Semiconductor Barrier Metal Segmentation for Adhesion
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Solution Overview
Problem
In semiconductor devices, titanium (Ti) films used as barrier metals on interlayer insulating films like BPSG absorb oxygen, forming titanium oxide (TiO2) which reduces adhesiveness and leads to peeling off of electrodes, compromising device reliability.
Innovation Solution
A semiconductor device design that includes a laminated first barrier metal portion of titanium (Ti) and titanium nitride (TiN) films at the bottom of openings in the insulating film, with a continuous titanium nitride film as the second barrier metal portion between the insulating film and the upper electrode, preventing the formation of TiO2 and enhancing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a titanium (Ti) film is used as a barrier metal on an interlayer insulating film containing oxygen, then the barrier metal prevents reaction between aluminum and silicon, but the titanium film absorbs oxygen and forms titanium oxide, reducing adhesiveness and causing electrode peeling
Solution Approach 1:
The barrier metal structure is segmented into two distinct portions: a first barrier metal portion (titanium film) at the bottom of the opening that contacts the semiconductor substrate, and a second barrier metal portion (titanium nitride film) on the upper surface of the insulating film. This segmentation prevents the titanium film from contacting oxygen-containing insulating film, thereby preventing titanium oxide formation while maintaining the barrier function.
Solution Approach 2:
The patent introduces an intermediary substance (titanium nitride film) as the second barrier metal portion that contacts the oxygen-containing insulating film. This intermediary prevents direct contact between titanium and oxygen, blocking the oxidation process while still providing effective barrier functionality against aluminum-silicon reaction.
2Reliability
If a titanium film is provided on the interlayer insulating film, then the barrier metal prevents reaction between aluminum and silicon, but the titanium film absorbs oxygen and leads to peeling off of the source electrode or emitter electrode
Solution Approach 1:
The barrier metal is segmented into two portions with different functions: the first barrier metal portion (titanium) provides excellent barrier properties at the interface with the semiconductor substrate, while the second barrier metal portion (titanium nitride) provides oxygen resistance at the interface with the insulating film. This segmentation resolves the contradiction between barrier effectiveness and adhesion stability.
Solution Approach 2:
The patent employs a composite barrier metal structure consisting of titanium and titanium nitride films. This composite structure combines the advantages of both materials: titanium's superior barrier properties and titanium nitride's oxygen resistance, thereby preventing both aluminum-silicon reaction and electrode peeling.
3Device complexity
If no barrier metal is provided between the insulating film and the upper electrode, then the structure is simplified, but the adhesion between the insulating film and the upper electrode is reduced
Solution Approach 1:
The second barrier metal portion (titanium nitride film) serves multiple functions: it acts as a barrier metal preventing aluminum-silicon reaction, provides oxygen resistance by not reacting with the insulating film, and enhances adhesion between the insulating film and the upper electrode. This multi-functionality resolves the contradiction without adding structural complexity.
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 significantly increases the adhesion between the insulating film and the upper electrode, improving the reliability of semiconductor devices by preventing electrode peeling and reducing electromigration and deformation due to temperature cycles.
Implementation Method 1
the Ti film absorbs oxygen contained in the interlayer insulating film and thereby the Ti film changes into a titanium oxide (hereinafter referred to as TiO2) film
Data Source
AI summary
A semiconductor device is provided that includes a semiconductor substrate; an insulating film that is provided on the semiconductor substrate, has an opening through which the semiconductor substrate is exposed, and contains oxygen; a first barrier metal portion that is provided at least on a bottom portion of the opening and in which one or more kinds of films are laminated; and an upper electrode provided above the insulating film. The barrier metal is not provided between an upper surface of the insulating film and the upper electrode, or the semiconductor device further comprises a second barrier metal portion between the upper surface of the insulating film and the upper electrode, the second barrier metal portion having a configuration different from that of the first barrier metal portion.