The pursuit of ultra-small pixel pitch InGaAs detectors necessitates a meticulous approach to addressing challenges associated with crosstalk reduction and dark current minimization. By developing the fabrication process technology of micro-mesa InGaAs detector, a test structure featuring a micro-mesa InGaAs photosensitive chip with 10 μm and 5 μm pixel pitch was successfully prepared. Subsequently, a comprehensive investigation was conducted to analyze the impact of the micro-mesa structure on crosstalk and dark current characteristics of the InGaAs detector. The obtained results revealed the efficacy of the micro-mesa structure in effectively suppressing crosstalk between adjacent pixels when the isolation trench etches into the absorption layer. However, a noteworthy challenge emerged as the fabrication processes induced material damage, leading to a considerable increase in recombination current and Ohmic leakage current. This adverse effect, in turn, manifested as a dark current escalation by more than one order of magnitude. The significance of these findings offers a novel perspective for the manufacturing of ultra-small pixel pitch InGaAs focal plane detectors.