Semiconductor Via Structure With Barrier-Free Contact Interface
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Solution Overview
Problem
The existing interconnect structures in integrated circuits face challenges in achieving reliable adhesion and thermal stability between conductive features, leading to increased resistance and potential interface degradation, which affects the yield and performance of semiconductor devices.
Innovation Solution
A method is introduced that involves forming a metal adhesion layer on an underlying conductive feature, blocking the formation of a barrier layer using a sacrificial layer, and then filling the via with a conductive material, thereby reducing contact resistance and improving thermal stability by creating a barrier-free interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer is formed on the conductive feature surface, then diffusion prevention is improved, but contact resistance increases and thermal stability deteriorates
Solution Approach 1:
The barrier layer is segmented into two parts: a first barrier layer portion formed on the sidewalls of the via opening, and a second barrier layer portion formed on the bottom surface. This segmentation allows the barrier layer to prevent diffusion while minimizing its presence on the conductive feature surface, thereby reducing contact resistance and improving thermal stability.
Solution Approach 2:
The barrier layer is applied selectively to different locations with different thicknesses and coverage. The sidewalls receive full barrier layer coverage for diffusion prevention, while the bottom surface receives a thinner or partial barrier layer to maintain electrical contact quality. This local quality differentiation resolves the contradiction between diffusion prevention and contact resistance reduction.
2Reliability
If a barrier layer is formed on the conductive feature surface, then diffusion prevention is improved, but thermal stability deteriorates
Solution Approach 1:
The barrier layer is divided into sidewall portions and bottom portions, allowing the thermal stability-critical interface to have minimal barrier layer presence while maintaining diffusion prevention capabilities through sidewall coverage.
Solution Approach 2:
The barrier layer thickness and coverage are optimized locally: thick coverage on sidewalls for diffusion prevention, and thin or partial coverage on the bottom surface where thermal stability is most critical. This local differentiation resolves the contradiction between diffusion prevention and thermal stability.
3Ease of manufacture
If the via opening is filled with conductive material directly, then manufacturing simplicity is maintained, but adhesion reliability deteriorates
Solution Approach 1:
The conductive material is deposited as a preliminary seed layer before the final copper fill. This preliminary conductive material layer is formed conformally on the sidewalls and bottom surface, creating a reliable adhesion interface. The subsequent copper fill completes the via while maintaining the adhesion benefits of the preliminary layer.
Solution Approach 2:
The preliminary conductive material layer acts as an intermediary between the barrier layer and the final copper fill. This intermediary layer ensures reliable adhesion and thermal stability while allowing the manufacturing process to remain relatively simple through conformal deposition techniques.
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 thermal stability and reduces contact resistance between conductive features, improving the yield and reliability of semiconductor devices by forming a metal adhesion layer and using a sacrificial layer to block the barrier layer formation.
Implementation Method 1
depositing a metal adhesion layer in the opening, wherein the metal adhesion layer covers the exposed surface of the conductive feature
Implementation Method 2
depositing a metal adhesion layer in the opening, wherein the metal adhesion layer covers the exposed surface of the conductive feature
Implementation Method 3
depositing a sacrificial layer in the opening, wherein the sacrificial layer selectively forms on the metal adhesion layer over surfaces of the second dielectric layer
Implementation Method 4
depositing a conductive material to fill the opening, wherein the conductive material covers the metal adhesion layer
Implementation Method 5
depositing a conductive material to fill the opening, wherein the conductive material covers the metal adhesion layer
Data Source
AI summary
A structure includes a first conductive feature in a first dielectric layer; a second dielectric layer over the first dielectric layer; and a second conductive feature extending through the second dielectric layer to physically contact the first conductive feature, wherein the second conductive feature includes a metal adhesion layer over and physically contacting the first conductive feature; a barrier layer extending along sidewalls of the second dielectric layer; and a conductive filling material extending over the metal adhesion layer and the barrier layer, wherein a portion of the conductive filling material extends between the barrier layer and the metal adhesion layer.