Trench Transistor Threshold Adjustment via Segmented Doping
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Solution Overview
Problem
Conventional threshold-adjusting ion implantation processes in semiconductor manufacturing reduce carrier mobility, leading to increased power consumption and reduced switching speed and current withstand capability of transistors.
Innovation Solution
A method involving the formation of a threshold-adjusting layer doped with specific ions in a trench of a semiconductor substrate, accompanied by a carrier drifting layer and a gate structure, to adjust the threshold voltage while minimizing the impact on carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If threshold-adjusting ion implantation process is performed to adjust threshold voltage, then threshold voltage is adjusted, but carrier mobility is reduced
Solution Approach 1:
The patent segments the semiconductor substrate into distinct regions: a threshold-adjusting region with doped ions for threshold voltage control, and a carrier drifting layer with high carrier mobility for efficient charge transport. This spatial segmentation allows independent optimization of threshold voltage and carrier mobility in different regions, resolving the contradiction between threshold adjustment and carrier mobility maintenance.
Solution Approach 2:
The patent applies local quality by creating a threshold-adjusting layer with specific doping concentration in certain regions while maintaining high carrier mobility in the carrier drifting layer. The doped ions are locally concentrated in the threshold-adjusting region rather than uniformly distributed, enabling threshold voltage adjustment without compromising overall carrier mobility in the channel region.
2Manufacturing precision
If doping concentration is increased to adjust threshold voltage, then threshold voltage is adjusted, but carrier mobility is reduced
Solution Approach 1:
The patent divides the semiconductor structure into a threshold-adjusting layer with high doping concentration and a carrier drifting layer with low doping concentration. This segmentation allows the threshold-adjusting layer to provide necessary threshold voltage adjustment through high doping, while the carrier drifting layer maintains high carrier mobility through low doping, eliminating the trade-off between threshold adjustment and carrier mobility.
Solution Approach 2:
The patent implements local quality by varying doping concentration spatially: high doping concentration in the threshold-adjusting layer for threshold control, and low doping concentration in the carrier drifting layer for high mobility. This localized doping strategy enables independent optimization of threshold voltage and carrier mobility in different spatial regions.
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 enhances carrier mobility and transistor performance by preventing diffusion of threshold-adjusting ions into the carrier drifting layer, thereby improving the short channel effect and overall transistor efficiency.
Implementation Method 1
The ion implantation process may be referred as a threshold-adjusting ion implantation process
Implementation Method 2
forming a carrier drifting layer on the threshold-adjusting layer
Data Source
AI summary
A method is provided for fabricating a transistor. The method includes providing a semiconductor substrate; and forming a trench in the semiconductor substrate by etching the semiconductor substrate. The methods also includes forming a threshold-adjusting layer doped with a certain type of threshold-adjusting ions to adjust the threshold voltage of the transistor on the semiconductor substrate in the trench; and forming a carrier drifting layer on the threshold-adjusting layer. Further the method includes forming a gate structure on the carrier drifting layer corresponding to the trench.