Contact Structure Liner Profile for Void-Free Narrow Openings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge of filling narrow openings in semiconductor devices with contact structures is exacerbated by shrinking technology nodes, leading to issues such as seam and void formation, increased resistance, and diffusion of materials, which are not adequately addressed by existing fabrication methods.
Innovation Solution
A modified profile for the liner layer is introduced, varying in thickness across different regions of the opening to ensure adequate adhesion and diffusion prevention while allowing for successful deposition of additional metal layers, reducing the likelihood of seam and void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing fabrication methods are used to form contact features in tightly constrained FinFET structures, then the process can be maintained with current capabilities, but seam and void formation occurs, increasing contact resistance and reducing reliability
Solution Approach 1:
The contact feature formation process is divided into multiple sequential steps: forming a mandrel structure, depositing a first contact material around the mandrel, removing the mandrel, and depositing a second contact material to fill remaining voids. This segmentation allows each step to address specific defects, preventing seam and void formation that would occur in a single-step process.
Solution Approach 2:
The mandrel structure is formed in advance before contact material deposition. This preliminary action creates a template that guides the sequential deposition of contact materials, ensuring proper positioning and preventing defects. The mandrel is removed after the first contact material is deposited, preparing the structure for the second material deposition.
2Productivity
If fin pitches are decreased and fin heights are increased to achieve scaling, then device density and performance are improved, but the ability to form contact features using existing processes is significantly constrained
Solution Approach 1:
The contact structure is built in nested layers: a mandrel is formed first, then a first contact material is deposited around it, the mandrel is removed, and a second contact material is deposited to complete the fill. This nested approach allows contact features to be formed in the tightly constrained spaces of scaled FinFET devices where traditional single-step filling would fail.
Solution Approach 2:
The process uses different deposition parameters and material properties for the first and second contact materials. The first contact material is deposited with parameters optimized for conformal coverage around the mandrel, while the second contact material is deposited to fill remaining voids and achieve final contact properties. This parameter optimization enables successful contact formation in scaled devices.
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 enhances the reliability of electrical connections by minimizing defects and maintaining low contact resistance, thereby improving the performance and manufacturing efficiency of semiconductor devices.
Implementation Method 1
the liner layer configured to prevent diffusion of the conductive material into the dielectric material
Implementation Method 2
A first deposition process forms a layer of material of a first composition on the sidewall and the bottom
Data Source
AI summary
Devices and methods that include for configuring a profile of a liner layer before filling an opening disposed over a semiconductor substrate. The liner layer has a first thickness at the bottom of the opening and a second thickness a top of the opening, the second thickness being smaller that the first thickness. In an embodiment, the filled opening provides a contact structure.