Acid bath wet etching process

Abstract

The invention provides an acid tank type wet etching process, comprising: performing acid tank etching for the first time after the acid tank is changed; calculating the etching according to the number of silicon wafers accumulatively processed in the acid tank during the small acid change cycle The process time is obtained according to the calculated etching rate and the etching amount of the thin film of the silicon wafer, and the actual etching rate is obtained by the measured value and the process time. Starting from the second acid bath etching, according to the last calculated etching rate The etching rate and the actual etching rate adjust the etching rate of this process. In the acid tank type wet etching process of the present invention, the etching rate of each batch of silicon wafers in the etching process is calculated by the cumulative number of silicon wafers processed in the small acid change cycle, reducing the actual etching rate before and after the small acid change. The impact of sudden changes in etching rate on the calculation of process control can finally improve the accuracy of process control and realize continuous etching of silicon wafers.

Description

technical field [0001] The invention relates to the technical field of semiconductor etching, in particular to an acid bath type wet etching process. Background technique [0002] With the continuous development of integrated circuits, the critical dimensions of semiconductor devices are getting smaller and smaller, and the cleaning process and etching process are becoming more and more important as indispensable processes in semiconductor production. Usually, the cleaning process is carried out in a tank wet cleaning machine. The wet etching in the etching process is carried out in a groove wet etching machine. With the progress of wet etching, the concentration of acid in the tank of the wet etching machine will gradually change, which will affect the etching rate. Therefore, it is necessary to partially replace the acid in the tank, which is called small acid exchange. . Taking phosphoric acid as an example, the current small acid change control method is to convert the...

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Problems solved by technology

[0003] The calculation of the process control time in the prior art is to adjust the current silicon wafer etching process processing time according to the process conditions of the previous silicon wafer etching process and the feedback etching rate of the previous batch of silicon wafers. In the small acid change period of the bath wet etching process, the etching rate decreases sequentially with the increase of the silicon wafers accumulated in the acid tank. The existing process cannot accurately control the influence of various factors on the etching rate, especially It is the case that the etch rate changes suddenly before and after a small acid change. Therefore, in order to obtain a feedback value that is closer to the actual etch rate, it is necessary to wait for the value after the last batch of silicon wafers to be etched to be measured. Therefore, the same time The number of batches of silicon wafers processed in a section is limited, and continuous operation is not possible

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