Evaporation Source with Non-Aligned Lid Openings for CIGS Deposition
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Solution Overview
Problem
The challenge in roll-to-roll deposition processes for CIGS solar cells is achieving uniform deposition of materials across large substrates due to difficulties in controlling the evaporation rate of source materials, especially under varying thermal conditions and fill levels, which affects the quality and cost-effectiveness of the production process.
Innovation Solution
The design of an evaporation source with a crucible having a thermal distributor and a lid with non-aligned openings, along with a thermal sensor and cooling assembly, to ensure uniform heat distribution and control the evaporation rate, enhancing deposition uniformity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional crucible design is used without thermal distribution components, then the device complexity is low, but the deposition uniformity across the substrate deteriorates due to uneven heat distribution
Solution Approach 1:
The crucible is segmented into multiple functional zones: a base region, sidewalls with varying thicknesses, and integrated thermal distribution fins. This segmentation allows different portions of the crucible to serve specific thermal functions, with thinner sidewalls facilitating heat distribution to areas that require more thermal energy for uniform evaporation.
Solution Approach 2:
Thermal distribution fins act as intermediary structures between the heat source and the source material. These fins conduct and redistribute thermal energy uniformly across the source material surface, mediating the heat transfer process to eliminate localized hot or cold spots that would cause non-uniform deposition.
2Productivity
If the evaporation rate is increased to improve productivity, then the deposition speed increases, but the deposition uniformity deteriorates due to thermal disturbances and varying fill levels
Solution Approach 1:
The system incorporates temperature sensors positioned to monitor thermal conditions within the crucible and deposition chamber. This feedback mechanism allows real-time detection of thermal disturbances and evaporation rate variations, enabling dynamic adjustment of heating parameters to maintain uniform deposition even at higher productivity levels.
Solution Approach 2:
The crucible design incorporates dynamic thermal management through varying wall thicknesses and integrated fins that adaptively distribute heat. As the source material fill level changes during operation, the thermal distribution structure dynamically adjusts heat flow paths to maintain uniform evaporation across the exposed material surface.
3Reliability
If thermal insulation is increased to maintain stable evaporation rate, then the evaporation rate stability improves, but the energy efficiency deteriorates due to higher energy consumption
Solution Approach 1:
Thermal insulation and heat distribution are applied locally rather than uniformly throughout the entire crucible structure. Insulation is concentrated in regions where thermal stability is most critical, while areas requiring active heat distribution have enhanced thermal conductivity pathways. This localized approach maintains evaporation stability without the energy penalty of comprehensive insulation.
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 solution improves the uniformity and consistency of material deposition across large substrates, leading to higher-quality CIGS solar cells and reduces production costs by maintaining a stable evaporation rate over extended periods.
Implementation Method 1
a thermal distributor disposed in the interior region of the crucible below the supporting ridge
Implementation Method 2
Each evaporation source includes a crucible to heat and vaporize source material that deposits onto the flexible substrate
Implementation Method 3
physical vapor deposition of material onto substrates, and more particularly to an apparatus and method of depositing a material using a physical vapor deposition process on large substrates in a vacuum environment
Implementation Method 4
along with a thermal sensor and cooling assembly, to ensure uniform heat distribution and control the evaporation rate
Data Source
AI summary
Embodiments of the disclosure generally relate to evaporation sources used for physical vapor deposition of material onto substrates and more particularly for controlled coating of large substrates, such as vacuum deposition of selenium on flexible substrates. In one embodiment an evaporation source for depositing a source material on a substrate is provided. The evaporation source includes a crucible having a base and a first plurality of walls surrounding an interior region of the crucible. The crucible further includes a supporting ridge extending inwardly towards the interior region. The evaporation source further includes a lid disposed on the supporting ridge, the lid including two or more adjacently positioned sheets, where each sheet includes a plurality of openings formed therethrough, and the plurality of openings in each sheet are not aligned with the plurality of openings formed in an adjacently positioned sheet.