Effect of hydrofluorocarbon structure of C3H2F6 isomers on high aspect ratio etching of silicon oxide

In Situ Monitoring of Etching Characteristic and Surface Reactions in Atomic Layer Etching of SiN Using Cyclic CF4/H2 and H2 Plasmas

“…In a conventional reactive ion etching, it has been reported that highly selective etch of SiN over SiO 2 can be achieved using hydrogen-contained plasmas, both with and without FC additives or HFCs. − Recently, Dussart et al also demonstrated the etch selectivities between SiN, SiO 2 , and Si materials by controlling bias voltage at cryogenic temperature regimes . Due to the scavenging reaction of H atoms with F, the concentration of F, which is considered as the main etchant for SiO 2 or Si, is expected to decrease with increasing H concentration.…”

Etching Mechanism Based on Hydrogen Fluoride Interactions with Hydrogenated SiN Films Using HF/H2 and CF4/H2 Plasmas

“…8,52,53 Due to the reactions between hydrogen-contained fluorocarbon plasma and SiN, these processes enable selective etching of SiN over SiO 2 and other Si-based materials. 10,[12][13][14]54 In these plasmas, the H atoms scavenge the F atoms, forming HF molecules, resulting in fluorine poor conditions and high polymer deposition rates. This phenomenon is particularly significant for Si and SiO 2 etching, as they are generally considered to have no reaction with gaseous HF.…”

“…The role of H atoms from both the plasmas and the films being etched has been widely investigated as one of the key factors in SiN etching using hydrogen-contained fluorocarbon gases. ,, Due to the reactions between hydrogen-contained fluorocarbon plasma and SiN, these processes enable selective etching of SiN over SiO 2 and other Si-based materials. ,− , In these plasmas, the H atoms scavenge the F atoms, forming HF molecules, resulting in fluorine poor conditions and high polymer deposition rates. This phenomenon is particularly significant for Si and SiO 2 etching, as they are generally considered to have no reaction with gaseous HF. ,, Based on the proposed model, it is evident that HF can react with the hydrogenated SiN surface.…”

“…Simultaneously, the Si material undergoes oxidation and becomes passive by converting into SiOF . It has also been reported that high SiN/SiO 2 selectivity can be achieved using gas mixtures such as NF 3 /O 2 or CF 4 /N 2 /O 2 plasmas, which is attributed to the influence of NO radicals. , The addition of hydrogen to fluorocarbon gas, leading to the generation of CH x F y ions, can be used to enhance the etch rate (ER) and/or selectivity of SiN/SiO 2 or SiN/Si. − Special hydrofluorocarbon gases have been used to achieve high etch selectivity for SiN over SiO 2 and Si. − Additionally, the dependence of selectivities between Si-based materials on substrate temperature has recently been investigated by various research groups. , In hydrogen-contained fluorocarbon plasmas, the formation of hydrogen fluoride (HF) is anticipated to have a detrimental effect on etching for Si-based materials, as it tends to scavenge F radicals . In the mechanism of SiN etching, the H also reacts with N and CF x species, resulting in the formation of HCN as a byproduct, which helps to reduce the FC polymerization and facilitates the progress of SiN etching. , Based on the experimental and simulation results, it has been reported that HF molecules appear to play an important role in the selective etching of SiN over SiO 2 in NF 3 /N 2 /O 2 /H 2 remote plasmas , On the other hand, recently, there have been investigations into the selective etching of SiO 2 over SiN or Si using an HF vaper, employing both computational simulations and experimental approaches. , …”

Database Development of SiO2 Etching with Fluorocarbon Plasmas Diluted with Various Noble Gases of Ar, Kr, and Xe

“…The addition of H 2 or O 2 gas in PFC plasmas has been widely employed to control the etching characteristics; while H atoms generated through the dissociation of H 2 in plasma act as a scavenger for F atoms, thereby lowering etch rates and increasing SiO 2 -to-Si selectivity, O atoms from O 2 dissociation consume C atoms on the material surfaces, reducing the formation of FC films [ 9 ]. Following the same mechanism as H 2 /O 2 addition, hydrofluorocarbon gases (HFC, CH x F 4−x with x = 1, 2, or 3) with H atoms in their molecular structures instead of F atoms are frequently adopted, and numerous studies on the mixture of PFC and HFC precursors have been reported over the years [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”