Aspect ratio independent etching of dielectrics

Hwang, Gyeong S.; Giapis, Konstantinos P.

doi:10.1063/1.119578

Cited by 49 publications

(61 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The entrance potential depends then on the aspect ratio and reduces the ion flux and energy at the bottom of the patterns. 25 In our case, the anisotropic behavior of the deposit thickness, and more particularly the nonobservable deposition on surfaces that are not in line of sight with the plasma, indicates that the deposit is either due to neutral species with a sticking coefficient close to 1 or to ion species. Indeed, neutral species with a sticking coefficient significantly below 1 would bounce around before sticking onto the sidewalls and would therefore lead to a significant deposit on surfaces that are not in line of sight with the plasma.…”

Section: Mechanism Of Passivation Stepmentioning

confidence: 96%

Deep germanium etching using time multiplexed plasma etching

Darnon

Lafontaine

Volatier

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

View full text Add to dashboard Cite

There is a growing need for patterning germanium for photonic and photovoltaics applications. In this paper, the authors use a time multiplexed plasma etch process (Bosch process) to deep etch a germanium substrate. They show that germanium etching presents a strong aspect ratio dependent etching and that patterns present scallops mostly on the upper part (aspect ratio below 0.8). Passivation layers are formed during the passivation step by neutrals' deposition and are reinforced during the etching step by the redeposition of sputtered fluorocarbon species from the etch front. When the sidewalls are passivated, reactive neutrals diffuse through Knudsen-like diffusion down to the bottom of the pattern to etch the germanium. The Knudsen-like diffusion is responsible for the aspect ratio dependent etching and makes difficult the etching of holes with aspect ratios above 10 while trenches with aspect ratio of 17 are still etched faster than 2 μm/min.

show abstract

Section: Mechanism Of Passivation Stepmentioning

confidence: 96%

Deep germanium etching using time multiplexed plasma etching

Darnon

Lafontaine

Volatier

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

View full text Add to dashboard Cite

show abstract

“…Thus, an increasing aspect ratio is expected to worsen both forms of charging damage. 4 As device rules get smaller, aspect ratios tend to increase. Combined with a reduction in gate oxide thickness-for larger transistor current and control of short-channel effects-increased gate electrode potentials during plasma etching could be detrimental to the device.…”

Section: Introductionmentioning

confidence: 99%

“…4 When not electrically connected to the edge line, the intermediate lines do not afford the same luxury; plasma electrons can reach their conductive sidewalls only through the trench opening. Thus, the geometric angle of electron irradiance of the conductive part of the sidewalls plays a critical role in allowing the necessary electrons to reach the gate electrode and reduce its charging potential.…”

Section: Introductionmentioning

confidence: 99%

“…3 Charging damage is influenced by the aspect ratio ͑etch depth over trench width͒. 4 For a given plasma, the charging potential at the bottom of each trench reflects the balance between the electron and ion currents flowing to the bottom insulating surface. 2 Since the electron angular distribution at the wafer is more isotropic than the ion angular distribution, 5 the aspect ratio determines the degree of electron shadowing of the trench bottom and, thus, the electron flux to that surface.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electron irradiance of conductive sidewalls: A determining factor for pattern-dependent charging

Hwang

Giapis

1997

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

Self Cite

View full text Add to dashboard Cite

Numerical simulations of charging and profile evolution during gate electrode overetching in high density plasmas have been performed to investigate the effect of long conductive sidewalls on profile distortion ͑notching͒. The results reveal that the angle of electron irradiance of the conductive portion of the sidewalls affects profoundly the charging potential of the gates. Larger angles, obtained for thinner masks and/or thicker polysilicon, result in reduced gate potentials which, through their influence on the local ion dynamics, cause more severe notching at all lines of the microstructure.

show abstract

“…Cumulative charge damage was found only under edge gates, in patterns separated by open areas covered with field oxide. 5 Here we focus on tunneling current transients in patterned antenna structures; being area intensive, antennas amplify the ion and electron current imbalance and can force large tunneling currents through small area gate oxides.' We are aware of only one prior simulation effort by Kinoshita et al,9 who studied current injection during etching of metal antenna structures by performing steadystate charging calculations; since the profile evolution was not simulated, no true current transients could be captured.…”

mentioning

confidence: 99%

On the Origin of Charging Damage during Etching of Antenna Structures

Hwang

Giapis

1997

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

Monte Carlo simulations of charging and profile evolution in patterned antenna structures during etching in high-density plasmas reveal a rapid change in the potential of the lines at end point, which causes a surge in electron tunneling through thin gate oxides and possibly charging damage. The condition of the substrate (grounded vs. floating) determines the magnitude of the surge and whether it will be followed by a steady-state current until all lines of the pattern become disconnected. A reduction in damage is possible by controlling the substrate condition, which may be assessed through notching experiments.When plasma-etching patterned wafers, the directionality difference between ions and electrons at the wafer causes differential microstructure charging,' which affects the in-trench etch rate,2 can lead to profile distortion (notching),34 and may induce electron tunneling through thin gate oxides.'5 Large tunneling currents are believed to cause electrical degradation or even breakdown of the oxide.6 Termed the "electron shading" effect,' this form of damage is particularly aggravating because of its latent nature and is feared to become a showstopper in the quest for smaller critical dimensions. Despite tremendous effort by researchers worldwide to fight the problem,7 a solution has yet to be found. The physics of the electron shading damage has been elusive, in part because of the experimental hurdles in measuring tunneling currents in situ under realistic processing conditions. Numerical simulations could provide insight into the origin of the tunneling currents and improve understanding of the limitations of existing etch tools and device layout rules. To be sure, such simulations are complex; the charging and etching processes are coupled, requiring the simultaneous handling of phenomena that occur over disparate time scales such as electron tunneling (<1 0' s), microstructure charging (10 5), and profile evolution (102 5), on patterned surfaces consisting of dissimilar materials. Results from such comprehensive calculations for gate electrode etching suggest that the period from open area clearing (end point) to trench bottom clearing is critical for damage.58 Tunneling current tran-

show abstract

Aspect ratio independent etching of dielectrics

Cited by 49 publications

References 12 publications

Deep germanium etching using time multiplexed plasma etching

Deep germanium etching using time multiplexed plasma etching

Electron irradiance of conductive sidewalls: A determining factor for pattern-dependent charging

On the Origin of Charging Damage during Etching of Antenna Structures

Contact Info

Product

Resources

About