Semiconductor Cap Layer Sublimation for Precise Barrier Openings
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in achieving precise and selective removal of materials, particularly in forming smaller devices with high precision, as conventional etching methods lack the necessary selectivity and accuracy, especially when dealing with thin barrier layers and thicker cap layers.
Innovation Solution
The method employs sublimation to selectively remove the cap layer down to the barrier layer with high precision, utilizing the difference in sublimation temperatures between materials like gallium nitride and aluminum nitride, allowing for the formation of precise openings and features in semiconductor structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to remove the cap layer, then the etching process can proceed, but the selectivity and precision are insufficient, causing damage to the underlying barrier layer
Solution Approach 1:
The patent changes the physical parameter of material removal from chemical etching to thermal sublimation. By controlling temperature and pressure parameters, the cap layer is selectively sublimed without damaging the barrier layer, achieving both high precision and reliability
Solution Approach 2:
The patent utilizes the phase transition of the cap layer material from solid to gas through sublimation. This phase change enables selective removal of the cap layer at controlled temperatures that do not affect the barrier layer, solving the precision and reliability contradiction
2Productivity
If the barrier layer is made thinner to improve device performance, then device performance improves, but the selectivity of material removal becomes more difficult to achieve
Solution Approach 1:
By utilizing the phase transition temperature difference between cap layer and barrier layer materials, the patent achieves selective cap layer removal even when the barrier layer is very thin. The sublimation process naturally stops at the barrier layer interface, providing inherent selectivity
Solution Approach 2:
The patent changes the material removal mechanism to thermal sublimation with controlled temperature and pressure parameters. This enables selective removal of the cap layer down to thin barrier layers without chemical damage, maintaining both device performance 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
This approach enables the creation of semiconductor devices with higher precision and selectivity, facilitating the use of thinner barrier layers and thicker cap layers, improving device performance and miniaturization without damaging the underlying barrier layers.
Implementation Method 1
The material properties of the cap layer, as compared to the barrier layer, can be relied upon to form the opening in the cap layer down to the top surface of the barrier layer using sublimation
Data Source
AI summary
Semiconductor structures and methods of fabricating semiconductor structures using sublimation are described. An example method includes forming an opening through a mask layer over a wafer. The wafer includes a substrate, a channel layer over the substrate, a barrier layer over the channel layer, and a cap layer over the barrier layer. The method also includes subliming away a region of the cap layer, within the opening in the mask layer, to form an opening in the cap layer down to a top surface of the barrier layer. The material properties of the cap layer, as compared to the barrier layer, can be relied upon to form the opening in the cap layer down to the top surface of the barrier layer using sublimation, with high selectivity. Sublimation will stop with higher precision and selectivity at the interface between the cap layer and the barrier layer, as compared to etching.