低电容TVS用常压外延工艺研究

Study on the AP Epitaxial Process of LCTVS Diode

低电容瞬态电压抑制器(TVS)由高阻外延的雪崩二极管与低阻衬底的导引二极管组合而成。区别于常规的单片减压外延工艺,在常压外延条件、多片生长模式下,通过衬底背面的自吸硅以及低温长缓冲层工艺,有效抑制了外延过程中的自掺杂,在P型重掺衬底上生长出薄层高阻的N型外延层,降低了低电容TVS雪崩二极管的反向击穿电压,提高了浪涌抑制能力。

Low Capacitance Transient Voltage Suppressor（LCTVS） is a semiconductor device consists of avalanche diode made of high resistivity epitaxial layer and steering diode made of low resistivity substrate.Unlike normally used single-wafer epitaxial process with reduced pressure, this study focuses on the multi-wafer process with atmospheric pressure（RP）. To suppress auto-doping from P＋ substrate and get N-type thin layer with high resistivity, the processes of self-coat for the back seal of substrate and buffer layer epitaxial under low temperature are utilized. With the new process in this study,the reverse breakdown voltage of the avalanche diode is lowered and the capability of surge suppression is improved.