AlN/GaN Seed Layer Oxidation for Metal-Polarity Control
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Solution Overview
Problem
Conventional semiconductor structures, particularly those using physical vapor deposition for metal nitride seed layers, face challenges with mixed polarity gallium nitride material formation, leading to dislocations and reduced device efficiency due to poor crystal orientation and high dislocation density, which existing technologies have been unable to consistently address.
Innovation Solution
The formation of an oxygen-rich layer over a physical vapor deposition seed layer, exposed to an oxygen-rich environment, creates a predominantly metal-polar growth condition, minimizing dislocations and enabling the growth of highly ordered gallium-containing material layers with reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical vapor deposition is used to form metal nitride seed layers, then the deposition process is simple and fast, but the resulting gallium nitride material exhibits mixed polarity with high dislocation density and poor crystal orientation
Solution Approach 1:
An oxygen-rich layer is formed on the substrate surface before depositing the metal nitride seed layer. This preliminary oxidation treatment modifies the substrate surface properties, creating favorable conditions for subsequent epitaxial growth that promotes single-polarity crystal orientation and reduces dislocation density, thereby resolving the contradiction between fast deposition and high crystal quality
Solution Approach 2:
The chemical composition and surface properties of the substrate are changed by introducing an oxygen-rich layer. This parameter change in the substrate surface chemistry alters the nucleation and growth behavior of the gallium nitride material, enabling control over crystal polarity and orientation while maintaining the simplicity and speed of the physical vapor deposition process
2Device complexity
If physical vapor deposition is used to form metal nitride seed layers, then the process complexity is reduced, but dislocation density increases leading to reduced device efficiency
Solution Approach 1:
The oxygen-rich layer is formed as a preliminary step before seed layer deposition. This pre-treatment modifies the substrate surface to promote better crystal growth, reducing dislocation density and improving device reliability without adding significant complexity to the overall fabrication process
Solution Approach 2:
The oxygen-rich layer acts as an intermediary between the substrate and the metal nitride seed layer. It mediates the interaction between the substrate and the growing crystal, controlling nucleation and growth to produce high-quality, low-dislocation gallium nitride material while keeping the process relatively simple
3Ease of manufacture
If no oxygen-rich layer is formed, then the fabrication process is simpler, but mixed polarity formation occurs causing poor crystal orientation
Solution Approach 1:
Forming the oxygen-rich layer as a preliminary step creates the right surface conditions for single-polarity crystal growth. This simple pre-treatment ensures consistent crystal orientation and polarity control, making the overall fabrication process more reliable and easier to manufacture high-quality devices
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 improved device quality and performance by reducing dislocation density and enhancing the crystalline structure of gallium nitride layers, allowing for the production of high-quality semiconductor structures with increased efficiency and reduced defects.
Implementation Method 1
exposing the seed layer to an oxygen rich environment having at least 23.5 vol. % oxygen based upon the volume of the environment
Implementation Method 2
forming a seed layer of a metal nitride material over a silicon substrate
Data Source
AI summary
The present technology includes semiconductor structures. Structures include a silicon-containing substrate, a layer of metal nitride overlying the silicon-containing substrate, a structure overlying the layer of the metal nitride, and an oxygen rich layer disposed between the layer of the metal nitride and the structure. The structure is formed from a material that includes a gallium-containing material, and aluminum nitride material, or a combination thereof, where at least about 90 wt. % of the material exhibits a metal-polarity.