SiC Wafer Grooves for Bowing Reduction
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Solution Overview
Problem
Semiconductor devices with silicon carbide (SiC) films face challenges such as wafer bowing and crystal defect propagation during high-temperature thermal treatment, which affect the quality and yield of the elements, especially when using large-diameter wafers and requiring precise pattern formation.
Innovation Solution
The method involves forming grooves in the SiC film on the semiconductor wafer, with specific shapes and directions determined by the wafer's deformation condition and crystal-defect distribution to relieve stresses, reduce bowing, and separate high-quality regions from defect-concentrated areas, thereby preventing defect propagation during thermal treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a SiC epitaxial film is formed by CVD or sublimation method, then the film can be grown with desired properties, but crystal defects such as dislocation cannot be reduced sufficiently
Solution Approach 1:
The SiC substrate surface is divided into high-quality regions and crystal-defect concentrated regions by forming grooves. This segmentation isolates defects to specific areas, preventing them from degrading element characteristics in the high-quality regions where devices are formed.
Solution Approach 2:
Crystal-defect concentrated regions are extracted or removed from the high-quality regions by forming grooves that separate these areas. The defects are effectively taken out from the functional device regions, allowing high-performance elements to be formed only in the defect-free zones.
2Reliability
If thermal treatment at high temperatures is performed for dopant activation, then electrical properties are improved, but recrystallization spreads defects into high quality regions
Solution Approach 1:
By segmenting the substrate into defect-isolated regions through groove formation, the patent prevents defect propagation during thermal treatment. The grooves act as barriers that contain defects within specific regions while allowing dopant activation to proceed in the high-quality regions without contamination from spreading defects.
3Productivity
If a large-diameter semiconductor wafer is used, then production capacity increases, but bowing of the SiC substrate becomes serious
Solution Approach 1:
The large-diameter wafer is effectively segmented into functional regions by grooves that run across the substrate. This segmentation counteracts the bowing effect by creating discrete zones that can be processed independently, allowing large wafers to be used without the entire surface being affected by deformation.
Solution Approach 2:
The patent applies local quality by ensuring that high-quality element-forming regions are maintained despite overall wafer bowing. The grooves create localized zones of controlled quality, allowing devices to be formed in regions where the substrate geometry does not compromise pattern formation precision.
4Manufacturing precision
If a stepper is used for patterning with equal to or less than 1 μm precision, then fine patterns can be formed, but the SiC substrate with large bowing makes fine pattern formation difficult
Solution Approach 1:
The patent ensures that local regions of the substrate maintain sufficient flatness and quality for high-precision stepper patterning, even when the overall wafer exhibits bowing. The grooves define specific zones where the substrate geometry is controlled, allowing fine patterns to be formed with the required precision in these localized areas.
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 effectively reduces wafer bowing and maintains high-quality element formation by relieving stresses and isolating crystal-defect regions, enhancing the semiconductor device's performance and yield by minimizing defect expansion during thermal processes.
Implementation Method 1
A SiC single-crystal epitaxial film is grown with chemical vapor deposition (CVD) method, a sublimation method, or the like
Implementation Method 2
the thermal treatment at high temperatures of around 1,200 to 1,800 degrees C. is necessary for activation of dopants and the like
Implementation Method 3
Recrystallization can spread a defect into a high quality region with few defects
Implementation Method 4
Film growth with CVD method is carried out using SiH4, C3H8, and H2 at a temperature more than 1,500 degrees C. in a hot-wall CVD reactor
Implementation Method 5
SiC powder confined in a crucible is heated up to nearly 2,000 degrees C. to grow SiC on a substrate in the sublimation method
Data Source
AI summary
The principal objects of the present invention are to provide structure of a semiconductor device capable of reducing a bowing of a wafer, and a method for fabricating the semiconductor device. The present invention is applied to a semiconductor device, which is fabricated with a semiconductor substrate having a silicon carbide (SiC) film. The method includes the steps of: forming the SiC film on a semiconductor wafer; discriminating a deformation condition of the semiconductor wafer; and forming grooves in the SiC film, the grooves having a shape determined in accordance with the deformation condition of the semiconductor wafer.