Preparation method of silicon drift detector

Abstract

The invention provides a preparation method of a silicon drift detector. The preparation method comprises a deposition step, which comprises: by taking germanium tetrafluoride, high-order silane and adopant silane as reaction gases, depositing a heavily-doped germanium film on a silicon substrate with a passivation film by adopting a chemical vapor deposition process, so that the heavily-doped germanium film forms a functional region in a corresponding region of the silicon substrate. According to the invention, high-order silane can be activated at a relatively low temperature to react withgermanium tetrafluoride, so that a low-temperature process can be adopted in a germanium film forming process; and the low-temperature process can avoid damage of high temperature in a diffusion process and a discrete injection process to a silicon substrate, so that the long body life can be obtained, and the energy resolution of a silicon drift detector can be improved.

Description

technical field [0001] This specification relates to the technical field of semiconductor devices, in particular to a method for preparing a silicon drift detector. Background technique [0002] Drift detectors are semiconductor detectors used to detect high-energy rays (generally, drift detectors are silicon-based detectors). When the drift detector is working, the drift ring makes the substrate in a completely depleted state, and the majority carriers formed on the substrate by high-energy rays passing through the incident window drift to the collector electrode along the direction of the device surface and are collected. [0003] In the current manufacturing process of silicon drift detectors, ion implantation is used to achieve doping of corresponding functional regions. Although the method of ion implantation can control the concentration of dopants and the doping depth of formation more accurately, it also has corresponding shortcomings: (1) During the ion implantatio...

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Problems solved by technology

Although the method of ion implantation can control the concentration of dopants and the doping depth of formation more accurately, it also has corresponding shortcomings: (1) During the ion implantation process, high-energy ions will cause damage to the surface of the silicon substrate; The damage needs to be repaired by high-temperature annealing process, but it cannot be completely repaired; (2) After boron ion implantation, a higher temperature is required for activation, and the activation temperature is about 1000 ° C; but the high-temperature activation process will cause the quality of the silicon substrate to deteriorate; (3) The minimum junction depth formed by ion implantation is 40nm, which is greater than the depth process requirements of ultra-shallow junctions currently required. This depth makes the preparation process of ultra-shallow junctions difficult; Conducive to the detection of low-energy X-rays: (4) During the activation process after ion implantation, there is a phenomenon of lateral expansion of dopant atoms, which increases the image size of the drift ring of the silicon drift detector

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