Porous Semiconductor Substrate for Low-Loss Epitaxial Lift-Off
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Solution Overview
Problem
Current semiconductor manufacturing methods lack efficiency in providing semiconductor wafers economically, particularly in forming high-quality epitaxial layers with controlled porosity for reduced material loss and improved crystal quality.
Innovation Solution
A method involving a semiconductor substrate with a base portion, an auxiliary layer, and a surface layer, where the auxiliary layer has a higher electrochemical dissolution efficiency than the surface layer, allowing for the formation of a porous structure through anodic dissolution, resulting in a coarse-porous and fine-porous layered portion, facilitating epitaxial growth and efficient separation of the epitaxial layer from the base portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form epitaxial layers on semiconductor substrates, then crystal quality can be achieved, but material loss increases and production cost rises
Solution Approach 1:
The patent applies porous silicon layer formation through anodic dissolution to create a porous intermediate layer between the epitaxial silicon layer and the solidification substrate. This porous structure allows for controlled material transformation and reduces waste by enabling selective dissolution and reuse of the substrate, while maintaining high crystal quality in the epitaxial layer.
Solution Approach 2:
The patent changes the physical and chemical parameters of the substrate by converting it into a porous structure through controlled anodic dissolution. This parameter change enables the substrate to be selectively removed or modified without damaging the epitaxial layer, reducing material loss and allowing substrate reuse while preserving crystal quality.
2Productivity
If conventional epitaxial growth methods are used, then semiconductor wafers can be produced, but production efficiency decreases and economic viability is reduced
Solution Approach 1:
The patent performs preliminary anodic dissolution of the substrate to create a porous structure before completing the epitaxial growth process. This preliminary action facilitates easier separation of the epitaxial layer from the substrate, reduces processing time, and improves production efficiency while maintaining economic viability through reduced material waste and potential substrate reuse.
Solution Approach 2:
The patent replaces mechanical separation methods with electrochemical dissolution to separate the epitaxial layer from the substrate. This substitution enables more precise and efficient separation, reduces mechanical stress on the brittle semiconductor materials, and improves production efficiency while maintaining economic feasibility.
3Device complexity
If the substrate is directly used for epitaxial growth without porous structure, then process simplicity is maintained, but separation of epitaxial layer becomes difficult and material loss increases
Solution Approach 1:
The patent introduces a porous intermediate layer formed by anodic dissolution of the substrate. This porous structure serves as a controlled interface that facilitates easy separation of the epitaxial layer while minimizing material loss. The porous structure acts as a natural separation plane that reduces the need for complex mechanical separation processes.
Solution Approach 2:
The patent introduces a porous silicon layer as an intermediary between the epitaxial silicon layer and the solidification substrate. This intermediary layer facilitates controlled separation, reduces direct contact and potential damage between the epitaxial layer and substrate, and minimizes material loss during the separation process while maintaining overall process simplicity.
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 cost-effective production of semiconductor devices with high crystal quality epitaxial layers, reduces material loss, and allows for reliable separation of the epitaxial layer, improving the economic viability of semiconductor wafer production.
Implementation Method 1
The auxiliary layer has a higher electrochemical dissolution efficiency than the surface layer, allowing for the formation of a porous structure through anodic dissolution
Implementation Method 2
After converting at least the portion of the auxiliary layer and at least the portion of the surface layer into the porous structure, an epitaxial layer is formed on the first main surface
Data Source
AI summary
A semiconductor substrate includes a base portion, an auxiliary layer and a surface layer. The auxiliary layer is formed on the base portion. The surface layer is formed on the auxiliary layer. The surface layer is in contact with a first main surface of the semiconductor substrate. The auxiliary layer has a different electrochemical dissolution efficiency than the base portion and the surface layer. At least a portion of the auxiliary layer and at least a portion of the surface layer are converted into a porous structure. Subsequently, an epitaxial layer is formed on the first main surface.