Cu Wiring Fabrication via iPVD Re-sputtering for Void-Free Trench Burial
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the formation of Cu wiring with fine trench sizes, where Cu film burial failures occur due to poor wettability and step coverage issues, leading to voids and lump formation at the bottom of trenches, especially as wiring widths increase beyond 50 nm.
Innovation Solution
A Cu wiring fabrication method involving the formation of a barrier film and an Ru film by CVD, followed by ionized physical vapor deposition (iPVD) with a re-sputtering step to stabilize Cu at the trench corners and a normal film forming step to prevent Cu lump formation, ensuring uniform burial regardless of trench size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If iPVD is used to bury Cu film in trench, then Cu film can be formed with good step coverage, but Cu lump forms at the bottom of wide trenches causing burial failure
Solution Approach 1:
The patent divides the Cu film formation process into two distinct stages: a first stage that forms an initial Cu film layer, and a second stage that forms the remaining Cu film thickness. This segmentation allows different process conditions to be optimized for each stage, preventing Cu lump formation while ensuring complete trench burial.
Solution Approach 2:
The first stage of Cu film formation performs a preliminary action by creating an initial Cu film layer that serves as a foundation for the second stage. This preliminary layer prevents uncontrolled Cu aggregation at the trench bottom before the main burial process begins.
2Reliability
If Ru film is formed by CVD to improve Cu wettability, then Cu can be buried successfully, but process complexity increases
Solution Approach 1:
The patent changes the parameters of the existing iPVD process (pressure, power, gas flow ratios) to achieve the desired Cu film formation characteristics without adding new material layers. This parameter optimization replaces the need for additional Ru film formation steps.
3Productivity
If trench width is increased for larger wiring, then wiring capacity increases, but Cu lump formation probability increases
Solution Approach 1:
The patent applies dynamic process control by adjusting iPVD parameters during the two-stage formation process. The first stage uses conditions optimized for preventing lump formation, while the second stage uses conditions optimized for completing the burial, adapting the process to the specific trench dimensions.
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 method effectively suppresses Cu lump formation and voids in trenches of varying widths, ensuring reliable Cu wiring fabrication with improved conductivity and reduced resistance.
Implementation Method 1
generate plasma by supplying a plasma generation gas to the processing container
Implementation Method 2
ionized physical vapor deposition (iPVD)
Implementation Method 3
re-sputtering the formed Cu film or Cu alloy film in a condition in which the formed Cu film or Cu alloy film is re-sputtered by an ion action of the plasma generation gas
Data Source
AI summary
Cu wiring fabrication method for fabricating Cu wiring with respect to substrate having interlayer dielectric film having trench formed thereon, includes: forming barrier film on surface of the trench; forming Ru film on surface of the barrier film by CVD; burying the trench by forming Cu film or Cu alloy film on the Ru film; forming Cu film or Cu alloy film at corners of bottom of the trench while re-sputtering the formed Cu film or Cu alloy film in a condition where first formed Cu film or Cu alloy film re-sputtered by an ion action of the plasma generation gas; and subsequently burying the Cu film or the Cu alloy film in the trench in condition where the Cu film or the Cu alloy film is formed on field portion of the substrate, and reflows in the trench by an ion action of the plasma generation gas.