Pulsed Bias Overhang Reduction in PVD Gap Filling
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Solution Overview
Problem
Physical vapor deposition (PVD) techniques face challenges in filling narrow gaps between semiconductor circuit elements due to overgrowth or overhang, which can create voids and weak seams, and current methods using continuous wave bias have limited power range and risk damaging the substrate.
Innovation Solution
Alternating low and high power RF biases at a predetermined frequency during PVD to reduce the difference in lateral thickness between the top and sidewall surfaces, allowing for controlled deposition and etching of material layers without damaging the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If continuous wave bias is applied to reduce overhang, then overhang reduction is achieved, but substrate damage occurs at high power levels
Solution Approach 1:
The patent applies pulsed RF bias that alternates between high power (for overhang removal) and low power (for substrate protection) in periodic cycles. This periodic action allows the system to achieve aggressive overhang reduction when needed while protecting the substrate during low-power phases, resolving the contradiction between effective overhang removal and substrate damage prevention
Solution Approach 2:
The patent dynamically adjusts the RF bias power level between high and low states based on process requirements. The pulsed nature creates a dynamic system that can switch between aggressive etching modes and protective modes, allowing optimal balance between overhang reduction effectiveness and substrate integrity maintenance
2Manufacturing precision
If continuous wave bias is used for overhang reduction, then overhang is reduced, but power range is limited
Solution Approach 1:
By using pulsed RF bias with variable duty cycles and pulse widths, the system can effectively utilize both high power levels (when pulses are active) and low power levels (during pulse off-times), thereby expanding the operational power range beyond what continuous wave bias can provide while maintaining effective overhang reduction
3Quantity of substance
If PVD is used to fill narrow gaps, then material deposition is achieved, but overhang creates voids and seams
Solution Approach 1:
The pulsed RF bias is applied during the PVD deposition process to preemptively remove overhang material as it forms. This preliminary action prevents the overhang from developing into voids or seams, ensuring high-quality gap filling while maintaining the benefits of PVD material deposition
Solution Approach 2:
The patent converts the harmful overhang effect into a beneficial process feature by using the deposited material itself as the etch target. The overhang material that would normally create defects is instead removed in-situ by the pulsed RF bias, transforming a process defect into a controlled etching opportunity that improves final gap filling 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
Effectively reduces overhang and enhances opening width in features, preventing voids and seams while maintaining substrate integrity, facilitating better metallization and gap filling.
Implementation Method 1
sputtering a material target in a physical vapor deposition (PVD) chamber to form a material layer on a substrate surface
Implementation Method 2
The material layer is etched from the substrate surface by biasing the substrate surface with an RF bias at a high power
Data Source
AI summary
Embodiments of the disclosure relate to methods for enlarging the opening width of substrate features by reducing the overhang of deposited films. Some embodiments of the disclosure utilize a high power bias pulse to etch the deposited film near the opening of the substrate feature. Some embodiments of the disclosure etch the deposited film without damaging the underlying substrate.