Cu Interconnect Dielectric Structure for TDDB Field Relaxation
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to increased electric field intensity on interlayer insulating films between Cu wirings, causing Time Dependence on Dielectric Breakdown (TDDB) issues, particularly due to the formation of damage layers by ammonia plasma treatment.
Innovation Solution
The formation of electric field relaxation layers with higher nitrogen concentrations than the interlayer insulating film, positioned deeper than the surface, helps to relax electric fields and improve TDDB life by reducing the concentration of electric fields at the interface between the insulating barrier film and the interlayer insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ammonia plasma treatment is applied to remove CuO from Cu wiring surface, then TDDB characteristics of Cu wiring are improved, but damage layers with high dielectric constant are formed on low-k interlayer insulating film surface causing RC characteristics deterioration
Solution Approach 1:
The patent applies different treatments to different locations: ammonia plasma treatment is applied selectively to Cu wiring surfaces to remove CuO, while the interlayer insulating film surface is protected from this treatment. This local differentiation allows CuO removal where needed without forming damage layers on the low-k dielectric surface, thus improving TDDB characteristics without degrading RC characteristics.
Solution Approach 2:
The patent introduces an intermediary step of forming a protective mask or using selective plasma conditions that prevent ammonia plasma from directly contacting the interlayer insulating film surface. This intermediary approach allows the beneficial CuO removal effect on Cu wiring while preventing the harmful damage layer formation on the low-k dielectric.
2Productivity
If device miniaturization is pursued to increase integration density, then productivity is improved, but electric field intensity on interlayer insulating film increases causing TDDB breakdown
Solution Approach 1:
The patent changes the chemical composition parameter of the interlayer insulating film by forming a nitrogen-containing film (such as SiCN or SiOCN) instead of conventional low-k dielectrics. This parameter change increases the dielectric's resistance to electric field-induced breakdown, allowing miniaturized device structures to maintain adequate TDDB life despite higher electric field intensities.
Solution Approach 2:
The patent employs composite material structures combining organic and inorganic components in the interlayer insulating film (e.g., SiOCN films containing silicon, oxygen, carbon, and nitrogen). This composite approach provides both the low dielectric constant needed for high-speed operation and the enhanced breakdown resistance required for miniaturized devices with high electric field stress.
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 significantly improves the TDDB life of semiconductor devices with Cu wirings by reducing the likelihood of breakdown at the interface between the insulating barrier film and the interlayer insulating film.
Implementation Method 1
subjecting the surfaces of the Cu wiring and the interlayer insulating film to ammonia (NH3) plasma treatment to reduce CuO on the surface of the Cu wiring to Cu
Implementation Method 2
treating the exposed surfaces with a high strength ammonia plasma to ion bombard the exposed inter line silicon oxide with nitrogen atoms, thereby converting the upper portion to silicon oxynitride
Data Source
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AI summary
A semiconductor device includes an interlayer insulating film INS2, adjacent Cu wirings M1W formed in the interlayer insulating film INS2, and an insulating barrier film BR1 which is in contact with a surface of the interlayer insulating film INS2 and surfaces of the Cu wirings M1W and covers the interlayer insulating film INS2 and the Cu wirings M1W. Between the adjacent Cu wirings M1W, the interlayer insulating film INS2 has a damage layer DM1 on its surface, and has an electric field relaxation layer ER1 having a higher nitrogen concentration than a nitrogen concentration of the damage layer DM1 at a position deeper than the damage layer DM1.