Gas Phase Junction Doping for High-Aspect-Ratio Semiconductor Features
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Solution Overview
Problem
Conventional doping methods for high aspect ratio structures, such as those in 3D DRAM devices, face challenges in achieving adequate doping depths, concentrations, and uniformity, particularly in recessed and non-line-of-sight features, leading to damage and increased processing costs.
Innovation Solution
The method involves a pre-clean operation to remove oxide layers, followed by gas phase doping with phosphine, arsine, or other dopant gases at elevated temperatures, allowing for precise doping of high aspect ratio channels and junctions without the need for line-of-sight access, reducing oxide content and processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used for high aspect ratio structures, then processing can be performed with standard equipment, but doping depth and concentration are insufficient and oxide removal is incomplete
Solution Approach 1:
The patent changes the physical state of the dopant from solid (conventional methods) to gas phase, enabling penetration into high aspect ratio structures. The process uses gas phase dopant sources that can diffuse into recessed features, achieving uniform doping concentrations that conventional solid phase methods cannot reach. Temperature parameters are also optimized to control dopant diffusion while minimizing oxide formation.
Solution Approach 2:
The patent replaces mechanical contact-based doping methods with a chemical vapor phase process. Instead of physically contacting the dopant to the substrate surface, the dopant is delivered through gas phase diffusion and chemical reactions, allowing access to non-line-of-sight areas within high aspect ratio structures without requiring direct mechanical access.
2Manufacturing precision
If oxide layers are present on target regions, then surface protection is maintained, but doping efficiency and depth are reduced
Solution Approach 1:
The patent performs preliminary oxide removal through a pre-clean operation before introducing the gas phase dopant. This preliminary action ensures that the substrate surface is free of oxide barriers that would impede dopant diffusion, allowing maximum doping depth and concentration to be achieved in the subsequent gas phase doping step.
Solution Approach 2:
The patent employs an inert or reducing atmosphere during the gas phase doping process to prevent re-oxidation of the substrate surface. By maintaining an oxygen-free environment with dopant gases, the process ensures that once oxides are removed, the surface remains clean and receptive to dopant incorporation throughout the doping cycle.
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 achieves higher doping concentrations and uniformity in high aspect ratio structures with minimal oxide presence, enhancing electrical properties and reducing processing complexity and costs.
Implementation Method 1
contacting the one or more undoped target regions with a gas phase dopant or a radical thereof and doping the one or more target regions
Implementation Method 2
subjecting the one or more undoped target region to a pre-clean operation, removing at least a portion of any oxide present on the one or more undoped target regions
Data Source
AI summary
Semiconductor processing methods and semiconductor structures are provided with improved doping in target regions. Methods include providing a substrate disposed within a semiconductor processing chamber, where one or more undoped target regions are formed on the substrate. Methods include subjecting the one or more undoped target regions to a pre-clean operation, removing at least a portion of any oxide present on the one or more undoped target regions. Methods include contacting the one or more undoped target regions with a gas phase dopant or a radical thereof, doping the one or more target regions.