Oxide Semiconductor Transistor Base Insulating Layer Oxygen Release
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Solution Overview
Problem
Transistors using oxide semiconductors face reliability issues due to fluctuations in threshold voltage after bias-temperature stress tests, primarily caused by oxygen deficiency and interface state trapping between the oxide semiconductor and insulating layers.
Innovation Solution
An insulating layer that releases oxygen by heating is used as a base layer, supplying sufficient oxygen to the oxide semiconductor layer to reduce interface state trapping and oxygen deficiency, thereby stabilizing the threshold voltage and improving transistor reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an oxide semiconductor layer is used to form a transistor, then the transistor can operate at higher speed and be manufactured more easily compared to amorphous silicon or polycrystalline silicon transistors, but the transistor exhibits low reliability due to threshold voltage fluctuation
Solution Approach 1:
The patent applies preliminary action by forming an insulating layer that releases oxygen before forming the oxide semiconductor layer. This oxygen release occurs during heating treatment at 400-650°C, which prepares the interface in advance to prevent oxygen deficiency and reduce interface states, thereby improving reliability before the transistor is fully assembled and operated.
2Device complexity
If a conventional insulating layer is used as the base layer of the oxide semiconductor layer, then the manufacturing process is simple, but oxygen deficiency occurs in the oxide semiconductor layer causing threshold voltage shift and charge trapping
Solution Approach 1:
The patent applies parameter changes by modifying the insulating layer to have oxygen release capability through heating. The insulating layer is formed with specific composition (containing oxygen) and undergoes thermal treatment at 400-650°C to change its oxygen release parameters, enabling it to supply oxygen to the oxide semiconductor layer and prevent oxygen deficiency.
Solution Approach 2:
The insulating layer acts as an intermediary between the substrate and the oxide semiconductor layer. It releases oxygen during heating to serve as an oxygen source for the oxide semiconductor layer, mediating the oxygen supply to prevent interface states and charge trapping without requiring direct contact with external oxygen sources.
3Reliability
If heating treatment is applied to release oxygen from the insulating layer, then oxygen deficiency in the oxide semiconductor layer is reduced and interface states are minimized, but additional manufacturing steps are required
Solution Approach 1:
The patent merges the oxygen release heating step with other necessary heating processes in the transistor manufacturing sequence. The insulating layer is formed first, then heated to release oxygen before the oxide semiconductor layer is formed, combining multiple functions (insulation, oxygen release, interface preparation) into an integrated process flow that minimizes additional steps.
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 suppresses charge trapping and fluctuation in threshold voltage, leading to reduced off-state current and enhanced reliability of oxide semiconductor transistors.
Implementation Method 1
an insulating layer from which oxygen is released by heating is formed as an insulating layer which is a base layer of an oxide semiconductor layer
Implementation Method 2
By supplying oxygen from the base insulating layer to the oxide semiconductor layer, an interface state between the base insulating layer and the oxide semiconductor layer can be reduced
Data Source
AI summary
An object of the present invention is to manufacture a semiconductor device where fluctuation in electrical characteristics is small and reliability is high in a transistor in which an oxide semiconductor is used. An insulating layer from which oxygen is released by heating is used as a base insulating layer of an oxide semiconductor layer which forms a channel. Oxygen is released from the base insulating layer, whereby oxygen deficiency in the oxide semiconductor layer and an interface state between the base insulating layer and the oxide semiconductor layer can be reduced. Thus, a semiconductor device where fluctuation in electrical characteristics is small and reliability is high can be manufactured.