Semiconductor Copper Interconnects Adhesion
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Solution Overview
Problem
In semiconductor devices, the use of copper interconnects requires a diffusion barrier film to prevent copper diffusion, but existing methods struggle to maintain adhesion between the insulating film and the diffusion barrier film while avoiding the formation of oxide layers and high relative permittivity in the insulating film, especially with SiOH, SiCOH, or organic polymer films.
Innovation Solution
A method involving plasma treatment with hydrocarbon gas to reduce oxide layers on conductive patterns and modify insulating film surfaces, followed by gradual addition of Si-containing gases during plasma CVD to form SiCH or SiCHN films as diffusion barriers, ensuring increased Si concentration and improved adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffusion barrier film is formed over copper interconnect to prevent copper diffusion, then copper diffusion is prevented, but adhesion between the insulating film and diffusion barrier film deteriorates
Solution Approach 1:
A CH film is formed as an intermediary layer between the insulating film and the diffusion barrier film. This CH film serves as a mediator that improves adhesion between the insulating film and the diffusion barrier film, while also preventing copper diffusion. The CH film is formed by plasma CVD using a hydrocarbon gas, creating a carbon-containing layer that bonds well with both the insulating film and the diffusion barrier film.
2Ease of manufacture
If CMP process is used to bury conductive pattern in insulating film, then conductive pattern is embedded, but oxide layer is formed on conductive pattern surface
Solution Approach 1:
The oxide layer formed on the conductive pattern surface during CMP is converted into a beneficial carbon-containing layer through plasma treatment with hydrocarbon gas. The plasma process reduces the oxide layer and simultaneously deposits carbon, transforming the harmful oxide into a protective carbon layer that prevents further oxidation and improves adhesion.
3Object-generated harmful factors
If reducing atmosphere is applied to remove oxide layer from conductive pattern, then oxide layer is reduced, but relative permittivity of insulating film increases
Solution Approach 1:
The plasma treatment with hydrocarbon gas is applied locally and selectively to the surface, affecting only the topmost layers. The treatment depth and intensity are controlled to reduce oxide layers and modify surface properties without penetrating deep into the insulating film bulk, thereby avoiding significant changes in the overall relative permittivity of the insulating film.
4Quantity of substance
If carbon-containing plasma is used to treat insulating film surface to lower permittivity, then relative permittivity is reduced, but adhesion between insulating film and diffusion barrier film deteriorates
Solution Approach 1:
The plasma treatment parameters are precisely controlled, including gas composition (hydrocarbon gas), power, pressure, and treatment time. These parameters are optimized to achieve the right balance: enough carbon deposition to lower permittivity and improve adhesion, but not so much that it creates a thick layer that would interfere with subsequent diffusion barrier film formation or cause other issues.
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 effectively prevents oxide layer formation, reduces insulating film permittivity, and maintains strong adhesion between the insulating and diffusion barrier films, enhancing the reliability and electro-migration characteristics of semiconductor devices.
Implementation Method 1
treating surfaces of the insulating film and the conductive pattern with plasma which includes a hydrocarbon gas as a treatment gas
Implementation Method 2
forming a diffusion barrier film, which is formed of an SiCH film, an SiCHN film, an SiCHO film or an SiCHON film, over the insulating film and the conductive pattern with performing a plasma CVD by adding an Si-containing gas to the treatment gas
Data Source
AI summary
A method includes burying a conductive pattern in an insulating film made of SiOH, SiCOH or organic polymer, treating surfaces of the insulating film and the conductive pattern with plasma which includes a hydrocarbon gas as a treatment gas, and forming a diffusion barrier film, which is formed of an SiCH film, an SiCHN film, an SiCHO film or an SiCHON film, over the insulating film and the conductive pattern with performing a plasma CVD by adding an Si-containing gas to the treatment gas while increasing an addition amount gradually or in a step by step manner.