Dual-Gate Semiconductor Device for Threshold Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As MOSFETs are scaled down, short channel effects lead to threshold voltage fluctuations due to variations in the thickness of the ultra-thin semiconductor layer, making it challenging to maintain control over the drain current and resulting in degraded subthreshold characteristics.
Innovation Solution
A semiconductor device with a front gate made of high-threshold voltage material and a back gate made of low-threshold voltage material, or both gates made of the same material with forward bias voltage applied, to stabilize the surface potential and alleviate the impact of thickness variations on the threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor layer thickness is reduced to create an ultra-thin channel, then the control of charges by gate voltage is enhanced, but the threshold voltage becomes remarkably sensitive to thickness variation
Solution Approach 1:
The gate control is segmented into two independent gates: a front gate for controlling charge in the channel and a back gate for compensating threshold voltage shifts. This segmentation allows each gate to independently address different aspects of device performance, resolving the contradiction between enhanced charge control and threshold voltage stability.
Solution Approach 2:
The back gate voltage is adjusted as a compensating parameter to counteract threshold voltage shifts caused by ultra-thin channel formation. By dynamically changing the back gate voltage parameter, the system maintains stable threshold voltage despite the reduced semiconductor layer thickness.
2Productivity
If the channel length is reduced to improve integration level, then manufacturing cost decreases, but short channel effects arise causing threshold voltage to drop
Solution Approach 1:
The solution moves from one-dimensional gate control (front gate only) to two-dimensional gate control by adding the back gate. This dimensional expansion allows independent control of channel charge and threshold voltage, enabling short channel devices to maintain stable operation despite reduced channel length.
Solution Approach 2:
The back gate voltage serves as an additional controllable parameter that compensates for threshold voltage drops in short channel devices. By adjusting this parameter, the system maintains reliable operation even as channel length is reduced for higher integration.
Data Source
AI summary
The present application discloses a semiconductor device comprising a source region and a drain region in an ultra-thin semiconductor layer; a channel region between the source region and the drain region in the ultra-thin semiconductor layer; a front gate stack above the channel region, the front gate comprising a front gate and a front gate dielectric between the front gate and the channel region; and a back gate stack below the channel region, the back gate stack comprising a back gate and a back gate dielectric between the back gate and the channel region, wherein the front gate is made of a high-Vt material, and the back gate is made of a low-Vt material. According to another embodiment, the front gate and the back gate are made of the same material, and the back gate is applied with a forward bias voltage during operation. The semiconductor device alleviates threshold voltage fluctuation due to varied thickness of the channel region by means of the back gate.