Multi-diffusion process used before glass passivation of FRGPP chip

Abstract

The invention discloses a multi-diffusion process used before glass passivation of an FRGPP chip. The multi-diffusion process includes the following steps that S1, phosphorus and boron primary diffusion is carried out for texturing, specifically, a phosphorus diffusion source is diffused on one surface of a silicon wafer subjected to diffusion pretreatment, a boron diffusion source or a boron-aluminum diffusion source is diffused on the other surface of the silicon wafer, and texturing of the silicon wafer is carried out; and S2, platinum diffusion is carried out, specifically, a platinum diffusion source is diffused on the silicon wafer after phosphorus and boron primary diffusion and texturing. The multi-diffusion process has the beneficial effects that the phosphorus diffusion source and the boron diffusion source or the boron-aluminum diffusion source are printed on the two surfaces of the silicon wafer correspondingly through a screen printing technology, so that a coating processof a silicon wafer liquid source is simplified, and the processing period is shortened; after liquid source coating, a one-time negative pressure diffusion process is adopted to reduce the source return condition at the edge of the silicon wafer, steps of the diffusion process are simplified, and diffusion efficiency is improved; manufactured PN junctions are uniform, and thus the processing costof the silicon wafer is lowered.

Description

technical field [0001] The invention belongs to the field of silicon chip manufacturing technology, and in particular relates to a multiple diffusion process before glass passivation of FRGPP chips. Background technique [0002] As a semiconductor diode with good switching characteristics and short reverse recovery time, fast recovery glass passivated diode (FRGPP) has a wide range of applications, mainly used in electronic circuits such as switching power supplies, PWM pulse width modulators, and frequency converters. The market prospect is broad and the development space is large. [0003] Under the traditional process, the platinum diffusion time is long, and the reverse recovery time (trr) performance of the silicon wafer after the platinum diffusion is uneven, resulting in a large leakage current IR of the finished product; at the same time, most of the silicon wafers are manufactured using the diffusion process to form a PN junction At present, the commonly used diffu...

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Problems solved by technology

[0003] Under the traditional process, the platinum diffusion time is long, and the reverse recovery time (trr) performance of the silicon wafer after the platinum diffusion is uneven, resulting in a large leakage current IR of the finished product; at the same time, most of the silicon wafers are manufactured using the diffusion process to form a PN junction At present, the commonly used diffusion process in the industry generally adopts one-time full diffusion of paper source or two-time diffusion of phosphorus and boron. Since the gap between the silicon wafers increases after the paper source is sintered, the volatile phosphorus source diffuses to the boron surface and causes back-to-source; two times The method of diffusion is cumbersome. After the phosphorus is diffused on one side, the other side needs to be sandblasted or chemically thinned to remove the reverse source, and then the boron is diffused. The cost is high, the diffusion efficiency is low, and it is easy to cause debris.