Semiconductor Channel Dopant Layer Design for Threshold Voltage Control
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Solution Overview
Problem
As semiconductor devices become highly integrated, MOS field effect transistors are scaled down, leading to deteriorated operating characteristics, particularly in terms of integration density and electrical performance.
Innovation Solution
A semiconductor device design that includes a semiconductor substrate with a well dopant layer, a channel dopant layer, and source/drain regions, where the channel dopant layer has a higher dopant concentration than the channel region, and a dopant diffusion barrier layer to maintain dopant concentration gradients, enhancing integration density and electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MOS field effect transistors are scaled down for high integration, then integration density is improved, but electrical characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a channel dopant layer with higher dopant concentration specifically in the channel region, while maintaining lower dopant concentration in other regions. This localized doping approach improves electrical characteristics in the critical channel area without adversely affecting other parts of the device, thereby resolving the contradiction between scaling for integration density and maintaining electrical performance.
Solution Approach 2:
The patent changes the dopant concentration parameter by introducing a channel dopant layer with higher dopant concentration than the well dopant layer. This parameter change in the channel region compensates for the effects of device scaling, allowing smaller transistors to maintain good electrical characteristics while achieving higher integration density.
2Manufacturing precision
If dopant concentration is increased to improve electrical characteristics, then threshold voltage control is improved, but dopant diffusion increases causing channel length reduction
Solution Approach 1:
The patent applies preliminary action by forming the channel dopant layer before forming the source/drain regions. This preliminary doping of the channel region establishes the desired dopant concentration profile and threshold voltage characteristics before subsequent processing steps. The channel dopant layer acts as a pre-established reservoir that compensates for dopant diffusion from source/drain regions, preventing channel length reduction while maintaining good threshold voltage control.
Solution Approach 2:
The patent applies preliminary anti-action by introducing a channel dopant layer with higher dopant concentration to counteract the harmful effects of dopant diffusion from source/drain regions. This preliminary opposing doping action prevents the net dopant diffusion that would otherwise reduce the effective channel length, thereby maintaining both threshold voltage control and channel dimensions.
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 design improves integration density and electrical characteristics by maintaining dopant concentration gradients, reducing threshold voltage variations and preventing channel length reduction due to dopant diffusion, thereby enhancing the performance of MOS transistors.
Implementation Method 1
a dopant diffusion barrier layer to maintain dopant concentration gradients, preventing channel length reduction due to dopant diffusion
Data Source
AI summary
A semiconductor device includes a semiconductor substrate including a well dopant layer having a first conductivity type, a gate electrode on the well dopant layer, a channel dopant layer in the well dopant layer and spaced apart from a top surface of the semiconductor substrate, a channel region between the gate electrode and the channel dopant layer, and source/drain regions in the well dopant layer at both sides of the gate electrode. The channel dopant layer and the channel region have the first conductivity type. The source/drain regions have a second conductivity type. A concentration of dopants having the first conductivity type in the channel dopant layer is higher than a concentration of dopants having the first conductivity type in the channel region. The semiconductor device may be used in a sense amplifier of a memory device.