particularly the short-channel effect, which affects their performance and reliability, especially when the channel length is shortened.
Innovation Solution
Incorporating a region with a dopant in the oxide semiconductor film, specifically forming two pairs of amorphous regions with varying dopant concentrations in the channel formation region, and using a c-axis aligned crystal (CAAC) oxide semiconductor to relieve the electric field and reduce fluctuations, thereby suppressing the short-channel effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the channel length is shortened for miniaturization, then the device size is reduced, but the short-channel effect causes fluctuation in electric characteristics
Solution Approach 1:
The patent applies local quality by creating regions with different dopant concentrations within the oxide semiconductor film. Specifically, it forms a first region with a first dopant concentration and a second region with a second dopant concentration that is higher than the first. This non-uniform dopant distribution allows the channel length to be shortened while maintaining electric characteristic stability through the compensated electric field effect of the high-concentration region.
2Length of moving object
If the channel length is shortened for miniaturization, then the device size is reduced, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent segments the oxide semiconductor film into distinct regions with different dopant concentrations. It forms a first region and a second region separately through selective doping processes, allowing independent control of dopant concentration in each region. This segmentation approach enables precise manufacturing control even when the overall channel length is reduced for miniaturization.
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
This approach allows for the miniaturization of transistors with improved electric characteristics and reliability, reducing the short-channel effect and maintaining function while reducing the size of semiconductor devices, leading to increased manufacturing efficiency and improved performance.
Implementation Method 1
an electric field generated in a drain region of the oxide semiconductor film can relieve an electric field applied to the channel formation region, and thus a short-channel effect can be suppressed
Data Source
AI summary
A semiconductor device in which fluctuation in electric characteristics due to miniaturization is less likely to be caused is provided. The semiconductor device includes an oxide semiconductor film including a first region, a pair of second regions in contact with side surfaces of the first region, and a pair of third regions in contact with side surfaces of the pair of second regions; a gate insulating film provided over the oxide semiconductor film; and a first electrode that is over the gate insulating film and overlaps with the first region. The first region is a CAAC oxide semiconductor region. The pair of second regions and the pair of third regions are each an amorphous oxide semiconductor region containing a dopant. The dopant concentration of the pair of third regions is higher than the dopant concentration of the pair of second regions.