Copper Interconnection Air Gap and Barrier Film for TDDB
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Solution Overview
Problem
The use of copper in semiconductor interconnections leads to shorter Time Dependence on Dielectric Breakdown (TDDB) life due to copper diffusion, increased parasitic capacitance, and misalignment issues with via holes, which degrade dielectric breakdown voltage and increase capacitance between interconnections.
Innovation Solution
A manufacturing method that includes forming interconnection trenches, depositing copper conductor films, and using barrier insulative films to prevent copper diffusion, while creating air gaps and reservoirs to reduce capacitance and improve alignment, thereby enhancing dielectric breakdown voltage and TDDB life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If copper is used as interconnection material, then electrical conductivity is improved, but TDDB life becomes shorter due to copper diffusion
Solution Approach 1:
A barrier insulative film is introduced as an intermediary layer between the copper interconnection and the surrounding insulative film. This barrier film prevents copper atoms from diffusing into the insulative film, thereby maintaining TDDB life while allowing copper to provide its excellent electrical conductivity. The barrier film acts as a mediator that isolates the copper from harmful interactions with the dielectric material.
Solution Approach 2:
The interconnection structure uses a composite material approach by combining copper with a barrier insulative film. This composite structure leverages the high electrical conductivity of copper while the barrier film provides diffusion prevention. The combination of these two materials creates a system that achieves both electrical performance and reliability.
2Quantity of substance
If insulative film of low dielectric constant is used, then interconnection capacitance is decreased, but dielectric breakdown voltage becomes lower
Solution Approach 1:
The barrier insulative film is applied locally at the interface between the copper interconnection and the low dielectric constant insulative film. This local application provides enhanced breakdown voltage protection precisely where copper diffusion would most harmfully affect the dielectric strength, while allowing the low dielectric constant material to maintain low capacitance in the bulk region.
3Quantity of substance
If air gap is formed between interconnections, then parasitic capacitance is decreased, but manufacturing precision becomes more difficult due to misalignment issues
Solution Approach 1:
The barrier insulative film is formed in advance before the low dielectric constant insulative film is deposited. This preliminary action creates a stable, adherent layer that ensures proper via hole alignment and prevents manufacturing defects. By establishing this barrier layer first, the subsequent formation of air gaps and low-K insulation can proceed with improved precision control.
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
The method effectively increases dielectric breakdown voltage, decreases capacitance between interconnections, and improves TDDB life by preventing copper diffusion and misalignment, leading to improved semiconductor device reliability and performance.
Implementation Method 1
the surface (bottom and lateral side) of the buried interconnection is covered with a thin barrier metal film such that the buried interconnection comprising copper is not in direct contact with the insulative film thereby suppressing or preventing copper in the buried interconnection from diffusing into the insulative film
Implementation Method 2
the capacitance between the interconnections is intended to be decreased by the air gap
Data Source
AI summary
In a semiconductor device, capacitance between copper interconnections is decreased and the insulation breakdown is improved simultaneously, and a countermeasure is taken for misalignment via by a manufacturing method including the steps of forming an interconnection containing copper as a main ingredient in an insulative film above a substrate, forming insulative films and a barrier insulative film for a reservoir pattern, forming an insulative film capable of suppressing or preventing copper from diffusing on the upper surface and on the lateral surface of the interconnection and above the insulative film and the insulative film, forming insulative films of low dielectric constant, in which the insulative film is formed such that the deposition rate above the opposing lateral surfaces of the interconnections is larger than the deposition rate therebelow to form an air gap between the adjacent interconnections and, finally, planarizing the insulative film by interlayer CMP.