GaN Single Crystal Growth Using Pattern Mask
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Solution Overview
Problem
Current methods for producing GaN single crystals, such as the ammonothermal method, face challenges in achieving high-quality crystals with low dislocation densities and large pit-free areas, which are essential for advanced semiconductor applications.
Innovation Solution
A GaN single crystal with a gallium polar surface and a nitrogen polar surface is produced using an ammonothermal method, where a pattern mask with linear openings is formed on the nitrogen polar surface, allowing GaN crystals to grow laterally and coalesce, resulting in a crystal with high pit-free areas and low dislocation densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ammonothermal method is used to grow GaN single crystals, then the crystals can be produced with controlled growth, but the resulting crystals have high dislocation densities and small pit-free areas
Solution Approach 1:
The invention divides the crystal growth process into segmented steps using a pattern mask with linear openings. The mask segments the growth area into multiple regions, allowing controlled lateral expansion of crystal nuclei. This segmentation enables the formation of large pit-free areas by preventing dislocation propagation across the entire surface, thereby resolving the contradiction between manufacturing precision and reliability.
Solution Approach 2:
The pattern mask is formed on the seed crystal surface before the actual crystal growth occurs. This preliminary action defines the growth pattern and prevents dislocation formation in advance. By establishing the linear opening pattern beforehand, the invention ensures that subsequent crystal growth will occur in controlled regions, achieving both low dislocation density and large pit-free areas.
2Manufacturing precision
If conventional crystal growth methods are used, then the growth process is simpler, but the crystal quality with respect to dislocation density and pit-free area is insufficient
Solution Approach 1:
The pattern mask serves as an intermediary element between the seed crystal and the growing GaN layer. This intermediary structure controls the growth process by providing a template with linear openings, enabling high crystal quality without requiring complex growth conditions. The mask mediates the interaction between the ammonia solution and the crystal surface, achieving improved crystal quality while maintaining relatively simple growth procedures.
3Manufacturing precision
If linear openings are formed in a pattern mask for crystal growth, then large pit-free areas are achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The invention utilizes parameter changes in the ammonia solution (temperature, pressure, concentration) to control crystal growth through the linear openings of the pattern mask. By adjusting these parameters, the process achieves large pit-free areas without requiring excessively complex manufacturing steps. The parameter optimization allows the pattern mask method to be practically implementable while maintaining high manufacturing precision.
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
The method produces GaN single crystals with improved quality, characterized by high pit-free areas and low dislocation densities, enabling enhanced semiconductor device performance.
Implementation Method 1
GaN dissolved in ammonia in a supercritical or subcritical state is precipitated as a single crystal on a seed
Implementation Method 2
GaN dissolved in ammonia in a supercritical or subcritical state is precipitated as a single crystal on a seed
Implementation Method 3
GaN dissolved in ammonia in a supercritical or subcritical state is precipitated as a single crystal on a seed
Data Source
AI summary
A GaN single crystal having a gallium polar surface which is a main surface on one side and a nitrogen polar surface which is a main surface on the opposite side, wherein on the gallium polar surface is found at least one square area, an outer periphery of which is constituted by four sides of 2 mm or more in length, and, when the at least one square area is divided into a plurality of sub-areas each of which is a 100 μm×100 μm square, pit-free areas account for 80% or more of the plurality of sub-areas.