Barrier Layer Via Step Coverage via Dynamic Bias Power
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Solution Overview
Problem
Copper interconnects in semiconductor manufacturing are prone to electromigration due to poor step coverage of barrier layers in vias or trenches, especially those with high aspect ratios, leading to malfunction and manufacturing issues.
Innovation Solution
A method involving sequential deposition steps under varying bias powers to form a barrier layer using high density plasma, with an adhesion layer and specific materials like titanium nitride, to enhance step coverage and prevent electromigration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer is deposited into vias or trenches using conventional methods, then the copper metal is protected from electromigration, but the step coverage of the barrier layer is poor, especially in high aspect ratio structures
Solution Approach 1:
The barrier layer deposition is divided into multiple sequential steps (first, second, and third deposition steps) with different bias powers. Each step deposits a portion of the total barrier layer thickness, allowing different regions (sidewalls vs. bottom) to receive optimized deposition conditions at different stages, thereby improving overall step coverage in high aspect ratio vias/trenches
Solution Approach 2:
The bias power is dynamically adjusted during the deposition process. The system transitions from a first bias power (100-550 W) for initial deposition, to a second bias power (550-800 W) for intermediate deposition, and finally to a third bias power (800-1200 W) for final deposition. This dynamic adjustment optimizes plasma interaction and material transport to achieve uniform coverage in high aspect ratio structures
2Reliability
If the barrier layer thickness is increased to ensure complete coverage, then electromigration protection is improved, but the manufacturing complexity and process difficulty increase
Solution Approach 1:
Instead of depositing the full barrier layer thickness in a single step, the process segments the deposition into three sequential steps with different bias powers. This allows the system to achieve the required total thickness while optimizing each sub-step for specific deposition goals, reducing the complexity of achieving uniform thick coverage in high aspect ratio structures
Solution Approach 2:
The process changes the bias power parameter across different deposition steps to optimize material transport and adhesion at each stage. By varying bias power from 100-550 W to 550-800 W to 800-1200 W, the system achieves better step coverage and uniformity without requiring excessive total thickness, thereby simplifying the overall manufacturing process
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
Improves the uniformity and thickness of the barrier layer, reducing electromigration risks and maintaining low electrical resistance, thus ensuring the reliability and performance of semiconductor devices.
Implementation Method 1
depositing a barrier material over the via or the trench by using the high density plasma
Implementation Method 2
generating a high density plasma in a chamber
Data Source
AI summary
The present invention provides a method of forming a barrier layer over a via or a trench. The method includes generating a high density plasma in a chamber and depositing a barrier material over the via or the trench by using the high density plasma. The depositing of the barrier material comprises at least a first deposition step, a second deposition step and a third deposition step in sequence. The first, second and third deposition steps is respectively performed under a first bias power, a second bias power and a third bias power. The third bias power is greater than the second bias power, and the second bias power is greater than the first bias power. The present invention also provides a via structure formed by the method.