Cu Wiring Formation with Manganese Oxide Cap
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Solution Overview
Problem
Current Cu wiring forming methods fail to achieve sufficient electromigration tolerance and are complicated, especially with the miniaturization of semiconductor devices, leading to void formation and increased leak current due to insufficient fillability and complex processes.
Innovation Solution
A Cu wiring forming method involving the formation of a barrier film, a Ru liner film, and a Cu film by PVD, followed by CMP polishing, and the deposition of a manganese oxide metal cap on the entire surface, including the insulating film, to enhance adhesivity and prevent voids and leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Cu plating is used to fill narrow trenches, then fillability is improved, but voids are formed due to insufficient fillability in miniaturized structures
Solution Approach 1:
The patent changes the filling method from Cu plating to Cu PVD (physical vapor deposition) to improve fillability in narrow trenches. By using PVD instead of plating, the process achieves better conformal coverage and complete filling without void formation in miniaturized structures with trench widths of several tens of nm.
Solution Approach 2:
The patent replaces the electrochemical Cu plating process with a physical vapor deposition process. This substitution eliminates the void formation issue associated with plating in narrow trenches by using physical deposition mechanisms that provide superior fillability and conformal coverage.
2Reliability
If a metal cap is selectively formed on Cu wiring to improve adhesivity, then electromigration tolerance is improved, but the process becomes too complicated
Solution Approach 1:
The patent forms the metal cap (Mn or MnOx) on the entire substrate surface including both Cu wiring regions and insulating film regions. This universal formation approach eliminates the need for complex selective formation processes while still achieving the desired adhesivity improvement and electromigration tolerance on the Cu wiring.
Solution Approach 2:
The metal cap material (Mn or MnOx) is deposited conformally over the entire surface, and through self-alignment and subsequent annealing processes, the material naturally adheres to and protects the Cu wiring regions. The process uses the material's own properties to achieve selective functionality without requiring complex patterning or selective deposition steps.
3Ease of manufacture
If a metal cap is formed on the insulating film to simplify the process, then leak current increases due to lack of selectivity
Solution Approach 1:
The patent introduces an additional layer (such as Ru or TaN) between the metal cap and the Cu wiring. This intermediary layer acts as a diffusion barrier and adhesion promoter, preventing direct contact between the metal cap material and the insulating film, thereby eliminating leak current paths while maintaining process simplicity through universal metal cap formation.
Solution Approach 2:
The patent creates different functional properties at different locations: the metal cap provides adhesivity enhancement on Cu wiring regions, while the additional layer prevents electrical leakage at the insulating film regions. This local differentiation of material properties resolves the contradiction between process simplification and leak current prevention.
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 ensures high electromigration tolerance and prevents void formation and increased leak current between Cu wirings, maintaining low wiring resistance and simplifying the process by forming a manganese oxide metal cap on the entire surface, including the insulating film.
Implementation Method 1
forming a barrier film at least on a surface of the recess
Implementation Method 2
forming a Cu film by PVD to fill the recess with the Cu film
Implementation Method 3
polishing an entire surface of the substrate by CMP to form the Cu wiring in the recess
Implementation Method 4
forming a metal cap formed of a manganese oxide film on an entire surface including the insulating film and the Cu wiring
Implementation Method 5
forming a metal cap formed of a manganese oxide film on an entire surface including the insulating film and the Cu wiring
Implementation Method 6
forming a metal cap formed of a manganese oxide film on an entire surface including the insulating film and the Cu wiring
Implementation Method 7
forming a Mn film by PVD, CVD or ALD; and forming the manganese oxide film by oxidizing the Mn film
Data Source
AI summary
A Cu wiring forming method forms Cu wiring in a recess of a predetermined pattern including a trench formed in an insulating film on a substrate surface. The method includes: forming a barrier film at least on a surface of the recess; forming a Cu film by PVD to fill the recess with the Cu film; forming an additional layer on the Cu film; polishing an entire surface by CMP to form the Cu wiring in the recess; forming a metal cap including a manganese oxide film on an entire surface including the insulating film and the Cu wiring of the substrate after performing the CMP polishing; and forming a dielectric cap on the metal cap.