Method for removing oxide film on edge of silicon wafer by using low-temperature HF etching solution

Abstract

The invention relates to a method for removing an oxide film on the edge of a silicon wafer by using a low-temperature HF etching solution, which comprises the following steps: 1. preparation of low-temperature HF etching solution, namely mixing HF and DIW (deionized water) in a mass ratio of 1:0.9-1:2.5 to obtain an HF etching solution, pouring the HF etching solution into an acid tank of a roller-type edge remover, adding DIW ice blocks which are as three times as the DIW by mass, evenly stirring, and standing for 25-30 minutes while controlling the temperature at 6+ / -0.7 DEG C; 2. installing a wafer rack provided with silicon wafers into the roller-type edge remover; 3. after finishing the removal treatment, taking out the wafer rack, cleaning, and finally, inspecting the edge removing effect; and 4. every time 200 wafers are processed, discharging and supplementing 10% of the low-temperature HF etching solution. The roller-type edge removing technique provided by the invention can be used for preparing polished wafers for large-scale integrated circuits and discrete devices, has the advantages of low cost, high production efficiency, strong practicality and the like, and is suitable for removing SiO2 films on the back edge in the large-scale industrial production process of polished wafers.

Description

technical field [0001] The invention relates to a back treatment technology of a silicon wafer of a semiconductor wafer, in particular to a method for removing an oxide film at the edge of a silicon wafer by using a low-temperature HF etching solution. Background technique [0002] The processing of polished silicon wafers generally includes slicing, chamfering, grinding, etching, back treatment, polishing, cleaning and other processes. The back treatment process generally includes back damage treatment, back sealing treatment and edge oxide film removal treatment. Edge oxide film removal is an important process in the processing of silicon wafer polishing, which plays a vital role in the yield of polished wafers, subsequent epitaxy and devices: the chamfered surface caused by the back sealing process, the front side of the silicon wafer SiO 2 Residues, even SiO on the back edge of the wafer 2 Residues may become nucleation centers in the epitaxial growth process, forming ...

AI Technical Summary

Problems solved by technology

The disadvantages of this technology are: it is not easy to control the amount of HF, it is not conducive to cost control, it may also cause harm to operators, and it is impossible to accurately control the range of HF removal

And since water is HF and SiO 2 The reaction product, H in solution 2 O, as a chemical reaction product, promotes the reaction to the reverse reaction direction, so it is necessary to contain a relatively high concentration of hydrofluoric acid in the corrosion solution to ensure the reaction rate, so that the range of action of the HF solution reaches the required corrosion width; on the other hand, if the corrosion solution is If the HF concentration is too high, the volatilized HF gas will quickly dissolve in the water vapor adsorbed on the surface of the silicon wafer to generate fluorine ions (F - ), a reaction occurs (the chemical reaction formula is: SiO 2 +4HF=SiF 4 +2H 2 O), etch the oxide film in a wider area; therefore, the concentration of the HF etching solution becomes difficult to choose, if the concentration is too low, the range of action of the HF solution is too short to reach the required etching width; and If the concentration is too high, hydrogen fluoride gas will make the range of removing the oxide layer too wide and also fail to meet the generation requirements