Calcium Phosphate Layer Formation on Silicon Substrates
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Solution Overview
Problem
Current technologies for silicon-containing substrates lack efficient and cost-effective methods for forming calcium phosphate or calcium arsenate layers, which are essential for various applications, including semiconductor production and phosphorus recovery from wastewater, due to the complexity and high costs associated with existing processes.
Innovation Solution
A silicon-containing substrate coated with one or more layers of calcium phosphate, calcium arsenate, or their mixed hydrates, where these layers are formed in situ using a calcium silicate hydrate phase as the calcium source and the substrate as a silicon source, through a process involving activation with a piranha solution, calcium hydroxide treatment, and subsequent exposure to phosphate or arsenate solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form calcium phosphate or calcium arsenate layers on silicon substrates, then layer formation is achieved, but the process becomes complex and costly
Solution Approach 1:
The patent applies preliminary action by first forming a calcium silicate hydrate (C-S-H) phase layer on the silicon substrate before forming the final calcium phosphate or calcium arsenate layer. This preliminary C-S-H layer serves as a foundation that simplifies subsequent layer formation and improves adhesion, thereby reducing overall process complexity while maintaining layer formation quality
Solution Approach 2:
The patent uses an intermediary approach by introducing calcium hydroxide treatment as a intermediate step between substrate preparation and final layer formation. The calcium hydroxide solution facilitates the formation of the C-S-H phase, which acts as an intermediary layer that simplifies the subsequent formation of calcium phosphate or calcium arsenate layers, reducing process complexity
2Manufacturing precision
If conventional methods are used to form calcium phosphate or calcium arsenate layers, then layers are deposited, but manufacturing costs increase
Solution Approach 1:
The patent applies self-service by utilizing the silicon substrate itself as the silicon source for forming the C-S-H phase layer. The substrate undergoes chemical treatment where silicon is extracted and reacts with calcium hydroxide to form the C-S-H phase in situ, eliminating the need for external silicon sources and reducing material costs while maintaining layer deposition quality
Solution Approach 2:
The patent uses parameter changes by controlling the chemical environment through pH adjustment and specific chemical treatments (piranha solution activation, calcium hydroxide immersion) to enable in situ formation of the C-S-H phase. These parameter changes allow the substrate to self-generate the required layers, reducing manufacturing costs while maintaining deposition quality
3Reliability
If calcium phosphate or calcium arsenate layers are formed on silicon substrates, then functional layers are created, but adhesion and stability challenges arise
Solution Approach 1:
The patent applies preliminary action by forming the C-S-H phase layer and ensuring proper substrate activation before depositing calcium phosphate or calcium arsenate layers. This preliminary preparation, including piranha solution treatment and calcium hydroxide immersion, creates optimal surface conditions that enhance layer adhesion and stability while managing process complexity through systematic preparation steps
Solution Approach 2:
The patent uses composite materials by creating a multi-layer structure consisting of the silicon substrate, C-S-H phase layer, and outer calcium phosphate or calcium arsenate layer. This composite structure leverages the complementary properties of each layer: the silicon substrate provides mechanical strength, the C-S-H phase provides adhesion and chemical stability, and the outer layer provides the desired functional properties, thereby achieving high reliability
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 formation of stable, easily handled substrates with excellent adhesion of calcium phosphate or calcium arsenate layers, facilitating efficient phosphorus recovery, semiconductor doping, and providing a cost-effective solution for wastewater treatment and semiconductor production.
Implementation Method 1
Activation of a silicon-containing substrate... the silicon-containing substrate is brought into contact with a solution of H2O2 and H2SO4
Implementation Method 2
bringing the silicon-containing substrate from step a) into contact with an aqueous calcium hydroxide solution (Ca(OH)2), wherein at least one CSH layer is formed on the silicon-containing substrate
Implementation Method 3
bringing the silicon-containing substrate from step b) into contact with an aqueous phosphate and/or arsenate solution... at least one layer contains or consists of calcium phosphate (Ca3(PO4)2), calcium arsenate (Ca3(AsO4)2)
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a silicon-containing substrate coated with one or more layers, at least one of which contains or is made of calcium phosphate (Ca3(PO4)2), calcium arsenate (Ca3(AsO4)2), mixed calcium phosphate-calcium arsenate layer or the corresponding hydrates, as well as to the production and use of said substrate.