Sputtering Overhang Reduction via Heavy Gas Plasma Etching
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Solution Overview
Problem
In the fabrication of integrated circuits and microelectronic devices, physical vapor deposition (PVD) processes face challenges with overhang buildup and insufficient step coverage in features, leading to premature closure of feature openings and void formation due to inadequate material deposition on sidewalls and top surfaces.
Innovation Solution
A method involving the use of a first plasma gas for sputtering a target to deposit material in substrate features, followed by etching with a second plasma gas of higher atomic mass to reduce overhang, where the atomic mass ratio of the second gas to the material is greater than 1:1, facilitating improved sidewall coverage and minimizing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PVD process deposits material to fill features, then material coverage on substrate surfaces is improved, but overhang buildup occurs at feature openings causing premature closure and void formation
Solution Approach 1:
The patent changes the atomic mass parameter of the plasma gas from a lighter gas (e.g., argon) to a heavier gas (e.g., krypton or xenon). This parameter change modifies the momentum transfer during sputtering, reducing the angular spread of deposited atoms and thereby reducing overhang buildup while maintaining step coverage
Solution Approach 2:
Instead of trying to prevent overhang formation during deposition, the patent inverts the approach by using a heavier plasma gas that naturally suppresses overhang during the deposition process itself, eliminating the need for subsequent overhang removal steps
2Productivity
If PVD process increases material deposition to fill features, then feature filling is improved, but overhang buildup accelerates causing feature opening closure
Solution Approach 1:
By changing the plasma gas atomic mass parameter, the patent enables higher deposition rates without the proportional increase in overhang buildup that occurs with lighter gases. The heavier gas maintains a more directional deposition pattern even at higher rates, preserving feature opening clearance
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 enhances material deposition on feature sidewalls, reducing void formation and ensuring more uniform coverage, thereby improving the filling of features in microelectronic devices.
Implementation Method 1
A plasma is formed from a process gas inside of the process chamber to sputter the material from the target and to deposit the material onto the substrate and within the features
Implementation Method 2
etching the deposited material in the process chamber using a plasma formed from a second gas, different than the first gas, to at least partially reduce overhang of the material in the feature
Data Source
AI summary
Embodiments of methods for depositing material in features of a substrate have been provided herein. In some embodiments, a method for depositing material in a feature of a substrate includes depositing a material in a feature of a substrate disposed in a process chamber by sputtering a target using a plasma formed from a first gas; and etching the deposited material in the process chamber using a plasma formed from a second gas, different than the first gas, to at least partially reduce overhang of the material in the feature, wherein an atomic mass of the second gas is greater than an atomic mass of the first gas.