This paper proposed a biochip that uses the aluminum oxide (Al 2 O 3 ) thin film passivation on the photoconductive layer surface. The Al 2 O 3 thin film was deposited by a high frequency (40.68 MHz) plasma-enhanced atomic layer deposition (VHF-PEALD) system to improve the photoconductive layer performance of the biochip. The proposed Al 2 O 3 thin film was measured and investigated by UV-visible spectroscopy (UV-Vis), atomic force microscope (AFM), transmission electron microscope (TEM), and I-V curve. An Al 2 O 3 thin film was deposited on the surface of the photoconductive layer to provide a smooth surface. Using a proposed 14 nm Al 2 O 3 thin film passivation on the 550 nm, the photoconductive layer effectively reduces the surface roughness from 8.47 to 6.87 nm. The biochip with Al 2 O 3 thin film passivation on photoconductive layer has better performance than conventional biochip. The maximum manipulation velocity of particles increased by 35%, and the screening efficiency was up to 80%. This method provides high-efficiency light-induced dielectrophoresis biochips.