Buried Gate Fabrication via Anti-Diffusion Ion Implantation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor device fabrication, the formation of buried gates is hindered by the difficulty in creating landing plugs due to decreasing open areas, leading to a trade-off between cell contact resistance and refresh performance, as increased dopant concentration in storage node contact plugs enhances resistance but deteriorates refresh performance.
Innovation Solution
The method involves forming first plugs over a substrate, creating contact holes, ion-implanting an anti-diffusion material like carbon into the plugs, and forming second plugs to fill these holes, which suppresses dopant diffusion and enhances cell contact resistance and refresh performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the concentration of dopant in storage node contact plugs is increased to increase cell contact resistance, then cell contact resistance is improved, but refresh performance deteriorates due to increased dopant diffusion into the substrate
Solution Approach 1:
An anti-diffusion material layer is introduced as an intermediary between the doped contact plug and the substrate. This intermediate layer acts as a barrier that prevents dopant atoms from diffusing into the substrate while allowing the contact plug to maintain its desired dopant concentration for low contact resistance
Solution Approach 2:
The anti-diffusion material is implanted into the contact plug before the dopant diffusion process occurs. This preliminary action creates a protective barrier in advance that prevents the harmful dopant diffusion into the substrate, allowing the dopant to remain confined to the contact plug region
2Reliability
If the concentration of dopant in storage node contact plugs is decreased to improve refresh performance, then refresh performance is improved, but cell contact resistance increases
Solution Approach 1:
The anti-diffusion material serves as a mediator that decouples the relationship between dopant concentration and dopant diffusion. This allows the contact plug to have low dopant concentration (for good refresh performance) without suffering from dopant diffusion into the substrate, as the intermediate layer blocks the diffusion path
3Productivity
If open areas of bit line contact and storage node contact are decreased, then device integration is improved, but formation of landing plug becomes difficult
Solution Approach 1:
The anti-diffusion material is implanted into the contact plug structure before the landing plug formation process. This preliminary action ensures that the anti-diffusion barrier is already in place, allowing subsequent processing steps to proceed without concern for dopant diffusion issues that would complicate landing plug formation
Solution Approach 2:
The invention changes the physical and chemical parameters of the contact plug by introducing anti-diffusion material, which fundamentally alters the diffusion characteristics. This parameter change enables the use of smaller open areas while maintaining proper dopant confinement, thus supporting higher device integration
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 reduces dopant diffusion into the substrate, increasing the dopant concentration in plugs while maintaining low cell contact resistance and improving refresh performance by preventing dopant diffusion into the substrate.
Implementation Method 1
ion-implanting an anti-diffusion material into the first plugs
Implementation Method 2
the amount of dopant diffused into the substrate 11 is increased
Data Source
AI summary
A method for fabricating a semiconductor device includes forming first plugs over a substrate, forming contact holes that expose the first plugs, ion-implanting an anti-diffusion material into the first plugs, and forming second plugs filling the contact holes.