ChemInform Abstract: Selective Dry Etching of Tungsten for VLSI Metallization.

Burba, M. E.; Degenkolb, E. O.; Henck, Steven A.; Tabasky, M.; Jungbluth, E. D.; Wilson, Riley

doi:10.1002/chin.198705324

Cited by 3 publications

(7 citation statements)

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“…In one pertinent study, Burba et al (15) observed an increase in the etch rate of sputtered tungsten with up to 46% oxygen in CF3C1 in a single-wafer reactor. The maximum IU~ I--Irestst 0.6um inorganic O0.Sur~ tungsten 7ura si [icon lull1 --I 1 Pesist tungsten silicon 1.0um O.…”

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“…In one pertinent study, Burba et al (15) observed an increase in the etch rate of sputtered tungsten with up to 46% oxygen in CF3C1 in a single-wafer reactor. etch rate of 25/~Jmin achieved at 160 mtorr and 0.22 W/cm 2 t,400-is quite low, and the slope of the etch rate response curve would suggest little or no additional advantage at higher t,266-02 concentrations.…”

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confidence: 97%

“…A worthy tungsten patterning process must create an anisotropic profile with an etch rate selectivity to the lithographic mask in excess of 1:1 and a selectivity to the support substrate normally of at least 3:1. The tungsten etch rate must be of a level consistent with manufacturing throughput considerations.Though there have been numerous investigations into the dry etching of tungsten and the other refractories (3-13) with either fluorinated or chlorinated chemistries, very few have approached tungsten etching using combinations of entities containing chlorine and fluorine (6, 14-16, 22) and fewer still have considered photoresist etch behavior coincidentally with tungsten (4,5,15,22).Most tungsten patterning efforts to date have relied on an inorganic or multilayer mask for dry etch resistance. In order to satisfy submicron lithographic requirements, the masking film thickness must be minimized.…”

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Reactive Ion Etching of Tungsten with Chlorinated Fluorocarbons

Daubenspeck

White

Sukanek

1989

J. Electrochem. Soc.

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Tungsten reactive ion etch (RIE) rate and resist selectivity behavior of three unique Freon systems are investigated using optical emission spectroscopy and electron scanning for chemical analysis (ESCA). An oxygen-rich CF3C1/O2 formulation exhibits an etch rate and selectivity to photoresist on the order of two-three times that possible with CF4/O2. An optical emission spectral analogue has led to the discovery that 5-15% CF2C12 added to CF4/O2 or CHFJO2 yields a similar etch rate and selectivity advantage.In recent history, universal advantage has been taken of the relationship between device performance and component miniaturization in the fabrication of VLSI circuitry. Refractory metals and their silicides have been the subject of increasing interest for their ability to serve as process-compatible, low resistivity substitutes in the partial or complete replacement of polysilicon, the formation of modified gate electrodes, or metal interconnects (1). In particular, the chemical and thermal stability of tungsten along with the commercial availability of chemical vapor deposition (CVD) processing equipment make it a suitable polysilicon replacement in the formation of a "polycide" composite or as an exclusive electrode film (2).With the implementation of CVD tungsten comes a need for the development of reliable dry etch processes for the patterning of submicron structures. A worthy tungsten patterning process must create an anisotropic profile with an etch rate selectivity to the lithographic mask in excess of 1:1 and a selectivity to the support substrate normally of at least 3:1. The tungsten etch rate must be of a level consistent with manufacturing throughput considerations.Though there have been numerous investigations into the dry etching of tungsten and the other refractories (3-13) with either fluorinated or chlorinated chemistries, very few have approached tungsten etching using combinations of entities containing chlorine and fluorine (6, 14-16, 22) and fewer still have considered photoresist etch behavior coincidentally with tungsten (4,5,15,22).Most tungsten patterning efforts to date have relied on an inorganic or multilayer mask for dry etch resistance. In order to satisfy submicron lithographic requirements, the masking film thickness must be minimized. However, because organic materials typically have a lower dry etch resistance than tungsten, it is often difficult or impossible for an organic mask to meet both the lithographic and RIE criteria simultaneously. In such instances, an interlevel inorganic film is employed as part of a multilayer nonerodible mask (NEM). As Fig. la illustrates, a thin resist pattern is used to define the lithographic image, which is transferred by RIE to the inorganic mask, which is on the order of a half micron in thickness. The final image transfer to the tungsten is carried out by RIE through the NEM. Singlelayer resist (SLR) processing (Fig. lb) is infinitely preferable, offering economic and processing advantages in addition to a real opportunity for defect redu...

