Performance Characterization Research Of Key Processes Of Silicon Photomultiplier

Silicon photomultiplier(SiPM)has a wide range of applications in nuclear medicine,high-energy physics,astrophysics and other fields,among which gettering and trench isolation processes are the key processes that affect the noise performance of devices.In this paper,the carrier lifetime characterization is used as a means to realize the guidance of the device preparation process by characterizing the electrical properties of silicon materials after gettering and trench isolation processes.The main research content of this paper is as follows:1.MOS structures designed based on p-type epitaxial silicon(electrode diameters of 0.5 mm and 1 mm,respectively)were tested for capacitance time(C-t)curves before and after the gettering process.The calculation results showed that the minority carrier lifetimes before and after gettering were 27.93 μs and 26.06μs,respectively.It is believed that the main process is the epitaxial process,while the heavily doped substrate completes the gettering process of the outer epitaxial layer,which is the reason why the minority carrier lifetime has hardly changed.It was found that the upward bias of the capacitor in the capacitance voltage(CV)curve is mainly due to the induced charge caused by the distribution of the external electric field on the surface of the electrode.2.A pn structure with trench isolation(STI)was designed,and it was found that the ideal factor of the forward I-V curve significantly increased under low current,while the reverse I-V curve and variable frequency C-V curve showed significant twisting and other phenomena in the range of 67 V.It is believed that there is interface damage in the STI structure.The interface density of states is about 1012 eV-1cm-2.