Carbon Ion Precursor Composition for Semiconductor Implantation
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Solution Overview
Problem
The use of carbon dioxide as a precursor for carbon ion implantation in semiconductor manufacturing leads to reduced operating lifetime of ion sources due to the generation of reactive oxygen atoms, which corrode the metal electrodes, and the addition of phosphine as a co-gas increases gas flow and pressure without providing additional usable material.
Innovation Solution
A carbon ion precursor composition comprising a mixture of a carbon oxide gas and methane gas is used to ionize and produce carbon ions, where the methane reacts with oxygen species to form water, reducing the adverse effects on the ion source and increasing the generation of carbon ions, with the optimal molar ratio of methane to carbon dioxide ranging from less than 30% to 70%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon dioxide is used as precursor for carbon ion implantation, then carbon ions are generated for implantation, but oxygen atoms are generated which corrode the ion source and reduce its operating lifetime
Solution Approach 1:
Methane is introduced as an intermediary substance that reacts with the oxygen atoms generated during carbon dioxide ionization. The methane molecules act as a sacrificial mediator, consuming the harmful oxygen through chemical reaction to form water, thereby protecting the ion source from corrosion while maintaining carbon ion generation
Solution Approach 2:
The harmful oxygen atoms generated as byproducts of carbon dioxide ionization are converted into beneficial water molecules through reaction with methane. This transforms the corrosive oxygen into harmless water vapor that can be evacuated, turning a detrimental side effect into a protective mechanism
2Reliability
If phosphine is added as co-gas to react with oxygen, then ion source corrosion is reduced, but gas flow and pressure increase without adding usable precursor material
Solution Approach 1:
The patent changes the chemical composition parameter of the gas mixture by substituting phosphine with methane. This parameter change maintains the protective function against oxygen corrosion while optimizing the gas flow and pressure characteristics, as methane provides both protective chemistry and usable carbon precursor material
3Duration of action of stationary object
If methane is added as co-gas to react with oxygen, then oxygen species production is reduced and ion source lifetime is extended, but gas mixture composition must be optimized
Solution Approach 1:
The patent systematically optimizes the concentration parameter of methane in the gas mixture, determining that a range of 1-10% methane by flow rate provides optimal protection. This parameter optimization balances the protective effect against oxygen corrosion with maintaining efficient carbon ion generation, resolving the complexity through defined operational ranges
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 introduction of methane as a co-gas significantly reduces the production of oxygen species, thereby minimizing ion source corrosion and extending its operating lifetime, while increasing the yield of carbon ions for implantation, as evidenced by the reduction in mass peaks corresponding to oxygen and carbon monoxide and the increase in carbon beam current.
Implementation Method 1
ionizing the carbon oxide gas and the methane gas with the ion source to create a plasma and produce ionized carbon species
Implementation Method 2
ionizing the carbon oxide gas and the methane gas with the ion source to create a plasma
Implementation Method 3
the methane reacts with oxygen species to form water
Implementation Method 4
exposing the workpiece to the ion beam to implant the ionized carbon into a workpiece
Data Source
AI summary
Methods and carbon ion precursor compositions for implanting carbon ions generally includes vaporizing and ionizing a gas mixture including carbon oxide and methane gases in an ion source to create a plasma and produce carbon ions. The ionized carbon within the plasma is then extracted to form an ion beam. The ion beam is mass analyzed with a mass analyzer magnet to permit the ionized carbon to pass therethrough and implant into a workpiece.