Switching Element Manufacturing via Thermal Diffusion
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Solution Overview
Problem
The existing manufacturing methods for switching elements with lateral surface p-type regions result in high crystal defect densities near the trench surfaces, leading to increased leakage currents due to the implantation of p-type impurities, which are difficult to eliminate.
Innovation Solution
A method involving the formation of lateral surface p-type regions by heating the semiconductor substrate to allow the body region to flow into the trench, resulting in a semiconductor region with extremely low crystal defect density, thereby reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p-type impurities are implanted into the lateral surface of the trench to form a lateral surface p-type region, then the switching element achieves low on-resistance when turned on, but crystal defects are formed in the semiconductor region near the lateral surface, leading to increased leakage current
Solution Approach 1:
The patent changes the formation method of the lateral surface p-type region from ion implantation to in-diffusion by heating. This parameter change in the manufacturing process eliminates crystal defects while still forming the necessary p-type region, thereby suppressing leakage current without compromising manufacturing precision.
Solution Approach 2:
The patent replaces the mechanical ion implantation process with a thermal diffusion process. By heating the semiconductor substrate, p-type impurities diffuse into the lateral surface region naturally, avoiding the crystal damage caused by ion bombardment while achieving the same electrical functionality.
2Manufacturing precision
If the semiconductor substrate is heated to allow the body region to flow into the trench, then crystal defect density is reduced to extremely low levels, but additional heating process time and energy are required
Solution Approach 1:
The patent merges the heating process for forming the lateral surface p-type region with the existing thermal processing steps in the manufacturing sequence. By integrating the heating step with other necessary thermal processes, the additional time loss is minimized while still achieving the crystal defect reduction benefit.
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 effectively suppresses leakage currents by forming lateral surface p-type regions with low crystal defect densities, enhancing the reliability of the switching element by minimizing electrical losses.
Implementation Method 1
A semiconductor region obtained by a semiconductor material being melted and then solidified has an extremely low crystal defect density
Implementation Method 2
heating the semiconductor substrate so as to make a part of the body region flow into the trench
Data Source
AI summary
A method of manufacturing a switching element is provided. The method including: preparing a semiconductor substrate which includes an n-type drain region, a p-type body region, and a trench penetrating the body region and reaching the drain region; and forming a lateral surface p-type region extending along a lateral surface of the trench below the body region by heating the semiconductor substrate so as to make a part of the body region flow into the trench. The switching element includes: a gate insulating layer covering an inner surface of the trench; a bottom p-type region in contact with the gate insulating layer at a bottom surface of the trench and connected to the lateral surface p-type region; an n-type source region; and a gate electrode provided in the trench.