Selective Metal Via Fill for High-Aspect-Ratio Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies face challenges in efficiently filling high aspect ratio via structures in semiconductor devices, particularly in forming bit lines of three-dimensional memory devices like NAND strings, due to issues with material deposition and integration.
Innovation Solution
A method involving selective metal deposition is employed, where a first metallic material nucleates and grows from the exposed surface of a metal interconnect structure, followed by a planarization process to form a metallic liner and fill material, and a copper-based conductive line structure is formed with a high copper content to fill the via and line cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal deposition is used to fill high aspect ratio via structures, then the via structures can be formed, but the filling process becomes difficult and unreliable
Solution Approach 1:
The patent employs a two-stage deposition process where a first metallic material (e.g., cobalt) is selectively deposited to form a liner in the via region, and a second metallic material (e.g., copper) is deposited to form the fill material. This local differentiation of material properties and deposition conditions enables reliable filling of high aspect ratio via structures by addressing the specific challenges of each region differently.
Solution Approach 2:
The patent changes deposition parameters between the two stages: the first metallic material is deposited under conditions that promote vertical growth and liner formation, while the second metallic material is deposited under conditions that promote lateral growth and cavity filling. This parameter optimization for each stage resolves the contradiction between via formation and filling reliability.
2Reliability
If a single metallic material is used for via and line structures, then the process is simpler, but the electrical connectivity and performance are compromised
Solution Approach 1:
The patent creates a composite interconnect structure where a first metallic material (e.g., cobalt) forms the liner providing adhesion and barrier properties, and a second metallic material (e.g., copper) forms the fill providing high electrical conductivity. This composite approach combines the advantages of different materials to achieve both mechanical reliability and electrical performance.
Solution Approach 2:
The patent segments the interconnect structure into functionally distinct regions: the via liner region containing the first metallic material and the via fill/line region containing the second metallic material. This segmentation allows each material to be optimized for its specific function, improving overall electrical connectivity while managing complexity through clear functional division.
3Manufacturing precision
If the metallic fill material contacts the dielectric material layer, then the filling is complete, but short circuits or reliability issues occur
Solution Approach 1:
The patent introduces a first metallic material liner as an intermediary barrier between the second metallic fill material and the dielectric material layer. This liner prevents direct contact between the conductive fill material and the dielectric, eliminating short circuit risks while maintaining complete via filling. The liner serves as both a physical barrier and an adhesion promoter.
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 enables effective filling of high aspect ratio via structures, enhancing the electrical connectivity and reliability of semiconductor devices by ensuring a robust metal interconnect assembly.
Implementation Method 1
a first metallic material nucleates and grows from the exposed surface of the metal interconnect structure
Implementation Method 2
depositing a first metallic material by performing an area selective deposition process
Implementation Method 3
removing portions of the second metallic material and the first metallic material from above the horizontal plane including a top surface of the second dielectric material layer by performing a planarization process
Data Source
AI summary
A metal interconnect assembly includes a first metal interconnect structure, and a second metal interconnect structure embedded in a second dielectric material layer and containing a metal line portion having a top surface located within a first horizontal plane and having a bottom surface located within a second horizontal plane, and further containing a metal via portion adjoined to a bottom of the metal line portion and contacting a top surface of the first metal interconnect structure. The second metal interconnect structure contains a metallic liner including a first metallic material that includes an entire volume of the metal via portion and an outer part of the metal line portion, and a metallic fill material portion contains a second metallic material that includes an inner part of the metal line portion, does not contact and is spaced from the second dielectric material layer by the metallic liner.