Oxide Semiconductor Threshold Voltage Stability via Oxygen Addition
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Solution Overview
Problem
Oxide semiconductor devices exhibit fluctuations in electrical characteristics, particularly due to oxygen vacancies and interface states at the interface between the oxide semiconductor layer and the gate insulating film, leading to instability in threshold voltage.
Innovation Solution
A method involving the formation of an insulating film that releases oxygen upon heating, in contact with the oxide semiconductor layer, and light irradiation treatment on the gate electrode to add oxygen, reducing oxygen vacancies and interface states in the region overlapping with the gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor devices are manufactured using conventional methods, then large area and uniform element characteristics can be achieved, but electrical characteristics fluctuate due to oxygen vacancies and interface states
Solution Approach 1:
An insulating layer releasing oxygen is formed in contact with the oxide semiconductor layer before light irradiation treatment. This preliminary preparation enables subsequent oxygen addition to reduce oxygen vacancies and interface states, improving electrical characteristic stability without requiring complex in-situ oxidation equipment
Solution Approach 2:
The insulating layer acts as an intermediary oxygen source between the external environment and the oxide semiconductor layer. It releases oxygen upon light irradiation directly at the interface where oxygen vacancies and interface states exist, effectively addressing the reliability issue through a simple structural addition
2Reliability
If light irradiation treatment is performed on the gate electrode, then oxygen is added to reduce oxygen vacancies and interface states, but the manufacturing process becomes more complex
Solution Approach 1:
The light irradiation step serves multiple functions simultaneously: it heats the gate electrode for work function adjustment, activates oxygen release from the insulating layer, and reduces oxygen vacancies and interface states in the oxide semiconductor layer. This multi-functionality approach improves reliability without proportionally increasing process complexity
Solution Approach 2:
The gate electrode undergoes parameter changes through light irradiation, including work function modification and oxygen concentration adjustment. By controlling irradiation conditions, the device achieves desired electrical characteristics while maintaining a relatively simple process flow
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 approach results in a highly reliable semiconductor device with minimal change in threshold voltage, enhancing stability and reliability by reducing oxygen-related defects.
Implementation Method 1
light irradiation treatment is performed on the gate electrode to add oxygen from the insulating layer in a region which overlaps with the gate electrode into the oxide semiconductor layer
Implementation Method 2
light irradiation treatment is performed on the gate electrode or a metal layer formed in a region which overlaps with the gate electrode. Accordingly, the insulating layer in a region which overlaps with the gate electrode is heated
Data Source
AI summary
A method for manufacturing a highly reliable semiconductor device with less change in threshold voltage is provided. An insulating film from which oxygen can be released by heating is formed in contact with an oxide semiconductor layer, and light irradiation treatment is performed on a gate electrode or a metal layer formed in a region which overlaps with the gate electrode, so that oxygen is added into the oxide semiconductor layer in a region which overlaps with the gate electrode. Accordingly, oxygen vacancies or interface states in the oxide semiconductor layer in a region which overlaps with the gate electrode can be reduced.