Profile evolution during polysilicon gate etching with low-pressure high-density Cl2/HBr/O2 plasma chemistries

Abstract

Articles you may be interested inLow-pressure inductively coupled plasma etching of benzocyclobutene with SF6/O2 plasma chemistry J. Vac. Sci. Technol. B 30, 06FF06 (2012); 10.1116/1.4758765Reduction of silicon recess caused by plasma oxidation during high-density plasma polysilicon gate etching Level set approach to simulation of feature profile evolution in a high-density plasma-etching system Profile evolution during polysilicon gate etching has been investigated with low-pressure high-density Cl 2 /HBr/O 2 plasma chemistries. Etching was performed in electron cyclotron resonance Cl 2 /HBr/O 2 plasmas as a function of HBr percentage in a Cl 2 /HBr mixture, using oxide-masked poly-Si gate structures. The linewidth was nominally 0.18 m, and the spacing between the two neighboring poly-Si lines was varied in the range ϳ0.2-10 m. In addition, the macroscopic open space of the oxide-masked sample was also varied over a wide range from Ϸ28% to Ϸ76%. As the HBr percentage in Cl 2 /HBr is increased from 0 to 100%, the linewidth shift ⌬L of poly-Si relative to the mask width ͑or the degree of sidewall tapering of poly-Si lines͒ first decreased linearly, passed through a minimum, and then increased considerably at above ϳ80%. In Cl 2 /O 2 plasmas without HBr addition, ⌬L was almost independent of the microscopic and macroscopic poly-Si open spaces although its value was relatively large; on the contrary, in HBr/O 2 plasmas, ⌬L increased with an increase of microscopic line spacing and/or the macroscopic open space of the sample. Comparisons of the etched profiles obtained in Cl 2 /HBr/O 2 plasmas with numerical profile simulations indicate that the strongly tapered sidewalls observed at high HBr percentages ͑տ80%͒ result from the simultaneous etch inhibitor deposition onto sidewalls during etching; moreover, such inhibitors are predicted to come from the plasma with a large sticking probability of ϳO(0.1). On the other hand, the relatively large ⌬L obtained in Cl 2 /O 2 plasmas is considered to be due to intrinsic sidewall tapering, rather than inhibitor deposition arriving from the plasma or redeposition of etch products desorbed from the surface in microstructures. Such intrinsic tapering is discussed in terms of the angular dependence of the Si etch yield.

Highly selective etch process for silicon-on-insulator nano-devices

“…Instead, chamber condition for plasma enhanced CVD are reached and deposition of SiO 2 occurs. A similar effect has been observed in [7]. For a process without parasitic deposition (O 2 flow of 4 sccm, chamber pressure of 12 mTorr), a selectivity of 100:1 is achieved.…”

“…SOI technology for multi-gate CMOS, however, results in a three-dimensional topography and therefore imposes new challenges for reactive ion etch (RIE) processes. In detail, an extremely high etch selectivity of polysilicon gates over thin gate oxides has to be achieved while maintaining anisotropic profiles [6][7][8][9].…”

Reduction of loading effects with the sufficient vertical profile for deep trench silicon etching by using decoupled plasma sources

“…This is caused by the incident ions scattered from the sheath and the mask edge. To reduce this phenomenon, trench etching was performed by using Cl 2 as the plasma-activating gas in an HBr base, which rarely causes spontaneous etching (Tuda et al, 2001). A hard mask was used for deep trench silicon etching.…”

Study of 3D metrology techniques as an alternative to cross-sectional analysis at the R&D level

“…New CD tips are in development in order to succeed in measuring spaced lines below 70 nm very soon. Dense lines measurements are very useful to clearly understand the microloading effect16,17,18 which occurs during etching processes or to estimate the in homogeneity of lithography processes in dense lines due for example to backscattering electrons during E-Beam exposure19,20 . Dense lines measurements : a-X-SEM front view; b-CD AFM scan line -Advanced lithography By using HSQ E-Beam resist, we are able to obtain isolated line of around 20 nm (cf.…”