Ion Source Oxidizing Co-Gas Control for Carbon Deposit Removal
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Solution Overview
Problem
Ion sources in ion implantation systems for molecular carbon implants face efficiency reduction and premature failure due to carbonaceous residue accumulation, which poisons the cathode and causes electrical shorts, limiting the lifetime of the ion source.
Innovation Solution
A system and method that introduces a molecular carbon source gas, such as toluene, and an oxidizing co-gas, like oxygen, into the ion source chamber to ionize and oxidize carbon deposits, forming carbon monoxide and carbon dioxide, which are then removed by a vacuum pump, minimizing residue buildup and extending the ion source's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If molecular carbon source gas is used for ion implantation, then carbon ions can be generated for doping semiconductor wafers, but carbonaceous residue accumulates on ion source structures causing cathode poisoning and electrical shorts
Solution Approach 1:
The patent introduces oxygen gas as a co-gas that reacts with carbonaceous residue to form carbon monoxide and carbon dioxide, converting the harmful carbon deposits into removable gaseous products. This oxidation process eliminates the residue that would otherwise poison the cathode and cause electrical shorts, thereby extending ion source lifetime while maintaining carbon ion generation capability
Solution Approach 2:
The patent modifies the gas composition parameters by adding oxygen to the molecular carbon source gas mixture. This parameter change enables chemical reactions that remove carbon residue through oxidation, transforming the operating conditions to prevent harmful accumulation while maintaining the desired ion generation process
2Productivity
If molecular carbon source gas is ionized in the ion source chamber, then carbon ions are produced for the ion beam, but carbon deposits form on chamber surfaces causing source failure
Solution Approach 1:
The oxygen co-gas converts harmful carbon deposits into beneficial gaseous oxidation products (CO and CO2) that can be pumped away. This process continuously cleans the chamber surfaces during operation, preventing the accumulation that leads to source failure while maintaining continuous ion beam production
Solution Approach 2:
The oxidation process operates continuously during ion source operation, providing ongoing removal of carbon deposits as they form. This continuous cleaning action ensures sustained ion beam production without interruption from residue accumulation or source failure
3Quantity of substance
If carbon source gas flows through the ion source chamber, then molecular carbon is available for ionization, but carbonaceous material coats insulators and bridges insulating gaps
Solution Approach 1:
The oxygen co-gas reacts with carbonaceous material that would otherwise coat insulators and bridge gaps, converting it into gaseous CO and CO2. This oxidation prevents the formation of conductive carbon paths on insulating surfaces, eliminating electrical shorts while maintaining carbon source availability
Solution Approach 2:
The patent employs oxygen as a strong oxidant that rapidly reacts with carbon deposits on insulator surfaces. This accelerated oxidation process effectively prevents carbon coating buildup that would otherwise lead to electrical shorts, maintaining the insulating properties of these components
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 approach effectively reduces carbon deposits within the ion source chamber, preventing electrical shorts and increasing the ion source's operational lifetime by maintaining its efficiency and performance.
Implementation Method 1
introduces a molecular carbon source gas, such as toluene, and an oxidizing co-gas, like oxygen, into the ion source chamber to ionize and oxidize carbon deposits
Implementation Method 2
introduces a molecular carbon source gas, such as toluene, and an oxidizing co-gas, like oxygen, into the ion source chamber to ionize and oxidize carbon deposits, forming carbon monoxide and carbon dioxide
Implementation Method 3
forming carbon monoxide and carbon dioxide, which are then removed by a vacuum pump
Data Source
AI summary
An ion source assembly and method has a source gas supply to provide a molecular carbon source gas to an ion source chamber. A source gas flow controller controls flow of the molecular carbon source gas to the ion source chamber. An excitation source excites the molecular carbon source gas to form carbon ions and radicals. An extraction electrode extracts the carbon ions from the ion source chamber, forming an ion beam. An oxidizing co-gas supply provides oxidizing co-gas to chamber. An oxidizing co-gas flow controller controls flow of the oxidizing co-gas to the chamber. The oxidizing co-gas decomposes and reacts with carbonaceous residues and atomic carbon forming carbon monoxide and carbon dioxide within the ion source chamber. A vacuum pump system removes the carbon monoxide and carbon dioxide, where deposition of atomic carbon within the ion source chamber is reduced and a lifetime of the ion source is increased.