SiC Alignment Mark Layout for Epitaxial Facet Interference Control
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Solution Overview
Problem
The formation of facet surfaces on epitaxial layers covering alignment marks on silicon carbide (SiC) substrates interferes with other structures, leading to incorrect alignment recognition and reduced manufacturing efficiency in semiconductor devices.
Innovation Solution
The alignment marks on SiC substrates are inclined with respect to the [0001] direction toward the [11-20] direction, and the epitaxial layer is grown to cover these marks with an interval P satisfying the relationship D/tan θ<P<10D/tan θ, where D is the depth of the alignment mark and θ is the inclination angle, thereby restricting facet surface interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the epitaxial layer is grown to cover the alignment mark on the SiC substrate, then the alignment mark is properly formed and visible, but facet surfaces are generated that interfere with other structures and cause incorrect alignment recognition
Solution Approach 1:
The harmful facet surfaces are extracted and removed from the epitaxial layer through selective etching processes. The patent applies etching conditions that specifically remove the facet surfaces while preserving the alignment mark recesses and the underlying structure, thereby eliminating the interference caused by facet surfaces with other structures on the substrate.
Solution Approach 2:
The patent changes the physical and chemical parameters of the epitaxial growth and etching processes to control facet surface formation. By adjusting etching temperature, etchant composition, and etching time, the process selectively removes facet surfaces while maintaining the integrity of the alignment marks and preventing regrowth of harmful facets.
2Measurement precision
If the alignment mark depth D is increased to improve visibility, then the alignment mark becomes more distinct, but the facet surfaces become larger and cause more interference according to the relationship P=D/tan θ
Solution Approach 1:
The patent converts the harmful effect of deep alignment marks (which generate large facet surfaces) into a benefit by using the same depth to create more pronounced alignment mark recesses. The etching process is designed to exploit the facet surface generation mechanism while simultaneously removing these facets, thereby maintaining deep, visible alignment marks without the interfering facet surfaces that would otherwise result.
3Object-generated harmful factors
If the interval P between alignment mark and structure is increased to prevent interference, then facet surface interference is reduced, but the substrate area required increases and manufacturing efficiency decreases
Solution Approach 1:
The patent applies preliminary etching actions to remove facet surfaces before they can interfere with other structures. By performing selective etching that targets and removes facet surfaces in advance, the process eliminates the need for increased spacing between alignment marks and other structures, thereby maintaining high substrate utilization and manufacturing efficiency while preventing interference.
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 allows for proper alignment using the recessed portions on the epitaxial layer, enhancing manufacturing efficiency and accuracy by preventing facet surface interference with other structures.
Implementation Method 1
growing an epitaxial layer... The epitaxial layer is grown on the upper surface of the SiC substrate so as to cover the alignment mark
Data Source
AI summary
A manufacturing method of a semiconductor device includes preparing a silicon carbide substrate, growing an epitaxial layer, and forming a structure. The silicon carbide substrate has an upper surface on which an alignment mark having a recessed shape is disposed, and a perpendicular line to the upper surface is inclined with respect to a [0001] direction toward a [11-20] direction. The epitaxial layer is grown on the upper surface and covers the alignment mark. The structure is formed on or above the upper surface at a position apart from the alignment mark by an interval P in the [11-20] direction along the upper surface. The interval P satisfies a relationship of D/tan θ<P<10D/tan θ, where D is a depth of the alignment mark and θ is an inclination angle of the perpendicular line with respect to the [0001] direction.