The invention discloses a preparation method of a 6LiF conversion film used for a 4H-SiC-based
semiconductor neutron detector. The preparation method mainly includes the following steps: a single-
crystal 4H-SiC matrix is respectively immersed in
acetone and absolute ethyl
alcohol for ultrasonic cleaning; impurities in the single-
crystal 4H-SiC matrix are removed by using of the method of unsymmetrical pressure anti-sputter-cleaning, and impurities of 6LiF target material are removed by using of the method of pre-sputter-cleaning; the 6LiF target material is used as a magnetic-control target, and a 6LiF
coating is deposited on the single-
crystal 4H-SiC matrix in a sputtered mode;
argon is used as luminance build-up gas for the
sputtering cleaning and the
sputtering deposition; and the
sputtering deposition is controlled by
magnetism so that the thickness of the 6LiF
coating can reach a designed thickness, the vacuum degree in a reaction magnetron sputtering coated
vacuum furnace is adjusted to not less than 10<-3>Pa, the 6LiF
coating is discharged from the furnace after natural cooling, and then the 6LiF coating conversion film deposited on the 4H-SiC matrix is obtained. The obtained 4H-SiC / 6LiF conversion film has the advantages of being small in size, high in detection efficiency,
irradiation-damage-resisting, heat-resisting, strong in n / gamma screening capacity and the like, preparation technology is simple in operation, and the thickness of the 6LiF conversion film can be controlled.