Superjunction Alignment via Integrated Trench Mask
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Solution Overview
Problem
Existing methods for aligning superstructures to superjunction structures in semiconductor devices are not reliable and economical, leading to potential misalignment and increased costs due to the need for critical lithography processes and separate alignment marks.
Innovation Solution
A method using a single trench mask to form first and second trenches, where position information is directly obtained from structures within the trenches, allowing for the formation of a superstructure aligned with a foundation that includes a superjunction structure, utilizing a contrast-enhanced alignment mark to reduce misalignment and simplify the alignment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate alignment marks and critical lithography processes are used to align superstructure to superjunction structure, then alignment precision can be improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the alignment mark formation with the superjunction structure formation by using the same trenches. The first trenches contain both the superjunction structure and alignment marks, eliminating the need for separate alignment mark structures and reducing overall device complexity while maintaining alignment precision.
Solution Approach 2:
The trenches serve multiple functions: they form the superjunction structure (first regions with opposite doping) and simultaneously create the alignment marks. This multi-functional approach reduces the number of separate structures needed, simplifying the device while preserving alignment capability.
2Reliability
If multiple separate structures are used for alignment marks, then alignment reliability can be improved, but manufacturing cost and process steps increase
Solution Approach 1:
The patent merges alignment mark formation with superjunction structure formation in the same trenches, reducing the total number of manufacturing steps and associated costs while maintaining alignment reliability through the dual-purpose structure.
Solution Approach 2:
The alignment marks are formed preliminarily during the superjunction structure creation process itself, rather than as a separate subsequent step. This preliminary integration reduces manufacturing complexity and cost while ensuring alignment reliability is established early in the process.
3Manufacturing precision
If statistical misalignment is reduced by using separate alignment marks, then alignment accuracy improves, but the number of process steps and time increase
Solution Approach 1:
By combining alignment mark and superjunction structure formation in the same trenches, the patent eliminates separate alignment mark fabrication steps, reducing overall process time while maintaining alignment accuracy through the integrated structure.
Solution Approach 2:
The alignment functionality is built into the superjunction structure formation process itself, performing alignment preparation preliminarily rather than requiring separate subsequent steps, thus reducing total process time while maintaining accuracy.
Data Source
AI summary
According to an embodiment of a semiconductor substrate, the semiconductor substrate includes a superjunction structure in a device region of a semiconductor layer and an alignment mark in a kerf region of the semiconductor layer. The superjunction structure includes first regions and second regions of opposite conductivity types, the first and the second regions alternating along at least one horizontal direction. The alignment mark includes a vertical step formed by an alignment structure projecting or recessed from a main surface of the semiconductor layer. The alignment structure is of a material of the first regions of the superjunction structure.