Memory Transistor Diffusion Layout for Breakdown Voltage Stability
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Solution Overview
Problem
The existing semiconductor memory devices face challenges in maintaining high breakdown voltage and current flow efficiency due to issues with impurity concentration and diffusion layer configurations in high voltage transistors, leading to reduced performance and reliability.
Innovation Solution
The semiconductor memory device incorporates a specific configuration of high-concentration and low-concentration N-type diffusion layers in high voltage transistors, with the high-concentration layer positioned to maintain impurity concentration and prevent depletion, enhancing breakdown voltage and current flow efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional diffusion layer configuration is used in high voltage transistors, then the device structure is simple, but the breakdown voltage decreases and current flow efficiency is reduced
Solution Approach 1:
The diffusion layer is segmented into multiple distinct layers with different impurity concentrations. Specifically, a first diffusion layer and a second diffusion layer are formed with different N-type impurity concentrations, allowing each layer to perform optimized functions for breakdown voltage maintenance and current flow efficiency.
Solution Approach 2:
Different regions of the diffusion structure are assigned different impurity concentrations tailored to local requirements. The first diffusion layer has a higher impurity concentration optimized for breakdown voltage, while the second diffusion layer has a lower impurity concentration optimized for current flow efficiency.
2Reliability
If impurity concentration is increased to maintain breakdown voltage, then breakdown voltage is maintained, but hot carrier generation increases causing performance degradation
Solution Approach 1:
The diffusion structure is divided into multiple layers with different impurity concentrations. The first diffusion layer with higher impurity concentration maintains breakdown voltage, while the second diffusion layer with lower impurity concentration reduces hot carrier generation by providing a transition region.
Solution Approach 2:
Impurity concentration is locally optimized in different diffusion layers. The first diffusion layer has high impurity concentration where breakdown voltage maintenance is critical, while the second diffusion layer has lower impurity concentration where hot carrier generation needs to be minimized.
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 configuration effectively maintains high breakdown voltage and prevents current reduction, ensuring reliable performance by trapping hot carriers and optimizing impurity distribution within the transistor structure.
Implementation Method 1
a first diffusion layer disposed in the semiconductor substrate, connected to a first contact electrode extending in the first direction, and containing a first conductive-type impurity, a second diffusion layer disposed in the semiconductor substrate, provided between the first region and the first diffusion layer, and containing the first conductive-type impurity
Implementation Method 2
This configuration effectively maintains high breakdown voltage and prevents current reduction, ensuring reliable performance by trapping hot carriers and optimizing impurity distribution within the transistor structure
Data Source
AI summary
A transistor for a semiconductor memory device includes a gate insulating film on a semiconductor substrate, a gate electrode on the gate insulating film, a side wall insulating film on both side surfaces of the gate electrode, a first diffusion layer disposed in the semiconductor substrate, connected to a contact electrode extending in a first direction intersecting a surface of the semiconductor substrate, and containing a first conductive-type impurity, a second diffusion layer disposed in the semiconductor substrate between the first diffusion layer and a region of the semiconductor substrate underneath the gate electrode, and containing the first conductive-type impurity, and a third diffusion layer disposed in the semiconductor substrate between the first diffusion layer and the second diffusion layer, connected to the second diffusion layer, and containing the first conductive-type impurity. A concentration of the second diffusion layer is higher than a concentration of the third diffusion layer.