Aluminum Paste Doping for Semiconductor Substrates
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Solution Overview
Problem
Current methods for forming p-doped regions on n-type semiconductor substrates, such as in solar cells, are limited in efficiency and require complex masking processes and harsh chemicals, which can lead to inefficiencies and environmental concerns.
Innovation Solution
A process involving the application and firing of an aluminum paste with 3 to 20 wt.% glass frit on an n-type semiconductor substrate, followed by water treatment to remove the fired composition, creating a p-doped surface region without the need for masking and using environmentally friendly methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal diffusion with masking is used to form p-doped regions, then precise doping patterns can be achieved, but the process complexity and use of harsh chemicals increase
Solution Approach 1:
The invention extracts and removes the masking step from the conventional thermal diffusion process. By applying aluminum paste directly to specific areas and using water-soluble glass frit as a temporary binder that can be easily removed, the process eliminates the need for complex masking materials and procedures while maintaining precise doping pattern formation.
Solution Approach 2:
The invention changes the chemical parameters of the doping process by using aluminum paste with water-soluble glass frit instead of conventional masking materials. This parameter change allows the paste to be applied directly to the substrate and removed simply by water rinsing, dramatically simplifying the process while maintaining precision.
2Reliability
If conventional aluminum paste firing is used, then p-doping can be achieved, but the fired composition is difficult to remove requiring harsh chemicals
Solution Approach 1:
The invention changes the chemical composition parameter of the glass frit to be water-soluble, which fundamentally alters the removal process. The glass frit contains water-soluble compounds such as water-soluble salts, water-soluble resins, or water-soluble polymers that dissolve in water, allowing the fired aluminum paste to be removed by simple water rinsing without harsh chemicals.
Solution Approach 2:
The glass frit acts as a temporary, disposable binder that serves its purpose during paste application and firing, then is easily removed by water. This disposable approach eliminates the need for complex removal processes and harsh chemicals, reducing environmental impact and simplifying the overall process.
3Stability of the object's composition
If glass frit content in aluminum paste is increased, then paste stability improves, but removal difficulty increases
Solution Approach 1:
The invention changes the chemical composition parameter of the glass frit to be water-soluble, which simultaneously achieves paste stability during processing and easy removal by water. The glass frit contains water-soluble compounds such as water-soluble salts, water-soluble resins, or water-soluble polymers that provide stability when fired but dissolve easily in water for simple removal.
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 process effectively forms a p-doped surface region with controlled penetration depth, enhancing semiconductor performance while reducing environmental impact and eliminating the need for harsh chemicals.
Implementation Method 1
The p-dopant may be thermally diffused into a surface region of the n-type silicon substrate thus forming a thin p-doped layer
Implementation Method 2
removal of the fired aluminum composition by treatment with water
Data Source
AI summary
A process for the formation of at least one aluminum p-doped surface region of an n-type semiconductor substrate comprising the steps:(1) providing an n-type semiconductor substrate,(2) applying and drying an aluminum paste on at least one surface area of the n-type semiconductor substrate,(3) firing the dried aluminum paste, and(4) removing the fired aluminum paste with water,wherein the aluminum paste employed in step (2) includes particulate aluminum, an organic vehicle and 3 to 20 wt. % of glass frit, based on total aluminum paste composition.