Isotropic Doping of Non-Planar Semiconductor Surfaces
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Solution Overview
Problem
Current methods for doping non-planar surfaces in semiconductor devices, such as ion implantation, are inadequate for uniformly doping curved or angled surfaces, leading to misalignment issues and degradation of device performance.
Innovation Solution
A method involving the formation of features with exposed top and sidewall surfaces, covered by dielectric material, where voids are etched to expose these surfaces, allowing for the application of a dopant gas or plasma to achieve isotropic doping of non-planar regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is used to dope non-planar surfaces, then doping can be achieved, but uniform distribution of dopant is not achieved leading to misalignment and device performance degradation
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical vapor deposition process. Instead of physically shooting ions at angled non-planar surfaces (mechanical approach), the invention uses dopant-containing vapor that chemically deposits onto exposed surfaces, allowing uniform dopant distribution across complex geometries without alignment issues.
Solution Approach 2:
The invention changes the fundamental parameter of dopant delivery from directional ion beams to isotropic vapor phase deposition. By transforming the doping mechanism from mechanical impact to chemical vapor deposition, the process achieves uniform doping on non-planar surfaces through parameter change rather than attempting to improve alignment precision.
2Adaptability or versatility
If ion implantation is used for doping, then shallow doping can be achieved, but it is only suitable for planar regions and cannot effectively dope non-planar surfaces
Solution Approach 1:
The vapor phase doping process creates a universal method that works on both planar and non-planar surfaces. The dopant vapor can access and deposit on any exposed surface geometry, making the process universally applicable to various surface configurations without requiring separate doping strategies for different geometries.
Solution Approach 2:
The invention transitions from two-dimensional planar doping to three-dimensional surface doping by introducing vapor phase deposition. The dopant vapor fills the third dimension of space, allowing uniform coating on surfaces with varying heights, angles, and curvatures that would be inaccessible to directional ion implantation.
3Manufacturing precision
If dopant gas is flowed over exposed surfaces, then isotropic doping can be achieved, but the process requires specific process conditions and equipment
Solution Approach 1:
The patent uses a carrier gas as an intermediary to deliver dopant molecules to the substrate surface. The carrier gas transports the dopant uniformly across the chamber, ensuring isotropic distribution without requiring complex targeting systems or precise alignment mechanisms that would increase process complexity.
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 enables uniform doping of non-planar surfaces, preventing misalignment and improving device performance by ensuring consistent dopant distribution across the semiconductor material.
Implementation Method 1
flowing a dopant gas over the exposed top surface portion and the exposed sidewall portion or b) exposing the exposed top surface portion and the exposed sidewall portion to a plasma containing the dopant gas
Data Source
AI summary
A method is described for isotropic or nearly isotropic shallow doping of a non-planar surface exposed in a void. The results of ion implantation, a common doping method, are inherently planar. Some fabrication methods and devices may require doping a surface of a non-planar feature exposed in a void, such as a trench. The feature is doped by flowing a gas which will provide the dopant over the exposed surfaces, or by exposing the surfaces to a plasma including the dopant. The feature may be a patterned feature, including a top surface and a sidewall. In a preferred embodiment, a semiconductor feature having a top surface and a sidewall is exposed in a trench formed in a dielectric, and a gas providing a p-type or n-type dopant is flowed in the trench, providing a p-type or n-type dopant to the semiconductor.