Oxide Semiconductor Transistor Barrier Film for Metal Diffusion Control
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Solution Overview
Problem
The challenge is to improve the processing stability of wiring formed using metals like copper, aluminum, gold, and silver in oxide semiconductor devices, reduce impurity concentration in the oxide semiconductor film, and enhance the electrical characteristics and reliability of semiconductor devices while enabling high-speed operation and reducing power consumption.
Innovation Solution
A semiconductor device with a transistor that includes an oxide semiconductor film, an oxide film with c-axis alignment, and conductive films containing copper, aluminum, gold, or molybdenum, where the oxide film acts as a barrier to prevent metal element transfer to the oxide semiconductor film, and a gate insulating film with a nitride layer to prevent diffusion of impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper, aluminum, gold, silver, or molybdenum is used as wiring material, then electrical conductivity is improved, but metal elements are diffused into the oxide semiconductor film during processing
Solution Approach 1:
An oxide film is introduced as an intermediary layer between the metal wiring and the oxide semiconductor film. This intermediate oxide film acts as a diffusion barrier, preventing metal elements from the wiring from diffusing into the oxide semiconductor film during processing, while still allowing the wiring to provide its electrical conductivity function.
2Ease of manufacture
If metal elements are diffused into the oxide semiconductor film, then processing is completed, but impurity concentration increases and electrical characteristics deteriorate
Solution Approach 1:
The oxide film serves as a protective intermediary that allows wiring formation to proceed while blocking metal element diffusion into the oxide semiconductor film, thereby maintaining low impurity concentration and preserving manufacturing precision.
3Speed
If copper, aluminum, gold, silver, or molybdenum is used in wiring, then wiring delay is reduced, but processing stability decreases due to difficulty in processing
Solution Approach 1:
The oxide film intermediary enables the use of high-speed wiring materials like copper and aluminum by preventing their diffusion into the semiconductor film during processing, thereby maintaining processing stability while achieving high signal transmission speed.
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 configuration increases processing stability, reduces impurity concentration, improves electrical characteristics, enhances reliability, enables high-speed operation, and reduces power consumption, leading to improved semiconductor device performance and productivity.
Implementation Method 1
The oxide film which includes the plurality of crystal parts and has c-axis alignment in the plurality of crystal parts, and in which the c-axes are aligned in a direction parallel to a normal vector of a top surface of the oxide semiconductor film or the oxide film is provided between the oxide semiconductor film and the pair of conductive films, whereby transfer of a metal element included in the pair of conductive films, typically, copper, aluminum, gold, silver, molybdenum, or the like, to the oxide semiconductor film can be prevented
Data Source
AI summary
The stability of a step of processing a wiring formed using copper, aluminum, gold, silver, molybdenum, or the like is increased. Moreover, the concentration of impurities in a semiconductor film is reduced. Moreover, the electrical characteristics of a semiconductor device are improved. In a transistor including an oxide semiconductor film, an oxide film in contact with the oxide semiconductor film, and a pair of conductive films being in contact with the oxide film and including copper, aluminum, gold, silver, molybdenum, or the like, the oxide film has a plurality of crystal parts and has c-axis alignment in the crystal parts, and the c-axes are aligned in a direction parallel to a normal vector of a top surface of the oxide semiconductor film or the oxide film.