Oxygen-Blocking Wiring Layer Structure for Oxide Semiconductor Reliability
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Solution Overview
Problem
Current semiconductor devices face challenges in achieving miniaturization, low power consumption, high reliability, low off-state current, long data retention, and eye-friendly display capabilities, particularly in the use of oxide semiconductors for transistors in display devices.
Innovation Solution
A method for manufacturing a wiring layer involves forming insulators and conductors in a specific structure to prevent oxygen penetration, using materials like tantalum nitride and tungsten nitride to reduce oxygen permeability, and employing chemical mechanical polishing to ensure the conductors are surrounded by oxygen-blocking layers, thereby maintaining the integrity of the semiconductor device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wiring structures are used in oxide semiconductor devices, then manufacturing is simpler, but oxygen penetration occurs causing device degradation
Solution Approach 1:
The wiring structure is segmented into multiple functional layers: a barrier layer (e.g., tantalum nitride) to block oxygen diffusion, a conductor layer for electrical conduction, and an upper barrier layer. This segmentation allows each layer to perform its specific function optimally, preventing oxygen penetration while maintaining manufacturability
Solution Approach 2:
The wiring structure uses composite materials combining different properties: tantalum nitride for oxygen barrier properties, tungsten or copper for high conductivity, and silicon nitride for structural stability. This composite approach achieves both reliability through oxygen blocking and acceptable manufacturing complexity
2Use of energy by moving object
If oxide semiconductor transistors are used, then power consumption is reduced, but oxygen diffusion degrades device performance
Solution Approach 1:
A barrier layer made of tantalum nitride is introduced as an intermediary between the oxide semiconductor transistor and the environment. This intermediary layer blocks oxygen diffusion pathways while allowing the transistor to maintain its low power consumption characteristics, thus resolving the contradiction between energy efficiency and performance stability
3Ease of manufacture
If conductor layers are exposed to oxygen, then manufacturing is easier, but oxidation increases resistance
Solution Approach 1:
The barrier layer is formed preliminarily before the conductor layer to prevent oxygen exposure during subsequent manufacturing steps. This preliminary protective action allows easier manufacturing processes while ensuring precise resistance control by preventing oxidation of the conductor material throughout the fabrication sequence
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 results in a miniaturized semiconductor device with low power consumption, high reliability, reduced off-state current, extended data retention, and the capability for eye-friendly displays, while preventing oxidation and maintaining device performance.
Implementation Method 1
using materials like tantalum nitride and tungsten nitride to reduce oxygen permeability
Implementation Method 2
employing chemical mechanical polishing to ensure the conductors are surrounded by oxygen-blocking layers
Data Source
AI summary
To provide a miniaturized semiconductor device with low power consumption. A method for manufacturing a wiring layer includes the following steps: forming a second insulator over a first insulator; forming a third insulator over the second insulator; forming an opening in the third insulator so that it reaches the second insulator; forming a first conductor over the third insulator and in the opening; forming a second conductor over the first conductor; and after forming the second conductor, performing polishing treatment to remove portions of the first and second conductors above a top surface of the third insulator. An end of the first conductor is at a level lower than or equal to the top level of the opening. The top surface of the second conductor is at a level lower than or equal to that of the end of the first conductor.