Semi-Dynamic Reflow Process for Semiconductor Interconnect Gap Fill
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Solution Overview
Problem
The challenge in semiconductor processing is the low throughput of wafer processing due to the need for multiple cycles in static reflow processes for filling trenches and vias, especially at 5 nm node structures and beyond, which hampers the scaling down of interconnects for smaller form factors.
Innovation Solution
A semi-dynamic reflow process is introduced, where a metallic material is deposited on a substrate, heated to a static reflow temperature, and then additional material is deposited during a dynamic reflow phase, with RF bias power applied to enhance heating, allowing for a single-chamber process that achieves bottom-up fill of 5 nm node structures with improved throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If static reflow processes are used to fill trenches/vias, then gap fill performance is achieved, but multiple cycles are required which dramatically decrease wafer throughput
Solution Approach 1:
The patent applies dynamics by transitioning from static reflow to dynamic reflow. During dynamic reflow, the substrate is moved through the deposition chamber while material is deposited, creating a relative motion between the substrate and deposited material. This dynamic approach allows gap filling to occur during the movement phase itself, eliminating the need for multiple static reflow cycles and dramatically improving wafer throughput while maintaining effective gap fill performance.
2Manufacturing precision
If multiple cycles of static reflow are used, then complete gap fill is achieved, but process time increases significantly
Solution Approach 1:
The patent implements continuity of useful action by performing gap filling during the continuous movement of the substrate through the deposition chamber. The dynamic reflow process occurs continuously during the transit phase, eliminating idle time between deposition and reflow steps. This continuous action achieves complete gap fill in a single pass through the chamber, significantly reducing the total process time compared to multiple discrete static reflow cycles.
3Volume of moving object
If interconnects are scaled down for smaller form factors, then device form factor is reduced, but trench/via filling becomes more challenging
Solution Approach 1:
The patent applies parameter changes by utilizing the relative motion parameter during deposition. The dynamic reflow process changes the operational parameters from static heating to dynamic movement through the chamber, altering how material is deposited and redistributed. This parameter change enables effective filling of scaled-down trenches and vias by controlling material flow during movement, making the manufacturing process adaptable to smaller form factors without sacrificing fill quality.
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 increases wafer throughput by 2-3 times compared to multicycle static reflow processes, enabling void-free gap fill performance for copper and other materials like aluminum or cobalt, while maintaining temperature control for effective metal film agglomeration and bottom-up fill.
Implementation Method 1
heating the substrate to a second temperature higher than the first temperature, heating of the substrate causing a static reflow of the metallic material on the substrate
Implementation Method 2
applying RF bias power during the dynamic reflow to heat the substrate
Data Source
AI summary
A method of filling structures on a substrate uses a semi-dynamic reflow process. The method may include depositing a metallic material on the substrate at a first temperature, heating the substrate to a second temperature higher than the first temperature wherein heating of the substrate causes a static reflow of the deposited metallic material on the substrate, stopping heating of the substrate, and depositing additional metallic material on the substrate causing a dynamic reflow of the deposited additional metallic material on the substrate. RF bias power may be applied during the dynamic reflow to facilitate in maintaining the temperature of the substrate.