Conoscopic Wafer Orientation for Precise SiC Ion Implant Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In silicon carbide (SiC) substrates, the depth of ion implantation and crystal damage are significantly affected by the alignment of ion trajectories with the crystal structure, making accurate substrate orientation crucial for efficient ion implantation.
Innovation Solution
The implementation of a conoscopy system within an ion implanter, which includes an illumination source, polarizers, a lens, and a detector, allows for in-situ determination of the substrate's crystallographic orientation and tilting to align the c-axis with the ion beam, thereby enhancing ion channeling and implant depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate orientation is not precisely aligned with the crystal structure, then the ion implantation process is simpler and faster, but the implant depth varies significantly and crystal damage increases
Solution Approach 1:
The conoscopy system performs substrate orientation determination before the ion implantation process begins. By pre-aligning the substrate using optical observation of the conoscopic pattern, the system ensures that the ion beam will be properly aligned with the crystal structure during implantation, thereby achieving precise implant depth control without requiring complex real-time adjustments during the implantation process itself.
Solution Approach 2:
The patent replaces complex mechanical alignment systems with an optical conoscopy system. Instead of using mechanical stages and physical alignment tools to orient the substrate, the system uses polarized light and conoscopic imaging to optically determine and guide the substrate orientation, thereby achieving precise alignment with reduced mechanical complexity.
2Manufacturing precision
If the ion beam is not aligned with the crystal direction, then the implantation process is faster, but the implant depth varies up to 100% or more and crystal damage increases
Solution Approach 1:
The conoscopy system provides visual feedback through the conoscopic pattern, allowing operators to directly observe the alignment between the ion beam and crystal direction. The pattern shows whether the substrate is properly oriented, enabling real-time adjustments to achieve optimal alignment before and during the implantation process, thereby minimizing implant depth variation and crystal damage.
3Reliability
If deep ion implantation is performed without proper alignment, then the process can be completed quickly, but the regions depleted of charge carriers cannot effectively withstand high voltages
Solution Approach 1:
The patent merges the orientation determination system with the ion implanter by integrating the conoscopy system directly into the implanter. This combination allows the substrate orientation to be determined and adjusted in-situ within the same chamber where ion implantation occurs, ensuring that the implantation process is performed with proper alignment to create effective high-voltage withstand regions while avoiding the need for separate alignment equipment.
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 precise alignment of the SiC substrate, leading to increased ion implant depth and reduced crystal damage for a given ion energy, thereby improving the efficiency and accuracy of high-voltage device manufacturing.
Implementation Method 1
a first polarizer, having a first polarization axis, disposed between the illumination source and the substrate position; a second polarizer, the second polarizer being disposed to receive the light after passing through the substrate position
Implementation Method 2
a lens, to receive the light after passing through the substrate position
Implementation Method 3
a detector, to detect the light after passing through the lens
Data Source
AI summary
An ion implanter may include an ion source to generate an ion beam. The ion implanter may include a set of beamline components to direct the ion beam to a substrate along a beam axis, as well as a process chamber to house the substrate to receive the ion beam. The ion implanter may include a conoscopy system, comprising: an illumination source to direct light to a substrate position; a first polarizer, having a first polarization axis, disposed between the illumination source and the substrate position; a second polarizer, the second polarizer being disposed to receive the light after passing through the substrate position. The conoscopy system may include a lens, to receive the light after passing through the substrate position, and a detector, to detect the light after passing through the lens.