Semiconductor Crystal Defect Alignment via Laser Annealing
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods face challenges in accurately aligning the crystal defect region with the cathode region, leading to unstable characteristics and increased losses in IGBT and diode performance due to relative positional misalignment.
Innovation Solution
A method involving charged particle implantation and n-type impurity implantation in specific ranges of a semiconductor substrate, followed by laser irradiation to create and maintain high crystal defect densities in one region and low in another, ensuring precise positioning of the crystal defect region relative to the cathode region through an amorphous region formation and subsequent crystallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If masks are used for charged particle implantation and n-type impurity implantation separately, then the manufacturing process can be performed with conventional equipment, but relative positional misalignment between the crystal defect region and the cathode region occurs
Solution Approach 1:
The patent combines the formation of the crystal defect region and the cathode region into a single charged particle implantation step. By implanting charged particles (such as carbon ions) to form both the amorphous layer (which becomes the crystal defect region after annealing) and the n-type impurity distribution (cathode region) simultaneously, the method eliminates the need for separate mask alignments, thereby resolving the positional misalignment issue while maintaining conventional manufacturing capabilities
Solution Approach 2:
The patent performs preliminary formation of the amorphous layer through charged particle implantation before subsequent thermal annealing. This preliminary action creates a structured region that will develop into the crystal defect region with precise positional control, as the amorphous layer formation occurs at a defined depth range that determines the final location of the crystal defect region after annealing
2Device complexity
If the crystal defect region position is misaligned closer to the IGBT, then the manufacturing process is simpler, but the ON-potential of the IGBT rises and loss increases
Solution Approach 1:
The patent replaces the mechanical mask alignment system with a depth-controlled implantation and thermal diffusion system. By controlling the implantation depth and subsequent annealing conditions, the crystal defect region is precisely positioned at the desired location without requiring complex mask alignment mechanisms, thereby preventing IGBT loss increase while maintaining manufacturing simplicity
Solution Approach 2:
The patent utilizes parameter changes in the charged particle implantation process, specifically controlling the implantation energy and dose to precisely control the depth and concentration profile of the amorphous layer. By adjusting these parameters, the crystal defect region can be positioned exactly where needed, preventing it from encroaching on the IGBT region and causing loss
3Ease of operation
If the crystal defect region position is misaligned from the cathode region, then mask alignment is easier to perform, but the reverse recovery characteristic of the diode deteriorates
Solution Approach 1:
The patent merges the formation of the crystal defect region and cathode region into a single charged particle implantation step, ensuring they are co-located by definition. This eliminates the need for separate mask alignment operations while guaranteeing that the crystal defect region is properly positioned relative to the cathode region, thereby maintaining excellent reverse recovery characteristics
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 relative positional misalignment between the crystal defect and cathode regions, stabilizing semiconductor device characteristics and reducing variations in mass production, thereby minimizing IGBT on-voltage and diode reverse recovery losses.
Implementation Method 1
implanting charged particles into a first range and a second range in a semiconductor substrate from at least one of a first surface of the semiconductor substrate and a second surface of the semiconductor substrate located on an opposite side of the first surface so as to increase crystal defect densities in the first range and the second range
Implementation Method 2
implanting n-type impurities into the first range from the first surface so as to make a region amorphous, the region being in the first range and disposed at the first surface
Implementation Method 3
irradiating the first surface with first laser after the implantation of the charged particles and the implantation of the n-type impurities so as to heat the first range and the second range
Implementation Method 4
As the amorphous region has a low thermal conductivity, heat does not transfer at a great degree to a deeper side of the amorphous region
Implementation Method 5
crystallizing the region which has been made amorphous in or after the irradiation of the first laser
Data Source
AI summary
A method of manufacturing a semiconductor device includes: implanting charged particles into a first range and a second range in a semiconductor substrate from at least one of a first surface of the semiconductor substrate and a second surface of the semiconductor substrate located on an opposite side of the first surface so as to increase crystal defect densities in the first range and the second range; implanting n-type impurities into the first range from the first surface so as to make a region amorphous, the region being in the first range and disposed at the first surface; irradiating the first surface with first laser after the implantation of the charged particles and the implantation of the n-type impurities so as to heat the first range and the second range; and crystallizing the region which has been made amorphous in or after the irradiation of the first laser.