Boron-Doped Diamond Growth Using Trimethylborate
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Solution Overview
Problem
Current methods for producing large area boron-doped diamond films with high boron doping levels and fast growth rates are cost-ineffective due to the use of expensive and hazardous gas precursors, and result in low temperature synthesis and inhomogeneous layer distribution.
Innovation Solution
A method using undiluted trimethylborate as the boron and carbon precursor in a microwave plasma chemical vapour deposition process, with controlled pressure and temperature, and hydrogen introduction to achieve high growth rates and doping levels, eliminating the need for additional gas sources and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If diborane is used as boron source precursor in large area microwave plasma CVD, then high boron doping levels can be achieved, but the process becomes expensive and hazardous due to the explosive and flammable nature of diborane
Solution Approach 1:
The patent replaces expensive and hazardous diborane with trimethylborate, a safer and more economical liquid precursor. Trimethylborate can be handled more safely as it is not explosive or flammable in the same manner, reducing both cost and hazard while maintaining effective boron doping capability in the diamond film
Solution Approach 2:
The patent changes the physical state and chemical composition of the boron precursor from gaseous diborane to liquid trimethylborate. This parameter change allows for safer handling and storage while achieving comparable or superior boron incorporation levels in the diamond film through controlled evaporation and deposition
2Productivity
If CO2 is added to the gas mixture to facilitate diamond growth at low temperatures, then growth rate improves, but electrical conductivity decreases due to reduced boron incorporation
Solution Approach 1:
The patent uses trimethylborate as a comprehensive precursor that simultaneously provides both carbon and boron atoms needed for diamond growth and doping. This eliminates the need to add CO2 as a separate carbon source, allowing the process to maintain both high growth rates and high electrical conductivity by optimizing the single-precursor composition rather than combining multiple precursors with conflicting requirements
3Productivity
If liquid precursors such as acetone or methanol/ethanol are used in chemical vapour deposition, then growth rates increase significantly, but layer homogeneity deteriorates
Solution Approach 1:
The patent employs trimethylborate, which provides both carbon and boron atoms in a controlled manner, achieving high growth rates while maintaining uniform boron distribution throughout the diamond film. The liquid precursor is evaporated and distributed evenly in the reaction chamber, ensuring homogeneous doping levels across the entire film surface, thus resolving the contradiction between high growth rate and uniform composition
4Reliability
If large area microwave plasma CVD is used to produce thick boron-doped diamond films, then substrate degradation is prevented, but the process becomes cost-ineffective due to high precursor costs
Solution Approach 1:
The patent replaces expensive gaseous diborane precursor with cheaper liquid trimethylborate, significantly reducing material costs while maintaining the ability to produce thick, high-quality boron-doped diamond films. This cost reduction enables large-area production of substrate-protecting diamond layers without making the process economically unviable
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 growth of high-quality, highly boron-doped diamond films with controlled crystal size and electrical properties, achieving growth rates up to 200 nm/hr and doping levels of 10^17 to 10^22 cm^-3, suitable for electrochemical applications and hard coatings, while reducing costs and safety hazards.
Implementation Method 1
A method using undiluted trimethylborate as the boron and carbon precursor in a microwave plasma chemical vapour deposition process
Implementation Method 2
microwave plasma chemical vapour deposition process
Implementation Method 3
introducing hydrogen into the reactor; wherein volume ratio between the evaporation and hydrogen is between 0.05% and 20%
Implementation Method 4
evaporating the undiluted trimethylborate and introducing the evaporation therefrom to the reactor
Data Source
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AI summary
The present invention relates to a method for growing a boron doped diamond using undiluted trimethylborate. The diamond structure is grown in chemical vapour deposition reactor at microwave power from 0,2 kW up to 100 kW at pressure less than 50 kPa. The method is capable to provide doped diamond with a wide range of doping levels. In a preferred embodiment, the present invention is capable to manufacture a boron-doped diamond layer employing linear antenna microwave chemical vapour deposition system without the need of addition of any other organic molecule, such as methane or methanol, to support the growth of the diamond structure. Electrical properties of such grown boron doped diamond can be controlled by adding additional source of oxygen.