We have developed heavily boron-doped piezoresistive single-crystalline silicon AFM cantilevers which aimed for operating at low temperatures including cryogenic temperature range. The optimization of design to increase the sensitivity and reduce noise at cryogenic temperature is considered by controlling the dopant concentration. The relatively low concentration of 6×10 18 atoms/cm 3 shows the lowest Minimum Detectable Force (MDF) at room temperature (R.T.) by calculation. However, it was predicted that the optimal concentration of dopant was shifted to a higher concentration at cryogenic temperature in MDF by calculation. Firstly we developed AFM cantilevers integrated with piezoresistive elements at the support of the cantilever. Actually the fabricated heavily doped cantilever shows that the sensitivity at cryogenic temperature increased by 1.6 times at 5 K than that at R.T.