We present a low temperature (<300°C) plasma deposition process to prepare novel fluorine-cont... more We present a low temperature (<300°C) plasma deposition process to prepare novel fluorine-containing silicon nitride films (p-SiN:F1 using SiH4-NF-N2 discharge mixtures at 14 MHz RF applied frequency. The deposition rate can be extremely high, up to 1600 A/min. p-SiN:F has electrical properties (dielectric constant, breakdown strength, resistivity, etc.) which compare favorably with high temperature CVD silicon nitride. By controlling the feed chemistry and physical variables of the discharge, a wide variety of film compositions are achieved. Two classes of films were identified as stable or unstable to air exposure and the instability of the films correlated with the atom fraction of fluorine initially incorporated. The results obtained from IR, AES, and RBS measurements show that low hydrogen-containing films are produced by the introduction of fluorine in the silicon nitride films. More importantly, the concentration of Si-H is extremely low because strong Si-F bonding replaces relatively weak Si-H bonds that satisfy free Si orbitals in conventional plasma nitride, and the hydrogen remaining in the film is present as stable N-H bonds. We believe this substitution of silicon-bound hydrogen, caused by the gas phase and surface-driven reactions, is a reason for superior film properties. The mechanism for this novel discharge chemistry is discussed.
The homogeneous reaction between F or F2 and SiF2, the latter formed by the high-temperature reac... more The homogeneous reaction between F or F2 and SiF2, the latter formed by the high-temperature reaction of solid silicon with SiF4, is accompanied by an intense chemiluminescent ’’flame’’ with the spectrum previously observed during silicon etching by F and F2. This experiment provides direct confirmatory evidence that chemiluminescence from both reactions arises from the homogeneous reaction between SiF2 and fluorine atoms or molecules.
Journal of vacuum science & technology, May 1, 1990
As the lateral dimensions of ultra-large-scale integration (ULSI) circuit features approach a few... more As the lateral dimensions of ultra-large-scale integration (ULSI) circuit features approach a few-tenths of a micron, demands on the etch transfer of patterns into thin films become increasingly challenging. These demands, combined with the greater susceptibility to create damage, require that new methods are evaluated and compared for etching fine structures in order to establish processing technologies. Submicron polysilicon etching has been performed on a single-wafer etcher using two different sources that sustain intense discharges at low pressure (≲10−3 Torr). The first is an electron cyclotron resonance (ECR) source operated at 2.45 GHz. The second source is a simple helical resonator (HR) structure operated at radio frequencies (RF). The comparisons made between the two sources were the etched profiles of polysilicon, material selectivity, polysilicon etch rates, and etch uniformity. These preliminary experiments show that both systems have great promise to successfully pattern ULSI structures. The advantages and disadvantages of ECR and improved HR sources will be discussed.
Journal of vacuum science & technology, Apr 1, 1983
Plasma etching techniques for III-V compound semiconductors are reviewed, emphasizing design cons... more Plasma etching techniques for III-V compound semiconductors are reviewed, emphasizing design considerations in the choice of gases, discharge parameters, and substrate temperature. Mechanisms are proposed for anisotropic, isotropic, and crystallographic chemical etching. Applications of plasma etching in device fabrication are given.
The copper-catalyzed fluorination of silicon is first order in [F2] and in [Cu]s until the covera... more The copper-catalyzed fluorination of silicon is first order in [F2] and in [Cu]s until the coverage reaches ∼4 monolayers. Above ∼4 monolayers the reaction rate is zero order in copper, suggesting a limited number of catalytically active Cu/Si sites. Copper islands form at high coverages, above saturation, and provide a reservoir of catalyst. The limited rate of surface diffusion of copper leads to anisotropic etching and feature size-dependent etch depths. The copper compounds, CuF2 and CuO, and copper silicides, Cu5Si and Cu3Si, all catalyzed the F2-Si reaction which suggests that they are all converted to the same active species. The results can be explained by mechanisms involving copper fluorides or copper silicides as active intermediates.
We find that gaseous ClF3 is an effective and selective etchant for a variety of transition metal... more We find that gaseous ClF3 is an effective and selective etchant for a variety of transition metals and metal compounds. Kinetics were studied for etching α-Ta (13–16 atom % N), Ta2N, and Ta2O5 in this gas, as a function of temperature and pressure, to provide effective activation energies of 4.0, 4.4, 7.7 kcal/mole, respectively. Relative etch rates measured in CF4/O2 and NF3 plasmas indicate that ClF3 gaseous etching has more than an order of magnitude better selectivity for nonoxidic metal compounds over the corresponding oxide. At 100 °C, selectivity for etching α-Ta or Ta2N over Ta2O5 is more than 160:1. Other materials used in semiconductor manufacture, such as SixNy, W, TaSi2, and photoresist, were also briefly surveyed and the results suggest ClF3 holds promise for isotropic etching applications that require high selectivity.
