Semiconductor Via Barrier Structure for Low Resistance and Diffusion Control
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Solution Overview
Problem
The scaling down of metal-oxide-semiconductor field-effect transistors (MOS-FETs) in semiconductor devices leads to deterioration in operational properties, necessitating improved electrical characteristics and fabrication methods to maintain performance.
Innovation Solution
A semiconductor device design featuring a via structure with a via portion and a barrier portion, both made of the same metal, integrated as a single object, where the barrier portion has a varying thickness to cover the inner surface of a line trench and prevent metal diffusion, while the via portion has a lower nitrogen concentration for low resistance, enhancing electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If MOS-FETs are scaled down to meet increasing demand for smaller pattern sizes, then the pattern size and design rule are reduced, but the operational properties of the semiconductor device deteriorate
Solution Approach 1:
The patent applies local quality by creating a via structure with non-uniform nitrogen concentration distribution. The barrier portion has a higher nitrogen concentration than the via portion, with the nitrogen concentration varying continuously or in steps from the via portion to the barrier portion. This localized variation in material properties optimizes each region for its specific function: low resistance in the via portion and diffusion prevention in the barrier portion, thereby maintaining device reliability despite scaling down.
Solution Approach 2:
The patent employs parameter changes by modifying the nitrogen concentration parameter within the via structure. The nitrogen concentration is varied spatially, being higher in the barrier portion and lower in the via portion. This parameter variation allows simultaneous optimization of electrical conductivity (via portion) and diffusion barrier performance (barrier portion), resolving the contradiction between device miniaturization and operational property maintenance.
2Reliability
If the barrier portion thickness is increased to prevent metal diffusion, then the diffusion prevention capability is improved, but the resistance of the via structure increases
Solution Approach 1:
The via structure implements local quality by having different nitrogen concentrations in different regions. The barrier portion has high nitrogen concentration for effective diffusion prevention, while the via portion has low nitrogen concentration for low resistance. This spatial differentiation of material properties allows the structure to simultaneously achieve both functions without compromise.
Solution Approach 2:
The nitrogen concentration parameter is varied continuously or in discrete steps from the via portion to the barrier portion. This gradient or stepped variation in nitrogen concentration enables a smooth transition between the low-resistance via region and the high-barrier-performance region, optimizing both electrical conductivity and diffusion prevention capability within a single integrated structure.
3Manufacturing precision
If the via portion has low nitrogen concentration for low resistance, then the electrical conductivity is improved, but the diffusion prevention capability is reduced
Solution Approach 1:
The via structure is segmented into two distinct functional regions: the via portion with low nitrogen concentration for electrical connectivity and the barrier portion with high nitrogen concentration for diffusion prevention. This segmentation allows each region to be optimized independently for its specific function, with the low nitrogen concentration in the via portion ensuring low resistance and the high nitrogen concentration in the barrier portion providing robust diffusion prevention.
Solution Approach 2:
Different nitrogen concentration levels are applied locally to different portions of the via structure. The via portion maintains low nitrogen concentration to preserve electrical conductivity, while the barrier portion has high nitrogen concentration for diffusion prevention. This localized optimization of material composition resolves the contradiction between electrical performance and diffusion barrier effectiveness.
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 design improves electrical characteristics by reducing resistance and preventing metal diffusion, thus maintaining performance and reliability in scaled-down MOS-FETs.
Implementation Method 1
a barrier portion that vertically extends from the via portion to cover an inner surface of the line trench. The barrier portion may be between the line structure and an interlayer insulating layer of the second metal layer. The nitrogen concentration of the barrier portion may be higher than a nitrogen concentration of the via portion.
Implementation Method 2
The via structure may include a via portion that is in the via hole and is coupled to the lower interconnection line. The nitrogen concentration of the barrier portion may be higher than a nitrogen concentration of the via portion.
Data Source
AI summary
A semiconductor device includes a transistor on a substrate, a first metal layer that is on the transistor and includes a lower wire electrically connected to the transistor, and a second metal layer on the first metal layer. The second metal layer includes an upper wire that is electrically connected to the lower wire and includes a via structure in a via hole and a line structure in a line trench. The via structure includes a via portion that is in the via hole and is coupled to the lower wire, and a barrier portion that vertically extends from the via portion to cover an inner surface of the line trench. The barrier portion is between the line structure and an insulating layer of the second metal layer. The barrier portion is thicker at its lower level than at its upper level.