Microwave Annealing Semiconductor Structures Using Energy-Converting Layer
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Solution Overview
Problem
Conventional annealing technologies, such as rapid thermal annealing and laser annealing, result in localized temperature non-uniformity and uneven heating due to varying heat emissivity across different substrate regions and limited penetration of photons, leading to inefficient dopant activation in semiconductor devices.
Innovation Solution
A system comprising an energy-converting structure with a high loss tangent to enhance microwave radiation absorption, combined with a heat reflecting structure that reflects thermal radiation back to the semiconductor structure, allowing for volumetric heating and uniform temperature distribution, thereby increasing electric field density and activating dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rapid thermal annealing or laser annealing is used, then dopant activation can be achieved, but localized temperature non-uniformity and uneven heating occur due to varying heat emissivity and limited photon penetration
Solution Approach 1:
The patent replaces conventional thermal conduction-based heating (RTA) or surface-limited laser heating with microwave-based volumetric heating. Microwaves penetrate the substrate and heat the entire volume simultaneously through dielectric heating, eliminating the localized temperature non-uniformity inherent in conventional methods while achieving uniform dopant activation throughout the substrate thickness.
Solution Approach 2:
The patent changes the heating mechanism from thermal conduction (RTA) or optical absorption (laser) to electromagnetic wave dielectric heating. By utilizing microwave frequencies and optimizing the loss tangent of the substrate material, the patent achieves deeper penetration and more uniform energy distribution throughout the substrate, resolving the contradiction between temperature uniformity and activation efficiency.
2Use of energy by moving object
If microwave radiation is applied directly to the semiconductor substrate, then volumetric heating can be achieved, but the substrate may not absorb sufficient microwave radiation due to low loss tangent
Solution Approach 1:
The patent introduces an intermediary layer with high loss tangent between the microwave source and the semiconductor substrate. This intermediary layer absorbs microwave radiation efficiently and converts it to thermal energy, which then conducts heat to the substrate. This mediator enables effective energy transfer while maintaining uniform temperature distribution, as the heat is generated throughout the intermediary layer and conducted evenly to the substrate.
Solution Approach 2:
The patent employs composite material structures combining materials with different loss tangents. The intermediary layer is made of materials specifically selected for their high microwave absorption capability (high loss tangent), while the substrate maintains its semiconductor properties. This composite approach allows the system to absorb sufficient microwave energy while maintaining controlled temperature distribution.
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 achieves uniform and efficient dopant activation by increasing the semiconductor structure's absorption of microwave radiation, reducing localized temperature non-uniformity and ensuring deeper penetration of heat, leading to improved dopant activation and reduced diffusion.
Implementation Method 1
An energy-converting structure capable of increasing the semiconductor structure's absorption of microwave radiation is provided
Implementation Method 2
When microwave radiation is applied to a certain material (e.g., a dielectric material) which includes electric dipoles, the dipoles change their orientations in response to the changing electric fields of the microwave radiation and thus the material may absorb the microwave radiation to generate heat
Implementation Method 3
A heat reflecting structure is provided between the energy-converting structure and the semiconductor structure, the heat reflecting structure being capable of reflecting thermal radiation from the semiconductor structure
Implementation Method 4
Microwave radiation is applied to the energy-converting structure and the semiconductor structure to anneal the semiconductor structure for fabricating semiconductor devices
Implementation Method 5
to anneal the semiconductor structure for fabricating semiconductor devices
Data Source
AI summary
Systems and methods are provided for annealing a semiconductor structure. In one embodiment, the method includes providing an energy-converting structure proximate a semiconductor structure, the energy-converting structure comprising a material having a loss tangent larger than that of the semiconductor structure; providing a heat reflecting structure between the semiconductor structure and the energy-converting structure; and providing microwave radiation to the energy-converting structure and the semiconductor structure. The semiconductor structure may include at least one material selected from the group consisting of boron-doped silicon germanium, silicon phosphide, titanium, nickel, silicon nitride, silicon dioxide, silicon carbide, n-type doped silicon, and aluminum capped silicon carbide. The heat reflecting structure may include a material substantially transparent to microwave radiation and having substantial reflectivity with respect to infrared radiation.