摘要:

An innovation to separate out ionic and neutral radicals from the beam coming out of a saddle field fast atom beam (FAB) source is reported. Diamondlike carbon (DLC) films were grown simultaneously by these ionic and filtered neutral radicals using methane(CH4)as the source gas in the FAB source, on to the substrates placed at different positions inside the deposition chamber. Faraday cup measurements carried out on the two beams confirm the separation of ionic and neutral radicals. It was found that the DLC films deposited by neutral radicals have higher hardness values(980–1070 kg/mm2)than those deposited by ionic radicals(810–970 kg/mm2),whereas, the values of optical band gap and refractive index are found to be higher in DLC films deposited by ionic radicals than those deposited by neutral radicals. It is emphasized that during normal operation of a saddle field source, to grow DLC films, one essentially has a mixed deposition with contributions both from neutral and ionized radicals. Higher hardness values(1050–1150 kg/mm2)of films grown this way may, perhaps, be due to an ion assisted process of network compaction leading to higher degree of overstraining.

ISSN:0734-2101    

DOI:10.1116/1.580971

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

ISSN:0734-2101    

DOI:10.1116/1.580973

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Chlorine-based plasma etching of polysilicon was characterized as a function of the impingingCl+,Cl–to–Cl+flux ratio, ion bombardment energy, ion bombardment angle, and the flux of etching by-products(SiCl2)using a multiple beam scattering apparatus. The ion-enhanced etching yield was a strong function of the neutral-to-ion flux ratio, and scaled linearly with the square root of the ion energy. The ion-enhanced etching yield was independent of the ion bombardment angle at near normal ion incidence angles, but decreased almost linearly above 40° off-normal angles. The presence ofSiCl2greatly suppressed the etching of polysilicon by eitherCl+orCl+with Cl. A Monte Carlo based profile simulator was constructed which incorporated the dominant reaction mechanisms of surface chlorination under ion bombardment, surface re-emission, and ion reflection. The profile evolution of patterned samples etched by Cl andCl+beams were simulated. Quantitatively good agreement was found between the simulated profiles and the measured profiles. A sensitivity analysis of the recombination probability of Cl on photoresist suggested that the recombination of atomic chlorine on the photoresist had a significant impact on the profile evolution.

ISSN:0734-2101    

DOI:10.1116/1.580974

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

In situFourier-transform infrared (FTIR) ellipsometry has been performed on silicon substrates processed in a rf-biased transformer coupled plasma reactor. Plasmas inCHF3,CF4,C2F6,andC4F8have been used. The reaction layer, which is present on the surface of the silicon wafer during the plasma process, has been analyzed in detail, addressing both chemical composition and thickness. The absolute reliability (expressed in terms of thickness) of the results is of the order of 0.01 nm, which corresponds to 3% of a monolayer. The instabilities of a silicon surface, which have been observed under specific conditions, can be of the order of tens of percents of a monolayer, which clearly illustrates the advantage of using a realin situtechnique like FTIR ellipsometry over quasiin situtechniques like x-ray photoemission spectroscopy and Auger electron spectroscopy. ForCHF3plasmas it has been found that, if the bias increases to moderate levels (30–50 V), the fluorocarbon film deposition rate decreases and the silicon etching reaction rate increases. The reaction layer changes from a thick, predominantlyCFxpolymerlike film to a thin, carbon dominated layer of plasma and etching products showing vibrational absorptions ofSiFx,C–C, andCF2.Increasing the bias voltage in aCHF3plasma has a similar effect as increasing the F/C ratio of the feed gas.

ISSN:0734-2101    

DOI:10.1116/1.580976

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The surface reaction ofCF2radicals on Si and fluorocarbon films was investigated in electron cyclotron resonance (ECR) Ar andH2/Ardownstream plasmas employingCF2radical injection technique. The effects ofAr+ions,Ar*metastable species and radiation from plasmas on the fluorocarbon film formation were evaluated in ECR Ar downstream plasma withCF2radical injection. As a result,CF2radicals with assistance ofAr+ion bombardment were found to play an important role in the fluorocarbon film formation. The adsorptive reactions ofCF2radicals on the fluorocarbon film surface with and without Ar andH2/Arplasma exposures were successfully investigated byin situFourier transform infrared reflection absorption spectroscopy andin situx-ray photoelectron spectroscopy. It was found that the formation of fluorocarbon film in the plasma proceeded through the adsorptive reaction ofCF2radicals at a high probability on the active sites formed by the bombardment ofAr+ions on the fluorocarbon film surface.

