SiC Wafer Edge Trenches for Crack-Arresting Scribe Lines
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Solution Overview
Problem
Silicon carbide semiconductor wafers are prone to chipping and crack propagation during scribing and handling due to their hardness and brittleness, which can lead to deterioration in withstand voltage characteristics and circuit functionality.
Innovation Solution
Incorporating trenches with a filler material of different thermal expansion at the scribe lines, oriented in specific directions relative to the crystal axis, to arrest crack propagation by forming distortions and stress concentrations at the corners of the trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon carbide is used as semiconductor substrate material, then thermal conductivity and heat resistance are improved, but machinability deteriorates and chipping occurs during scribing
Solution Approach 1:
The patent applies preliminary action by forming trenches at scribe lines before the dicing process. These trenches are filled with materials having different coefficients of thermal expansion to create pre-positioned stress concentration points that will arrest cracks before they can propagate into the IC regions during subsequent scribing and dicing operations.
Solution Approach 2:
The patent uses an intermediary material filled in the trenches that has a different coefficient of thermal expansion from silicon carbide. This intermediary material creates distortions and stress concentrations at the trench corners, serving as a mediator to arrest crack propagation while allowing the silicon carbide substrate to maintain its high heat resistance properties.
2Loss of energy
If silicon carbide is used as semiconductor substrate material, then thermal conductivity is improved, but brittleness increases and crack propagation occurs during handling
Solution Approach 1:
The patent applies preliminary action by pre-forming trenches and filling them with appropriate materials before handling and dicing operations. This creates predetermined stress concentration points that will arrest cracks during handling, thereby improving crack resistance while preserving the high thermal conductivity of the silicon carbide substrate.
Solution Approach 2:
The patent applies local quality by creating localized modifications only at the scribe line regions through trench formation and filling. The bulk silicon carbide substrate maintains its excellent thermal conductivity properties, while the localized trench regions provide crack arrest functionality without compromising overall material performance.
3Manufacturing precision
If chipping occurs at outer periphery portions during scribing, then manufacturing precision deteriorates, but no solution is provided to prevent crack propagation to active regions
Solution Approach 1:
The patent applies preliminary action by forming trenches and filling them with materials of different thermal expansion coefficients before scribing. This creates pre-positioned crack arrest points at the scribe lines that prevent cracks from propagating into the IC regions, thereby protecting withstand voltage characteristics even when chipping occurs at the outer periphery during scribing.
Solution Approach 2:
The patent converts the potentially harmful effect of chipping at scribe lines into a beneficial outcome by using the trench structures to arrest crack propagation. The chipping that occurs during scribing is contained within the trench regions and cannot propagate into the active IC regions, thereby converting a manufacturing defect into a protected state.
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
Effectively restrains crack propagation during scribing and handling, reducing the likelihood of new cracks forming in divided semiconductor devices and maintaining the integrity of silicon carbide ICs.
Implementation Method 1
a plurality of trenches or portions of trenches formed at the periphery portion, an interior of each of the trenches being filled with a material with a different coefficient of thermal expansion from the silicon carbide
Data Source
AI summary
A semiconductor device, including: a semiconductor substrate formed of silicon carbide, components being formed at one surface of the semiconductor substrate; a periphery portion disposed at a pre-specified region of a periphery of the semiconductor substrate, the components not being formed at the periphery portion; and a plurality of trenches or portions of trenches formed at the periphery portion, an interior of each of the trenches being filled with a material with a different coefficient of thermal expansion from the silicon carbide.