This paper describes the deposition of dielectric silicon oxide from TEOS in helium/oxygen mixtur... more This paper describes the deposition of dielectric silicon oxide from TEOS in helium/oxygen mixtures in a parallel plate rf plasma reactor. Under appropriate process conditions, highly directional deposition of low-stress stoichiometric silicon oxide is achieved. The step coverage profiles and the chemical and physical properties of these Si02 films were studied to gain an understanding of t,he origin of preferentially vertical deposition. The typical deposition conditions used in this study were 1 torr total pressure, 320' C substrate temperature, 1-40% TEOS and 0-80% O2 in low power density (0.1-0.4 W/cm2) 14 MHz rf discharges. Step coverage, chemical stability and film stress were found to be most dependent on the 02:TEOS gas flow ratio. This dependence will be explained by the various effects involved in the oxide deposit ion mechanism.
Etching of silicon by molecular fluorine is accelerated when trace quantities of copper are prese... more Etching of silicon by molecular fluorine is accelerated when trace quantities of copper are present on the surface. Copper is a residue formed when sputter-deposited aluminum (containing 0.5 % copper) is selectively removed by HF from the silicon surface. The temperature dependence of the etching rate was studied in the range 60–290°C. At temperatures higher than 80°C copper causes a ˜100-fold increase in the rate of etching of the underlying silicon (100), compared to unmetallized samples. Above 180°C, F2 exhibits a higher absolute etch rate than equivalent concentrations of fluorine atoms. Preliminary results for other metal contaminants and etchant gases indicate that silver also accelerates F2 etching, and copper enhances etching by NF3. The results are interpreted in terms of a catalytic mechanism.
ABSTRACT A description is given of the deposition of dielectric silicon oxide from TEOS in helium... more ABSTRACT A description is given of the deposition of dielectric silicon oxide from TEOS in helium/oxygen mixtures in a parallel-plate RF plasma reactor. Under appropriate process conditions, highly directional deposition of low-stress stoichiometric silicon oxide is achieved. The step coverage profiles and the chemical and physical properties of these SiO2 films were studied to gain an understanding of the origin of preferentially vertical deposition. The typical deposition conditions used in this study were 1 torr total pressure, 320°C substrate temperature, 1-40% TEOS, and 0-80% O2 in low-power-density (0.1-0.4 W/cm2) 14 MHz RF discharges. Step coverage, chemical stability and film stress were found to be most dependent on the O2:TEOS gas flow ratio. This dependence can be explained by the various effects involved in the oxide deposition mechanism
Journal of The Electrochemical Society, Apr 1, 1983
Monitoring optical emission has become a valuable tool for the plasma processing of semiconductor... more Monitoring optical emission has become a valuable tool for the plasma processing of semiconductor materials. We haveextended this technique by monitoring atomic emission from etch products excited in an auxiliary discharge located downstreamof the plasma ...
ABSTRACT We have studied the chemical and physical properties of silicon oxide films plasma depos... more ABSTRACT We have studied the chemical and physical properties of silicon oxide films plasma deposited from TEOS (tetraethoxysilane), to gain an understanding of the origins of (1) step coverage and (2) film stability. TEOS was diluted in helium/oxygen mixtures and deposited as a function of discharge frequency (150 kHz and 14 MHz) and 02 flow in a parallel plate reactor. The typical deposition conditions were 1 torr total pressure, 320°C substrate temperature, 1 -9% TEOS, 1 -80% 02, and -0.1 W/cm2 discharge power. Films deposited at high frequency with excess oxygen were generally oxygen-rich, chemically unstable and hygroscopic, while films deposited at low frequency were stable to moisture and slightly deficient in oxygen. However, coverage profiles of high frequency films showed an unusual degree of directionality, which could be used to advantage for the coating of high aspect ratio features. We suggest that a judicious combination of high and low frequency discharges may improve film properties while maintaining directional step coverage. Isotopic labeling experiments were performed using 1802 to gain insight into the origins of the oxygen that is contained in these PECVD films. Complete isotopic scrambling was not observed. Film composition data suggest that there is one tenacious Si-0 bond which remains with the silicon from the original TEOS molecule during the reaction to form Si02.
This title has been withdrawn: please see Elsevier Policy on Article Withdrawal ( http://www.else... more This title has been withdrawn: please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). This Book/Chapter has been withdrawn as Elsevier no longer has the publishing rights.
