SiC Substrate Recess Alignment Mark for High-Temperature Annealing
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Solution Overview
Problem
The existing methods for manufacturing silicon carbide semiconductor devices face challenges with alignment marks made of SiO2 films, which cannot withstand high temperatures during activation annealing, preventing their reuse before and after annealing.
Innovation Solution
A method involving the formation of a recess in a silicon carbide substrate, which serves as a heat-resistant alignment mark, allowing its use before and after activation annealing, by partially etching the substrate and depositing a mask layer for impurity implantation and electrode patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an SiO2 film alignment mark is used, then the alignment mark can be formed easily by photolithography, but the alignment mark cannot withstand high temperature activation annealing (1500°C or more)
Solution Approach 1:
The invention extracts the alignment mark function from the SiO2 film layer and relocates it to the silicon carbide substrate by forming a recess. This separates the alignment mark from the temperature-sensitive SiO2 film, allowing the mark to withstand high-temperature activation annealing while maintaining ease of formation through photolithography processes.
Solution Approach 2:
The recess in the silicon carbide substrate serves as an intermediary structure that provides heat resistance during activation annealing. Unlike the SiO2 film that decomposes at high temperatures, the recess in the substrate maintains structural integrity, enabling the alignment function to persist through the annealing process.
2Productivity
If the alignment mark is made of SiO2 film, then it can be formed before activation annealing, but it cannot be used after activation annealing due to decomposition
Solution Approach 1:
The alignment mark function is extracted from the temporary SiO2 film and embedded into the permanent substrate structure as a recess. This allows the alignment mark to survive the activation annealing process and be reused in subsequent photolithography steps, improving productivity while maintaining reliability.
Solution Approach 2:
Instead of discarding the alignment mark after initial use, the invention creates a substrate-based recess that can be recovered and reused multiple times throughout the manufacturing process, including before and after activation annealing, eliminating the need to create new alignment marks.
3Manufacturing precision
If a new alignment mark is created after activation annealing, then accurate alignment can be maintained, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The recess in the silicon carbide substrate serves as a universal alignment mark that functions throughout the entire manufacturing process, including before and after activation annealing. This multi-functional approach eliminates the need for separate pre-annealing and post-annealing alignment marks, reducing process complexity while maintaining alignment accuracy.
Solution Approach 2:
The alignment mark (recess) is formed in advance in the substrate before any photolithography steps. This preliminary creation of the alignment mark ensures it is available for all subsequent alignment operations, including those after high-temperature annealing, without requiring additional mark creation 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 approach enables the same alignment mark to be used throughout the manufacturing process, ensuring heat resistance and accurate alignment during high-temperature annealing, thereby improving the manufacturing efficiency of silicon carbide semiconductor devices.
Implementation Method 1
The recess as an alignment mark is formed of the silicon carbide substrate. The recess thus has sufficient heat resistance at a temperature of the activation annealing as well.
Implementation Method 2
The silicon carbide substrate is annealed in order to activate the impurity
Implementation Method 3
A mask layer having a pattern is formed on the silicon carbide substrate by means of photolithography using the recess in the silicon carbide substrate as an alignment mark
Implementation Method 4
An impurity is implanted into the silicon carbide substrate using the mask layer
Data Source
AI summary
A recess is formed by partially etching a silicon carbide substrate. A mask layer is formed on the silicon carbide substrate by means of photolithography using the recess as an alignment mark. An impurity is implanted into the silicon carbide substrate using the mask layer. The silicon carbide substrate is annealed. After the annealing, a first electrode layer is deposited on the silicon carbide substrate. The first electrode layer is patterned by means of photolithography using the recess in the silicon carbide substrate as an alignment mark.