Sulfur hexafluoride is a gas with excellent insulating properties and is often used in high-voltage arc extinguishing and transformers, high-voltage transmission lines, transformers, etc. However, in addition to these functions, sulfur hexafluoride can also be used as an electronic etchant. Electronic grade high-purity sulfur hexafluoride is an ideal electronic etchant, which is widely used in the field of microelectronics technology. Today, Niu Ruide special gas editor Yueyue will introduce the application of sulfur hexafluoride in silicon nitride etching and the influence of different parameters.
We discuss the SF6 plasma etching SiNx process, including changing the plasma power, the gas ratio of SF6/He and adding the cationic gas O2, discussing its influence on the etching rate of the SiNx element protection layer of TFT, and using plasma radiation The spectrometer analyzes the concentration changes of each species in SF6/He, SF6/He/O2 plasma and the SF6 dissociation rate, and explores the relationship between the change of SiNx etching rate and the plasma species concentration.
Studies have found that when the plasma power is increased, the etching rate increases; if the flow rate of SF6 in the plasma is increased, the F atom concentration increases and is positively correlated with the etching rate. In addition, after adding the cationic gas O2 under the fixed total flow rate, it will have the effect of increasing the etching rate, but under different O2/SF6 flow ratios, there will be different reaction mechanisms, which can be divided into three parts: (1 ) The O2/SF6 flow ratio is very small, O2 can help the dissociation of SF6, and the etching rate at this time is greater than when O2 is not added. (2) When the O2/SF6 flow ratio is greater than 0.2 to the interval approaching 1, at this time, due to the large amount of dissociation of SF6 to form F atoms, the etching rate is the highest; but at the same time, the O atoms in the plasma are also increasing and It is easy to form SiOx or SiNxO(yx) with the SiNx film surface, and the more O atoms increase, the more difficult the F atoms will be for the etching reaction. Therefore, the etching rate begins to slow down when the O2/SF6 ratio is close to 1. (3) When the O2/SF6 ratio is greater than 1, the etching rate decreases. Due to the large increase in O2, the dissociated F atoms collide with O2 and form OF, which reduces the concentration of F atoms, resulting in a decrease in the etching rate. It can be seen from this that when O2 is added, the flow ratio of O2/SF6 is between 0.2 and 0.8, and the best etching rate can be obtained.
Post time: Dec-06-2021
