PVD Substrate Processing With Alternating RF Bias for Gap Fill
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Solution Overview
Problem
Current PVD techniques face challenges in filling gaps between circuit elements with high aspect ratios, leading to overhang and void formation due to limited power range in continuous wave bias, which can damage the substrate.
Innovation Solution
A method involving alternating RF bias at low and high power frequencies to deposit and etch material layers, reducing the thickness difference between the top surface and sidewalls of features, using a predetermined frequency to minimize overhang.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If continuous wave bias is used to reduce overhang, then overhang is reduced, but the power range is limited and substrate damage occurs at high power levels
Solution Approach 1:
The patent applies periodic pulsed RF bias instead of continuous wave bias to reduce overhang. The pulsed nature allows the system to operate at high power levels during brief intervals to effectively reduce overhang, while avoiding continuous high-power exposure that causes substrate damage. This periodic action enables broader power range utilization while protecting the substrate.
Solution Approach 2:
The patent transitions from static continuous wave bias to dynamic pulsed RF bias with variable pulse widths and frequencies. This dynamic approach allows optimization of power delivery timing to achieve effective overhang reduction while preventing substrate damage, enabling operation beyond the limited power range of continuous wave methods.
2Quantity of substance
If PVD deposition is used to fill gaps, then material is deposited on sidewalls, but overgrowth and overhang occur at the top of the gap
Solution Approach 1:
The patent uses periodic pulsed RF bias during PVD deposition to control material accumulation. The pulsed timing creates alternating deposition and removal cycles that prevent excessive material buildup at the gap top, thereby reducing overhang formation while maintaining effective gap filling through controlled material transport.
Solution Approach 2:
The patent changes the bias power parameter dynamically through pulsed RF application during deposition. By modulating the bias power in pulses rather than maintaining constant bias, the system controls the deposition rate and material distribution, preventing overgrowth at the gap top while ensuring complete gap filling.
3Length of moving object
If feature dimensions are reduced for miniaturization, then circuit element size decreases, but gap filling becomes more difficult with voids and weak seams
Solution Approach 1:
The patent employs periodic pulsed RF bias to enhance material transport and distribution into high aspect ratio gaps formed by miniaturized features. The pulsed action creates dynamic conditions that promote uniform material deposition throughout the gap, preventing voids and weak seams that typically occur when filling narrow, tall gaps in miniaturized circuits.
Solution Approach 2:
The patent utilizes parameter changes in RF bias power and pulse timing to optimize material deposition into miniaturized features. By dynamically adjusting bias parameters during deposition, the system achieves uniform filling of high aspect ratio gaps created by feature miniaturization, eliminating voids and ensuring structural integrity.
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 effectively reduces overhang and facilitates complete gap filling without substrate damage, enabling easier subsequent metallization steps.
Implementation Method 1
sputtering a material from a target in a physical vapor deposition (PVD) chamber to form a material layer on a layer comprising a feature
Implementation Method 2
depositing additional material on the layer by biasing the layer with an RF bias at a low power
Implementation Method 3
etching the material layer from the layer by biasing the layer with an RF bias at a high-power
Implementation Method 4
sputtering a material from a target in a physical vapor deposition (PVD) chamber to form a material layer
Data Source
AI summary
Methods and apparatus for processing a substrate are provided. For example, a method includes sputtering a material from a target in a PVD chamber to form a material layer on a layer comprising a feature of the substrate, the feature having an opening width defined by a first sidewall and a second sidewall, the material layer having a greater lateral thickness at the top surface of the layer than a thickness on the first sidewall or the second sidewall within the feature, depositing additional material on the layer by biasing the layer with an RF bias at a low power, etching the material layer from the layer by biasing the layer with an RF bias at a high-power, and repeatedly alternating between the low power and the high-power at a predetermined frequency.