Trench Doping Profile Shaping for Super-Junction Semiconductors
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Solution Overview
Problem
Existing semiconductor device manufacturing methods face challenges in achieving precise and adjustable doping profiles, particularly in super-junction structures, where a reproducible and homogeneous doping along the lateral direction and adjustable vertical direction are necessary for optimal electric field profiles and breakdown voltage capabilities.
Innovation Solution
A method involving the formation of trenches in a semiconductor body, followed by ion implantation of dopants at the trench bottom and top, with a filling material introduced and thermally processed to intermix dopants vertically, allowing for precise control of doping profiles through diffusion processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used, then doping can be achieved, but precise and adjustable doping profiles particularly in super-junction structures cannot be achieved
Solution Approach 1:
The doping process is segmented into multiple ion implantation steps targeting different regions (first region at trench bottom, second region at trench top) followed by separate thermal processing steps. This segmentation allows independent control of dopant concentration and depth distribution, achieving precise and adjustable doping profiles required for super-junction structures
Solution Approach 2:
Dopants are introduced into the filling material before the final semiconductor structure is complete. The filling material serves as a preliminary dopant reservoir that releases dopants during subsequent thermal processing, enabling precise control over doping depth and concentration profiles before the device structure is finalized
2Length of stationary object
If greater depth of doping is achieved, then breakdown voltage capability improves, but area consumption increases
Solution Approach 1:
The doping approach transitions from lateral area-based doping to vertical depth-based doping by introducing dopants into the filling material that subsequently diffuse vertically during thermal processing. This dimensional shift allows achieving greater breakdown voltage through increased doping depth without proportionally increasing device area, as the dopants are delivered through the vertical trench structure rather than requiring lateral expansion
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 the creation of semiconductor devices with deep and precisely controlled doping profiles, enhancing electric characteristics such as avalanche robustness and breakdown voltage capabilities while minimizing area consumption.
Implementation Method 1
introducing dopants into a first region at a bottom side of the trench by ion implantation
Implementation Method 2
thermal processing of the semiconductor body configured to intermix the dopants from the first and second regions by a diffusion process along a vertical direction
Data Source
AI summary
A method of forming a semiconductor device includes forming a trench in a semiconductor body; at least partially filling the trench with a filling material; introducing dopants into a portion of the filling material; and applying a first thermal processing to the semiconductor body to spread the dopants in the filling material along a vertical direction of the filling material by a diffusion process. The vertical doping profile of the dopants within the doped filling material is shaped during the first thermal processing. Additionally, the dopants are substantially confined to within the trench and substantially do not diffuse from the doped filling material into the semiconductor body during the first thermal processing. A second thermal processing is applied to the semiconductor body after the first thermal processing to cause diffusion of the dopants from the doped filling material into the semiconductor body adjoining the trench.