Abstract: The resistivity-temperature characteristics of polysilicon films heavily doped with B, which is deposited on the AlN substrate are studied. It is found that the R-T characteristics show a U type curve within a wide temperature from 25℃~450℃, and the criterion depends on the processing techniques. The theroetical analysis shows that the minium of resistivity exists due to the interface barrier,and the result can be used to adjust the criterion and TCR.