Parallel Impurity Regions for Precise Resistance Tuning
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Solution Overview
Problem
Existing variable resistors in semiconductor devices, particularly those using MOS transistor structures, face limitations in adjusting resistance values due to surface defects and material characteristics, resulting in a limited resistance range and requiring adjustments in circuit design or diffusion material concentration.
Innovation Solution
A variable resistance device with a parallel structure comprising impurity regions and conductive lines, where the resistance value is adjusted by applying control voltages to the conductive lines, allowing for precise adjustment of resistance values through the parallel connection of impurity regions with different concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a MOS transistor structure is used as a variable resistor, then the device can be integrated into IC circuits, but the resistance value adjustment range is limited due to surface defects and material characteristics
Solution Approach 1:
The variable resistance device is divided into multiple impurity regions (first impurity region, second impurity region, third impurity region) with different impurity concentrations arranged in parallel. Each region contributes differently to the total resistance, enabling broader and more precise resistance adjustment range compared to a single-channel MOS structure.
Solution Approach 2:
Different impurity regions are doped with different concentrations of impurities (first impurity region has lower concentration, second has higher concentration). This local variation in impurity concentration allows each region to provide different resistance characteristics, expanding the overall adjustable resistance range while improving precision.
2Device complexity
If the channel of a MOS transistor is used as the variable resistive element, then the device structure is simple, but the variable resistance range is limited and the linear control range is small
Solution Approach 1:
Instead of using a single MOS transistor channel, the invention segments the resistive element into multiple impurity regions with different doping concentrations. These regions are connected in parallel between source and drain, creating a more complex but effective structure that expands the variable resistance range while maintaining reasonable device simplicity.
Solution Approach 2:
The variable resistance device uses a composite structure combining multiple impurity regions with different electrical characteristics (different impurity concentrations) within a single device. This composite approach allows the device to achieve a broader resistance range and improved linearity without requiring multiple separate components.
3Manufacturing precision
If circuit design or diffusion material concentration is adjusted to change the size of the variable resistive element, then the resistance value can be modified, but the manufacturing process becomes more complex
Solution Approach 1:
The impurity regions are pre-doped with different impurity concentrations during the manufacturing process. This preliminary action of creating regions with fixed, different doping levels allows for precise resistance control without requiring complex post-manufacturing adjustments or iterative design changes, simplifying the overall manufacturing process while maintaining high precision.
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 precise adjustment of resistance values, expanding the resistance range and allowing for linear control of resistance values, unlike the quadratic changes seen in traditional MOS transistor-based devices, thereby improving the flexibility and accuracy of resistance tuning.
Implementation Method 1
a voltage (Vc) is applied to a gate electrode of a MOS transistor... The gate voltage (Vc) is changed
Data Source
AI summary
A variable resistance device includes a parallel structure. The variable resistance device is formed using a silicon (Si) substrate. In the variable resistance device, a conductive line arranged in a current direction is formed over an impurity region, and a resistance value of the resistance device is precisely adjusted by adjusting a level of a voltage applied to the conductive line. The variable resistance device includes a first impurity region formed in a substrate, a second impurity region formed in the substrate and arranged parallel to the first impurity region, a conductive line formed over the first impurity region, and electrode terminals formed at both longitudinal ends of the second impurity region to be coupled to the second impurity region.