Ion Source Carbon Deposition Mitigation via Hydrogen Peroxide Co-Gas
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Solution Overview
Problem
Ion sources in ion implantation systems face efficiency reduction and shortened lifetime due to carbon buildup from carbon-containing source gases, which affects electron emission and ion beam production during semiconductor fabrication.
Innovation Solution
The introduction of a hydrogen peroxide co-gas with a molecular carbon source gas, such as toluene, in the ion source chamber, where hydrogen peroxide decomposes to form free hydrogen and oxide radicals that react with atomic carbon, producing secondary hydrocarbons and gases that are removed, minimizing carbon deposition and extending the ion source's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon-containing source gases (e.g., toluene) are used in the ion source chamber, then carbon ion beam production is enabled, but carbon deposits accumulate on chamber surfaces, reducing ion source efficiency and lifetime
Solution Approach 1:
The patent introduces hydrogen peroxide as a co-gas that decomposes to form oxygen radicals, which react with the harmful carbon deposits to convert them into volatile carbon dioxide and carbon monoxide gases. This transforms the harmful carbon accumulation into beneficial volatile products that are easily removed by vacuum pumping, thereby maintaining ion source efficiency and extending lifetime while preserving carbon ion beam production
Solution Approach 2:
Hydrogen peroxide serves as a strong oxidant that accelerates the oxidation of carbon deposits on chamber surfaces. The decomposition of hydrogen peroxide produces highly reactive oxygen radicals that rapidly oxidize carbon into carbon dioxide and carbon monoxide, preventing carbon buildup and maintaining clean chamber surfaces for sustained ion source operation
2Reliability
If carbon deposits accumulate on chamber surfaces, then electron emission is poisoned, but introducing cleaning mechanisms increases system complexity
Solution Approach 1:
The system uses the existing vacuum pump infrastructure already present in the ion implantation system to remove the volatile oxidation products (carbon dioxide and carbon monoxide). No additional dedicated cleaning apparatus is required - the vacuum system performs dual functions of maintaining operating vacuum and removing carbon deposit oxidation products, thereby avoiding increased system complexity while preserving electron emission performance
Solution Approach 2:
The hydrogen peroxide co-gas injection system integrates the cleaning function into the existing gas delivery infrastructure. The same vacuum pumping system that maintains operating conditions also removes oxidation byproducts. This multi-functional approach eliminates the need for separate cleaning mechanisms, maintaining simplicity while effectively preserving electron emission performance
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 approach enhances ion implantation performance by increasing beam current and extending the ion source's operational life by reducing carbon layer buildup and maintaining electron emission, allowing for more efficient semiconductor processing.
Implementation Method 1
hydrogen peroxide decomposes to form free hydrogen and oxide radicals
Implementation Method 2
oxide radicals that react with atomic carbon, producing secondary hydrocarbons and gases
Implementation Method 3
hydrogen peroxide decomposes to form free hydrogen and oxide radicals that react with atomic carbon
Data Source
AI summary
An ion source assembly and method is provided for improving ion implantation performance. The ion source assembly has an ion source chamber and a source gas supply provides a molecular carbon source gas such as toluene to the ion source chamber. A source gas flow controller controls a flow of the molecular carbon source gas to the ion source chamber. An excitation source excites the molecular carbon source gas, forming carbon ions and atomic carbon. An extraction electrode extracts the carbon ions from the ion source chamber, forming an ion beam. A hydrogen peroxide co-gas supply provides a predetermined concentration of hydrogen peroxide co-gas to the ion source chamber, and a hydrogen peroxide co-gas flow controller controls a flow of the hydrogen peroxide gas to the ion source chamber. The hydrogen peroxide co-gas decomposes within the ion source chamber and reacts with the atomic carbon from the molecular carbon source gas in the ion source chamber, forming hydrocarbons within the ion source chamber. An inert gas is further introduced and ionized to counteract oxidation of a cathode due to the decomposition of the hydrogen peroxide. A vacuum pump system removes the hydrocarbons from the ion source chamber, wherein deposition of atomic carbon within the ion source chamber is reduced and a lifetime of the ion source chamber is increased.