Magnetically Confined Plasma Collimation for Trench And Via Filling
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Solution Overview
Problem
In semiconductor manufacturing, sputtering deposition on high aspect ratio substrates faces challenges in achieving uniformity, particularly in depositing materials into trenches and via, where broad angular distribution of deposition atoms or ions leads to pinching off the upper entrance, preventing further deposition, and requires low pressure to maintain directionality, but also causes re-sputtering and clogging.
Innovation Solution
A plasma source with a closed-loop magnetic field and a collimation apparatus that includes parallel ribbons to focus and tilt ions, reducing electron leakage and operating pressure, and allowing precise control of self-bias voltage, enabling uniform deposition and etching in high aspect ratio structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If larger deposition sources are used to achieve deposition uniformity, then broader angular distribution of deposition atoms is obtained, but material accumulates at upper portion of sidewalls and pinches off the upper entrance of trenches and via, preventing further deposition
Solution Approach 1:
A collimator is introduced as an intermediary component between the deposition source and the substrate. The collimator consists of parallel plates or ribs that physically block off-angle deposition atoms while allowing parallel ions to pass through. This mediator selectively filters the angular distribution of deposited material, preventing sidewall accumulation and trench pinch-off while maintaining deposition uniformity.
Solution Approach 2:
The system changes the operational parameters by operating at low pressure to maintain ion directionality and parallel beam formation. By controlling pressure and ionization percentage, the system achieves a narrow angular distribution of ions that can reach the bottom of high aspect ratio trenches without accumulating on sidewalls.
2Manufacturing precision
If low pressure operation is used to maintain directionality of ions and atoms, then deposition into trenches and via is increased, but re-sputtering and reactive etching of trenches and via are enhanced
Solution Approach 1:
The system optimizes pressure parameters to a specific low pressure range that maintains ion directionality while controlling re-sputtering. By precisely controlling pressure, ionization percentage, and ion energy, the system achieves the desired balance between deposition efficiency and minimizing harmful re-sputtering effects.
3Manufacturing precision
If 100% ionization of deposition atoms is achieved to form parallel ion beam, then directionality is improved, but electron leakage from plasma source increases and operating pressure must be reduced
Solution Approach 1:
The collimator serves as a mediator that compensates for electron leakage issues. By physically blocking off-angle particles and focusing the ion beam, the collimator ensures that even with some electron leakage, the deposited material maintains the desired directionality and uniform distribution in high aspect ratio structures.
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
Enhances plasma density, reduces operating pressure, and achieves precise control over ion directionality and energy, improving deposition uniformity and reducing re-sputtering, thereby enhancing the filling of trenches and via while minimizing material on sidewalls or bottoms as needed.
Implementation Method 1
a first plasma source configured to produce a plasma confined in a magnetic field
Implementation Method 2
produce a plasma of ions to sputter atoms off a sputtering target
Implementation Method 3
The first set of parallel ribbons and the second set of parallel ribbons can collimate the atoms and ions produced by the first plasma source and direct the ions to a substrate
Implementation Method 4
all require low pressure operation to avoid gas scattering. The ions and atoms that collide with residue process gases before they reach the substrate surface increase the divergence angles
Data Source
AI summary
A plasma deposition apparatus includes a first plasma source that can produce a plasma confined in a magnetic field. The first plasma source includes a closed-loop electrode defining a center region therein and a central axis through the central region, and one or more magnets that are outside an inner surface of the closed-loop electrode. The magnets can produce a magnetic field in the center region. The one or more magnets can be at least partially embedded in the closed-loop electrode. The closed-loop electrode and the magnets can produce a plasma of ions to sputter atoms off a sputtering target or a backing plate.