The Optimization of the Gate Polysilicon Deposition Process for Power MOSFETs

During the fabrication of Shielded-Gate Trench MOSFETs (SGT MOSFETs), the trench associated with the gate is filled with polysilicon. Polysilicon is essential to the performance and stability of integrated circuits in semiconductor manufacture. Poor quality polysilicon film leads to the degradation of device performance and may cause circuit failure. This study investigates the polysilicon film quality of trenches under different processing conditions in two types of furnace systems: UPOLY and DPOLY. In UPOLY system, the results of experiment revealed that temperature has the most significant influence on film quality. Within the temperature range of 580-535 °C, lower temperatures resulted in better film quality. This result was validated in DPOLY system. This work provides guidance for obtaining optimal processing conditions for the growth of polysilicon in filled trenches.