Metal Fill Nucleation Layers for Line Bending and Resistivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenges in semiconductor fabrication include reducing fluorine incorporation, resistance, stress, and line bending during metal fill processes, particularly in features with narrow widths and complex structures, which affect device performance and yield.
Innovation Solution
A method involving multiple conformal nucleation layers with controlled deposition conditions, including varying reducing agent chemistry, flow sequences, and chamber parameters, is used to mitigate line bending and reduce fluorine incorporation, while ensuring low resistivity and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single conformal metal nucleation layer is deposited during metal fill, then the feature filling is simplified, but line bending occurs due to interatomic forces between sidewalls
Solution Approach 1:
The single nucleation layer is divided into multiple nucleation layers (first nucleation layer and second nucleation layer) with different deposition conditions. The first nucleation layer is deposited at conditions promoting roughness to prevent line bending, while the second nucleation layer is deposited at conditions optimizing for low resistivity and smooth morphology, thereby resolving the contradiction between structural simplicity and line bending control.
Solution Approach 2:
Different regions of the nucleation structure are given different properties through multiple layers. The first nucleation layer has rough surface quality to disrupt interatomic forces and prevent line bending, while the second nucleation layer has smooth quality for low resistivity. This local differentiation resolves the contradiction by assigning different qualities to different functional requirements.
2Manufacturing precision
If deposition conditions are optimized for smooth nucleation layer, then resistivity is reduced, but line bending occurs due to cohesive forces
Solution Approach 1:
The nucleation layer deposition process is segmented into two separate deposition steps with different optimized conditions. The first deposition optimizes for roughness to prevent line bending, while the second deposition optimizes for smoothness and low resistivity. This segmentation allows both contradictory requirements to be satisfied in different layers.
Solution Approach 2:
The nucleation structure becomes a composite of multiple layers with different morphological and electrical properties. The first nucleation layer provides mechanical stability and line bending prevention through roughness, while the second nucleation layer provides electrical conductivity through smoothness. This composite structure resolves the contradiction between line bending control and resistivity reduction.
3Manufacturing precision
If multiple nucleation layers are deposited to prevent line bending, then line bending is reduced, but process complexity increases
Solution Approach 1:
The deposition process uses parameter changes between the two nucleation layer depositions, specifically varying the reducing agent chemistry, flow sequences, and chamber parameters. These controlled parameter changes enable the first layer to be rough for line bending prevention while keeping the process variations systematic and manageable, thereby reducing the effective complexity despite multiple layers.
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 reduces line bending, fluorine incorporation, and resistivity, resulting in uniform feature fill and improved device yield by preventing cohesive forces between sidewalls and controlling grain growth.
Implementation Method 1
depositing a first conformal metal nucleation layer in the plurality of features under supersaturated conditions by exposing the feature to alternating doses of a reducing agent and a metal precursor
Implementation Method 2
exposing the feature to alternating doses of a reducing agent and a metal precursor
Data Source
AI summary
Methods of mitigating line bending during feature fill include deposition of a nucleation layer having increased roughness. In some embodiments, the methods include depositing two or more metal nucleation layers.