Solar Cell Substrate Cleaning for Metal Ion Removal Before Oxidation
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Solution Overview
Problem
Existing methods for cleaning semiconductor substrates for solar cells are inadequate in removing contaminants, particularly metal ions, which can lead to reduced performance and efficiency of solar cells.
Innovation Solution
A method involving a pre-oxidising step with a hydrogen chloride solution, followed by an oxidising step to form an oxide on the substrate's surface, and then removing the oxide with an oxide removing solution, effectively reduces metallic contamination and enhances cleaning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional wet bench chemistry cleaning methods are used, then the cleaning process is simple, but metallic contamination on substrate surfaces cannot be effectively removed
Solution Approach 1:
The cleaning process is divided into three distinct segments: pre-oxidation step using hydrogen chloride solution to remove metal ions, oxidation step to form oxide layer, and oxide removal step. This segmentation allows each step to target specific contaminants systematically, improving overall cleaning effectiveness while maintaining process manageability
Solution Approach 2:
A pre-oxidation step is introduced before the main oxidation process. This preliminary action uses hydrogen chloride solution to remove metal ions from the substrate surface beforehand, preventing them from being incorporated into the oxide layer and ensuring better final cleaning results
2Manufacturing precision
If hydrogen fluoride is used to remove oxide, then oxide removal is effective, but safety risks and environmental hazards increase
Solution Approach 1:
The invention changes the chemical parameters of the oxide removal solution by using hydrogen chloride-based solutions with controlled concentrations and temperatures instead of traditional hydrogen fluoride. This parameter change maintains oxide removal effectiveness while significantly reducing safety hazards and environmental impact
Solution Approach 2:
The invention converts the potentially harmful effect of using strong acids into a benefit by carefully controlling the pre-oxidation and oxide removal steps. The hydrogen chloride solution, when properly managed, effectively removes oxide and metal ions while being safer than hydrogen fluoride, turning a potential hazard into a safe and effective cleaning method
3Manufacturing precision
If multiple acid components are used in pre-oxidising solution, then cleaning effectiveness improves, but chemical complexity and safety risks increase
Solution Approach 1:
The invention extracts and removes unnecessary acid components from the pre-oxidising solution, using only hydrogen chloride. This simplification maintains metal ion removal effectiveness by focusing on the essential active ingredient while eliminating redundant chemicals that add complexity and safety concerns
Solution Approach 2:
The invention applies local quality by using hydrogen chloride specifically in the pre-oxidation step where metal ion removal is needed, rather than using multiple different acids for different purposes. This targeted approach simplifies the overall process while maintaining effectiveness at each specific stage
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
The proposed method improves the cleaning efficiency of semiconductor substrates, reducing metallic contamination and leading to higher performance and efficiency of solar cells, as evidenced by increased open circuit voltage in solar cells fabricated using substrates cleaned by this method.
Implementation Method 1
the pre-oxidising solution is configured to remove metal ions from the surface of the substrate prior to the formation of the oxide on the substrate's surface
Implementation Method 2
oxidising the substrate with an oxidising solution to form an oxide on the surface of the substrate
Implementation Method 3
removing the oxide from the surface of the substrate with an oxide removing solution
Data Source
AI summary
A method of cleaning a semiconductor substrate for a solar cell, the method comprising: providing a semiconductor substrate; pre-oxidising the substrate with a pre-oxidising solution; oxidising the substrate with an oxidising solution to form an oxide on the surface of the substrate; removing the oxide from the surface of the substrate with an oxide removing solution; wherein the pre-oxidising solution is configured to remove metal ions from the surface of the substrate prior to the formation of the oxide on the substrate's surface, wherein the pre-oxidising solution is an acid solution comprising hydrogen chloride, and no other acid forming component.