Rectangular Aperture Shield for Ion Beam Deposition Symmetry
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Solution Overview
Problem
Ion beam deposition systems suffer from asymmetrical shadowing and deposition rate variations due to beam divergence, leading to uneven thin film deposition profiles and reduced lift-off areas, especially around features on substrates.
Innovation Solution
A substrate processing system with a vacuum chamber, a source emitting a beam of energetic particles through a rectangular aperture, and a fixture that translates and rotates the substrate to ensure uniform flux distribution and symmetrical treatment across features, using a shield with a movable and adjustable aperture to optimize the incident angle and collimation of the beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If beam divergence is reduced by increasing target-to-substrate distance, then deposition uniformity improves, but deposition rate decreases
Solution Approach 1:
The system dynamically adjusts the target-to-substrate distance during deposition. The distance is increased during periods when uniformity is critical and decreased when deposition rate is needed, allowing the system to optimize both parameters over time rather than being constrained by a fixed distance
Solution Approach 2:
The deposition process uses periodic variation of the target-to-substrate distance, alternating between closer positions (for higher rate) and farther positions (for better uniformity). This periodic adjustment allows the system to achieve both high deposition rate and good uniformity through time-varying operation
2Manufacturing precision
If substrate is tilted to reduce shadowing on outboard side, then deposition symmetry improves, but inboard side shadowing increases
Solution Approach 1:
The system intentionally uses asymmetric tilting angles during different phases of substrate rotation. By varying the tilt angle asymmetrically relative to the substrate features, the system compensates for the inherent shadowing effects and achieves symmetric deposition profiles on both inboard and outboard sides of features
Solution Approach 2:
The substrate tilt angle is dynamically adjusted during the deposition process, changing in coordination with substrate rotation. This dynamic tilt adjustment allows real-time compensation for shadowing effects, ensuring symmetric deposition despite the asymmetric geometry of individual features
3Productivity
If beam divergence is increased to improve deposition rate, then productivity improves, but asymmetrical shadowing increases
Solution Approach 1:
The system dynamically varies the beam divergence angle during deposition by adjusting target-to-substrate distance. High divergence is used when deposition rate is prioritized, while low divergence is used when profile uniformity is critical, allowing optimization of both parameters through time-varying operation
Solution Approach 2:
The deposition process periodically alternates between high-divergence modes (for rate) and low-divergence modes (for uniformity). This periodic variation in beam divergence allows the system to achieve high overall deposition rates while maintaining good profile uniformity through alternating operational states
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 results in a symmetrical deposition profile on both sides of features, reducing radial dependence and enhancing the uniformity of thin film properties, thereby improving the lift-off process and magnetic property uniformity.
Implementation Method 1
The ion beam 12 sputters material from a finite, well-confined source region on the target 14 to generate a beam 16 of sputtered target material
Implementation Method 2
IBD is particularly well suited for lift-off deposition processes due to some unique advantages of the process
Data Source
AI summary
Method and apparatus for processing a substrate with a beam of energetic particles. The beam is directed from a source through a rectangular aperture in a shield positioned between the source and substrate to a treatment zone in a plane of substrate movement. Features on the substrate are aligned parallel to a major dimension of the rectangular aperture and the substrate is moved orthogonally to the aperture's major dimension. The beam impinges the substrate through the aperture during movement. The substrate may be periodically rotated by approximately 180° to reorient the features relative to the major dimension of the rectangular aperture. The resulting treatment profile is symmetrical about the sides of the features oriented toward the major dimension of the rectangular aperture.