Anti-fuse Memory Element Using Epitaxial Layer on SOI Substrate
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Solution Overview
Problem
The challenge in semiconductor devices using a silicon on insulator (SOI) substrate is the difficulty in forming a high-concentration impurity diffusion region on the upper surface for capacitor structures, which leads to depletion issues and increased power consumption due to low drain withstand voltage, making it hard to perform write operations effectively.
Innovation Solution
The solution involves setting an insulating film between the gate electrode and an epitaxial layer as the target for dielectric breakdown in the anti-fuse element, using a high-concentration diffusion region to prevent depletion and reduce power consumption by ensuring a reliable dielectric breakdown with lower voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-concentration impurity diffusion region is formed on the upper surface of the SOI substrate to create a capacitor structure, then depletion can be prevented and dielectric breakdown can be achieved, but it is difficult to form such a region on the SOI substrate due to manufacturing constraints
Solution Approach 1:
The patent transitions from forming the capacitor structure in the vertical dimension (high-concentration impurity diffusion region on the substrate surface) to forming it in the lateral dimension (epitaxial layer with high-concentration diffusion region adjacent to the gate electrode). This dimensional shift allows achieving the same electrical function without the manufacturing difficulties of the original approach on SOI substrates.
Solution Approach 2:
The patent introduces an epitaxial layer as an intermediary structure between the gate electrode and the substrate. This epitaxial layer contains the high-concentration diffusion region and is positioned adjacent to the gate electrode side wall, serving as a mediator to provide the necessary capacitor function without directly modifying the substrate surface.
2Extent of automation
If high voltage is applied to the gate electrode to achieve dielectric breakdown in conventional anti-fuse elements, then information can be written, but the selection transistor deteriorates due to low drain withstand voltage on SOI substrate
Solution Approach 1:
The epitaxial layer with high-concentration diffusion region acts as an intermediary that enables dielectric breakdown at lower voltages. By positioning this structure adjacent to the gate electrode, it facilitates charge accumulation that assists in breaking down the insulating film, thereby reducing the voltage stress on the selection transistor.
Solution Approach 2:
The patent changes the electrical parameters of the system by introducing the epitaxial layer with high-concentration diffusion region, which alters the electric field distribution and enables dielectric breakdown to occur at lower gate electrode voltages, thus protecting the selection transistor from excessive voltage stress.
3Loss of information
If the insulating film between the bulk silicon substrate and gate electrode is set as the target for dielectric breakdown, then information storage is achieved, but the electric field is hardly applied to the gate electrode when the channel is depleted
Solution Approach 1:
The epitaxial layer with high-concentration diffusion region serves as a mediator that ensures electric field application to the gate electrode regardless of channel depletion status. This intermediary structure provides a pathway for charge accumulation that maintains the electric field necessary for dielectric breakdown even when the channel is depleted.
Solution Approach 2:
The patent implements preliminary action by forming the epitaxial layer with high-concentration diffusion region before the write operation. This pre-formed structure ensures that the electric field can be effectively applied to the gate electrode during the write operation, preventing the issue of field application failure due to channel depletion.
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 improves the performance and reliability of semiconductor devices by enabling effective dielectric breakdown and reducing power consumption, while preventing deterioration of selection transistors on the SOI substrate.
Implementation Method 1
writing of information is performed by causing dielectric breakdown of the insulating film
Implementation Method 2
an epitaxial layer including a high-concentration diffusion region
Data Source
AI summary
An insulating film, which is sandwiched between a gate electrode formed on an SOI layer constituting an SOI substrate and an epitaxial layer formed on the SOI layer and including a high-concentration diffusion region and is formed in contact with a side wall of the gate electrode, is set as a target of dielectric breakdown in a write operation in an anti-fuse element.