Cobalt Contact Metallization for Void-Free Gap Fill
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Solution Overview
Problem
Contact openings in integrated circuit fabrication present challenging geometry, leading to difficulties in metal deposition, resulting in voids and seams that increase contact resistance and affect IC reliability.
Innovation Solution
A cobalt (Co) metallization process using a co-deposition/reflow physical vapor deposition (PVD) method with independent RF power control to fill contacts with aspect ratios between 3 to 10 and heights greater than 60 nm, ensuring effective gap fill by balancing deposition and reflow processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metal deposition is used to fill contact openings, then the deposition process is simple, but voids and seams form in the contact, increasing resistance and reducing reliability
Solution Approach 1:
The patent applies dynamics by making the deposition process adjustable and controllable through independent RF power sources. The system transitions from a static, fixed deposition process to a dynamic one where deposition rate, reflow rate, and plasma density can be independently controlled and optimized in real-time to achieve complete contact filling without voids
Solution Approach 2:
The patent implements parameter changes by independently controlling multiple RF power parameters (deposition RF power, reflow RF power, plasma density) to optimize the deposition process. By adjusting these parameters, the system achieves better gap fill properties and eliminates void formation while maintaining process simplicity
2Length of moving object
If contact opening geometry is made smaller and more challenging, then device scaling is achieved, but metal deposition becomes unable to fill contacts without voids or seams
Solution Approach 1:
The dynamic control of deposition parameters allows the process to adapt to smaller and more challenging contact geometries. By independently adjusting deposition rate and reflow rate through separate RF power sources, the system maintains effective filling even as contact dimensions decrease and aspect ratios increase
Solution Approach 2:
The patent employs periodic action through the cyclic interaction of deposition and reflow phases. The oscillating plasma and controlled material flow create periodic cycles of deposit formation and redistribution, which help fill complex geometries uniformly without creating voids or seams
3Manufacturing precision
If independent RF power control is implemented for co-deposition/reflow, then gap fill properties improve, but device complexity increases
Solution Approach 1:
The system achieves multi-functionality by using a single PVD reactor configuration to perform both deposition and reflow operations. The same reactor with independently controlled RF power sources can execute multiple process functions (deposition, reflow, cleaning) without requiring separate equipment, thereby managing complexity while improving gap fill properties
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 achieves improved gap fill properties, reducing void formation and enhancing contact reliability by optimizing metal deposition and reflow processes, thereby ensuring reliable metal contact formation in complex contact geometries.
Implementation Method 1
depositing a barrier layer in the contact opening, depositing a liner layer on the barrier layer, depositing a first metal layer on the liner layer to partially fill the contact opening, and depositing a second metal layer on the first metal layer to fill the contact opening
Implementation Method 2
depositing the second metal layer includes sputter depositing the second metal layer
Implementation Method 3
a first RF power and a DC power applied to a target and a second RF power applied to an electrostatic chuck in contact with the substrate
Implementation Method 4
reflowing the second metal layer using a second RF power
Data Source
AI summary
The present disclosure describes a method to a metallization process with improved gap fill properties. The method includes forming a contact opening in an oxide, forming a barrier layer in the contact opening, forming a liner layer on the barrier layer, and forming a first metal layer on the liner layer to partially fill the contact opening. The method further includes forming a second metal layer on the first metal layer to fill the contact opening, where forming the second metal layer includes sputter depositing the second metal layer with a first radio frequency (RF) power and a direct current power, as well as reflowing the second metal layer with a second RF power.