Gold Evaporative Source Cleaning for Thin-Film Deposition
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Solution Overview
Problem
The gold evaporative process in thin-film deposition often experiences 'spitting' due to surface contaminants, leading to in-film defects and reduced deposition rates, which conventional methods struggle to control effectively.
Innovation Solution
A method involving burnishing gold evaporative sources with a liquid slurry under controlled vibratory action followed by leaching with boiling nitric acid to remove contaminants, reducing surface roughness and embedded impurities without altering the surface morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power input is increased to compensate for reduced deposition rate, then deposition rate is improved, but spitting occurs leading to in-film defects
Solution Approach 1:
The gold evaporative source undergoes preliminary cleaning treatments (mechanical polishing, chemical etching, and ultrasonic cleaning) before being placed in the evaporation chamber. This preliminary action removes surface contaminants that would otherwise cause spitting during high-power deposition, enabling increased deposition rates without defect formation.
Solution Approach 2:
The invention changes the surface condition parameter of the gold evaporative source through controlled cleaning processes. By modifying the surface cleanliness and roughness parameters before evaporation, the system can operate at higher power levels without experiencing spitting, thus resolving the contradiction between deposition rate and defect formation.
2Ease of manufacture
If conventional cleaning methods are used, then manufacturing simplicity is maintained, but surface contaminants remain leading to spitting
Solution Approach 1:
The cleaning process is segmented into multiple distinct steps: mechanical polishing to remove rough contaminants, chemical etching to dissolve embedded impurities, and ultrasonic cleaning to dislodge remaining particles. This segmentation allows each step to target specific types of contaminants, achieving thorough cleaning while maintaining procedural simplicity.
Solution Approach 2:
Chemical reagents serve as intermediaries between the cleaning system and the gold evaporative source surface. The chemicals facilitate the removal of contaminants that mechanical methods alone cannot eliminate, bridging the gap between simple manufacturing processes and effective contaminant removal.
3Manufacturing precision
If power input is controlled to prevent spitting, then in-film defects are reduced, but deposition rate decreases
Solution Approach 1:
By performing thorough preliminary cleaning of the gold evaporative source, the system eliminates the need for conservative power control. The cleaned surface prevents spitting even at high power levels, allowing the process to achieve both high deposition rates and defect-free films simultaneously.
Solution Approach 2:
The invention changes the surface condition parameter of the evaporative source to enable high-power operation without spitting. This parameter change (surface cleanliness) decouples the trade-off between power input and film quality, allowing both high deposition rate and high film quality to be achieved.
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
Significantly reduces surface contaminants, minimizing the occurrence of spitting and resulting in higher-quality gold films with reduced defects and improved deposition rates.
Implementation Method 1
burnishing the gold evaporative sources against each other in the presence of a liquid slurry at ambient temperature under a controlled vibratory action, thereby loosening and removing at least a portion of contaminants
Implementation Method 2
leaching the partially cleaned gold evaporative sources with boiling nitric acid to dislodge and remove contaminants along at least one of the first face, the second face or the one or more surfaces
Implementation Method 3
Electron beam or resistance heating elements can serve as the heat source 104 to melt the gold evaporative source 102. The melting of the gold evaporative source 102 creates a liquid pool 105
Implementation Method 4
The gold evaporative source in molten form is further heated until vaporization occurs. The gold vapor traverses upwards within the interior of the tool 101, and ultimately condenses and deposits as a thin-film onto one or more surfaces of a series of wafers 106
Data Source
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Figure 3(a)~3(b)
AI summary
A unique sequence of steps is provided to reduce contaminants along one or more surfaces and faces of gold evaporative sources without deleteriously impacting the structure of the gold evaporative sources. Edges are deburred; contaminants are successfully removed therealong; and surface smoothness is substantially retained. The resultant gold evaporative source is suitable for use in evaporative processes as a precursor to gold film deposition without the occurrence or a substantial reduction in the likelihood of spitting by virtue of significantly reduced levels of contaminants, in comparison to gold evaporative sources subject to a standard cleaning protocol.