We present a low temperature (<300°C) plasma deposition process to prepare novel fluorine-cont... more We present a low temperature (<300°C) plasma deposition process to prepare novel fluorine-containing silicon nitride films (p-SiN:F1 using SiH4-NF-N2 discharge mixtures at 14 MHz RF applied frequency. The deposition rate can be extremely high, up to 1600 A/min. p-SiN:F has electrical properties (dielectric constant, breakdown strength, resistivity, etc.) which compare favorably with high temperature CVD silicon nitride. By controlling the feed chemistry and physical variables of the discharge, a wide variety of film compositions are achieved. Two classes of films were identified as stable or unstable to air exposure and the instability of the films correlated with the atom fraction of fluorine initially incorporated. The results obtained from IR, AES, and RBS measurements show that low hydrogen-containing films are produced by the introduction of fluorine in the silicon nitride films. More importantly, the concentration of Si-H is extremely low because strong Si-F bonding replaces relatively weak Si-H bonds that satisfy free Si orbitals in conventional plasma nitride, and the hydrogen remaining in the film is present as stable N-H bonds. We believe this substitution of silicon-bound hydrogen, caused by the gas phase and surface-driven reactions, is a reason for superior film properties. The mechanism for this novel discharge chemistry is discussed.
The homogeneous reaction between F or F2 and SiF2, the latter formed by the high-temperature reac... more The homogeneous reaction between F or F2 and SiF2, the latter formed by the high-temperature reaction of solid silicon with SiF4, is accompanied by an intense chemiluminescent ’’flame’’ with the spectrum previously observed during silicon etching by F and F2. This experiment provides direct confirmatory evidence that chemiluminescence from both reactions arises from the homogeneous reaction between SiF2 and fluorine atoms or molecules.
Journal of vacuum science & technology, May 1, 1990
As the lateral dimensions of ultra-large-scale integration (ULSI) circuit features approach a few... more As the lateral dimensions of ultra-large-scale integration (ULSI) circuit features approach a few-tenths of a micron, demands on the etch transfer of patterns into thin films become increasingly challenging. These demands, combined with the greater susceptibility to create damage, require that new methods are evaluated and compared for etching fine structures in order to establish processing technologies. Submicron polysilicon etching has been performed on a single-wafer etcher using two different sources that sustain intense discharges at low pressure (≲10−3 Torr). The first is an electron cyclotron resonance (ECR) source operated at 2.45 GHz. The second source is a simple helical resonator (HR) structure operated at radio frequencies (RF). The comparisons made between the two sources were the etched profiles of polysilicon, material selectivity, polysilicon etch rates, and etch uniformity. These preliminary experiments show that both systems have great promise to successfully pattern ULSI structures. The advantages and disadvantages of ECR and improved HR sources will be discussed.
Journal of vacuum science & technology, Apr 1, 1983
Plasma etching techniques for III-V compound semiconductors are reviewed, emphasizing design cons... more Plasma etching techniques for III-V compound semiconductors are reviewed, emphasizing design considerations in the choice of gases, discharge parameters, and substrate temperature. Mechanisms are proposed for anisotropic, isotropic, and crystallographic chemical etching. Applications of plasma etching in device fabrication are given.
The copper-catalyzed fluorination of silicon is first order in [F2] and in [Cu]s until the covera... more The copper-catalyzed fluorination of silicon is first order in [F2] and in [Cu]s until the coverage reaches ∼4 monolayers. Above ∼4 monolayers the reaction rate is zero order in copper, suggesting a limited number of catalytically active Cu/Si sites. Copper islands form at high coverages, above saturation, and provide a reservoir of catalyst. The limited rate of surface diffusion of copper leads to anisotropic etching and feature size-dependent etch depths. The copper compounds, CuF2 and CuO, and copper silicides, Cu5Si and Cu3Si, all catalyzed the F2-Si reaction which suggests that they are all converted to the same active species. The results can be explained by mechanisms involving copper fluorides or copper silicides as active intermediates.
We find that gaseous ClF3 is an effective and selective etchant for a variety of transition metal... more We find that gaseous ClF3 is an effective and selective etchant for a variety of transition metals and metal compounds. Kinetics were studied for etching α-Ta (13–16 atom % N), Ta2N, and Ta2O5 in this gas, as a function of temperature and pressure, to provide effective activation energies of 4.0, 4.4, 7.7 kcal/mole, respectively. Relative etch rates measured in CF4/O2 and NF3 plasmas indicate that ClF3 gaseous etching has more than an order of magnitude better selectivity for nonoxidic metal compounds over the corresponding oxide. At 100 °C, selectivity for etching α-Ta or Ta2N over Ta2O5 is more than 160:1. Other materials used in semiconductor manufacture, such as SixNy, W, TaSi2, and photoresist, were also briefly surveyed and the results suggest ClF3 holds promise for isotropic etching applications that require high selectivity.
