Investigating Penetration Depth of Boron into P-Doped Silicon by Diffusion Process for P+NN+ SDR Impatt Structure at KA-Band

Penetration depth of boron in phosphorous-doped silicon for p⁺nn⁺ SDR type IMPATT structure is experimentally investigated by Secondary Ion Mass Spectrometry (SIMS) technique, and also validated using Scanning Electron Microscopy (SEM) instrument in this work. Spatial distribution of the impurity profile for the dopants and also of the constituent atoms is experimentally investigated to evaluate the near-accurate length of junction depth, which is well supported by the SEM measurement also. The measurement clearly gives a pictorial representation of the variation of atoms inside the device. Operating frequency of the device is directly dependent on junction depth, and hence its accurate evaluation carries significant role in designing the device. Two-step diffusion mechanism is considered for fabrication of the device, and impurity profile is numerically solved from Fick's law. Theoretical and experimental data have a very close resemblance which speaks about the accuracy of the investigation. Temperature and orientation dependence of diffusivity is also computed for near accurate estimation. Results are very important for design and fabrication of SDR IMPATT device for microwave performance.