Semiconductor Substrate Defect Removal via Masked Etching
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Solution Overview
Problem
The development of high-quality single crystalline forms of semiconductive materials like gallium nitride (GaN) is hindered by the presence of extended defects such as threading dislocations, stacking faults, and antiphase boundaries, which reduce the performance and operational lifetime of light-emitting diodes and other semiconductor devices.
Innovation Solution
A method involving the formation of a base layer of Group 13-15 material on a growth substrate, followed by the creation of a mask with gap regions, and subsequent preferential removal of the base layer using an etching process to reduce dislocation density, all conducted within a single growth chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If epitaxial growth process is used to form bulk GaN crystals, then crystal formation is achieved, but extended defects such as threading dislocations are generated
Solution Approach 1:
The patent segments the base layer into multiple regions by forming a mask with openings at specific positions. This segmentation allows different areas of the base layer to undergo different processing - regions under mask openings have defects removed while regions under mask portions retain their structure, thereby reducing overall defect density while maintaining crystal formation.
Solution Approach 2:
The patent extracts harmful extended defects (threading dislocations) from the base layer by selectively removing material at defect locations through the mask openings. This extraction process eliminates the harmful elements while preserving the beneficial crystal structure in other regions.
2Reliability
If mask and etching process are added to reduce dislocation density, then defect removal is achieved, but process complexity increases
Solution Approach 1:
The patent merges multiple process steps into a single integrated sequence within the growth chamber. The mask formation and etching processes are combined and performed consecutively without removing the substrate from the growth chamber, thereby reducing overall process complexity despite adding functional steps for defect removal.
Solution Approach 2:
The mask serves as an intermediary element that enables selective defect removal. By introducing this intermediate component, the patent achieves precise control over which regions undergo etching, allowing complex defect removal patterns to be implemented through a relatively simple mask formation and etching sequence.
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 semiconductor substrate with significantly lower dislocation density, enhancing the light-emitting efficiency and operational stability of devices by removing high-defect regions during the epitaxial growth process.
Implementation Method 1
preferentially removing a portion of the base layer underlying the mask
Implementation Method 2
forming a base layer of a Group 13-15 material on a growth substrate during a growth process
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A method of forming a semiconductor substrate including forming a base layer of a Group 13-15 material on a growth substrate during a growth process, forming a mask having mask regions and gap regions overlying the base layer during the growth process, and preferentially removing a portion of the base layer underlying the mask during the growth process.