Self-Aligned Source Region in Power Semiconductor Devices
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Solution Overview
Problem
Existing power semiconductor devices face challenges in minimizing switching and on-state losses, and ensuring high reliability, particularly in the accurate formation of doped semiconductor regions for efficient energy conversion and motor driving applications.
Innovation Solution
A method involving the formation of trenches in a semiconductor body with protruding trench sections, followed by tilted implantation to create a semiconductor zone, which helps in forming a source region and body region within a mesa region, allowing for precise control of load current and reduced losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional implantation methods are used to form doped regions, then the manufacturing process is simpler, but the positioning precision of the source region deteriorates
Solution Approach 1:
The method performs preliminary actions by forming protruding trench sections before the implantation step. These protruding sections serve as pre-positioned masks that define the exact location where the source region will be formed, ensuring precise positioning before the actual doping process occurs.
Solution Approach 2:
The protruding trench sections act as an intermediary element between the implantation process and the final source region formation. These sections serve as a mask structure that mediates the implantation process, allowing precise control over where dopants are introduced into the semiconductor body.
2Loss of energy
If the source region is formed adjacent to both trench sidewalls, then the structure is more symmetric, but the control over load current and reduction of losses deteriorates
Solution Approach 1:
The method deliberately creates an asymmetric source region configuration where the source region is formed adjacent to only one trench sidewall rather than both. This asymmetric positioning allows for optimized electrical characteristics that reduce switching and on-state losses, demonstrating that symmetry is not always optimal for device performance.
Solution Approach 2:
The protruding trench sections enable local quality control by allowing the source region to be positioned specifically adjacent to one sidewall. This localized doping strategy optimizes the electrical properties in critical areas, improving device performance by reducing energy losses where it matters most.
3Manufacturing precision
If the trench sections are flush with the semiconductor body surface, then the device structure is simpler, but the ability to use trenches as masks during tilted implantation deteriorates
Solution Approach 1:
The method performs preliminary action by extending the trench sections above the semiconductor body surface before implantation. This preliminary structural modification creates the necessary mask geometry that enables precise source region formation during the subsequent tilted implantation process.
Solution Approach 2:
The trench sections are extended into a third dimension (vertical dimension above the surface) to create protruding structures. This dimensional change transforms the trenches from simple planar features into three-dimensional masks that can effectively control the implantation process, enabling precise source region formation.
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 enhances the control of load current, reduces losses, and improves the reliability of power semiconductor devices by accurately forming doped regions, thereby optimizing their performance in energy conversion and motor driving applications.
Implementation Method 1
subjecting the mesa region to an implantation processing step for forming a semiconductor zone in the mesa region
Data Source
AI summary
An auxiliary layer is formed above a semiconductor body surface of a semiconductor body, the auxiliary layer being coupled to the semiconductor body and having an auxiliary layer surface. Trenches extend from the auxiliary layer surface along a vertical direction through the auxiliary layer into the semiconductor body, wherein two facing trench sidewalls of two adjacent trenches laterally confine a mesa region of the semiconductor body along a first lateral direction, each adjacent trench including a trench section protruding out of the semiconductor body surface. The trenches are filled with a trench filler material which is planarized to expose the auxiliary layer. The auxiliary layer is removed to least partially while maintaining the protruding trench sections. The mesa region is subjected to an implantation tilted by an angle of at least 10°, the protruding trench sections of the adjacent trenches serving at least partially as a mask during the implantation.