Heterogeneous Buffer Layer for Semiconductor Dislocation and Cracking
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Solution Overview
Problem
The existing semiconductor manufacturing process faces challenges with high-density dislocation and cracking due to lattice mismatch between stacked layers, particularly between the substrate and the AlGaN layer, which silicon nitride masks fail to adequately address, requiring a more effective method to reduce dislocation and prevent cracking.
Innovation Solution
A semiconductor structure incorporating a buffer layer with a heterogeneous material structure, comprising a first and second buffer structure with different materials, where the second buffer structure has a greater thickness and is partially disposed on the first, effectively reducing dislocation and uniformizing stress to prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon nitride mask buffer layer is used to reduce dislocation, then dislocation density is reduced, but the epitaxial layer requires lateral growth to a certain thickness and stress changes cause cracking
Solution Approach 1:
The buffer layer is segmented into multiple sub-layers with different materials (e.g., AlN, GaN, AlGaN) and different thicknesses. Each sub-layer has a specific function: the first buffer layer (thinner) reduces dislocation density, while the second buffer layer (thicker) compensates for stress and prevents cracking. This segmentation allows independent optimization of dislocation reduction and stress management.
Solution Approach 2:
The patent changes the material composition and thickness parameters of the buffer layer. By using heterogeneous materials with different lattice constants and elastic properties, and by optimizing the thickness of each sub-layer, the buffer layer can simultaneously reduce dislocation density and manage stress to prevent cracking during epitaxial growth and cooling.
2Manufacturing precision
If lateral growth of epitaxial layer is performed to reduce dislocation, then dislocation density is reduced, but stress changes during cooling cause cracking
Solution Approach 1:
The buffer layer is designed beforehand to compensate for the stress that will occur during cooling. The thicker second buffer layer acts as a cushion that absorbs and distributes the thermal stress generated when the epitaxial layer cools down, preventing cracking while allowing the necessary lateral growth for dislocation reduction.
3Device complexity
If a single-material buffer layer is used, then the structure is simple, but it cannot effectively reduce dislocation and prevent cracking simultaneously
Solution Approach 1:
The buffer layer uses composite materials with different properties (AlN, GaN, AlGaN) arranged in specific configurations. These composite materials provide complementary functions: some materials are better at reducing dislocation, while others are better at stress management. The combination achieves both goals simultaneously, though it increases structural complexity.
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate. The semiconductor structure also includes a buffer layer disposed on the substrate. The semiconductor structure further includes a first semiconductor layer disposed on the buffer layer. The buffer layer includes a first buffer structure and a second buffer structure partially disposed on the first buffer structure. The material of the first buffer structure is different from the material of the second buffer structure.