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Reactive Ion Etching of Tungsten with Chlorinated Fluorocarbons

Daubenspeck

White

Sukanek

1989

J. Electrochem. Soc.

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“…RIE WSi x etching has been optimized based on the different CF 4 and O 2 flow ratio. As far as the side-wall profiles and surface damages are concerned, we conclude that with a flow rate ratio of 10:1 is the best etching condition for WSi x materials.…”

Section: Discussionmentioning

confidence: 99%

Reactive-ion etching of WSix in CF4+O2 and the associated damage in GaAs

Chan

1996

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

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Articles you may be interested in 0.1 μm WSiN-gate fabrication of GaAs metal-semiconductor field effect transistors using electron cyclotron resonance ion stream etching with SF 6 -CF 4 -SiF 4 -O 2Competitive reactions of fluorine and oxygen with W, WSi2, and Si surfaces in reactive ion etching using CF4/O2Assessments of WSi x reactive-ion etching in terms of the different CF 4 to O 2 flow rate ratio were characterized. Based upon the evaluations from etching rates, side-wall profiles, surface roughness, and damages, we observed that the optimum etching condition was at a ratio of 10:1. The recovery of reactive-ion-etching-treated GaAs damaged layers through the thermal treatment was also investigated as a function of the annealing temperatures and duration times. These parameter evaluations were for the purpose of achieving a high performance GaAs metal-semiconductor field-effect transistor.

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“…Empirical model for CF3CI/02 etching.--The first of two models has resulted from the merging of two extreme case experimental observations within one expression to describe CF3C1/Q etching 9 The CF3-CI bond energy of 86.1 kcal/mol is less than the 117 kcal/mol required to break the CF2C1-F bond (23). As a result, C1 is formed readily by electron impact dissociation of CF3C1 by the reaction (20) CF3C1 + e ---> CF3 + C1 + e-Thus, atomic chlorine is the predominant etchant atom (20), although minor quantities of atomic fluorine have been detected by Mogab et al at 10% 02 (24,25).…”

Section: (-28sv)mentioning

confidence: 99%

Investigation and Modeling of Mixed Halogen Freon/Oxygen Plasma Chemistries for Tungsten Etching

Daubenspeck

Sukanek

1989

J. Electrochem. Soc.

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Chlorofluorocarbon/oxygen reactive-ion etch (RIE) chemistries for tungsten etching exhibit a thermal etch rate independence "lot associated with CF4/Q. Substitution of C12 for CF2C12 in the CF4/O~ system has led to the discovery that the role of the chlorofluorocarbon is essentially one of atomic C1 generation. Etch rate and optical emission spectral data obtained from plasma and RIE-mode etching, from selective loading experiments, and from variation of the macroscopic process control parameters for the chlorofluorocarbon/oxygen systems, have led to the formulation of a hypothetical reaction pathway involving neutrals. By the proposed mechanism, atomic C1 is thought to be indirectly responsible for improving the contact efficiency between the plasma and metallic tungsten. Etch rate models based upon this hypothesis are shown to agree well with actual data.

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ChemInform Abstract: Selective Dry Etching of Tungsten for VLSI Metallization.

Cited by 3 publications

References 1 publication

Reactive Ion Etching of Tungsten with Chlorinated Fluorocarbons

Reactive Ion Etching of Tungsten with Chlorinated Fluorocarbons

Reactive-ion etching of WSix in CF4+O2 and the associated damage in GaAs

Investigation and Modeling of Mixed Halogen Freon/Oxygen Plasma Chemistries for Tungsten Etching

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