Simulation of profile evolution in silicon reactive ion etching with re-emission and surface diffusion

Singh, Vivek K.

doi:10.1116/1.586084

Cited by 144 publications

(64 citation statements)

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“…However, there are numerous mechanisms other than etch inhibition that could be invoked to explain the data: image force deflection, 29 bulk diffusion from the plasma to the surface, field curvature near conductive topography 3,27,28,30 and surface diffusion. 32,33 Image force deflection gives rise to an increasing RIE lag with decreasing feature size, contrary to our observations. Bulk diffusion can be neglected since all mean free paths of importance are much larger than the feature sizes etched.…”

Section: B Nonaspect-ratio Scalingcontrasting

confidence: 57%

“…1 The fact that many of these mechanisms may be important to varying degrees in every plasma etching situation has been repeatedly shown in profile simulations. 11,[32][33][34] The plethora of possible mechanisms is also evident in the difficulty process engineers have in determining optimum etch conditions for next generation design rules.…”

Section: Introductionmentioning

confidence: 99%

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Scaling of Si and GaAs trench etch rates with aspect ratio, feature width, and substrate temperature

Bailey

Sanden

Gregus

et al. 1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The scaling of etch rates with feature dimensions is an important issue in the fabrication of microelectronic and photonic devices. Because etch rates depend on circuit layouts and design rules, considerable effort is spent to modify processes each time changes in design are made. Knowing how etch rates scale with design parameters should accelerate the introduction of new designs into manufacturing while minimizing the cost of doing so. Recently it has been shown that etch rates for a variety of conditions scale with the depth/width or aspect ratio and not on width or depth alone. While various mechanisms might be responsible for such scaling, isolating one mechanism from another is not straight forward. Nonetheless, it is important to understand the underlying mechanisms so that differences in etch chemistry and etch reactor design can be accounted for when scaling plasma processes from one design or reactor to another. To assess the effects of etch chemistry alone, the trench etch rates of Si and GaAs are compared under constant plasma conditions. Substrate temperature is varied to further assess the relative importance of surface vs transport phenomena during the etching process. At higher temperatures, both Si and GaAs trench etch rates scale only with aspect ratio in an Ar/Cl2 electron cyclotron resonance plasma. The results are consistent with an ion-neutral synergy model based on Langmuir adsorption kinetics where the scaling can be explained by the aspect ratio dependence of the neutral reactant transport into the trench: charging effects, ion shadowing, and Knudsen transport are not consistent with the data. At −45 °C, the etch rate no longer scales with aspect ratio alone, but now also depends on trench width. The data at this lower temperature are well described by a model incorporating the deposition of an etch inhibiting layer. While the trench etch rates for GaAs and Si scale in similar ways with aspect ratio and trench width, the dependence on feature dimensions of the Si etch rate is much stronger than that for GaAs at all substrate temperatures because the steady-state surface coverage of Cl is smaller for Si. This results in a greater sensitivity to the incoming, aspect ratio dependent, neutral fluxes. The implications of the models on the goal of aspect ratio independent etching are also discussed.

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Section: B Nonaspect-ratio Scalingcontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Scaling of Si and GaAs trench etch rates with aspect ratio, feature width, and substrate temperature

Bailey

Sanden

Gregus

et al. 1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…28,29 In our experiment, the undercutting at the 92 cm position is particularly relevant to the ultimate potential of neutral beam etching because the beam of neutral F atoms interacted with the Si surface under conditions where gas-phase scattering was negligible and background pressure was low. Therefore, the undercutting must be the result of one or more surface mediated processes.…”

Section: Etching Resultsmentioning

confidence: 99%

“…Therefore, the undercutting must be the result of one or more surface mediated processes. In RIE profiles, undercutting has been commonly attributed to thermal desorption 6,8,29 and surface diffusion 30 of unreacted fluorine atoms from the bottom of the trenches. Singh et al 29 explored these processes in a model of the profile evolution during RIE in an SF 6 plasma.…”

Section: Etching Resultsmentioning

confidence: 99%

“…In RIE profiles, undercutting has been commonly attributed to thermal desorption 6,8,29 and surface diffusion 30 of unreacted fluorine atoms from the bottom of the trenches. Singh et al 29 explored these processes in a model of the profile evolution during RIE in an SF 6 plasma. Their simulation was based on a fit of one experimental profile which determined the value of the sticking probability as well as the neutral-to-ion flux ratio on the etched surface.…”

Section: Etching Resultsmentioning

confidence: 99%

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Hyperthermal neutral beam etching

Giapis¹,

Moore²,

Minton³

1995

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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A pulsed beam of hyperthermal fluorine atoms with an average translational energy of 4.8 eV has been used to demonstrate anisotropic etching of Si. For 1.4 Hz operation, a room-temperature etch rate of 300 Å/min for Si͑100͒ has been measured at a distance of 30 cm from the source. A 14% undercutting for room-temperature etching of Novolac-masked Si features was achieved under single-collision conditions, with no detectable mask erosion. Translational energy and angular distributions of scattered fluorine atoms during steady-state etching of Si by a normal-incidence, collimated beam demonstrate that unreacted F atoms can scatter inelastically, retaining a significant fraction of their initial kinetic energies. The observed undercutting can be explained by secondary impingement of these high-energy F atoms, which are more reactive upon interaction with the sidewalls than would be expected if they desorbed from the surface at thermal energies after full accommodation. Time-of-flight distributions of volatile reaction products were also collected, and they show evidence for a dominant nonthermal reaction mechanism of the incident atoms with the surface in addition to a thermal reaction channel.

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Metal Contacts to GaN and Processing

Morkoç̌

2008

Handbook of Nitride Semiconductors and Devices

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Simulation of profile evolution in silicon reactive ion etching with re-emission and surface diffusion

Cited by 144 publications

References 0 publications

Scaling of Si and GaAs trench etch rates with aspect ratio, feature width, and substrate temperature

Scaling of Si and GaAs trench etch rates with aspect ratio, feature width, and substrate temperature

Hyperthermal neutral beam etching

Metal Contacts to GaN and Processing

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