Vertical Oxide Semiconductor Transistor Contacts With Nitrided Interfaces
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Solution Overview
Problem
Existing semiconductor devices with vertical transistors face challenges in maintaining reliable contact and reducing self-diffusion in oxide conductor portions, leading to degraded characteristics due to grain boundaries and oxidation issues during manufacturing.
Innovation Solution
Incorporating a nitrogen-containing portion between the metal and oxide conductor portions, and between the gate insulating layer and electrodes, formed by nitriding surfaces, to enhance the work function and reduce self-diffusion and oxidation, thereby improving the transistor's OFF characteristics and overall performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide conductor portions are used in vertical transistors, then electrical conductivity is improved, but self-diffusion and oxidation occur during manufacturing leading to degraded characteristics
Solution Approach 1:
A nitrogen-containing portion is introduced as an intermediary layer between the oxide conductor portion and other structures. This nitrogen-containing layer acts as a barrier that prevents self-diffusion and oxidation of the oxide conductor portions during manufacturing processes, thereby maintaining contact reliability while eliminating harmful effects.
Solution Approach 2:
The work function of the oxide conductor portion is increased by introducing nitrogen-containing portions. This parameter change modifies the electrical characteristics of the conductor, improving OFF characteristics and reducing the harmful effects of self-diffusion and oxidation by changing the chemical and electrical environment at the interfaces.
2Ease of manufacture
If grain boundaries are present in oxide semiconductor, then manufacturing is simplified, but transistor characteristics are degraded
Solution Approach 1:
Nitrogen-containing portions are introduced as intermediary layers at critical interfaces. These nitrogen-containing layers compensate for the presence of grain boundaries by providing stable chemical and electrical properties that prevent degradation of transistor characteristics, allowing simplified manufacturing to proceed without sacrificing device performance.
3Reliability
If metal portions are used for electrodes, then electrical conductivity is improved, but oxidation occurs during manufacturing degrading contact reliability
Solution Approach 1:
Nitrogen-containing portions are positioned between metal portions and oxide conductor portions, serving as protective intermediary layers. These nitrogen-containing layers prevent oxidation of the metal portions during subsequent manufacturing processes such as heating treatments, thereby maintaining contact reliability while allowing the use of highly conductive metal materials.
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 reduces self-diffusion and oxidation, ensuring reliable contact and enhancing the vertical MOS transistor's characteristics, including lower wiring resistance and improved OFF characteristics, while preventing reattachment and maintaining high work function.
Implementation Method 1
incorporating a nitrogen-containing portion between the metal and oxide conductor portions, and between the gate insulating layer and electrodes, formed by nitriding surfaces
Implementation Method 2
reduces self-diffusion and oxidation, ensuring reliable contact and enhancing the vertical MOS transistor's characteristics
Data Source
AI summary
According to one embodiment, a semiconductor device includes a pillar of an oxide semiconductor material and a gate insulating layer that surrounds a side surface of the pillar. The gate insulating layer includes a lower portion, an upper portion, and an intermediate portion. A gate electrode surrounds the intermediate portion of the gate insulating layer. A lower electrode is provided that includes a first oxide conductor portion that is connected to a lower surface of the pillar. An upper electrode is provided connected to an upper surface of the pillar. The gate electrode includes a metal portion containing a metallic element and a first nitrogen-containing portion between the metal portion and the gate insulating layer. The first oxide conductor portion includes a second nitrogen-containing at an interface between the first oxide conductor portion and the gate insulating layer.