Multi-Cathode PVD Chamber for High-Aspect-Ratio Seed Coverage
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Solution Overview
Problem
Physical vapor deposition (PVD) processes face challenges in achieving uniform film deposition and step coverage for high aspect ratio features due to the line-of-sight nature of the process, leading to poor coverage and uniformity in features like high aspect ratio vias.
Innovation Solution
A PVD chamber design with multiple targets and a rotating pedestal allows for simultaneous control of voltage biases for each target, enabling different sputtering profiles and ion energy distributions to improve uniformity and step coverage by adjusting the throw distance, deposition angle, and magnetic confinement, thereby providing a broader or narrower profile as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single source PVD sputtering is used, then hardware cost is reduced, but film deposition uniformity and step coverage for high aspect ratio features deteriorates
Solution Approach 1:
The single sputtering source is divided into multiple independent targets (first target and second target) positioned at different distances from the workpiece. Each target can be independently controlled with separate voltage biases, allowing different sputtering profiles to be generated simultaneously. This segmentation enables the first target to provide broader coverage while the second target provides narrower, more focused deposition, resolving the uniformity issue without requiring a completely complex multi-source system.
Solution Approach 2:
Different regions of the processing chamber are assigned different sputtering characteristics through the multiple targets. The first target (closer to workpiece) provides a first ion energy distribution and deposition profile, while the second target (farther from workpiece) provides a second ion energy distribution and deposition profile. This local differentiation of deposition quality allows optimization for both step coverage and overall uniformity simultaneously.
2Device complexity
If a single source PVD sputtering is used, then device complexity is reduced, but step coverage and sidewall coverage for high aspect ratio vias deteriorates
Solution Approach 1:
The sputtering system is segmented into multiple targets with independent control, allowing each target to be optimized for specific deposition angles and profiles. The first target can be optimized for sidewall coverage while the second target optimizes for bottom coverage, achieving comprehensive step coverage without requiring overly complex mechanical systems.
Solution Approach 2:
The system changes multiple parameters simultaneously including throw distance, deposition angle, and ion energy distribution by using multiple targets at different positions. Each target operates with independently controllable voltage bias, allowing dynamic adjustment of sputtering parameters to achieve optimal step coverage for high aspect ratio features.
3Manufacturing precision
If PVD sputtering is performed for longer time to improve coverage, then step coverage improves, but productivity decreases
Solution Approach 1:
Multiple targets operate simultaneously to deposit material onto the workpiece, providing continuous and enhanced material flux. This parallel deposition action from multiple sources increases the overall deposition rate while maintaining improved step coverage, eliminating the need for extended processing times.
Solution Approach 2:
The system optimizes deposition parameters including ion energy distribution and throw distance to enhance deposition efficiency. By controlling the voltage bias and position of multiple targets, the system achieves both improved step coverage and maintained productivity through parameter optimization rather than extended processing time.
4Manufacturing precision
If multiple targets with different distances from workpiece are used, then film deposition uniformity improves, but device complexity increases
Solution Approach 1:
The system is segmented into a minimal necessary number of targets (first and second targets) positioned at different distances, providing the required deposition profiles without excessive complexity. Each target serves a specific function in the deposition pattern, achieving uniformity with a manageable configuration.
Solution Approach 2:
Multiple targets serve multiple functions simultaneously: they provide different throw distances, different deposition angles, and different ion energy distributions. This multi-functionality allows a single target configuration to achieve what would otherwise require multiple separate processing steps or more complex mechanical systems.
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 film deposition uniformity and coverage across high aspect ratio features, allowing for more flexible process parameters to balance coverage, throughput, and layer characteristics, improving the reliability of electroplating processes.
Implementation Method 1
The magnet array forms a magnetic field that traps electrons and thus confines a significant portion of the plasma close to the target
Implementation Method 2
The high voltage generates an electric field inside the PVD chamber that is used to enable sputtering of the target material and generate and emit electrons from the target
Implementation Method 3
The collision between the trapped electron(s) and gas atoms will cause the gas atoms to emit electrons that are used to sustain and further increase the plasma density within the processing region
Implementation Method 4
The argon ions are accelerated towards the target due to the negative bias and collide with a surface of the target causing atoms of the target material to be ejected therefrom
Implementation Method 5
The ejected atoms of target material then travel towards the workpiece and chamber shielding to incorporate into the growing thin film thereon
Data Source
AI summary
Apparatus and methods for multi-cathode barrier seed deposition for high aspect ratio features in a physical vapor deposition (PVD) process are provided herein. In some embodiments, a PVD chamber includes a pedestal disposed within a processing region of the PVD chamber. The pedestal rotates with a workpiece on it. The PVD chamber includes a lid assembly includes a first target and a second target of a same target material, where a first surface of the first target defines a first zone of the processing region a first distance from the upper surface of the pedestal, and a second surface of the second target defines a second zone of the processing region a second distance from the plane of the upper surface of the pedestal. A system controller is configured to simultaneously control a first voltage bias for the first target and a second voltage bias for the second target.