ISSN:0734-2101    

DOI:10.1116/1.580977

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

For various fluorocarbon processing chemistries in an inductively coupled plasma reactor, we have observed relatively thick (2–7 nm) fluorocarbon layers that exist on the surface during steady state etching of silicon. In steady state, the etch rate and the surface modifications of silicon do not change as a function of time. The surface modifications were characterized byin situellipsometry and x-ray photoelectron spectroscopy. The contribution of direct ion impact on the silicon substrate to the etching mechanism is reduced with increasing fluorocarbon layer thickness. Therefore, we consider that the silicon etch rate is controlled by a neutral etchant flux through the layer. Our experimental data show, however, that ions play an import role in the transport of silicon etching precursors through the layer. A model is developed that describes the etch kinetics through a fluorocarbon layer based on a fluorine diffusion transport mechanism. The model is consistent with the data when one or two of the following roles of the ions on the etching process are assumed. The first role is an enhancement in the diffusivity of fluorine atoms through the fluorocarbon layer and an enhancement in the reaction probability of fluorine in the fluorocarbon layer. In this case the fluorine is assumed to originate from the gas phase. The second role includes ion fragmentation and dissociation of the fluorocarbon surface molecules.

ISSN:0734-2101    

DOI:10.1116/1.580978

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Reactive interactions in plasma etching have been investigated. Simple gas-phase transport of etchants and the reaction by-products in the wafer near-surface area are discussed. A new reincidence parameter, determined with a proposed near-surface model, was used to formulate metal etch rates. The experimental results obtained from an electron cyclotron resonance microwave plasma etching system revealed that the measured etching rate agreed well with those obtained by the near-surface model. It was found that reaction by-products repeatedly arrived at the surface depending on the reincidence numbers for the metal etching. The reincidence is the result of the diffusional transport in the vicinity of the wafer and is given by the expression {(one-half of the wafer radius)/(mean-free path)}. The ratio of the by-product flux is expressed by the product of the etching-rate flux times the reincidence number. Then, the resulting ratio of the reaction products in the flux becomes very high when we compare it to those obtained by the residential time model. Based on the near-surface model, the reactive interactions between the wall near-surface and the wafer near-surface make it possible to relate the etching of the wall materials to side-etching width control. The effects of wall etching on the feature profile control are clarified through the inter-near-surface mechanism in metal etching. The use of an oxygen-free reactor inner wall and a C additive to the source gas are found to be effective for enabling highly selective metal etching with fine features.

ISSN:0734-2101    

DOI:10.1116/1.580979

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

As device geometries continue to shrink below 0.5μm, previously acceptable levels of silicon contamination and lattice damage from energetic ion bombardment in reactive ion etchers are beginning to affect device performance and reliability through increased junction leakage and higher contact resistance. The Applied Materials remote plasma source (RPS), an isotropic chemical downstream etcher, was used to remove surface residues, impurity penetration, and silicon lattice damage to recover a device quality surface. Several diagnostic methods, including transmission electron microscopy, Rutherford backscattering, and x-ray photoelectron spectroscopy, are used to investigate the effectiveness of a controlled silicon etch process in the RPS chamber.

ISSN:0734-2101    

DOI:10.1116/1.580980

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The sticking process ofCl2on the Si(100) surfaces has been studied by employing a molecular-beam method. Initial sticking probabilities,S0,were measured as a function of the incident energy,Ei,and the surface temperature,Ts.TheS0versusEias well asS0versusTscurves were analyzed with a kinetic model, which includes both a direct sticking channel and a precursor-mediated sticking channel. The physisorption lifetimes were measured as a function ofTsto evaluate the depth of the physisorption well and the preexponential factor for the detrapping rate. The potential structure and the intermediate transition state relevant to theCl2sticking on the Si(100) surface were discussed.

ISSN:0734-2101    

DOI:10.1116/1.580981

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Chlorine atom recombination coefficient(γCl)measurements are reported for a variety of surfaces and at a range of surface temperatures. The surfaces include crystalline silicon, quartz, anodized aluminum, tungsten, stainless steel, polycrystalline silicon, and photoresist. Surface temperatures ranged from about−90 °Cup to 85 °C. Measurements were made in a vacuum chamber with chlorine atoms and molecules effusing from an external discharge source as a molecular beam and impacting a selected surface. The incident and reflected beam compositions calculated using a modulated beam mass spectrometer were used to infer the recombination coefficient. At room temperature, the values ofγClranged from below the detection sensitivity (about 0.01) for crystalline silicon to∼0.85for stainless steel. Other surfaces displayed intermediate values between these extremes. For example,γClfor polycrystalline silicon is about 0.2–0.3 at room temperature. All surfaces, except stainless steel, displayed increasing values ofγClas surface temperature was lowered below room temperature, down to the freezing temperature of chlorine(−101 °C).TheγClfor stainless steel appeared to saturate at 0.85 as temperature was lowered. All surfaces displayed decreasing values for the recombination coefficient as surface temperature was raised above room temperature. TheγCldata as a function of temperature were fit to a phenomenological model. The phenomenological model assumes Cl atoms adsorb into a weakly bound physisorbed, state on at least 1 monolayer of strongly bound, chemisorbed chlorine. After adsorption, the model assumes that thermally activated diffusion and atomic recombination occur with a rate that is first order in physisorbed chlorine. Thermal desorption competes with diffusion and reaction, and is also thermally activated. Fits to the data were made, and the physical interpretation of the model parameters is discussed.

ISSN:0734-2101    

DOI:10.1116/1.580982

出版商:American Vacuum Society    

年代:1998

数据来源: AIP