Silicon Substrate Gradient Doping for Nitride Semiconductor Warpage

The patent applies local quality by creating a substrate with non-uniform impurity distribution, specifically a gradient structure where the impurity concentration varies through the thickness of the substrate. The first region (near the nitride layer) has lower impurity concentration (1×10^16 to 1×10^18 atoms/cm³) to ensure good crystallinity, while the second region (deeper in the substrate) has higher impurity concentration (1×10^19 to 1×10^20 atoms/cm³) to provide mechanical strength and reduce warpage. This spatial differentiation of impurity concentration allows simultaneous optimization of both crystallinity and substrate strength.

The patent applies parameter changes by modifying the impurity concentration parameter within the substrate to achieve the desired mechanical properties. Instead of increasing substrate thickness (which would cause fabrication difficulties), the invention changes the chemical composition parameter (impurity concentration) to enhance substrate strength and reduce warpage. The specific impurity concentration range (1×10^19 to 1×10^20 atoms/cm³ in the second region) provides sufficient mechanical support while maintaining standard substrate thickness and avoiding fabrication challenges.

The patent applies local quality by creating a gradient impurity distribution where different regions of the substrate have different impurity concentrations tailored to their specific functions. The first region near the nitride semiconductor layer has lower impurity concentration to ensure excellent crystallinity and interface quality, while the second region deeper in the substrate has higher impurity concentration to provide mechanical strength and control warpage. This localized optimization of impurity concentration achieves superior warpage control and crystallinity simultaneously, avoiding the high costs and insufficient results of uniform oxygen concentration control methods.