Abstract: MIS device have been made making use of the insulating characteristics ofthe L-B film Studying the MIS structure and capancitance-voltage (C-U) curve, it is found that L-B film can improve the function and eliminate the abnormal phenomena of the C-U characteristic curve of the MOS device. Being a probe, the C-U characteristic Curve of the L-B film can be ed as a tool tO verify the quality of the L-B film deposition.Making use of the Value of the capacitance atzerobias, the dielectric constant of L-Bfilm materials can be calculated.