Semiconductor Threshold Voltage Adjustment via Counter Doping
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Solution Overview
Problem
Conventional semiconductor devices have fixed threshold voltages, making them unadjustable and inflexible during manufacturing.
Innovation Solution
A semiconductor device design with a substrate, buried layers, diffusion regions, and a gate structure where the impurity type of the third diffusion regions is opposite to the second diffusion region, allowing for adjustable impurity concentration and threshold voltage control through the size and arrangement of these regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional semiconductor device manufacturing process is used, then the device structure is simple and manufacturing is easy, but the threshold voltage is fixed and unadjustable
Solution Approach 1:
The diffusion layer is segmented into multiple diffusion regions (first diffusion region, second diffusion region, and third diffusion regions) with different impurity types and concentrations. This segmentation allows independent control of threshold voltage while maintaining a manageable structural complexity through systematic arrangement of the segmented regions.
Solution Approach 2:
Different regions of the diffusion layer are assigned different local qualities (impurity types and concentrations). The first diffusion region has one impurity type, the second diffusion region has an opposite impurity type, and the third diffusion regions have impurity types opposite to the second diffusion region. This local quality variation enables precise threshold voltage adjustment in specific areas without affecting the entire device structure.
2Adaptability or versatility
If multiple diffusion regions with opposite impurity types are formed, then threshold voltage becomes adjustable, but the manufacturing process becomes more complex
Solution Approach 1:
The patent forms the first and second diffusion regions with opposite impurity types as preliminary structures before forming the third diffusion regions. This preliminary action establishes the basic threshold voltage characteristics, and subsequent formation of third diffusion regions provides fine-tuning capability. The preliminary structured approach simplifies the overall manufacturing process by breaking it into manageable stages.
Solution Approach 2:
The manufacturing process controls threshold voltage by changing parameters such as impurity concentration, diffusion depth, and region dimensions. By adjusting these parameters during the diffusion process, the patent achieves threshold voltage control without fundamentally changing the manufacturing workflow, thereby maintaining ease of manufacture while gaining adjustability.
3Manufacturing precision
If third diffusion regions are formed in the second diffusion region, then impurity concentration can be controlled for threshold voltage adjustment, but the device structure becomes more complex
Solution Approach 1:
The third diffusion regions are formed within the second diffusion region with impurity types opposite to the second diffusion region. This creates localized areas with different impurity concentrations, enabling precise control of threshold voltage in specific regions. The local quality approach allows manufacturing precision without requiring complex overall device structure.
Solution Approach 2:
The third diffusion regions are nested within the second diffusion region, creating a hierarchical structure where smaller diffusion regions are contained within larger ones. This nesting arrangement achieves precise impurity concentration control through multiple levels of diffusion regions, while the nested structure itself is more compact and manageable than a fully expanded structure would be.
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
Enables the production of semiconductor devices with changeable thresholds, improving voltage resistance and simplifying manufacturing by allowing for both normally-on and normally-off type devices to be produced simultaneously, reducing design complexity and cost.
Implementation Method 1
forming a diffusion layer having a first diffusion region and a second diffusion region on the buried layer, wherein an impurity type of the second diffusion region is opposite to an impurity type of the first diffusion region
Data Source
AI summary
A semiconductor device includes a substrate (110); a buried layer (120) formed on the substrate (110), a diffusion layer (130) formed on the buried layer (120), wherein the diffusion layer (130) includes a first diffusion region (132) and a second diffusion region (134), and an impurity type of the second diffusion region (134) is opposite to an impurity type of the first diffusion region (132); the diffusion layer (134) further comprises a plurality of third diffusion regions (136) formed in the second diffusion region, wherein an impurity type of the third diffusion region (136) is opposite to the impurity type of the second diffusion region (134); and a gate (144) formed on the diffusion layer (130).