摘要:

The relations between the surface reaction probability β of an atom or a radical in a reactive gas discharge, its diffusive flux to the wall, spatial density profile and temporal density decay during the postdischarge, are examined. Then, the values of β for H,SiH3,andSi2H5on a growinga-Si:H film, andCH3andC2H5on ana-C:H film are derived from the temporal decay of radical densities during the discharge afterglow by using time-resolved threshold ionization mass spectrometry. ForSiH3ona-Si:H,β=0.28±0.03in excellent agreement with previous determinations using other experimental approaches, and forSi2H5,0.1<β<0.3.For H ona-Si:H,0.4<β<1and mostly consists of surface recombination asH2,while the etching probability of Si asSiH4is onlyε≈0.03at 350 K in good agreement with other studies of H reaction kinetics on crystalline silicon. At high dilution ofSiH4inH2the sticking probabilities of Si hydride radicals are affected by the flux of H atoms of hydrogen ions which enhances surface recombination at the expense of sticking. ForCH3orC2H5ona-C:H it is shown that β is not constant during the discharge afterglow, decreasing from about 0.01 down to 0.001. This reveals that chemisorption of these radicals on the H-saturateda-C:H surface is entirely governed by the competition between desorption and creation of active sites by ion bombardment or H atoms. The differences between the surface reaction kinetics ofSiH3ona-Si:H andCH3ona-C:H are discussed within a unified model of precursor-mediated chemisorption.

ISSN:0734-2101    

DOI:10.1116/1.580983

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

To gain insight into surface processes in plasma processing, basic ion beam experiments are performed on two representative polyatomic-ion species: hydrocarbon ions CHx+for deposition processes and fluorocarbon ions CFx+for etching processes(x=1,2,…). A single ion species is extracted from an inductive plasma via a mass filter and directed onto aluminum surfaces at energies100 eV) incidence of both CHx+and CFx+species gives rise to dissociation into smaller fragment ions, probably via electronic excitation.

ISSN:0734-2101    

DOI:10.1116/1.580984

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Anomalous etching, caused by the local charging of a patterned wafer surface immersed in a plasma, is one of the obstacles which must be overcome in plasma processing. We have developed a quantitative argument for the potential control of both the fluxes and the velocity components of charged particles on the wafer in a pulsed radio frequency plasma with a short off-cycle in SF6. We have then used relaxation continuum/Boltzmann equation model to create a phase-space model.

ISSN:0734-2101    

DOI:10.1116/1.580985

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

This article investigates the overall charging of a nonconducting, plane wall (for instance a wafer) in a low pressure inductively coupled plasma. The problem is addressed using a two-dimensional kinetic model for a low pressure inductive discharge. Comparisons to experimental results show good agreement with the charging profiles predicted by the model. It is pointed out that the surface charge profile on a nonconducting wall is determined by the plasma homogeneity and the high energy part of the electron distribution function. An interpretation of the radial profiles of the sheath potential drop and of the surface charge potential in terms of the differential temperature of the electron distribution function in different energy ranges is presented.

ISSN:0734-2101    

DOI:10.1116/1.580986

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Temporally and spatially resolved optical emission, as well as Langmuir and electric probe measurements, were used to investigate the effects of radio frequency (rf) biasing near an electrode in an inductively coupled plasma cell. The plasma source is a modification of the Gaseous Electronics Conference rf Reference Cell. Emission from the atomic argon 750.387 nm transition was observed. With the lower electrode grounded, the optical emission did not exhibit any rf modulations. However, for a constant rf bias power of 9 W at frequencies from 1.695 to 33.9 MHz applied to the lower electrode, various waveforms were observed in the temporal evolution of the optical emission near the electrode as well as in the bulk plasma. Also, for pressures between 0.67 and 13.3 Pa of argon and a rf power of 9 W at a frequency of 2.712 MHz, the oscillations in the optical emission near the biased electrode showed the presheath/sheath region rapidly shrinking with increasing pressure. The dc sheath voltage drop, determined from Langmuir and electric probe measurements, did not exhibit a dependence on the applied rf frequency, but varied nearly linearly with the ratio of the bias power to the power dissipated in the plasma.