This paper describes the deposition of dielectric silicon oxide from TEOS in helium/oxygen mixtur... more This paper describes the deposition of dielectric silicon oxide from TEOS in helium/oxygen mixtures in a parallel plate rf plasma reactor. Under appropriate process conditions, highly directional deposition of low-stress stoichiometric silicon oxide is achieved. The step coverage profiles and the chemical and physical properties of these Si02 films were studied to gain an understanding of t,he origin of preferentially vertical deposition. The typical deposition conditions used in this study were 1 torr total pressure, 320' C substrate temperature, 1-40% TEOS and 0-80% O2 in low power density (0.1-0.4 W/cm2) 14 MHz rf discharges. Step coverage, chemical stability and film stress were found to be most dependent on the 02:TEOS gas flow ratio. This dependence will be explained by the various effects involved in the oxide deposit ion mechanism.
Etching of silicon by molecular fluorine is accelerated when trace quantities of copper are prese... more Etching of silicon by molecular fluorine is accelerated when trace quantities of copper are present on the surface. Copper is a residue formed when sputter-deposited aluminum (containing 0.5 % copper) is selectively removed by HF from the silicon surface. The temperature dependence of the etching rate was studied in the range 60–290°C. At temperatures higher than 80°C copper causes a ˜100-fold increase in the rate of etching of the underlying silicon (100), compared to unmetallized samples. Above 180°C, F2 exhibits a higher absolute etch rate than equivalent concentrations of fluorine atoms. Preliminary results for other metal contaminants and etchant gases indicate that silver also accelerates F2 etching, and copper enhances etching by NF3. The results are interpreted in terms of a catalytic mechanism.
ABSTRACT A description is given of the deposition of dielectric silicon oxide from TEOS in helium... more ABSTRACT A description is given of the deposition of dielectric silicon oxide from TEOS in helium/oxygen mixtures in a parallel-plate RF plasma reactor. Under appropriate process conditions, highly directional deposition of low-stress stoichiometric silicon oxide is achieved. The step coverage profiles and the chemical and physical properties of these SiO2 films were studied to gain an understanding of the origin of preferentially vertical deposition. The typical deposition conditions used in this study were 1 torr total pressure, 320°C substrate temperature, 1-40% TEOS, and 0-80% O2 in low-power-density (0.1-0.4 W/cm2) 14 MHz RF discharges. Step coverage, chemical stability and film stress were found to be most dependent on the O2:TEOS gas flow ratio. This dependence can be explained by the various effects involved in the oxide deposition mechanism
Journal of The Electrochemical Society, Apr 1, 1983
Monitoring optical emission has become a valuable tool for the plasma processing of semiconductor... more Monitoring optical emission has become a valuable tool for the plasma processing of semiconductor materials. We haveextended this technique by monitoring atomic emission from etch products excited in an auxiliary discharge located downstreamof the plasma ...
ABSTRACT We have studied the chemical and physical properties of silicon oxide films plasma depos... more ABSTRACT We have studied the chemical and physical properties of silicon oxide films plasma deposited from TEOS (tetraethoxysilane), to gain an understanding of the origins of (1) step coverage and (2) film stability. TEOS was diluted in helium/oxygen mixtures and deposited as a function of discharge frequency (150 kHz and 14 MHz) and 02 flow in a parallel plate reactor. The typical deposition conditions were 1 torr total pressure, 320°C substrate temperature, 1 -9% TEOS, 1 -80% 02, and -0.1 W/cm2 discharge power. Films deposited at high frequency with excess oxygen were generally oxygen-rich, chemically unstable and hygroscopic, while films deposited at low frequency were stable to moisture and slightly deficient in oxygen. However, coverage profiles of high frequency films showed an unusual degree of directionality, which could be used to advantage for the coating of high aspect ratio features. We suggest that a judicious combination of high and low frequency discharges may improve film properties while maintaining directional step coverage. Isotopic labeling experiments were performed using 1802 to gain insight into the origins of the oxygen that is contained in these PECVD films. Complete isotopic scrambling was not observed. Film composition data suggest that there is one tenacious Si-0 bond which remains with the silicon from the original TEOS molecule during the reaction to form Si02.
This title has been withdrawn: please see Elsevier Policy on Article Withdrawal ( http://www.else... more This title has been withdrawn: please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). This Book/Chapter has been withdrawn as Elsevier no longer has the publishing rights.
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