Thinning corrosion method for heavily-doped stibium silicon chip

Abstract

The invention discloses a thinning corrosion method for a heavily-doped stibium silicon chip, which comprises the following steps: treating the heavily-doped stibium silicon chip by using mixed liquidof hydrogen peroxide and ammonia water; cleaning the heavily-doped stibium silicon chip by using deionized water; and putting the heavily-doped stibium silicon chip of which a water film is reservedon the surface into acid corrosive liquid mainly comprising hydrofluoric acid and nitric acid to react. By using the thinning corrosion method for the heavily-doped stibium silicon chip, the corrodedsilicon chip has a smooth and consistent surface, has no white print, and has good ohmic contact property after alloying.

Description

【Technical field】 [0001] The invention relates to a wet etching method in a semiconductor manufacturing process, in particular to a method for thinning and etching heavily doped antimony silicon wafers. 【Background technique】 [0002] At present, acid etchant (HF acid and HNO 3 ) for corrosion, the corrosion mechanism is: nitric acid first oxidizes the silicon surface into SiO 2 , and then the SiO 2 Corrosion and dissolution, the reaction equation is Si+HNO 3 +HF→H 2 SiF 6 +HNO 2 +H 2 O+H 2 . However, when etched with conventional acidic etchants (HF acid and HNO3), irregular white marks are formed on the surface (see figure 1 ), these white marks are mainly generated by the combined action of nitric acid vapor and decomposition gas in a short period of time when the silicon wafer enters the nitric acid, and these white marks cannot be removed by conventional methods unless the silicon wafer is re-grinded. It will appear again when it enters the corrosive solution,...

AI Technical Summary

Problems solved by technology

However, when etched with conventional acidic etchants (HF acid and HNO3), irregular white marks are formed on the surface (see figure 1 ), these white marks are mainly generated by the combined action of nitric acid vapor and decomposition gas within a short period of time when the silicon wafer enters the nitric acid, and these white marks cannot be removed by conventional methods unless the silicon wafer is re-grinded. It will appear again when it enters the corrosive solution, and these white imprints cannot achieve good ohmic contact at all. figure 2 shown

Another solution is to use alkaline etching solution for thinning and etching. However, as a semiconductor production line, it is taboo to introduce alkali metal ions, because alkali metal ions are highly mobile in semiconductor materials. In-chip movement, seriously impairing device electrical performance and long-term reliability

There are also hexavalent chromium combined with HF acid for thinning corrosion treatment, but the oxidation reaction speed of hexavalent chromium is too slow, and it also causes heavy metal pollution of chromium

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