Formation and removal of composite halogenated silicon oxide and fluorocarbon films deposited on chamber walls during plasma etching of multiple film stacks

Ullal, Saurabh J.; Singh, Harmeet; Daugherty, J. E.; Vahedi, Vahid; Aydil, Eray S.

doi:10.1116/1.1502698

Cited by 40 publications

(84 citation statements)

References 14 publications

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“…Rf capacitive discharge in SF 6 is widely applied in technological processes of etching silicon-based materials [2,3], GaAs [4], treatment of polyethylene films [5] and textile [6], cleaning walls of technological vessels from etching or deposition products [7], etc. Therefore a large number of papers are devoted to studying rf discharge in SF 6 both in experiment and in theory.…”

Section: Introductionmentioning

confidence: 99%

Modes of rf capacitive discharge in low-pressure sulfur hexafluoride

Lisovskiy¹,

Booth²,

Jolly³

et al. 2007

J. Phys. D: Appl. Phys.

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This paper presents the results of an experimental study of rf capacitive discharge in low-pressure SF 6 . The rf discharge in SF 6 is shown to exist not only in weak-current (α-) and strong-current (γ -) modes but also in a dissociative δ-mode. This δ-mode is characterized by a high degree of SF 6 dissociation, high plasma density, electron temperature and active discharge current, and it is intermediate between α-and γ -modes. The δ-mode appears due to a sharp increase in the dissociation rate of SF 6 molecules via electron impact starting after a certain threshold value of rf voltage. At the same time the threshold ionization energy of SF x (x = 1-5) radicals formed is below the ionization potential of SF 6 molecules. The double layer existing in the anode phase of the near-electrode sheath is shown to play an important role in sustaining the α-mode as well as the δ-mode but it is not a cause of the rf discharge transition from α-to δ-mode.

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Section: Introductionmentioning

confidence: 99%

Modes of rf capacitive discharge in low-pressure sulfur hexafluoride

Lisovskiy¹,

Booth²,

Jolly³

et al. 2007

J. Phys. D: Appl. Phys.

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“…The small peak at 973 cm −1 is not observed in a similar experiment by Ullal et al [12]. The closest candidate is the Si-OH stretching mode at 980 cm −1 referred in Lang et al [17].…”

Section: A Analysis Of the Deposition Film On The Chamber Wallmentioning

confidence: 73%

“…In the model, it is assumed that the deposition rate is proportional to oxygen flow rate although no experimental data is provided. In the further studies about SF 6 plasma cleaning, they confirmed that fluorination of the OSi-Cl layer propels the cleaning process [13,14].…”

Section: Introductionmentioning

confidence: 69%

“…In a series of following reports using the same monitor, Ullal et al examined the characteristics of silicon-oxychloride (OSi-Cl) deposition during silicon etching using Cl 2 /O 2 plasma [11][12][13][14]. They found the enhancement of OSi-Cl growth by oxygen addition and proposed a reaction model of the deposition rate [12]. In the model, it is assumed that the deposition rate is proportional to oxygen flow rate although no experimental data is provided.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Godfrey et al installed an ATR prism on the chamber wall of inductively coupled plasma (ICP) source to monitor the growth of a silicon oxychloride film on the prism [10]. In a series of following reports using the same monitor, Ullal et al examined the characteristics of silicon-oxychloride (OSi-Cl) deposition during silicon etching using Cl 2 /O 2 plasma [11][12][13][14]. They found the enhancement of OSi-Cl growth by oxygen addition and proposed a reaction model of the deposition rate [12].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Growth and Cleaning Rates of Chamber-Wall Deposition during Silicon Gate Etching

Tanaka

Shiraishi

2013

e-J. Surf. Sci. Nanotechnol.

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To assure the repeatability of the gate etching process, in situ plasma cleaning is used to remove the depositions on the chamber wall. We studied the mechanism of deposition and cleaning of silicon containing films on the chamber wall formed during silicon etching using the attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). During the silicon etching with a Cl2/O2 plasma, a silicon-oxychloride film grows on the chamber wall due to the oxidation of the etch products. In the growth of the deposition films, the oxygen gas plays a key role. In a pure Cl2 plasma the deposition is removed even while the silicon etching is proceeding on the wafer. It was also found that the deposition rate is square proportional to the O2 gas flow rate. A simple kinetic model that attributes the square dependence to the consecutive oxidations of the two adjacent dangling bonds of a silicon atom has been described. Then the in situ cleaning of silicon-oxychloride with SF6 plasma was investigated with regard to the cleaning rate. Although oxygen gas is often added to the cleaning gas so as to remove commonly seen residues such as carbon or sulfur, there is a concern that oxidation may reduce the cleaning rate. It was confirmed that an oxygen addition of 30 sccm to the SF6 gas of 150 sccm causes insignificant effect. Further study to increase the cleaning rate revealed that lower pressure and larger total gas flow rate are effective. The effect of pressure is understood combined with the change in the plasma density. On the other hand, the total gas flow rate changes the density of etch products near the chamber wall. It was confirmed that the total gas flow rate does not change the etching rate of silicon-oxychloride on the wafer as it lies near the stagnation point of the gas flow.

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Correlation and Interaction between Sidewall Passivation and Chamber Walls Deposition During Silicon Gate Etching

Kogelschatz

Cunge

Joubert

et al. 2004

Contrib. Plasma Phys.

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The aim of the present paper is to review our work on plasma-surface interactions during the etching of silicon gates in low pressure high density HBr/Cl2/O2 based plasmas. In integrated circuit manufacturing, the transfer of patterns onto the polysilicon layer relies on the formation of a passivation layer on sidewalls of the etched features, which protects the silicon gate sidewall from isotropic etching. At the same time, a layer with an almost identical chemical composition is also deposited on the reactor walls and can modify the process parameters by changing the radicals' surface loss probability. In this work we use a new "plasma etching-sputtering" diagnostic technique, involving a subsequent "mild etching" of the layer deposited on the chamber walls by a few % SF6-containing Ar plasma. Thus we investigate the chemical composition of this layer. This chemical composition is deduced from the time variation of the gas phase concentration of different atoms and radicals, the etch products of the wall deposited layer, monitored during the "mild etching" of the layer by time-resolved optical emission spectroscopy and mass spectrometry.Optical absorption spectroscopy and mass spectrometry have been employed to characterize the HBr/Cl2/O2 plasma, currently used for the gate etching, and to estimate the absolute flux of neutral and ionic deposition precursors reaching the reactor walls. It comes out that the silicon wafer etch byproducts, SiClx radicals (x<2) and SiOyCl + x ions, are the main depositing agents. Finally, the chemical topography analysis method, based on the X-ray photoelectron spectroscopy, has been used to determine the chemical composition of the layer formed on the sidewalls of the silicon etched features.We show that the layers deposited on the sidewalls and on the chamber walls are both silicon oxyhalogenides (SiOyClx) compounds, formed by the subsequent oxidation of the deposited silicon chloride etching by-products.

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Formation and removal of composite halogenated silicon oxide and fluorocarbon films deposited on chamber walls during plasma etching of multiple film stacks

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Cited by 40 publications

References 14 publications

Modes of rf capacitive discharge in low-pressure sulfur hexafluoride

Modes of rf capacitive discharge in low-pressure sulfur hexafluoride

Evaluation of Growth and Cleaning Rates of Chamber-Wall Deposition during Silicon Gate Etching

Correlation and Interaction between Sidewall Passivation and Chamber Walls Deposition During Silicon Gate Etching

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