ISSN:0734-2101    

DOI:10.1116/1.580987

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The effect of spatial gradients, whether associated with surfaces or otherwise, on charged particle phase-space distribution functions and transport properties is a long-standing problem in the kinetic theory of gases. This article first discusses the necessary ingredients for an accurate kinetic theory analysis of the space–time behavior of electrons in gases and compares the different approaches currently in use. We then focus upon the electrons in a radio-frequency discharge away from the walls, where gradients are weak, and point out that the fundamental kinetic theory of even the boundary-free problem still warrants more careful attention than has been given to it in much of the contemporary literature. We highlighted the importance of careful analysis by presenting results for the first comprehensive “multiterm” solution of Boltzmann’s equation furnishing the complete set of hydrodynamic transport coefficients for electrons in an ac field undergoing ionization and attachment.

ISSN:0734-2101    

DOI:10.1116/1.580989

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Comprehensive simulations of the processing plasmas used in semiconductor fabrication will depend on the availability of basic data for many microscopic processes that occur in the plasma and at the surface. Cross sections for electron collisions, a principal mechanism for producing reactive species in these plasmas, are among the most important such data; however, electron-collision cross sections are difficult to measure, and the available data are, at best, sketchy for the polyatomic feed gases of interest. While computational approaches to obtaining such data are thus potentially of significant value, studies of electron collisions with polyatomic gases at relevant energies are numerically intensive. In this article, we report on the progress we have made in exploiting large-scale distributed-memory parallel computers, consisting of hundreds of interconnected microprocessors, to generate electron-collision cross sections for gases of interest in plasma simulations.

ISSN:0734-2101    

DOI:10.1116/1.580990

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have developed a coupled system of Monte Carlo simulation codes for modeling of electron, ion, and fast neutral kinetics in low pressure, low current discharges. The procedure was tested for ion drift tube data by using different cross-section sets including the recent anisotropic set of Phelps [A. V. Phelps, J. Appl. Phys.76, 747 (1994)]. The code was applied to modeling absolute emission profiles obtained at very high electric field to gas number density ratio, where heavy particle excitation dominates electron excitation by more than two orders of magnitude, and also to an inhomogeneous field experiment of Scott and Phelps [D. A. Scott and A. V. Phelps, Phys. Rev. A43, 3043 (1991)]. The qualitative agreement between the Monte Carlo and experimental results is good, giving confidence in the available models and data for ion and fast neutral transport in gas discharges, and for their interaction with surfaces.

ISSN:0734-2101    

DOI:10.1116/1.580991

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We report the observation of thed 3Πg→a 3ΠuSwan bands of theC2molecule both in absorption and emission in aH2/Ar/CH4microwave discharge plasma. The input mole fraction of methane is varied from 1% to 33%. From the observed absorptions, we calculate the column density of gas phaseC2.The calculated concentration ofC2is higher in discharges containing large fractions of argon than in discharges containing large fractions of hydrogen. These observations are useful in understanding the contribution of theC2molecule to the gas phase chemistry of the microwave plasma-assisted chemical vapor deposition of diamond.

ISSN:0734-2101    

DOI:10.1116/1.580992

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Association of super-advanced electronics technologies (ASET) is a Japanese electronics research and development consortium that was founded on 29 February 1996. The target of the plasma research group in ASET is to make breakthroughs for future dry etching technology by investigating the mechanisms of dry etching scientifically. The plasma research group is investigating plasma diagnostics, plasma generation and its transportation, plasma surface reaction and vapor phase reaction, plasma modeling/simulation directed toward plasma control, and the mechanism of silicon oxide etching in high aspect ratio, narrow contact holes, and will develop a new chemistry, a new plasma source, and a new monitoring method.

ISSN:0734-2101    

DOI:10.1116/1.581003

出版商:American Vacuum Society    

年代:1998

数据来源: AIP