Oxide Semiconductor Insulation Film Oxygen Diffusion Control
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Solution Overview
Problem
Semiconductor elements with oxide semiconductors like IGZO face challenges in maintaining stable characteristics during light illumination due to surface defects caused by protective layer formation and exposure to moisture, leading to threshold voltage shifts.
Innovation Solution
A semiconductor element manufacturing method involving the formation of a first insulation film, followed by a heat treatment in an oxidizing atmosphere, and a second insulation film, where the thickness of the first insulation film and heat treatment temperature are adjusted to optimize oxygen diffusion and reduce surface defects, ensuring stable characteristics during light exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is formed on the exposed surface of an active layer to protect it from moisture and contaminants, then the reliability of the semiconductor element is improved, but surface defects are caused during light illumination leading to threshold voltage shifts
Solution Approach 1:
The patent changes the physical and chemical parameters of the protective layer by forming it as a multi-layer structure with specific thicknesses and material compositions. The first protective layer has a thickness of 1-10 nm and the second protective layer has a thickness of 10-100 nm, with specific oxygen concentrations and material compositions that optimize both protection and light illumination characteristics
Solution Approach 2:
The patent uses composite material structures where the protective layer consists of multiple layers with different material compositions. The first protective layer and second protective layer are formed with different materials and properties, creating a composite structure that provides both moisture protection and reduces surface defects during light illumination
2Reliability
If the thickness of the first protective layer is increased to improve protection, then reliability is improved, but oxygen diffusion to the active layer is blocked during heat treatment
Solution Approach 1:
The patent optimizes the thickness parameter of the first protective layer to be within 1-10 nm, which is thin enough to allow oxygen diffusion during heat treatment but thick enough to provide protective function. This precise parameter control resolves the contradiction between protection quality and oxygen diffusion
3Reliability
If heat treatment temperature is increased to improve oxygen supply to the active layer, then element characteristics are stabilized, but the protective layer may deteriorate
Solution Approach 1:
The patent optimizes the heat treatment temperature parameter to be within 200-400°C, which is high enough to enable sufficient oxygen diffusion to the active layer for stabilizing threshold voltage but low enough to prevent deterioration of the protective layer structure and material properties
4Ease of manufacture
If a single thick protective layer is formed to simplify the manufacturing process, then ease of manufacture is improved, but precise control of oxygen diffusion and defect reduction is difficult
Solution Approach 1:
The patent divides the protective layer into two distinct layers: a first protective layer (1-10 nm) and a second protective layer (10-100 nm). This segmentation allows precise control of oxygen diffusion through the first layer while maintaining protective function, and enables independent optimization of each layer's properties for specific manufacturing requirements
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 method effectively stabilizes element characteristics by rectifying surface defects and improving threshold voltage stability during light illumination, enhancing the reliability of semiconductor elements.
Implementation Method 1
a heat treatment is applied in an oxidizing atmosphere; a diffusion distance of oxygen into the first insulation film and the semiconductor film
Implementation Method 2
heat treatment in an oxidizing atmosphere; oxygen is supplied through the aperture portions and exposed portions of the active layer
Data Source
AI summary
There is provided a method of manufacturing a semiconductor element including: forming a semiconductor film of which a principal constituent is an oxide semiconductor; forming a first insulation film on a surface of the semiconductor film; applying a heat treatment in an oxidizing atmosphere; and, forming a second insulation film on a surface of the first insulation film, wherein a thickness of the first insulation film and a temperature of the heat treatment in the third step are adjusted such that, if the thickness of the first insulation film is represented by Z (nm), the heat treatment temperature is represented by T (° C.) and a diffusion distance of oxygen into the first insulation film and the semiconductor film is represented by L (nm), the relational expression 0<Z<L=8×10−6×T3−0.0092×T2+3.6×T−468±0.1 is satisfied.