Semiconductor Device Threshold Adjustment via Electron Trapping
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Solution Overview
Problem
Miniaturization of transistors leads to deterioration of electrical characteristics such as on-state current, off-state current, threshold, and subthreshold swing, and increases power consumption, while also making it challenging to retain data when the power supply is stopped.
Innovation Solution
A semiconductor device with a structure that includes a first semiconductor, an electrode, a gate electrode, an electron trap layer, and a gate insulating layer, where electrons are trapped by heat treatment and potential control to adjust the threshold voltage, reducing electrical characteristic deterioration and enabling low power consumption and data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the channel length is decreased to increase on-state current, then the on-state current increases, but the off-state current increases and threshold voltage varies
Solution Approach 1:
The patent applies preliminary action by performing heat treatment before the transistor is fully operational to pre-trap electrons in the oxide semiconductor layer. This pre-trapping of electrons adjusts the threshold voltage in advance, ensuring stable electrical characteristics when the transistor is subsequently miniaturized with reduced channel length.
Solution Approach 2:
The patent changes physical parameters by applying heat treatment at specific temperatures (typically 100°C to 450°C) to alter the electrical characteristics of the oxide semiconductor layer. This parameter change traps electrons within the semiconductor layer, thereby adjusting the threshold voltage and improving device reliability without requiring channel length reduction.
2Productivity
If the channel width is decreased to increase integration, then the on-state current decreases
Solution Approach 1:
The patent changes the electrical parameters of the oxide semiconductor layer through heat treatment, trapping electrons to adjust the threshold voltage. This allows the transistor to maintain adequate on-state current even when the channel width is reduced for higher integration density, as the trapped electrons compensate for the reduced conduction channel.
3Reliability
If heat treatment is applied to trap electrons and adjust threshold voltage, then the threshold voltage is adjusted appropriately, but additional process steps are required
Solution Approach 1:
The patent merges the threshold voltage adjustment process with existing manufacturing steps by performing heat treatment during or after the oxide semiconductor layer formation. This integration of the electron-trapping process into the standard fabrication sequence minimizes additional process complexity while achieving reliable threshold voltage control.
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
The solution effectively adjusts the threshold voltage, suppresses the deterioration of electrical characteristics, enhances integration, reduces power consumption, and allows data retention even when the power supply is stopped, resulting in a highly reliable semiconductor device.
Implementation Method 1
electrons are trapped in the electron trap layer by performing heat treatment at higher than or equal to 125° C. and lower than or equal to 450° C. and at the same time, keeping the potential of the first gate electrode higher than the potential of the electrode for one second or longer
Data Source
AI summary
A manufacturing method of a semiconductor device in which the threshold is adjusted to an appropriate value is provided. The semiconductor device includes a semiconductor, a source or drain electrode electrically connected to the semiconductor, a first gate electrode and a second gate electrode between which the semiconductor is sandwiched, an electron trap layer between the first gate electrode and the semiconductor, and a gate insulating layer between the second gate electrode and the semiconductor. By keeping a potential of the first gate electrode higher than a potential of the source or drain electrode for 1 second or more while heating, electrons are trapped in the electron trap layer. Consequently, threshold is increased and Icut is reduced.