Compound Semiconductor Substrate Interface Engineering
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Solution Overview
Problem
The challenge lies in reducing crystal dislocations and improving the quality of compound semiconductor layers grown on Si substrates, as existing methods face difficulties due to lattice constant and thermal expansion mismatches, leading to defects that affect the electrical and optical characteristics of devices like HEMTs and optical devices.
Innovation Solution
A method involving pre-irradiation with As on a hydrogen-terminated Si substrate before epitaxial growth, where As is uniformly distributed and a group III element is supplied, creating an island-like substance with higher As concentration at the interface, which absorbs strain and improves crystallinity, reducing dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If epitaxial growth is performed on a Si substrate to achieve larger diameter substrates, then substrate size and cost-effectiveness are improved, but crystal dislocation density increases due to lattice constant and thermal expansion mismatches
Solution Approach 1:
The patent applies preliminary action by performing pre-irradiation with As atoms onto the Si substrate surface before epitaxial growth of the compound semiconductor layer. This pre-treatment modifies the substrate surface to reduce lattice mismatch effects and suppress dislocation formation during subsequent growth, enabling larger substrate diameters while maintaining acceptable crystal quality
Solution Approach 2:
The patent introduces an intermediary layer or interface modification through As pre-irradiation that mediates between the Si substrate and the compound semiconductor layer. This intermediary treatment reduces the direct lattice mismatch interaction, allowing for reduced dislocation density in large-diameter substrates
2Ease of manufacture
If the substrate temperature is raised to remove SiO2 oxide before epitaxial growth, then oxide removal is achieved, but mass-productivity decreases due to inferior TAT (turnaround time)
Solution Approach 1:
The patent changes the parameter approach by using As pre-irradiation at controlled temperatures instead of high-temperature thermal treatment for oxide removal. This parameter change enables effective oxide removal while maintaining shorter processing times and better mass-productivity compared to conventional high-temperature methods
3Ease of manufacture
If chemical treatment with hydrofluoric acid is used to remove SiO2 oxide, then oxide removal is achieved and surface is hydrogen-terminated, but additional initial growth to control hydrogen release is required
Solution Approach 1:
The patent merges multiple functions into a single pre-irradiation step: As atom deposition simultaneously removes SiO2 oxide and creates the appropriate surface termination for epitaxial growth. This combined approach eliminates the need for separate chemical treatment and hydrogen management steps, reducing overall process complexity
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 results in a compound semiconductor substrate with reduced dislocation density, enhancing the quality of electronic and optical devices by improving the interface crystallinity and allowing for larger substrate sizes without yield limitations.
Implementation Method 1
pre-irradiation with As on a hydrogen-terminated Si substrate before epitaxial growth, where As is uniformly distributed
Implementation Method 2
epitaxial growth of a compound semiconductor on a group IV semiconductor substrate
Data Source
AI summary
A method for manufacturing the compound semiconductor substrate having a reduced dislocation density at an interface between a Si substrate. Contaminants, such as organic matter and metal, on a surface of a Si substrate are removed whereby a flat oxide film is formed. The oxide film on the surface is removed by using an aqueous hydrogen fluoride solution, whereby hydrogen termination treatment is performed. Immediately after being subjected to the hydrogen termination treatment the temperature of the Si substrate is raised in a vacuum apparatus. If the substrate temperature is raised without any operation, the termination hydrogen is released. Before the hydrogen is released, pre-irradiation with As is performed. Thus, an interface between the Si substrate and the compound semiconductor layer is prepared. Several minutes later, irradiation with Ga and As is performed. Thereby, the compound semiconductor is formed.