Composite Barrier Via for Low Resistance Semiconductor Interconnects
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Solution Overview
Problem
Conventional semiconductor manufacturing techniques face challenges in forming low-resistance, high-reliability conductive structures, particularly in high aspect ratio openings, due to poor step coverage and increased resistivity, which degrades device performance and reliability.
Innovation Solution
The use of a composite barrier layer comprising an atomic layer deposition (ALD) layer, a Ta or Ti layer, and a Mn-based layer, combined with a copper film, provides excellent step coverage, adhesion, and diffusion barrier properties, improving interconnect reliability and resistivity through a process involving ALD, PVD, and thermal annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PVD or CVD methods are used to fill contact or via openings, then the process is simple and straightforward, but the step coverage is poor and voids form in high aspect ratio openings, increasing resistance
Solution Approach 1:
The barrier layer is segmented into multiple distinct layers: an ALD layer for conformal coverage, a Ta or Ti layer for adhesion enhancement, and a Mn-based layer for diffusion barrier properties. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between achieving good step coverage and maintaining process simplicity.
Solution Approach 2:
The patent employs a composite barrier layer structure combining different materials (ALD material, Ta/Ti, and Mn-based materials) to achieve properties that no single material could provide alone. This composite approach enables excellent step coverage, adhesion, and diffusion barrier performance simultaneously.
2Manufacturing precision
If the aspect ratio of openings is increased to accommodate smaller device features, then device scaling is achieved, but it becomes more difficult to completely fill the openings in a void-free manner, increasing contact or via resistance
Solution Approach 1:
The ALD layer is deposited first to provide conformal coverage and prepare the surface, followed by the Ta or Ti layer to enhance adhesion before copper deposition. These preliminary actions ensure that the subsequent copper fill will adhere properly and fill the high aspect ratio opening completely without voids, thereby maintaining both manufacturing precision and device reliability.
Solution Approach 2:
The patent changes the physical and chemical parameters of the barrier layer by using multiple materials with different properties. The ALD layer provides conformal deposition characteristics, the Ta or Ti layer provides adhesion properties, and the Mn-based layer provides diffusion barrier properties. These parameter changes enable successful filling of high aspect ratio openings.
3Reliability
If a single-layer barrier structure is used, then the process is simpler and fewer materials are required, but adhesion and diffusion barrier properties are insufficient, degrading interconnect reliability
Solution Approach 1:
The barrier function is segmented into three specialized layers: ALD layer for conformal coverage, Ta or Ti layer for adhesion, and Mn-based layer for diffusion barrier properties. This segmentation resolves the contradiction by assigning specific functions to each layer, achieving superior interconnect reliability despite increased structural complexity.
Solution Approach 2:
The composite barrier layer structure combines materials with complementary properties to achieve adhesion and diffusion barrier performance that no single material could provide alone, thereby improving interconnect reliability.
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 solution enhances the reliability and reduces the resistivity of interconnect structures, enabling scalable and high-performance semiconductor devices by ensuring void-free filling and improved adhesion, thus addressing the limitations of conventional PVD and CVD methods.
Implementation Method 1
an atomic-layer-deposition (ALD) layer along sidewalls and a bottom of an opening
Implementation Method 2
The conductive structure also includes a Cu film substantially filling the opening and bounding the Mn-based layer
Data Source
AI summary
The structures and methods described above provide mechanisms to improve interconnect reliability and resistivity. The interconnect reliability and resistivity are improved by using a composite barrier layer, which provides good step coverage, good copper diffusion barrier, and good adhesion with adjacent layers. The composite barrier layer includes an ALD barrier layer to provide good step coverage. The composite barrier layer also includes a barrier-adhesion-enhancing film, which contains at least an element or compound that contains Mn, Cr, V, Ti, or Nb to improve adhesion. The composite barrier layer may also include a Ta or Ti layer between the ALD barrier layer and the barrier-adhesion-enhancing layer.