SiC Film Surface Silicon-Rich Treatment for Copper Diffusion Barrier
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Solution Overview
Problem
In semiconductor devices with multilayer wiring, the use of low-k materials for insulating films reduces dielectric constants but can lead to copper diffusion through the barrier metal film, increasing leakage current and wire resistance due to the formation of α-Ta crystals, which compromises the reliability of the device.
Innovation Solution
The method involves forming a silicon-rich surface on SiC films using hydrogen plasma treatment or other plasma treatments to suppress the formation of α-Ta crystals, ensuring that the surfaces of the SiC films touching the barrier metal films remain silicon-rich, thereby preventing copper diffusion while maintaining a low dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-k materials are used for insulating films to reduce dielectric constant, then inter-wire capacitance is reduced and operation speed is improved, but copper diffusion through barrier metal film increases causing leakage current and wire resistance
Solution Approach 1:
The patent applies local quality by creating a silicon-rich surface layer specifically at the interface between the SiC film and barrier metal film, while maintaining the bulk SiC film's low-k properties. This localized modification prevents copper diffusion at the critical interface without compromising the overall low dielectric constant of the insulating film.
Solution Approach 2:
The patent changes the compositional parameter of the SiC film by controlling the carbon-to-silicon ratio during CVD deposition. By adjusting deposition conditions (such as source gas composition and temperature), the film transitions from carbon-rich to silicon-rich at the surface, thereby preventing α-Ta crystal formation and copper diffusion while maintaining low-k characteristics in the bulk.
2Reliability
If low-k materials are used for insulating films, then dielectric constant is reduced, but mechanical strength of the film decreases
Solution Approach 1:
The patent applies local quality by creating a silicon-rich surface layer specifically at the interface between the SiC film and barrier metal film, while maintaining the bulk SiC film's low-k properties. This localized modification prevents copper diffusion at the critical interface without compromising the overall low dielectric constant of the insulating film.
Solution Approach 2:
The patent changes the compositional parameter of the SiC film by controlling the carbon-to-silicon ratio during CVD deposition. By adjusting deposition conditions (such as source gas composition and temperature), the film transitions from carbon-rich to silicon-rich at the surface, thereby preventing α-Ta crystal formation and copper diffusion while maintaining low-k characteristics in the bulk.
3Reliability
If wire thickness is reduced to decrease inter-wire capacitance, then inter-wire capacitance is reduced, but wire resistance increases and operation speed cannot be increased
Solution Approach 1:
The patent uses a thin silicon-rich surface layer (approximately 1 nm thick) as a disposable protective interface that prevents copper diffusion. This ultra-thin layer provides effective barrier functionality without significantly increasing the overall film thickness or compromising the low-k properties, thereby allowing continued use of thin wire structures.
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 approach effectively suppresses copper diffusion and maintains a low dielectric constant, resulting in a high-performance semiconductor device with improved reliability by preventing the formation of α-Ta crystals and maintaining the integrity of the barrier metal films.
Implementation Method 1
making a surface of an SiC film which gets exposed in the groove at the time of the groove being formed silicon-rich
Data Source
AI summary
A semiconductor device in which the diffusion of copper from a wire is prevented and a method for fabricating such a semiconductor device. For example, a via groove and a wire groove are formed in a multilayer structure including a UDC diffusion barrier film, a porous silica film, a middle UDC stopper film, a porous silica film, a UDC diffusion barrier film, and the like, and the surfaces the UDC diffusion barrier film, the middle UDC stopper film, and the UDC diffusion barrier film that get exposed in the via groove and the wire groove are irradiated with hydrogen plasma, thereby making the surface of each exposed SiC film silicon-rich. After the plasma irradiation, a Ta film is formed in the via groove and the wire groove and copper is embedded in these grooves. By making the surface of each SiC film which is to touch the Ta film silicon-rich in advance, the crystal structure of the Ta film can be controlled so that copper cannot pierce through the Ta film. This prevents copper from diffusing from a wire.