Antireflective Coating Pin Hole Density Evaluation via Electroplating
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Solution Overview
Problem
The porosity of silicon nitride antireflective coatings in solar cells, caused by pin holes, adversely affects the optical and passivation properties, leading to inefficient solar cell performance, and existing methods fail to characterize or optimize this porosity effectively.
Innovation Solution
Electroplating is used to fill pin holes in the patterned antireflective coating with a metallic material, allowing for the determination of pin hole quantity and density, which informs a cleaning process optimization to achieve satisfactory porosity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a silicon nitride layer is deposited on a textured surface to improve light absorption, then the optical properties are improved, but pin holes are introduced into the film causing porosity that adversely impacts film properties and solar cell performance
Solution Approach 1:
The patent acknowledges that the silicon nitride film inherently contains pin holes creating porosity. Rather than attempting to eliminate all porosity, the invention uses electroplating to selectively fill pin holes with metallic material, transforming the harmful porosity into a controlled feature that maintains light absorption while reducing adverse effects on film integrity and electrical properties.
2Reliability
If electroplating is used to fill pin holes in the antireflective coating, then the porosity is reduced and film properties are improved, but the process complexity increases
Solution Approach 1:
The patent combines the electroplating step with the existing metallic grid formation process. The same electroplating bath and equipment used to create the metallic grid contacts are utilized to simultaneously fill the pin holes in the antireflective coating, thereby improving film integrity without adding separate process steps or equipment.
Solution Approach 2:
The electroplating process serves multiple functions: it forms the metallic grid contacts for electrical extraction and simultaneously fills pin holes to reduce porosity and improve passivation. This multi-functionality eliminates the need for separate processing steps.
3Use of energy by moving object
If the quantity of pin holes in the antireflective coating is increased, then the porosity increases which may improve certain optical properties, but the passivation properties are adversely impacted
Solution Approach 1:
The patent changes the physical and chemical parameters of the pin holes by filling them with metallic material through electroplating. This transformation alters the electrical properties at the pin hole sites, improving passivation while maintaining the overall optical performance of the antireflective coating.
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 method enables the optimization of the cleaning process to reduce pin hole density, thereby improving the optical and passivation properties of the antireflective coating, enhancing solar cell efficiency.
Implementation Method 1
A front side surface metallic film is formed within the grid pattern by electrodeposition, wherein during the electrodeposition the pin holes in the patterned antireflective coating are filled with a metallic material.
Data Source
AI summary
A method to determine the cleanness of a semiconductor substrate and the quantity/density of pin holes that may exist within a patterned antireflective coating (ARC) is provided. Electroplating is employed to monitor the changes in the porosity of the ARC caused by the pin holes during solar cell manufacturing. In particular, electroplating a metal or metal alloy to form a metallic grid on an exposed front side surface of a substrate also fills the pin holes. The quantity/density of metallic filled pin holes (and hence the number of pin holes) in the patterned ARC can then be determined.