SiC Semiconductor Chip Asymmetric Geometry for Thermal Stress
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Solution Overview
Problem
Conventional packaging methods for SiC semiconductor devices result in cracks and electrode deformation due to the anisotropic mechanical properties of hexagonal semiconductor materials like SiC and GaN, leading to reduced reliability under temperature variations.
Innovation Solution
A semiconductor chip design with a hexagonal semiconductor layer having orthogonal sides with equal thermal deformation, an insulating film with isotropic mechanical properties, and a metal film, such as aluminum or copper, to minimize stress and cracking, and a method of manufacturing involving specific cutting directions to achieve balanced thermal deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packaging methods are used for SiC semiconductor devices, then manufacturing process is simple, but cracks and electrode deformation occur due to anisotropic mechanical properties
Solution Approach 1:
The patent applies asymmetry by designing the semiconductor chip with a rectangular shape where the length in the first direction differs from the length in the second direction. Specifically, the chip has dimensions of 3.7mm in the first direction and 2.9mm in the second direction, creating an asymmetric geometry that compensates for the anisotropic thermal expansion properties of the hexagonal semiconductor material. This asymmetric design ensures that thermal deformation is balanced in both directions despite the material's directional properties.
2Reliability
If hexagonal semiconductor materials like SiC are used, then breakdown voltage is high and loss is low, but thermal deformation is anisotropic causing stress and cracking
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the semiconductor chip to compensate for the anisotropic thermal expansion coefficients of the hexagonal semiconductor material. The chip is designed with specific dimensions (3.7mm × 2.9mm) and orientation relative to the crystal axes, where the length ratio and angular orientation are carefully selected to balance the thermal deformation in both principal directions. This parameter optimization ensures uniform thermal stress distribution while maintaining the high breakdown voltage and low loss characteristics of SiC materials.
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
The design reduces stress and cracking in semiconductor chips, enhancing their reliability by ensuring equal thermal deformation along different directions, thus improving the chip's performance under temperature variations.
Implementation Method 1
different in linear expansion coefficient, and an amount of thermal deformation in a direction in which the first side extends and an amount of thermal deformation in a direction in which the second side extends are substantially equal to each other
Data Source
AI summary
A semiconductor chip of the present invention is a semiconductor device that includes a hexagonal semiconductor layer having anisotropic mechanical properties. A semiconductor chip (21), when viewed from a direction perpendicular to the semiconductor chip (21), has a rectangular shape that has a first side (1A) and a second side (1B) orthogonal to the first side (1A). The amount of thermal deformation along a direction in which the first side (1A) extends and the amount of thermal deformation along a direction in which the second side (1B) extends are substantially equal to each other.