Method for implementing aluminum diffusion on silicon wafer

Abstract

The invention relates to a method for implementing aluminum diffusion on a silicon wafer. The method includes making a texture surface on the front surface of the silicon wafer, and coating a silicon oxide isolating membrane on the back surface of the silicon wafer; implanting ions, in other words, selecting solid AlCl<3> as an aluminum diffusion source, heating the solid aluminum source under a high-vacuum condition so that the solid aluminum source sublimates at the temperature of 120-170 DEG C, loading the solid aluminum source into a source region of a filament of an ion implanter by using argon as a carrier, enabling the solid aluminum source to be collided with electrons generated by the filament to form the charged aluminum ions, accelerating the charged aluminum ions by high voltage, screening the ions by a magnetic analyzer, and further doping aluminum impurities into the silicon wafer; cleaning the silicon wafer; dehydrating the cleaned silicon wafer by anhydrous ethanol and placing the silicon wafer in a drying oven at the temperature of 100-110 DEG C to dry the silicon wafer; and placing the dried silicon wafer in a diffusion furnace, heating the diffusion furnace so that the temperature of the diffusion furnace is 1250-1260 DEG C, and keeping the temperature constant for 10-12 hours. The method has the advantages that the total doping contents for ion implantation are accurately controlled, the precision and the repeatability of a diffusion process are improved, and a large-area uniform doping effect is realized.

Description

technical field [0001] The invention relates to a diffusion technology in the semiconductor preparation process, in particular to a method for implementing aluminum diffusion on a silicon chip, which belongs to the technical category of power semiconductor devices. Background technique [0002] In the manufacturing technology of high-voltage semiconductor devices such as thyristors and transistors, in order to achieve higher voltages, low-concentration deep junction diffusion is required, and the junction depth is required to be more than 80 microns. Based on this, the aluminum diffusion method is preferred. Aluminum in Silicon has the advantages of low impurity concentration and fast diffusion speed, which can realize high voltage and reduce the time for high temperature diffusion. At the same time, the atomic radius of aluminum matches the crystal lattice of silicon very well, and there are few defects in silicon after high temperature diffusion. But so far, there are two ...

AI Technical Summary

Problems solved by technology

But so far, there are two major difficulties in aluminum diffusion on silicon: (1) There is no ideal aluminum impurity source (no aluminum gas source, no aluminum liquid source, no mature aluminum solid source), and the process technology leading to aluminum diffusion is either very difficult. It is complicated, but it is difficult to control accurately, or it is easy to realize but the uniformity and repeatability are poor; (2), without an ideal masking film, the selective diffusion of aluminum cannot be achieved on silicon wafers