On mechanisms influencing etching/polymerization balance in multi-component fluorocarbon gas mixtures

On Relationships between Plasma Chemistry and Surface Reaction Kinetics Providing the Etching of Silicon in CF4, CHF3, and C4F8 Gases Mixed with Oxygen

“…Obviously, the last two features are due to the low sample size that limits both consumption of active species for chemical reaction and the flux of etching products leaving the surface. It important to note also that all above findings confirm those obtained in our previous works [ 9 , 10 , 11 , 13 , 14 , 20 , 27 ]. The latter assumes the applicability of earlier used statements and approaches for the analysis of experimental and model-provided data.…”

“…Like in our previous works [ 9 , 10 , 11 ], plasma diagnostics and etching experiments were conducted in the planar inductively coupled plasma (ICP) reactor with cylindrical ( = 13 cm, = 16 cm) chamber made from the anodized aluminum. Schematic diagram of experimental equipment may be found in [ 10 ].…”

“…As a result, the low polymerizing ability produces the thinness of even the noncontinuous (islandlike) polymer film on the etched surface. Oppositely, the plasma excited in C 4 F 8 ( = 2) exhibits the much higher polymerizing ability because of the domination of CF x radicals over F atoms in a gas phase [ 9 , 10 , 11 ]. That is why the corresponding RIE process is featured by the deposition of thick (up to tens of microns [ 6 , 7 , 8 ]) and continuous polymer film.…”

“…The effective method to adjust the etching/polymerization balance in given RIE process is to combine highly or moderately polymerizing fluorocarbon gas with the additive component that suppresses the polymerization. From [ 11 , 12 , 13 , 14 ], it can be understood that the addition of O 2 always lowers the density of CF x radicals in a gas phase through the CF x + O/O( 1 D) → CF x−1 O + F reaction family as well as causes the oxidative destruction of deposited polymer film. Though mixtures of fluorocarbons with oxygen and other additive gases have been intensively studied during the last decade, the main attention was attracted to CF 4− based plasmas.…”

Noble gas effect on ACL etching selectivity to SiO2 films

“…Therefore, the general rule is that the lower ion flux $${{\rm{\Gamma }}}_{+}\approx {j}_{+}/e$$, the higher remaining negative potential on the bottom electrode. Earlier, several works [ 19,27 ] have suggested that the intensity of ion bombardment may be traced by the parameter $$\sqrt{{M}_{i}{\varepsilon }_{i}}{{\rm{\Gamma }}}_{+}$$, where the multiplicand under the square root reflects the momentum transferred from the incident ion to the surface atoms. In our case, this parameter decreases monotonically in the range of 2.6 × 10 17 –1.4 × 10 17 , or by ∼1.9 times, for 0%–100% He in Ar + He couple.…”