Semiconductor Doping Mask Layout for Lower Recovery Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices face challenges in reducing carrier accumulation in diode regions during free wheeling, leading to increased recovery loss and potential snapback issues due to varying doping concentrations and trench configurations.
Innovation Solution
A fabrication method involving a mask with varying covering densities is used to implant P-type dopants, allowing for the formation of second conductivity type regions with different doping concentrations in specific regions of the semiconductor substrate, thereby optimizing the transistor and diode portions to minimize carrier accumulation and snapback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If uniform doping concentration is used in diode region, then manufacturing process is simple, but carrier accumulation occurs during free wheeling causing increased recovery loss
Solution Approach 1:
The patent applies local quality by creating a non-uniform doping concentration distribution within the diode region. Specifically, the doping concentration is set to be higher near the cathode and lower near the anode, forming a gradient structure. This localized variation in doping concentration optimizes carrier extraction during free wheeling operation, reducing carrier accumulation and thereby decreasing recovery loss without requiring complex external control mechanisms.
Solution Approach 2:
The patent implements parameter changes by varying the doping concentration parameter across the diode region. The doping concentration is changed from uniform to graded, with specific concentration values defined at different positions (higher near cathode, lower near anode). This parameter variation enables the diode to efficiently manage carrier accumulation during free wheeling, reducing recovery loss while maintaining manufacturing feasibility through a single ion implantation process with selective masking.
2Reliability
If higher doping concentration is used in diode region, then breakdown voltage is improved, but snapback issues occur due to carrier accumulation
Solution Approach 1:
The patent applies local quality by creating spatially varying doping concentration within the diode region. The doping concentration is locally optimized with higher values near the cathode to ensure adequate breakdown voltage, and lower values near the anode to prevent carrier accumulation and snapback. This localized differentiation resolves the contradiction between achieving high breakdown voltage and preventing snapback phenomena.
Solution Approach 2:
The patent implements parameter changes by transitioning from uniform to graded doping concentration distribution. The doping concentration parameter is varied across the diode region, with specific values optimized for different locations. This parameter variation enables the structure to simultaneously achieve high breakdown voltage (through adequate doping near cathode) and prevent snapback (through lower doping near anode that reduces carrier accumulation).
3Manufacturing precision
If multiple ion implantation processes are used to create different doping concentrations, then doping precision is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent applies merging by combining multiple doping concentration creation steps into a single ion implantation process. Instead of performing separate ion implantation processes for different doping regions, the invention uses one implantation process with a specifically designed mask pattern that exposes different areas to the ion beam for different durations. This merging approach achieves precise doping concentration distribution while significantly reducing fabrication time and process complexity.
Solution Approach 2:
The patent implements preliminary action by pre-configuring a mask with specific transparency patterns before the ion implantation process. The mask is designed in advance to control the ion beam exposure, creating the desired doping concentration gradient in a single step. This preliminary preparation enables precise doping control without requiring multiple sequential implantation processes, thereby maintaining manufacturing precision while improving productivity.
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 effectively reduces carrier accumulation and recovery loss, enhancing the semiconductor device's performance by optimizing doping concentrations and trench configurations, thus improving breakdown voltage and reducing snapback occurrences.
Implementation Method 1
implanting P-type dopants
Data Source
AI summary
A method includes: forming a mask above the semiconductor substrate such that a covering density for a predetermined first region of the semiconductor substrate by the mask is higher than a covering density for a predetermined second region of the semiconductor substrate by the mask; performing ion implantation of a dopant in each of the first region and the second region for forming a second conductivity type region on a front surface of the semiconductor substrate; diffusing the implanted dopant into the semiconductor substrate, where the mask includes a covering portion and an uncovering portion, a width of the covering portion is equal to or greater than 0.25 times and equal to or smaller than 0.8 times a diffusion depth of the dopant, a width of the uncovering portion is equal to or greater than one-third and equal to or smaller than once the width of the covering portion.