Oxide Semiconductor Relative Permittivity Measurement
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Solution Overview
Problem
The correlation between electric characteristics of transistors with oxide semiconductor layers and their physical properties is not well understood, and existing methods struggle to measure the relative permittivity of these layers effectively, which is crucial for enhancing on-current and drive force.
Innovation Solution
A novel oxide semiconductor layer with higher relative permittivity (>13) is developed by reducing carrier density, and a MOS capacitor structure is used to measure this permittivity, preventing ohmic contact and carrier injection to accurately calculate the capacitance and permittivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional oxide semiconductor layer is used, then the measurement structure is simple, but the relative permittivity is low (≤12) and on-current is limited
Solution Approach 1:
An insulating layer is introduced as an intermediary between the semiconductor substrate and the oxide semiconductor layer. This intermediary prevents ohmic contact and carrier injection from the substrate, enabling accurate measurement of the oxide semiconductor's intrinsic capacitance and relative permittivity while maintaining a relatively simple overall structure
Solution Approach 2:
The oxide semiconductor layer is engineered to achieve higher relative permittivity (≥13) by controlling its physical properties, including reducing carrier density and adjusting composition. This parameter change directly increases on-current while the measurement structure complexity remains manageable through the use of the insulating layer intermediary
2Measurement precision
If AC voltage is applied to electrodes in contact with oxide semiconductor layer, then capacitance measurement is attempted, but ohmic contact causes carrier injection and prevents accurate permittivity measurement
Solution Approach 1:
The insulating layer serves as a mediator that blocks carrier injection from the semiconductor substrate while still allowing the oxide semiconductor layer to be part of the measurement structure. This enables accurate capacitance measurement under AC voltage without the harmful effects of ohmic contact
Solution Approach 2:
The measurement structure extracts only the capacitance contribution of the oxide semiconductor layer by using the insulating layer to block substrate effects. This separation allows precise determination of the oxide semiconductor's relative permittivity without interference from carrier injection
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 approach increases the on-current and drive force of transistors by enhancing the relative permittivity of the oxide semiconductor layer and provides a method to effectively measure this property, overcoming previous measurement challenges.
Implementation Method 1
the saturation capacitance Ca in an accumulation region is measured, and the saturation capacitance Ca in an accumulation region is substituted into the following formula, thereby the relative permittivity can be calculated
Implementation Method 2
a method for measuring a relative permittivity of an oxide semiconductor layer is provided
Data Source
AI summary
The field of an oxide semiconductor has been attracted attention in recent years. Therefore, the correlation between electric characteristics of a transistor including an oxide semiconductor layer and physical properties of the oxide semiconductor layer has not been clear yet. Thus, a first object is to improve electric characteristics of the transistor by control of physical properties of the oxide semiconductor layer. A semiconductor device including at least a gate electrode, an oxide semiconductor layer, and a gate insulating layer sandwiched between the gate electrode and the oxide semiconductor layer, where the oxide semiconductor layer has the relative permittivity of equal to or higher than 13 (or equal to or higher than 14), is provided.