Sidewall Junction Diffusion Barrier for Dopant Control
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Solution Overview
Problem
The existing sidewall contact process for semiconductor devices can lead to excessive diffusion of dopants, resulting in the generation of floating bodies and potential threshold voltage drops in vertical transistor structures, particularly when forming one-side junctions without a diffusion barrier.
Innovation Solution
A method is introduced that involves forming a diffusion barrier region with an interstitial impurity like carbon, which prevents excessive dopant diffusion by ion implantation, and then forming a sidewall junction through annealing of a doped polysilicon layer, ensuring controlled dopant distribution and preventing floating body formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a diffusion barrier is formed between the buried bit line and the side junction, then dopant diffusion is controlled, but agglomeration is caused
Solution Approach 1:
The patent introduces a diffusion barrier layer as an intermediary substance between the doped polysilicon layer and the semiconductor substrate. This intermediate layer prevents direct contact and excessive diffusion while avoiding the agglomeration problems associated with alternative approaches. The diffusion barrier layer acts as a mediator that controls the interaction between the dopant source and the substrate.
2Object-generated harmful factors
If no diffusion barrier is formed and doped polysilicon layer is directly formed, then agglomeration is avoided, but excessive dopant diffusion occurs causing floating body generation
Solution Approach 1:
The patent applies local quality by creating a diffusion barrier layer only in specific regions where it is needed - between the doped polysilicon layer and the semiconductor substrate in the side junction area. This localized application prevents excessive diffusion and floating body generation in critical regions while maintaining the benefits of direct contact in other areas. The barrier layer's properties are tailored to the local requirements of dopant control.
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 effectively suppresses excessive dopant diffusion, preventing floating body generation and maintaining stable transistor operation by controlling the depth and concentration of the sidewall junction, thereby enhancing the reliability of semiconductor devices.
Implementation Method 1
forming a diffusion barrier region with an interstitial impurity like carbon, which prevents excessive dopant diffusion by ion implantation
Implementation Method 2
forming a sidewall junction through annealing of a doped polysilicon layer
Implementation Method 3
forming a sidewall junction through annealing of a doped polysilicon layer
Data Source
AI summary
A method for fabricating a semiconductor device includes forming a plurality of bodies that are each isolated from another by a trench and each include a diffusion barrier region with a sidewall exposed to the trench, forming a doped layer gap-filling the trench, forming a sidewall junction at the exposed sidewall of the diffusion barrier region by annealing the doped layer, and forming a conductive line coupled with the sidewall junction to fill the trench.