TiN Adhesion Layer Composition for Stable Ru or Mo Wiring
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Solution Overview
Problem
The degradation in etching processability and resistivity of metal layers in semiconductor devices, particularly due to high-temperature thermal processing, is exacerbated by the diffusion of titanium from titanium nitride adhesion layers into ruthenium or molybdenum wiring, leading to unsatisfactory manufacturing outcomes.
Innovation Solution
Adjusting the composition ratio of nitrogen to titanium in the titanium nitride adhesion layer to 0.6 or more, preferably between 0.6 and 1.0, stabilizes the titanium nitride layer, preventing titanium diffusion and maintaining etching processability and resistivity during high-temperature thermal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-temperature thermal processing is performed on the semiconductor device, then the metal layer undergoes necessary thermal treatment, but titanium diffuses from the titanium nitride adhesion layer into the metal layer, degrading etching processability and resistivity
Solution Approach 1:
A diffusion barrier layer is introduced between the titanium nitride adhesion layer and the metal layer (ruthenium or molybdenum). This barrier layer acts as an intermediary that prevents titanium diffusion into the metal layer during high-temperature thermal processing, thereby maintaining etching processability and resistivity while allowing the metal layer to undergo necessary thermal treatment
Solution Approach 2:
The adhesion structure is transformed from a single-material titanium nitride layer to a composite structure consisting of titanium nitride adhesion layer combined with a diffusion barrier layer. This composite material approach provides both adhesion functionality and diffusion prevention, resolving the contradiction between enabling high-temperature processing and maintaining material properties
2Strength
If the titanium nitride adhesion layer is used to prevent wiring separation from the interlayer insulating film, then adhesion is improved, but titanium diffusion occurs during thermal processing, causing degradation in metal layer properties
Solution Approach 1:
The adhesion layer is segmented into two distinct functional layers: the titanium nitride adhesion layer that provides bonding strength to the interlayer insulating film, and a separate diffusion barrier layer that prevents titanium diffusion into the metal layer. This segmentation allows each layer to perform its specific function without interfering with the other
Solution Approach 2:
The diffusion barrier layer serves as an intermediary between the titanium nitride adhesion layer and the metal layer, blocking the harmful titanium diffusion while allowing the titanium nitride layer to maintain its adhesion function
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
Prevents the degradation of etching processability and resistivity of metal layers by ensuring the titanium nitride layer remains stable, thereby maintaining manufacturing quality and efficiency.
Implementation Method 1
the diffusion of titanium from titanium nitride adhesion layers into ruthenium or molybdenum wiring
Implementation Method 2
performing a thermal processing on the insulating layer, the adhesion layer, and the metal layer
Data Source
AI summary
A method of manufacturing a semiconductor device including an insulating layer, an adhesion layer composed of a titanium nitride, and a metal layer, includes: forming the adhesion layer on the insulating layer; forming the metal layer on the adhesion layer; and performing a thermal processing on the insulating layer, the adhesion layer, and the metal layer, wherein, in the forming of the adhesion layer, a composition ratio of nitrogen to titanium in the titanium nitride constituting the adhesion layer is 0.6 or more.