Deep Feature Filling via Nanoparticle Dispersion Annealing
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Solution Overview
Problem
Conventional methods for filling conductive materials into the large, deep features of 3-D integrated circuit structures face challenges such as void formation and discontinuous seed layers, leading to unreliable electrical properties and low throughput.
Innovation Solution
A method involving the deposition and annealing of a dispersion containing copper nanoparticles into features with widths of at least 5 micrometers and depths of at least twice the width, eliminating the need for continuous seed layers and enabling defect-free filling through surface tension and subsequent fusion of particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electroplating is used to fill deep features in 3-D integration structures, then narrow and high aspect ratio features can be filled in a bottom-up fashion without voids, but continuous and uniform barrier and copper seed layers on the internal surfaces of extremely deep vias (depths of 50 μm or more) are very difficult to deposit
Solution Approach 1:
The invention extracts and eliminates the requirement for continuous seed layers on the internal surfaces of deep vias. Instead of attempting to deposit uniform seed layers into extremely deep features (depths of 50 μm or more), the process uses electroplating directly onto the substrate or previously formed structures, bypassing the seed layer deposition step that causes discontinuities and voids in conventional approaches.
Solution Approach 2:
The invention inverts the conventional sequence by performing electroplating before forming continuous seed layers. Rather than depositing seed layers first and then electroplating copper, the process electroplates directly onto the substrate or existing structures, then forms the barrier and seed layers afterward, eliminating the fundamental problem of seed layer discontinuities in deep vias.
2Manufacturing precision
If electroplating is used to fill large features in 3-D integration structures, then voids can be avoided through bottom-up filling, but the throughput is reduced due to limited plating current densities
Solution Approach 1:
The invention segments the filling process into distinct stages: first electroplating to establish a foundation, then forming barrier and seed layers, and finally completing the fill. This segmentation allows each step to be optimized independently, maintaining void-free filling while improving overall throughput by allowing parallel processing and optimized parameters for each stage.
Solution Approach 2:
The invention performs preliminary electroplating and barrier/seed layer formation before the final copper fill. This preliminary action prepares the structure in advance, allowing the main fill operation to proceed more efficiently with higher current densities since the foundation is already established, thus improving throughput while maintaining filling quality.
3Ease of manufacture
If conventional electroplating is used for 3-D integration, then cost-effective filling can be achieved, but discontinuous seed layers lead to unreliable electrical properties
Solution Approach 1:
The invention introduces an intermediary step of forming continuous barrier and seed layers after the preliminary electroplating. This intermediary action ensures that the final copper fill has reliable electrical properties by establishing continuous conductive paths, while the overall process remains cost-effective by using electroplating rather than more expensive deposition techniques.
Solution Approach 2:
The invention changes the sequence and parameters of the deposition process. Instead of depositing seed layers first at low current densities that cause discontinuities, the process uses electroplating at optimized current densities followed by barrier and seed layer formation, ensuring continuous layers and reliable electrical properties while maintaining cost-effectiveness.
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 allows for cost-effective, void-free filling of large features, improving the reliability and electrical properties of 3-D interconnects while increasing throughput by avoiding the limitations of electroplating techniques.
Implementation Method 1
The ink is dried so that the copper particles remain in the feature
Implementation Method 2
The copper particles are annealed in the feature to form a copper structure in the feature
Data Source
AI summary
A method of filling a conductive material in a three dimensional integration structure feature formed on a surface of a wafer is disclosed. The feature is filled with a dispersion containing a plurality of conductive particles and a solvent. Then, the solvent is removed from the feature, leaving the plurality of conductive particles in the feature. These two steps are repeated until the feature is filled up with the conductive particles. Then, the conductive particles are annealed in the feature, thereby forming a dense conductive plug in the feature.