Porous Silicon Separation Layer for Precise Dopant Control
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Solution Overview
Problem
Current methods for forming semiconductor devices face challenges in achieving accurate dopant distribution and control, particularly in the separation of semiconductor devices from substrates, where the existing separation layers do not allow for precise control of dopant diffusion and substrate reuse.
Innovation Solution
A method involving the formation of a first semiconductor layer with a higher dopant concentration than the substrate, increasing its porosity, and annealing at 1050°C or higher, followed by the formation and separation of a second semiconductor layer within the first layer, which reduces dopant diffusion and enables precise dopant distribution and substrate reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a porous Si separation layer is formed on the substrate surface, then the separation of semiconductor devices from substrate is enabled, but the control of dopant diffusion and thickness precision deteriorates
Solution Approach 1:
The invention divides the semiconductor structure into multiple layers: a substrate, a porous Si separation layer, and an active Si layer grown on top. This segmentation allows the porous layer to serve as a dedicated separation interface while the active Si layer provides the functional semiconductor region with controlled dopant distribution, resolving the contradiction between separation capability and dopant control precision.
Solution Approach 2:
The invention applies different material properties to different regions: the porous Si layer provides high porosity for separation and dopant trapping, while the active Si layer provides controlled crystalline structure for precise dopant distribution. Each layer is optimized locally for its specific function, enabling both easy separation and precise dopant control.
2Strength
If the dopant concentration in the first semiconductor layer is high, then the separation strength is improved, but the dopant diffusion into the second semiconductor layer increases
Solution Approach 1:
The porous Si layer acts as an intermediary between the substrate and the active Si layer. It provides mechanical strength for separation while its porous structure traps dopants, preventing them from diffusing into the active Si layer. This mediator layer resolves the contradiction by decoupling the strength function from the dopant source function.
Solution Approach 2:
The invention utilizes the porous Si layer's unique properties: high porosity for dopant trapping and mechanical interlocking for separation strength. The porous structure provides a large surface area for dopant absorption while maintaining structural integrity, enabling strong separation without harmful dopant diffusion into the active layer.
3Quantity of substance
If the porosity of the first semiconductor layer is increased, then the dopant concentration is reduced to 5×10^16 cm^-3 or less, but the structural stability deteriorates
Solution Approach 1:
The invention changes the porosity parameter of the Si layer to control dopant concentration. By increasing porosity, the effective dopant concentration is reduced to 5×10^16 cm^-3 or less, while the layer thickness and substrate support provide the necessary structural stability, resolving the contradiction between dopant reduction and stability maintenance.
4Manufacturing precision
If annealing is performed at high temperature (≥1050°C), then the dopant distribution is improved, but the energy consumption and process complexity increase
Solution Approach 1:
The porous Si layer is formed beforehand to create a dopant-trapping structure before dopant introduction. This preliminary action allows subsequent low-temperature processing to achieve precise dopant distribution without requiring high-energy annealing, resolving the contradiction between dopant precision and energy consumption.
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 improves dopant distribution and reduces dopant diffusion into the second semiconductor layer, allowing for more precise control and efficient reuse of semiconductor substrates, thereby enhancing the reproducibility and quality of semiconductor device formation.
Implementation Method 1
first annealing the first semiconductor layer at a temperature of at least 1050° C.
Implementation Method 2
increasing the porosity of the first semiconductor layer
Data Source
AI summary
A method of forming a semiconductor device, including forming a first semiconductor layer on a semiconductor substrate, the first semiconductor layer being of the same dopant type as the semiconductor substrate, the first semiconductor layer having a higher dopant concentration than the semiconductor substrate, increasing the porosity of the first semiconductor layer, first annealing the first semiconductor layer at a temperature of at least 1050° C., forming a second semiconductor layer on the first semiconductor layer and separating the second semiconductor layer from the semiconductor substrate by splitting within the first semiconductor layer.