High Aspect Ratio Metallization with Noble Metal Plug
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Solution Overview
Problem
High aspect ratio metallization structures in semiconductor devices often develop key-hole seams due to conventional plating techniques, which negatively affect contact performance as circuit densities increase and device sizes scale.
Innovation Solution
A noble metal-containing material is selectively deposited within the lower region of high aspect ratio contact openings, reducing the aspect ratio and eliminating key-hole seams by using a U-shaped diffusion barrier and optional plating seed layer, with the noble metal being Ru, Rh, Ir, Pt, Co, or Pd, and the conductive metal being Cu, Al, or W, formed through processes like CVD or ALD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plating techniques are used to fill high aspect ratio contact openings, then copper and copper alloys can be deposited with lower electrical resistivity, but key-hole seams and voids develop within the contact structure
Solution Approach 1:
The contact opening filling process is segmented into multiple stages: first depositing a noble metal-containing material (Ru, Rh, Ir, Pt, Co, or Pd) in the lower region, then adding conductive metal (Cu, Al, or W) in the upper region. This segmentation allows each material to be deposited under optimized conditions, preventing key-hole seam formation while achieving low electrical resistivity.
Solution Approach 2:
The noble metal-containing material is deposited as a preliminary layer before the conductive metal. This preliminary action creates a foundation that prevents key-hole seam formation during subsequent plating, ensuring proper filling of high aspect ratio openings while maintaining electrical conductivity.
2Productivity
If circuit densities are increased and device sizes are scaled, then more advanced semiconductor devices can be produced, but the aspect ratio of contact openings increases making adequate plating difficult
Solution Approach 1:
Different regions of the contact opening are assigned different materials with specific local qualities: the lower region receives noble metal-containing material to prevent seam formation, while the upper region receives conductive metal for optimal electrical performance. This local differentiation allows the structure to handle high aspect ratios while maintaining productivity.
3Area of moving object
If the width of contact structures is decreased to increase circuit density, then more devices can be integrated, but the aspect ratio increases making conventional plating inadequate
Solution Approach 1:
The noble metal-containing material acts as an intermediary layer between the contact opening walls and the conductive metal. This intermediary prevents direct interaction that would cause key-hole seam formation in narrow, high aspect ratio openings, enabling successful plating of decreased width contacts.
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 solution provides a reliable high aspect ratio metallization structure without key-hole seams, enhancing contact performance by reducing the aspect ratio and eliminating voids, thereby improving the reliability of semiconductor devices.
Implementation Method 1
formed through processes like CVD or ALD
Implementation Method 2
formed through processes like CVD or ALD
Implementation Method 3
using a U-shaped diffusion barrier
Data Source
AI summary
A high aspect ratio metallization structure is provided in which a noble metal-containing material is present at least within a lower portion of a contact opening located in a dielectric material and is in direct contact with a metal semiconductor alloy located on an upper surface of a material stack of at least one semiconductor device. In one embodiment, the noble metal-containing material is plug located within the lower region of the contact opening and an upper region of the contact opening includes a conductive metal-containing material. The conductive metal-containing material is separated from plug of noble metal-containing material by a bottom walled portion of a U-shaped diffusion barrier. In another embodiment, the noble metal-containing material is present throughout the entire contact opening.