Ion Implantation Gas Injection Mitigates Carbon Contamination
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Solution Overview
Problem
Ion implantation processes in semiconductor fabrication are plagued by the unwanted introduction of atomic or molecular contaminant particles, which can degrade or fail devices by being implanted into or deposited onto target wafers, particularly due to contamination from carbon-based sources within the ion implantation system and photoresist materials.
Innovation Solution
The introduction of atmospheric or reactive gases during the ion implantation process, which form volatile compounds or a passivation layer to mitigate contamination by interacting with contaminants, preventing them from being implanted into the target devices, using a system with a gas source, controller, and valve to manage the flow and composition of gases in the process chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed in vacuum to maintain process control, then manufacturing precision is improved, but contamination from carbon-based sources and photoresist materials is introduced into the ion beam and deposited onto target wafers
Solution Approach 1:
A gas flow is introduced as an intermediary substance between the ion beam and the wafer surface. The gas reacts with contaminant particles (particularly carbon-based contaminants) to form volatile compounds that are pumped away, or creates a passivation layer on the wafer surface, thereby mediating the harmful interaction between contaminants and the wafer while maintaining vacuum conditions for precise ion implantation
2Reliability
If reactive gas is introduced to mitigate contamination, then wafer surface protection is improved, but process complexity increases due to additional gas management systems
Solution Approach 1:
The process utilizes changes in gas flow rate, gas composition, and pressure parameters to achieve contamination mitigation. By carefully controlling these parameters, the system achieves effective protection against contaminants while managing the complexity of the gas management system through optimized parameter selection rather than additional hardware
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 effectively reduces contamination by forming volatile compounds that can be pumped away or creating a passivation layer that acts as a diffusion barrier, thereby preventing contaminants from being implanted into underlying layers of semiconductor devices, enhancing the quality and reliability of fabricated devices.
Implementation Method 1
formation of gaseous volatile compounds by the reactive gas, which interact with the contaminants at the target surface
Implementation Method 2
formation of a surface layer, such as a passivation layer, created by the presence of the reactive gas during ion implantation
Data Source
AI summary
A contamination mitigation or surface modification system for ion implantation processes includes a gas source, a controller, a valve, and a process chamber. The gas source provides delivery of a gas, be it atmospheric or reactive, to the valve and is controlled by the controller. The valve is located on or about the process chamber and controllably adjusts flow rate and/or composition of the gas to the process chamber. The process chamber holds a target device, such as a target wafer and permits interaction of the gas with an ion beam to mitigate contamination of the target wafer and/or to modify the existing properties of the processing environment or target device to change a physical or chemical state or characteristic thereof. The controller selects and adjusts composition of the gas and flow rate according to contaminants present within the ion beam, or lack thereof, as well total or partial pressure analysis.