Epitaxial Impurity Region in Semiconductor Rectifier
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Solution Overview
Problem
Ion implantation damage in high-concentration impurity regions of semiconductor rectifying devices, such as MPS, leads to increased on-voltage and switching loss due to delayed hole injection and electric field concentration, which degrades breakdown voltage and increases leakage current.
Innovation Solution
The impurity region is formed through epitaxial growth instead of ion implantation, and a second semiconductor layer with higher impurity concentration is epitaxially formed in the corner portion of the recess to reduce ion implantation damage and electric field concentration, thereby enhancing hole injection efficiency and maintaining high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion implantation is used to form high-concentration impurity region, then impurity concentration is increased, but ion implantation damage occurs causing increased on-voltage and switching loss
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical epitaxial growth process. Instead of physically implanting ions into the semiconductor lattice (mechanical system), the impurity region is formed through controlled chemical deposition where impurities are incorporated during crystal growth. This substitution eliminates mechanical damage to the lattice structure while achieving the desired high impurity concentration, thereby reducing switching loss.
Solution Approach 2:
The patent changes the formation method parameter from ion implantation to epitaxial growth. By controlling the epitaxial growth conditions (temperature, pressure, gas flow ratios of reactants), the impurity concentration can be precisely controlled at high levels without causing damage. This parameter change fundamentally alters how the impurity region is formed, eliminating the trade-off between concentration and damage.
2Quantity of substance
If ion implantation is used to form high-concentration impurity region, then impurity concentration is increased, but on-voltage increases due to ion implantation damage
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical epitaxial growth process. Instead of physically implanting ions into the semiconductor lattice (mechanical system), the impurity region is formed through controlled chemical deposition where impurities are incorporated during crystal growth. This substitution eliminates mechanical damage to the lattice structure while achieving the desired high impurity concentration, thereby reducing switching loss.
3Quantity of substance
If ion implantation is used to form impurity region, then impurity concentration is increased, but hole injection is delayed
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical epitaxial growth process. Instead of physically implanting ions into the semiconductor lattice (mechanical system), the impurity region is formed through controlled chemical deposition where impurities are incorporated during crystal growth. This substitution eliminates mechanical damage to the lattice structure while achieving the desired high impurity concentration, thereby reducing switching loss.
4Quantity of substance
If ion implantation is used to form high-concentration impurity region, then impurity concentration is increased, but breakdown voltage decreases due to electric field concentration
Solution Approach 1:
The patent replaces the mechanical ion implantation process with a chemical epitaxial growth process. Instead of physically implanting ions into the semiconductor lattice (mechanical system), the impurity region is formed through controlled chemical deposition where impurities are incorporated during crystal growth. This substitution eliminates mechanical damage to the lattice structure while achieving the desired high impurity concentration, thereby reducing switching 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 approach suppresses ion implantation damage-related losses, decreases leakage current, and maintains high breakdown voltage, resulting in a low-loss and high-breakdown-voltage semiconductor device with reduced production costs.
Implementation Method 1
the impurity region is formed by ion implantation of an impurity. However, ion implantation damage exists in the high-concentration impurity region formed by the ion implantation. Therefore, unfortunately an on-voltage of the semiconductor rectifying device is increased
Data Source
AI summary
A semiconductor device according to an embodiment includes a first-conductive-type semiconductor substrate; a first-conductive-type first semiconductor layer formed on the semiconductor substrate, and having an impurity concentration lower than that of the semiconductor substrate; a second-conductive-type second semiconductor layer epitaxially formed on the first semiconductor layer; and a second-conductive-type third semiconductor layer epitaxially formed on the second semiconductor layer, and having an impurity concentration higher than that of the second semiconductor layer. The semiconductor device also includes a recess formed in the third semiconductor layer, and at least a corner portion of a side face and a bottom surface is located in the second semiconductor layer. The semiconductor device also includes a first electrode in contact with the third semiconductor layer; a second electrode connected to the first electrode while being in contact with the second semiconductor layer at the bottom surface of the recess; and a third electrode in contact with a lower surface of the semiconductor substrate.