Semiconductor Substrate Backside Grooves for Warp Control
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Solution Overview
Problem
Semiconductor devices face challenges due to warping of the substrate, which affects the flatness required for photolithography processes, leading to deviations in focus points and degradation of electrical characteristics, particularly exacerbated by larger wafer diameters.
Innovation Solution
A semiconductor device with a semiconductor substrate featuring a plurality of concave portions on its surface, aligned perpendicular to the direction of warping, along with an impurity region and electrode formation, to minimize warping and improve substrate flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer diameter is increased to improve productivity, then the productivity is improved, but the substrate warping increases due to greater curvature influence
Solution Approach 1:
The back surface of the substrate is segmented into multiple regions by forming protrusions and/or recesses. This segmentation creates localized structural support that counteracts the overall warping tendency of the large-diameter substrate, allowing the substrate to maintain flatness despite the increased diameter.
Solution Approach 2:
Instead of uniformly modifying the entire substrate, the invention applies local modifications by forming protrusions and/or recesses at specific locations on the back surface. These localized structures are strategically positioned to counteract warping forces without affecting the overall substrate integrity or front surface quality.
2Shape
If the substrate flatness is improved by forming mesh-like convex portions and concave portions, then the substrate flatness is improved, but the manufacturing complexity increases
Solution Approach 1:
The complex warping compensation structure is segmented into discrete protrusions and/or recesses that can be independently formed and controlled. This segmentation simplifies the manufacturing process compared to forming continuous mesh-like structures, as each protrusion or recess can be created using standard photolithography and etching techniques.
Solution Approach 2:
Instead of adding complex structures to the front surface where device fabrication occurs, the invention inverts the approach by creating the warping compensation structures on the back surface of the substrate. This inversion simplifies the front surface processing while achieving the same flatness improvement goal.
3Manufacturing precision
If the substrate flatness is improved by forming protrusions and recesses, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The invention moves the complexity from the front surface (where precision device fabrication occurs) to the back surface of the substrate. By forming protrusions and/or recesses on the back surface, the front surface remains simple and suitable for high-precision photolithography, while the back surface absorbs the structural complexity needed for warping compensation.
Solution Approach 2:
The protrusions and/or recesses are formed with specific local qualities - particular heights, widths, and spacing - that are optimized to counteract warping. These locally tailored structures achieve precise flatness control without requiring complex modifications across the entire substrate or device structure.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having a first surface, a second surface facing the first surface, and an outline, and an impurity region located on a side of the first surface in the semiconductor substrate. The second surface has a plurality of concave portions, and each of the plurality of concave portions open toward a side opposite to the first surface and extend along a direction perpendicular to a direction in which the semiconductor substrate is susceptible to warping most.