Semiconductor Carrier Lifetime Control via Electron Beam and Hydrogen Implantation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor manufacturing methods face challenges in locally controlling carrier lifetime at low cost without increasing leak current or contaminating the manufacturing line, particularly with light ion irradiation and heavy metal diffusion methods.
Innovation Solution
A semiconductor device manufacturing method that forms defects in the semiconductor substrate by breaking inter-atomic bonds using electron beam irradiation and then locally recovers these defects through hydrogen ion implantation from the rear surface, creating a high hydrogen concentration region with longer carrier lifetime on the rear surface compared to the front surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light ion irradiation or heavy metal diffusion is used to control carrier lifetime, then carrier lifetime can be controlled, but manufacturing cost increases and manufacturing line contamination occurs
Solution Approach 1:
The patent uses electron beam irradiation instead of expensive light ion irradiation or heavy metal diffusion. The electron beam is a temporary, non-material processing method that does not require consuming expensive materials or risking manufacturing line contamination, effectively replacing costly and problematic processing methods with a cleaner, more economical alternative.
Solution Approach 2:
The patent replaces the mechanical/chemical processes of light ion irradiation and heavy metal diffusion with an electromagnetic field-based electron beam processing method. This substitution eliminates the need for physical material introduction and complex chemical reactions, reducing both cost and contamination risk while achieving the same carrier lifetime control objective.
2Productivity
If electron beam irradiation with high acceleration energy is used, then processing is efficient, but the electron beam transmits through the substrate and carrier lifetime becomes uniform instead of localized
Solution Approach 1:
The patent changes the acceleration energy parameter of the electron beam from high to low levels. This parameter modification allows the electron beam to have sufficient energy to process the substrate effectively while having limited penetration depth, enabling localized carrier lifetime control in the vicinity of the irradiation site rather than uniform distribution throughout the substrate.
3Manufacturing precision
If acceleration energy is decreased to achieve localized carrier lifetime control, then defects can be generated locally, but the mass of electrons is too small to generate sufficient defects
Solution Approach 1:
The patent introduces hydrogen ion implantation as an intermediary process that works in conjunction with low-energy electron beam irradiation. The hydrogen ions serve as a mediator to enhance defect generation and carrier lifetime control in the low-energy electron irradiated regions, compensating for the insufficient defect generation capability of low-mass electrons at low acceleration energies.
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 method allows for local control of carrier lifetime at low cost without increasing leak current or contaminating the manufacturing line, improving the soft recovery characteristic of the diode by reducing oscillations in current/voltage waveforms during reverse recovery.
Implementation Method 1
defects are formed in a semiconductor substrate by dangling bonds generated by breaking of inter-atomic bonds of atoms constituting the semiconductor substrate
Implementation Method 2
breaking of inter-atomic bonds of atoms constituting the semiconductor substrate
Implementation Method 3
a high hydrogen concentration region, of which hydrogen concentration is higher than a front surface side of the semiconductor substrate, is formed in a surface layer of a rear surface of the semiconductor substrate by introducing hydrogen atoms
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
First, a front surface element structure is formed on the front surface side of an n--type semiconductor substrate. Then defects (12) are formed throughout the entire n--type semiconductor substrate by electron beam irradiation and furnace annealing, so as to adjust the carrier lifetime. Next, the thickness of the n--type semiconductor substrate is decreased by grinding the rear surface of the n--type semiconductor substrate. Then n-type impurities are ion-implanted from the ground rear surface side of the n--type semiconductor substrate, and an n+-type cathode layer (4) is formed on the surface layer of the rear surface of the n--type semiconductor substrate. Thereafter, hydrogen ions are ion-implanted (14) from the rear surface side of the n--type semiconductor substrate, and a hydrogen implanted region having a hydrogen concentration higher than the hydrogen concentration of a bulk substrate is formed on the surface layer of the rear surface of the n--type semiconductor substrate. Then a cathode electrode is formed after activating the n+-type cathode layer (4) by laser annealing. By so doing, carrier lifetime can be locally controlled at low cost, without increasing leak current or contaminating the manufacturing line.