SiC Doping via Pulsed Laser Source Film Irradiation
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Solution Overview
Problem
Wide band gap semiconductors like silicon carbide (SiC) have a small diffusion coefficient for impurity elements, making it difficult to dope them at high concentrations exceeding thermodynamic equilibrium concentrations, especially for applications in power semiconductor devices.
Innovation Solution
A method involving the deposition of a source film containing impurity elements on a semiconductor substrate, followed by irradiation with a light pulse of specific energy density and duration to dope impurity elements deeply into the substrate, exceeding the thermodynamic equilibrium concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal diffusion or conventional ion implantation is used to dope impurity elements into SiC substrate, then the doping process can be performed, but the doping concentration is limited to around 1×10^16 cm^-3 at depths of 50-100 nanometers due to the extremely small diffusion coefficient of impurity elements in SiC
Solution Approach 1:
The patent replaces conventional thermal diffusion and ion implantation methods with laser beam irradiation. The laser beam provides direct energy input to the SiC substrate surface, enabling impurity elements to be incorporated at concentrations exceeding 1×10^20 cm^-3 without relying on thermal diffusion processes that are limited by SiC's extremely small diffusion coefficient.
Solution Approach 2:
The patent changes the physical and chemical parameters of the doping process by using laser irradiation with specific wavelengths and intensities. This creates a non-equilibrium state that allows impurity elements to be doped at concentrations far exceeding the thermodynamic equilibrium concentration and the solid solubility limit of approximately 1×10^16 cm^-3.
2Quantity of substance
If high-dose ion implantation is performed to achieve high doping concentration, then the activation of impurity elements is promoted, but high-temperature annealing at 1600-1800°C is required which is complex and time-consuming
Solution Approach 1:
The patent substitutes the complex high-temperature annealing process with laser beam irradiation. The laser provides localized, high-intensity energy that activates impurity elements and facilitates doping without requiring prolonged exposure to extreme temperatures, thereby simplifying the overall manufacturing process.
Solution Approach 2:
The patent uses pulsed laser irradiation instead of continuous heating. The periodic nature of the laser pulses delivers energy in controlled bursts, enabling impurity activation and doping while avoiding the need for sustained high-temperature annealing at 1600-1800°C.
3Quantity of substance
If laser irradiation is used to dope impurity elements, then doping concentration can exceed thermodynamic equilibrium concentration, but the doping depth is limited to approximately 50-100 nanometers
Solution Approach 1:
The patent adjusts laser irradiation parameters including wavelength, intensity, and pulse duration to control the penetration depth and energy distribution. By optimizing these parameters, the method achieves both high doping concentrations exceeding 1×10^20 cm^-3 and increased doping depths beyond the conventional 50-100 nanometer limit.
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 method allows for high-concentration doping of impurity elements at depths of up to 50 nanometers or more, improving the electrical characteristics of semiconductor devices by enhancing the doping concentration beyond typical limits, thus overcoming the limitations of traditional doping techniques.
Implementation Method 1
irradiating the source film by the light pulse with the irradiation time and the energy density so as to dope the impurity elements into the target object at a concentration exceeding a thermodynamic equilibrium concentration
Data Source
AI summary
Impurity elements are doped at a high concentration exceeding a thermodynamic equilibrium concentration into a solid material having an extremely small diffusion coefficient of the impurity element. A method for doping impurities includes steps for depositing source film made of material containing impurity elements with a film thickness on a surface of a solid target object (semiconductor substrate) made from the solid material. The film thickness is determined in consideration of irradiation time per light pulse and the energy density of the light pulse. The method also includes a step for irradiating the source film by the light pulse with the irradiation time and the energy density so as to dope the impurity elements into the target object at a concentration exceeding a thermodynamic equilibrium concentration.