Composite Nitride Film Structure for Dislocation Reduction
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Solution Overview
Problem
The existing methods for growing nitride semiconductor crystals on bulk substrates face challenges due to lattice mismatch, leading to high dislocation densities and increased production costs and complexity, particularly in the Epitaxial Lateral Overgrowth (ELO) method which requires multiple processing steps and expensive equipment.
Innovation Solution
A composite nitride-based film structure is formed using a bulk single crystal substrate with nitride microcrystals and an amorphous nitride thin film, created through a reactive sputtering method that generates plasma under controlled conditions, reducing dislocation density and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ELO method is used to grow nitride semiconductor crystals on bulk substrates, then dislocation density is reduced, but the number of processing steps and device complexity increase
Solution Approach 1:
The patent combines multiple functions into a single sputtering process: forming the underlayer, creating the mask pattern, and enabling lateral overgrowth all in one step. The amorphous nitride film serves both as an underlayer for crystal growth and as a mask material, eliminating the need for separate mask deposition and patterning steps required in traditional ELO methods
Solution Approach 2:
The amorphous nitride film formed by sputtering automatically serves as the mask material for lateral overgrowth. The film's inherent properties (amorphous structure, appropriate thickness) make it suitable for both supporting crystal growth and blocking vertical growth in masked regions, without requiring additional mask materials or complex patterning processes
2Ease of operation
If traditional ELO method with amorphous mask materials is used, then lateral growth is achieved, but adsorption of raw material molecules becomes unreliable
Solution Approach 1:
The patent changes the formation parameters of the amorphous nitride film through controlled sputtering conditions (gas composition with 30% or more nitrogen, pressure 0.1-0.5 Pa, substrate temperature 25-1000°C, pulse duty ratio 0.1-30%). These parameter changes optimize the film's surface properties for reliable raw material molecule adsorption while maintaining its amorphous structure for effective masking
3Productivity
If reactive sputtering method is used to form composite nitride-based film structure, then production time and cost are reduced, but control of film structure and orientation becomes more challenging
Solution Approach 1:
The patent employs specific sputtering parameters including nitrogen content (30% or more), pressure (0.1-0.5 Pa), substrate temperature (25-1000°C), and pulse duty ratio (0.1-30%) to precisely control the formation of the composite film structure. These parameter changes enable reproducible formation of the specific structure containing amorphous nitride film and nitride microcrystals with desired orientation
Solution Approach 2:
The patent creates a composite film structure consisting of amorphous nitride film and nitride microcrystals with specific orientation relationships. This composite structure combines the benefits of amorphous materials (easy formation, good coverage) with crystalline materials (defined orientation, reliable adsorption sites), achieving both productivity and 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 achieves a nitride crystal quality comparable to ELO without the need for extensive processing steps, reducing production costs and time, while maintaining a flat and uniform surface with controlled microcrystal spacing and orientation.
Implementation Method 1
applying a power pulse of which a proportion of time applying power at a frequency of 1 kHz to 100 kHz is 0.1% to 30%, under a pressure of 0.1 Pa to 0.5 Pa and at a temperature of the bulk single crystal substrate of 25° C. to 1000° C., to generate a plasma
Implementation Method 2
forming a plurality of nitride microcrystals and an amorphous nitride thin film surrounding the plurality of nitride microcrystals and covering the entire surface of the bulk single crystal substrate, on the bulk single crystal substrate by a reactive sputtering method
Data Source
AI summary
A composite nitride-based film structure includes a bulk single crystal, a plurality of nitride microcrystals, and an amorphous nitride thin film. The plurality of nitride microcrystals is provided on the bulk single crystal, and has a specific orientation relationship with a crystal structure of the bulk single crystal. The nitride thin film is provided on the bulk single crystal, surrounds the nitride microcrystal, and covers a surface of the bulk single crystal.