AlN Barrier Layer Crystal Quality for GaN-on-Si Substrate Warp Control
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Solution Overview
Problem
The existing methods for growing GaN-based semiconductor layers on silicon substrates fail to adequately reduce substrate warp, despite the use of AlGaN layers as barrier layers, due to poor crystal quality of the AlN layer, leading to significant substrate warping and potential cracking.
Innovation Solution
A semiconductor substrate is developed with an AlN layer of improved crystal quality, as indicated by a Full Width at Half Maximum (FWMH) of the rocking curve of the (002) plane less than or equal to 1500 seconds, which allows for the formation of a GaN-based semiconductor layer that compensates for stress through the use of an AlGaN layer, reducing substrate warp by achieving sufficient compressive stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an AlGaN layer is provided on the AlN layer to reduce substrate warp, then the crystal quality of the GaN layer is improved, but the substrate warp is not sufficiently reduced
Solution Approach 1:
The invention changes the critical parameter of AlN layer crystal quality by specifying that the FWMH of the rocking curve of the (002) plane must be 1500 seconds or less. This parameter control ensures sufficient compressive stress in the AlN layer to counterbalance the tensile stress from the GaN layer, thereby reducing substrate warp while maintaining high crystal quality of the GaN layer.
Solution Approach 2:
The AlN layer serves as an intermediary barrier layer between the Si substrate and the GaN-based semiconductor layer. By controlling its crystal quality (FWMH ≤ 1500 seconds), it mediates the stress relationship between the Si substrate and GaN layer, providing sufficient compressive stress to reduce substrate warp while preventing direct reaction between Si and Ga.
2Reliability
If an AlN layer is interposed between the Si substrate and the GaN-based semiconductor layer as a barrier layer, then the reaction between Si and Ga is prevented, but the substrate warp is not reduced
Solution Approach 1:
The invention changes the parameter of AlN layer crystal quality (FWMH of rocking curve ≤ 1500 seconds) to ensure the layer has sufficient compressive stress. This parameter control allows the AlN barrier layer to simultaneously prevent Si-Ga reaction and reduce substrate warp by counterbalancing the tensile stress from the GaN layer.
3Adaptability or versatility
If a GaN-based semiconductor layer is formed on a Si substrate with AlN barrier layer, then high-frequency and high-power semiconductor devices can be realized, but significant substrate warping and potential cracking occur
Solution Approach 1:
The invention changes the parameter of AlN layer crystal quality (FWMH ≤ 1500 seconds) to ensure sufficient compressive stress that counterbalances the tensile stress from the GaN-based semiconductor layer. This prevents substrate warping and cracking, maintaining substrate integrity while enabling high-frequency and high-power device functionality.
Solution Approach 2:
The high-quality AlN layer acts as an intermediary that not only prevents Si-Ga reaction but also provides sufficient compressive stress to counterbalance the tensile stress from the GaN-based semiconductor layer, thereby preventing substrate cracking and maintaining structural integrity for high-power applications.
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 approach effectively reduces substrate warp to a practical level, ensuring the semiconductor substrate's usability and preventing cracking, with a warp magnitude of less than ±50 μm and a radius of curvature greater than ±25 m, thereby enhancing the reliability of semiconductor devices.
Implementation Method 1
the AlN layer has a sufficient compressive stress, and thus a warp of a substrate can be reduced by providing the AlGaN layer on the AlN layer
Implementation Method 2
As Si and Ga react easily, an AlN layer is interposed between the Si substrate and the GaN-based semiconductor layer as a barrier layer
Data Source
AI summary
A semiconductor substrate includes an AlN layer that is formed so as to contact a Si substrate and has an FWMH of a rocking curve of a (002) plane by x-ray diffraction, the FWMH being less than or equal to 1500 seconds, and a GaN-based semiconductor layer formed on the AlN layer.