Variable-Diameter Semiconductor Column for High On/Off Ratio
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Solution Overview
Problem
Current semiconductor devices face challenges in increasing the on/off current ratio while reducing on-resistance, particularly in transistor devices where the on-resistance is high and the on/off current ratio is not adequately enhanced.
Innovation Solution
A semiconductor device design featuring a column portion with a source and drain portion of the same conductivity type, a channel portion with lower impurity concentration, and a drift portion of the same conductivity type as the drain, along with a gate electrode at the sidewall of the channel portion via an insulating portion, where the diameter of the column portion at the drift portion is larger than at the channel and source portions, facilitating improved current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the channel portion has a uniform diameter throughout, then the manufacturing process is simpler, but the on/off current ratio cannot be sufficiently increased
Solution Approach 1:
The column portion is segmented into distinct regions with different diameters: a first region (source/drain area) with a larger diameter, a second region (channel area) with a smaller diameter, and a third region (drift area) with an intermediate diameter. This segmentation allows the channel region to be fully depleted for high off-state current while maintaining larger source/drain regions for low on-resistance, thereby achieving a high on/off current ratio.
Solution Approach 2:
Different regions of the column portion are given different local geometrical properties (diameters) to optimize their specific functions. The narrower channel region enables complete depletion for high off-state characteristics, while the wider source/drain regions reduce contact resistance and improve on-state current flow,实现ing both high on/off ratio and low on-resistance simultaneously.
2Reliability
If the channel portion diameter is reduced to increase on/off ratio, then the on/off current ratio improves, but the on-resistance increases
Solution Approach 1:
The column portion is divided into multiple regions with different diameters: the channel region (second region) has a smaller diameter to enable complete depletion and high on/off ratio, while the source and drain regions (first region) have larger diameters to reduce contact resistance. This spatial segmentation resolves the contradiction by allowing the channel to be narrow for switching performance while source/drain remain wide for low resistance contact.
Solution Approach 2:
The invention transitions from a uniform one-dimensional channel to a multi-region structure where the diameter varies along the vertical axis. By introducing dimensional variation (different diameters at different heights), the patent achieves both complete channel depletion (narrow region) and low contact resistance (wide regions) simultaneously, resolving the trade-off between on/off ratio and on-resistance.
3Ease of manufacture
If a uniform column structure is used, then the device is easier to manufacture, but pressure resistance and dislocation control are insufficient
Solution Approach 1:
The column portion is segmented into regions with different diameters and impurity concentrations. The drift region (third region) has an intermediate diameter between the channel and source/drain regions, creating a gradual transition that helps manage stress and dislocation. This segmented structure improves pressure resistance and dislocation control while remaining compatible with existing manufacturing processes.
Solution Approach 2:
The invention varies multiple parameters along the column portion: diameter (larger at source/drain, smaller at channel, intermediate at drift) and impurity concentration (higher at source/drain, lower at channel). These parameter changes optimize both electrical performance and mechanical reliability, including pressure resistance and dislocation management, while maintaining manufacturability through controlled growth processes.
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 design effectively increases the on/off current ratio while reducing on-resistance, enabling a normally-off state and improved pressure resistance by ensuring complete depletion of the channel portion and minimizing dislocation risks due to lattice constant differences.
Implementation Method 1
a gate electrode provided at a sidewall of the column portion at the channel portion via an insulating portion and configured to control a current of the channel portion
Data Source
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AI summary
A semiconductor device includes a column portion including a source portion and a drain portion constituted by semiconductors having the same conductivity type, a channel portion provided between the source portion and the drain portion and constituted by a semiconductor having a lower impurity concentration than those of the source portion and the drain portion, and a drift portion provided between the channel portion and the drain portion and constituted by a semiconductor having the same conductivity type as that of the drain portion; and a gate electrode provided at a sidewall of the column portion at the channel portion via an insulating portion and configured to control the current of the channel portion. The diameter of the column portion at the drift portion is larger than the diameter of the column portion at the channel portion and the diameter of the column portion at the source portion.