Semiconductor Alignment Groove Structure for Epitaxial Mark Visibility
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Solution Overview
Problem
Existing alignment structures on semiconductor substrates deteriorate or become buried under epitaxial layers, leading to inaccurate optical alignment mark recognition and increased process instability during semiconductor device manufacturing.
Innovation Solution
Forming a groove pattern on the semiconductor substrate with grooves aligned in a specific crystallographic direction that slows down epitaxial growth, preserving alignment structures by creating visible edges or voids detectable by optical or infrared methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alignment structures are formed using conventional trench-like blocks, then alignment marks can be initially created, but the alignment structures become blurred or deteriorate during epitaxial processes leading to inaccurate optical alignment mark recognition
Solution Approach 1:
The alignment structure is segmented into multiple parallel grooves rather than a solid trench, creating a grid-like pattern that allows selective epitaxial growth. This segmentation preserves optical contrast while managing epitaxial overgrowth behavior.
Solution Approach 2:
Different regions of the substrate receive different treatments - the alignment structure area has grooves oriented in a specific crystallographic direction to control local epitaxial growth rate, while adjacent areas have different growth characteristics. This creates localized quality differences that preserve alignment marks.
Solution Approach 3:
The groove orientation parameter is specifically aligned with crystallographic directions that exhibit slower epitaxial growth rates. This parameter change in groove orientation relative to the crystal lattice enables differential growth rates between the alignment structure region and surrounding areas.
2Measurement precision
If wider trenches are used for alignment structures, then alignment marks are more visible, but unwanted black silicon is generated during etching
Solution Approach 1:
The alignment structure uses a porous or grooved pattern rather than a solid trench, allowing the structure to maintain visibility while reducing the continuous material removal that causes black silicon. The grooved pattern enables better stress distribution during etching.
Solution Approach 2:
The continuous trench is segmented into parallel grooves, which reduces the cumulative etching stress and prevents the formation of black silicon while maintaining sufficient width for optical detection.
3Object-generated harmful factors
If narrower trenches are used for alignment structures, then black silicon formation is reduced, but the alignment marks vanish more easily when overgrown by thick epitaxial layers
Solution Approach 1:
The groove orientation is aligned with specific crystallographic directions that exhibit slower epitaxial growth rates. This parameter change creates a protective effect where the alignment structure region grows slower than surrounding areas, preventing complete overgrowth and maintaining visibility.
Solution Approach 2:
The grooves are pre-formed with specific orientations before epitaxial growth begins, establishing a growth rate differential in advance that protects the alignment structure from being completely buried during subsequent thick epitaxial layer deposition.
4Measurement precision
If alignment structures are refreshed frequently to maintain accuracy, then alignment mark recognition accuracy is improved, but manufacturing time and process complexity increase
Solution Approach 1:
The alignment structure is designed with groove orientations that create slower epitaxial growth rates in advance, providing long-term protection against overgrowth. This preliminary design prevents the need for frequent refreshes during manufacturing.
Solution Approach 2:
By changing the groove orientation parameter to align with slow-growth crystallographic directions, the alignment structure achieves enhanced durability that reduces the frequency of refresh operations needed to maintain measurement precision.
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
Maintains accurate alignment mark recognition and reduces the need for frequent refreshes, enhancing process stability and device quality by ensuring alignment structures remain visible and detectable even under epitaxial layers.
Implementation Method 1
An epitaxial layer is deposited on the surface of the semiconductor base substrate... the specific crystallographic direction provides for a slower epitaxial growth rate on such a groove-patterned base substrate surface area compared to the epitaxial growth on a surface of the semiconductor base substrate adjacent to the area
Data Source
AI summary
A semiconductor substrate includes a semiconductor base substrate. An alignment structure is formed on a surface of the semiconductor base substrate. An epitaxial layer is deposited on the surface of the semiconductor base substrate. The alignment structure includes an area of the surface of the semiconductor base substrate that is formed as a groove pattern. Grooves of the groove pattern are aligned with a specific crystallographic direction of the semiconductor base substrate. The specific crystallographic direction provides for a slower epitaxial growth rate on such a groove-patterned base substrate surface area compared to epitaxial growth on a surface of the semiconductor base substrate adjacent to the groove-patterned area.