SiC Implantation Mask Segmentation for Impurity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for manufacturing silicon carbide semiconductor devices require multiple process steps to form regions with different impurity concentrations, leading to increased work time and costs, especially when high-energy Al-ion implantation is involved, as the ion-implantation time is prolonged due to low beam current and limited diffusion of impurities in silicon carbide.
Innovation Solution
A method involving the formation of an implantation mask with multiple unit masks of varying sizes and intervals, where the length from any point in the unit mask to its end is set to be equal to or less than the scattering length of the implanted ion, allowing for the formation of regions with different impurity concentrations in a single mask and ion implantation step, thereby reducing the number of necessary steps and thermal diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mask steps are used to form regions with different impurity concentrations, then the precision of impurity concentration control is improved, but the manufacturing time and cost increase
Solution Approach 1:
The mask is segmented into multiple unit masks with different aperture ratios arranged in different regions. Each unit mask corresponds to a specific region requiring a particular impurity concentration. This segmentation allows different impurity concentrations to be formed in different regions simultaneously during a single ion implantation step, eliminating the need for multiple sequential mask steps while maintaining precise concentration control.
Solution Approach 2:
Multiple mask patterns that would traditionally require separate mask steps are merged into a single mask structure containing multiple unit masks. This merged mask enables simultaneous formation of multiple impurity regions with different concentrations in one ion implantation process, reducing the total number of process steps and manufacturing time while preserving the precision of concentration control.
2Manufacturing precision
If high-energy Al-ion implantation is used to achieve required impurity concentration, then the impurity concentration is sufficient, but the ion-implantation time is prolonged due to low beam current
Solution Approach 1:
The mask is designed with unit masks having different aperture ratios tailored to the specific requirements of each region. Regions requiring higher impurity concentrations have larger aperture ratios allowing greater ion flux, while regions requiring lower concentrations have smaller aperture ratios. This local optimization of aperture ratios enables sufficient impurity concentration to be achieved in each region without requiring uniformly high implantation energy throughout, thereby reducing the overall implantation time while maintaining the necessary concentration levels.
3Manufacturing precision
If multiple ion implantation steps are performed to form different impurity regions, then the impurity concentration distribution is precise, but the total process time increases
Solution Approach 1:
The single mask is segmented into multiple unit masks, each designed with specific aperture ratios for different regions. This segmentation allows the mask to function as multiple separate masks would, enabling precise control of impurity concentration distribution across different regions while performing only a single ion implantation step, thus reducing device complexity and process time.
Solution Approach 2:
The single mask structure is designed to perform multiple functions that would traditionally require separate masks. Each unit mask within the single mask serves a specific function of controlling impurity concentration in a particular region. This multi-functional mask design enables precise impurity concentration distribution to be achieved in one implantation step, reducing the total number of process steps while maintaining the precision of concentration control.
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 enables the formation of continuous impurity regions with varying concentrations in a single mask step, reducing manufacturing time and costs by controlling the ion implantation amount through adjustable mask apertures, and shortening the high-energy ion implantation time, applicable to devices like Schottky diodes, MOSFETs, and IGBTs.
Implementation Method 1
implanting predetermined ion in the silicon carbide semiconductor layer at a predetermined implantation energy by using the implantation mask
Implementation Method 2
a length from any point in the unit mask to an end of the unit mask can be equal to or less than a scattering length obtained when the predetermined ion is implanted in silicon carbide
Data Source
AI summary
A method of manufacturing a silicon carbide semiconductor device according to the present invention includes the steps of (a) forming an implantation mask made up of a plurality of unit masks on a silicon carbide semiconductor layer, and (b) implanting predetermined ion in the silicon carbide semiconductor layer at a predetermined implantation energy by using the implantation mask. In the step (a), the implantation mask is formed such that a length from any point in the unit mask to an end of the unit mask can be equal to or less than a scattering length obtained when the predetermined ion is implanted in silicon carbide at the predetermined implantation energy and the implantation mask can have a plurality of regions different from each other in terms of a size and an arrangement interval of the unit masks.