Pipeline system and method for improving stability of etching speed selectivity ratio

Abstract

The invention relates to the field of microelectronics, in particular to a pipeline system and method for improving the stability of an etching speed selectivity ratio. According to the pipeline system and method for improving the stability of the etching speed selectivity ratio, disclosed by the invention, an auxiliary trench is additionally arranged and is connected with a plurality of process trenches to form a circulation, thereby etching solutions in various process trenches tend to be identical and the etching speeds tend to be identical; in addition, the volume of the etching solution participating in the circulation is increased and the content change of SiO2 is relatively reduced, thereby the etching speed selectivity ratio is relatively stable; acid change setting is omitted anda small amount of etching solution is drained at set intervals or after a certain amount of silicon chips are produced; and the etching solution is supplemented from the auxiliary trench, and therebythe problem of greater damage to an oxidation film caused when the content of SiO2 in the novel etching solution is relatively and excessively high and silicon nitride is etched is solved.

Description

technical field [0001] The invention relates to the field of microelectronics, in particular to a pipeline system and method for improving the stability of the etching rate selection ratio. Background technique [0002] Silicon nitride (SiN) is a material widely used in integrated circuit manufacturing processes. It is often used as a hard mask for ionization etching, and thermal etching is one of the common methods to remove this layer of silicon nitride hard mask. ; Since hot phosphoric acid has a higher etch rate for silicon nitride and a lower etch rate for oxide film, it can effectively remove silicon nitride with less damage to oxide film. Among them, the control of selectivity is the process key process. [0003] 3Si 3 N 4 +27H 2 O+4H 3 PO 4 ?à4(NH 4 ) 3 PO 4 +9H 2 SiO 3 (Formula 1) [0004] h 2 SiO 3 ?à SiO 2 +H 2 O (Equation 2) [0005] Formulas 1 and 2 are the etching reaction formulas for silicon nitride and silicon oxide in a boiling phosph...

AI Technical Summary

Problems solved by technology

When a certain amount of silicon wafers are processed, the etching rate will decrease to a rate that cannot meet the production needs. At this time, a new etching solution needs to be replaced, but due to the SiO 2 The content is low, so SiO 2 Etch rate will be relative to Si 3 N 4 The etch rate is too high to meet the process requirements

That is, as the etching process progresses, the H in the etching solution 2 O and SiO 2 The content will be low, resulting in a decrease in the etching rate, unable to meet the process requirements; and replacing a new etching solution, due to the SiO 2 The content is relatively low, which will cause great damage to the oxide film when etching silicon nitride

Although at present, some silicon nitride barriers are processed before the production of products, so that SiO 2 The etching rate is reduced to a suitable range, but the process is difficult to control, and the effect is not obvious

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