Kinetics of the deposition step in time multiplexed deep silicon etches

Saraf, Iqbal; Goeckner, Matthew; Goodlin, Brian; Kirmse, K. H. R.; Nelson, Caleb T.; Overzet, Lawrence

doi:10.1116/1.4769873

Cited by 10 publications

(11 citation statements)

References 24 publications

(23 reference statements)

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“…where K i is the number of carbon atoms incorporated into the film by neutral species i and q film is the density of deposited film. Saraf et al 17 estimated the upper bound of the largest possible sticking coefficient was only 0.15%. This indicates that neutral C x F y monomers are subject to frequent reflections by the feature walls before they are finally sticking to the growing film.…”

Section: B Deposition Mechanismmentioning

confidence: 98%

Finite-element simulation models and experimental verification for through-silicon-via etching: Bosch process and single-step etching

Ouyang

Ruzic

et al. 2014

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

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In this study, time-dependent simulation models are established for both the Bosch process and single-step through-silicon-via (TSV) etching using SF 6 and C 4 F 8 chemistry by employing a finite-element-method method. The simulation models take into account the thermal etching of F radicals, ion-enhanced etching, neutral deposition and ion-enhanced deposition mechanisms, as well as the angular dependence of the ion sputtering with aspect to a surface element. Comparison between the simulation results and experiments suggests that consideration of two ion fluxes (high-energy and low-energy) is critical for matching the simulation etch profile with the experiments. It is found that the underlying reason for the transition formed on the TSVs using the single-step etching originates from the difference of the ion angular distributions of etching species and depositing species. The Bosch process model successfully predicted profile details, such as the top scallops of the TSV profile, and the model established for single-step etching can be used to predict the transition position shown on the sidewalls. The simulation models can be used to study the individual effects of low-energy ions and the high-energy ions in the etching and passivation mechanisms for TSV etching in both Bosch process and single-step etching techniques. V

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Section: B Deposition Mechanismmentioning

confidence: 98%

Finite-element simulation models and experimental verification for through-silicon-via etching: Bosch process and single-step etching

Ouyang

Ruzic

et al. 2014

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

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show abstract

“…Operating with different cycle times enables control over the proportion of the IEDs in the high and low energy peaks, while keeping the energy of the peaks essentially unchanged. This could be valuable for other gases with more complicated etching mechanisms, such as C 4 F 8 , 31 which benefit from a controllable distribution of ions having both low and high energies.…”

Section: Custom Frequency Waveformsmentioning

confidence: 99%

Effects of a chirped bias voltage on ion energy distributions in inductively coupled plasma reactors

Lanham

Kushner

2017

Journal of Applied Physics

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The metrics for controlling reactive fluxes to wafers for microelectronics processing are becoming more stringent as feature sizes continue to shrink. Recent strategies for controlling ion energy distributions to the wafer involve using several different frequencies and/or pulsed powers. Although effective, these strategies are often costly or present challenges in impedance matching. With the advent of matching schemes for wide band amplifiers, other strategies to customize ion energy distributions become available. In this paper, we discuss results from a computational investigation of biasing substrates using chirped frequencies in high density, electronegative inductively coupled plasmas. Depending on the frequency range and chirp duration, the resulting ion energy distributions exhibit components sampled from the entire frequency range. However, the chirping process also produces transient shifts in the self-generated dc bias due to the reapportionment of displacement and conduction with frequency to balance the current in the system. The dynamics of the dc bias can also be leveraged towards customizing ion energy distributions.

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“…Fluorocarbon film deposition from C 4 F 8 /Ar plasmas is thought to be predominantly ion-enhanced, [17][18][19][20] which causes the AR dependence to be controlled by the ion angular distribution function (IADF). The IADF narrows as the chuck RF bias power increases, which allows a larger fraction of the incoming ions to reach trench bottom and enhances the fluorocarbon film growth there.…”

Section: A Estimated Ar Dependenciesmentioning

confidence: 99%

Correction of aspect ratio dependent etch disparities

Bates¹,

Goeckner²,

Overzet³

2014

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

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Articles you may be interested inDependence of selectivity on plasma conditions in selective etching in submicrometer pitch grating on InP surface by CH4/H2 reactive ion etching J. Appl. Phys. 109, 073516 (2011); 10.1063/1.3573536 Model for aspect ratio dependent etch modulated processing J. Vac. Sci. Technol. A 28, 334 (2010); 10.1116/1.3305716Aspect ratio dependent etching lag reduction in deep silicon etch processes Maximum achievable aspect ratio in deep reactive ion etching of silicon due to aspect ratio dependent transport and the microloading effect Kinetics and crystal orientation dependence in high aspect ratio silicon dry etchingThe etch rate of deep features in silicon, such as trenches and vias, can vary significantly with the feature aspect ratio (AR). Small AR features generally etch faster than large AR features. The reasons for this AR dependence include a slowing of the etch rate with increasing AR due to the necessary transport of molecules into and out of the features as well as ion flux reductions at feature bottom due to the angular spread of the ion flux and ion deflection caused by differential charging of the microstructures. Finding ways to reduce, eliminate, or reverse this AR dependence is both an active subject of research and difficult. In this work, instead of focusing on methods to reduce or prevent AR dependence in an etch process, the authors focus on methods to correct it after the fact. The authors show that an inhibitor film deposition step can be used under some circumstances to allow feature depth disparities to be corrected. This process can be used to correct feature depth disparities whenever the AR dependence of the inhibitor film deposition step is worse (larger) than the AR dependence of the following inhibitor etch step. To test the theory, a plasma process through SF 6 /C 4 F 8 /Ar mixtures was used to both produce trenches of various ARs having significant depth disparities and correct those disparities. The etch depth of small AR features can be held essentially constant while that of larger AR features is increased to match or even exceed.

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Kinetics of the deposition step in time multiplexed deep silicon etches

Cited by 10 publications

References 24 publications

Finite-element simulation models and experimental verification for through-silicon-via etching: Bosch process and single-step etching

Finite-element simulation models and experimental verification for through-silicon-via etching: Bosch process and single-step etching

Effects of a chirped bias voltage on ion energy distributions in inductively coupled plasma reactors

Correction of aspect ratio dependent etch disparities

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