Factors Influencing Spatial Resolution in EBCMOS Devices Under Substrate Bulk Gradient Doping

Electron-bombarded complementary metal –oxide–semiconductor (EBCMOS) imaging is an advanced imaging technology that integrates electron beam bombardment with CMOS techniques. With the aim of enhancing the imaging quality of EBCMOS and attaining high-resolution low-light imaging devices, we here investigated the factors influencing the spatial resolution of EBCMOS under substrate bulk gradient doping in the electron-multiplication (EM) layer. We established a theoretical model to calculate the spatial resolution within the EM layer based on carrier transport and recombination theory combined with the Monte Carlo method. Simulations were then conducted to analyze the effects on spatial resolution of substrate thickness, bulk doping concentration, doping depth, and surface doping concentration under substrate bulk gradient doping. We demonstrated that the diffusion radius of multiplied electrons can be minimized by thinning the substrate, reducing the bulk doping concentration, and appropriately increasing the doping depth in a gradient-doped substrate structure, thereby improving the resolution of EBCMOS imaging devices. The spatial resolution reached a maximum value (51 lp/mm) at a surface doping concentration of$10^{{19}}$atom/cm3. Through optimization, we achieved a proposed gradient-doped substrate structure with a substrate thickness of$10~\boldsymbol {\mu} $m, bulk doping concentration of$10^{{19}}$atom/cm3, doping depth of$0.8~\mu $m, and surface doping concentration of$10^{{19}}$atom/cm3. This work provides a theoretical foundation to optimize the EM layer structure and enhance the spatial resolution of EBCMOS devices.