Silicon Carbide Chip Sidewall Geometry for Crack-Resistant Dicing
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Solution Overview
Problem
The dicing process in semiconductor manufacturing often results in unreliable semiconductor chips due to stress concentrations and cracking, particularly when silicon carbide chips are attached to lead frames using solder materials, which can lead to thermo-mechanical stress and chip destruction.
Innovation Solution
The silicon carbide chips are designed with a side face angle greater than 78° and a radius of curvature greater than 0.5 μm, and a method involving a multi-beam laser dicing process with controlled energy distribution and annealing to create a robust, rounded sidewall shape, reducing stress and intermetallic compound formation, and using a solder material like AuSn alloy for connection to a lead frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dicing process is used to separate silicon carbide chips, then manufacturing efficiency is maintained, but stress concentrations and cracking occur leading to chip destruction
Solution Approach 1:
The patent applies preliminary action by performing annealing treatment on the silicon carbide wafer before the dicing process. This pre-treatment modifies the material properties of the wafer, making it more resistant to stress concentrations during dicing. The annealing process creates a more favorable stress distribution state in advance, preventing cracking during subsequent chip separation without requiring complex dicing equipment or procedures.
Solution Approach 2:
The patent changes physical parameters of the silicon carbide wafer through controlled annealing at specific temperatures and durations. This parameter change modifies the material's mechanical properties, particularly its resistance to stress and cracking. By adjusting temperature, time, and atmospheric conditions during annealing, the wafer achieves optimal properties for dicing while maintaining manufacturing efficiency.
2Reliability
If solder material is used to connect silicon carbide chips to lead frames, then electrical connection is achieved, but thermo-mechanical stress causes intermetallic compound formation and chip destruction
Solution Approach 1:
The patent applies preliminary action by performing annealing treatment before soldering to pre-establish a favorable stress distribution state in the silicon carbide chip. This pre-treatment reduces the chip's susceptibility to thermo-mechanical stress during subsequent soldering and operation, preventing intermetallic compound formation and connection failures without requiring modified soldering processes.
Solution Approach 2:
The patent changes the thermal and mechanical parameters of the silicon carbide chip through controlled annealing. This parameter modification adjusts the material's response to subsequent thermal cycling and mechanical stress during soldering and operation, reducing intermetallic compound formation and improving connection reliability under thermo-mechanical conditions.
3Reliability
If sharp corners are present at the intersection of side face and second main surface, then manufacturing simplicity is maintained, but stress concentrations lead to chip cracking
Solution Approach 1:
The patent applies spheroidality by rounding the corners at the intersection of the side face and second main surface of the silicon carbide chip. Instead of sharp 90-degree angles, the corners are formed with a specified radius of curvature. This geometric modification eliminates stress concentration points that would otherwise lead to cracking during dicing and operation, while the rounding process can be integrated into existing manufacturing steps.
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 design and manufacturing method significantly reduces chip cracking and destruction by minimizing stress concentrations and evenly distributing the intermetallic compound, enhancing the robustness and reliability of the silicon carbide chips.
Implementation Method 1
performing an annealing process to increase a width of the dicing kerf
Data Source
AI summary
A silicon carbide chip includes a first main surface, a second main surface, and a side face. An angle α between the side face and a horizontal plane measured in the silicon carbide material is more than 78°, the angle α being measured in a region adjacent to the second main surface. Also described is a method for manufacturing the silicon carbide chip.