Plasma Doping for 3D Semiconductor Sidewalls
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Solution Overview
Problem
Current methods for doping three-dimensional (3D) semiconductor structures face challenges in achieving precise control over doping depth and concentration, particularly in narrow gaps between conductive structures, leading to shadowing effects and floating body issues.
Innovation Solution
A plasma doping method is employed, where a conductive structure with a sidewall is formed, and a doped region is created on the sidewall through a plasma doping process, using a protective layer and annealing to activate the dopant, while avoiding tilt angles to prevent shadowing and allowing for shallow doping depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tilt ion implantation is used to dope specific regions of conductive structures, then doping can be performed at predetermined angles, but shadow effects occur and target regions cannot be doped due to neighboring structures blocking the ion beam
Solution Approach 1:
The patent replaces the mechanical ion beam implantation system with a plasma-based doping system. Instead of using directed ion beams that are blocked by shadow effects, the invention uses plasma doping where dopant atoms are delivered through a plasma environment that can access narrow gaps between conductive structures without being blocked by geometric shadows, thereby eliminating the shadow effect while maintaining precise doping location control
Solution Approach 2:
The patent introduces a plasma environment as an intermediary medium for doping. The plasma acts as a carrier that delivers dopant atoms to the target regions through the narrow gaps between conductive structures, serving as a mediator that overcomes the direct line-of-sight limitation of ion beam implantation and enables doping in previously inaccessible shadowed regions
2Manufacturing precision
If tilt ion implantation is performed to dope target regions, then doping can be attempted in narrow gaps, but it is difficult to achieve desired doping concentration and doping depth control when conductive structures are relatively tall
Solution Approach 1:
The patent changes the fundamental parameters of the doping process by transitioning from ion beam implantation to plasma doping. This parameter change enables independent control of doping depth and concentration through plasma process conditions (such as plasma power, gas flow rates, and temperature), allowing precise doping even in tall conductive structures with narrow gaps where ion beam geometry control becomes impractical
3Ease of manufacture
If thermal diffusion method is used to dope target regions, then doping can be performed through annealing, but doping depth and doping dose are difficult to control and dopant loss occurs when doped material is removed
Solution Approach 1:
The patent replaces the thermal diffusion process with a plasma-based doping method. Instead of relying on thermal diffusion where dopant atoms migrate through the material lattice during annealing (which is difficult to control precisely), the invention uses plasma doping where dopant atoms are directly delivered and incorporated into the target regions, providing superior control over both doping depth and dose while eliminating the need for subsequent material removal that causes dopant loss
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 method enables precise control over doping depth and concentration, preventing floating body effects and allowing for the formation of doped regions at desired locations without shadowing, enhancing semiconductor device fabrication.
Implementation Method 1
forming a doped region in the exposed portion of the sidewall by performing a plasma doping process
Implementation Method 2
performing an annealing process to activate the doped region
Data Source
AI summary
A doping method that forms a doped region at a desired location of a three-dimensional (3D) conductive structure, controls the doping depth and doping dose of the doped region relatively easily, has a shallow doping depth, and prevents a floating body effect. A semiconductor device is fabricated using the same doping method. The method includes, forming a conductive structure having a sidewall, exposing a portion of the sidewall of the conductive structure, and forming a doped region in the exposed portion of the sidewall by performing a plasma doping process.