Charles Richard Guarnieri

Optical properties of amorphous SixGe1−x(H) alloys prepared by R.F. Glow discharge

Amorphous alloys of Si and Ge have been prepared over the entire composition range by r.f. plasma decomposition of mixed gases of SiH4 and GeH4. The optical absorption edge is found to have a linear dependence on alloy composition given by: Eg = 0.95 + 0.70x (eV).

Internal stress and elasticity of synthetic diamond films

The internal tensile stress in polycrystalline diamond films deposited on silicon substrates has been measured from 100 to 700 K by a vibrating‐membrane method. The stress increases strongly with temperature, in a manner consistent with the elastic accommodation of the differential thermal strain between diamond and silicon. The results indicate that the films contain a tensile growth stress of about 500 MPa at the deposition temperature of 1123 K. Derived values of the biaxial elastic modulus fall in the range 730–850 GPa.

Enhanced nucleation and growth of diamond on SiC by plasma enhanced chemical vapor deposition using thin metal films

Presented is a method for growing crystalline diamond films by plasma enhanced chemical vapor deposition without the need for seeding with diamond particles. Instead, diamond nucleation and growth is ‘‘catalyzed’’ by a thin metal film which has been either abraded or deposited onto a SiC coated substrate. In the first experiment Fe, Cu, Ti, Nb, Mo, and Ni were abraded onto a SiC surface resulting in varying degrees of diamond nucleation and growth. In the second experiment, Fe films with thickness varying from 5 to 80 A were evaporated onto the SiC. Although the 5 A Fe film did not influence the initial nucleation and growth rate, greater thicknesses did. Preliminary studies of Fe on Si have not shown this effect.Presented is a method for growing crystalline diamond films by plasma enhanced chemical vapor deposition without the need for seeding with diamond particles. Instead, diamond nucleation and growth is ‘‘catalyzed’’ by a thin metal film which has been either abraded or deposited onto a SiC coated substrate. In the first experiment Fe, Cu, Ti, Nb, Mo, and Ni were abraded onto a SiC surface resulting in varying degrees of diamond nucleation and growth. In the second experiment, Fe films with thickness varying from 5 to 80 A were evaporated onto the SiC. Although the 5 A Fe film did not influence the initial nucleation and growth rate, greater thicknesses did. Preliminary studies of Fe on Si have not shown this effect.

Fast photoconductor coupled liquid‐crystal light valve

Short low‐energy pulses of laser light have been used to switch spots on a liquid crystal (LC) through a coupled photoconductive film of glow‐discharge‐produced amorphous Si (GD/a‐Si). The a‐Si responds rapidly to a light pulse, yet retains sufficient photoconductivity in the slow portion of the decay to match the slower response time of the LC. Spots have been written with laser pulses 10 μs long, about 10−3 the response time of the LC, and with a pulse energy of 1–10 μJ/cm2, less than 10−4 the energy required for thermal writing.

Reaction of niobium with diamond films

Abstract The reaction of niobium with diamond films leads to the formation of Nb 2 C at 700°C and to that of a carbon deficient NbC at 900°C. Both processes seem to be dominated by grain boundary diffusion, so that the growths do not proceed in smooth layers parallel to the substrate, but seemingly homogeneously throughout the thickness of the reacting metal (then Nb 2 C) film. The results of backscattering and X-ray diffraction analyses are discussed in terms of what is known about these two compounds with respect to their thermodynamic, kinetic and structural characteristics. The formation of ordered phases with carbon deficiency such as Nb 4 C 3 , or Nb 6 C 5 , and nucleation processes resulting from this are presumed to hinder the formation of near-stoichiometric NbC.

Across wafer etch rate uniformity in a high density plasma reactor: Experiment and modeling

A study of silicon oxide etch rate uniformity in a high density, rf inductively coupled system with an rf capacitively coupled substrate electrode is presented. By introducing spatial variation of rf coupling to the substrate, etch rate uniformity across the wafer can be altered from a profile that is ∼20% higher in the center to one that is ∼10% lower in the center. The effect of spatially varying rf coupling impedance to the substrate is dependent on substrate resistance. Predicted etch rate profiles are obtained with a two‐dimensional analytic model of the plasma source that is coupled to an equivalent circuit discretization of the electrode assembly, substrate, and sheath. Model results compare favorably with experimental measurements.

Detection of particle traps by spatially resolved optical emission spectroscopy over grooved electrodes in radio frequency discharges

Isophotal maps of spatially resolved optical emission signal from neutral, excited argon are used to detect regions of enhanced electron induced excitation over topographically contoured, rf‐coupled electrodes in argon discharges. By aligning a lengthwise groove in one such electrode with the optical axis, it is possible to monitor the plasma homogeneity inside, along and above the groove. The use of a grooved electrode, previously shown to ‘‘trap’’ particles, is also shown to produce enhanced excitation in localized, well defined regions, depending on the discharge pressure and sheath thickness. At low and intermediate pressures (<100 mTorr) a single ‘‘bright’’ spot is noted above the center of the groove. Higher pressure operation causes two bright spots to form, symmetrically placed, close to the groove sidewalls. Laser light scattering is used to simultaneously detect the coordinates of suspended particles during the discharge. A correlation is noted between these bright spots and the location of trap...

Novel Si-based composite thin films for 193/157-nm attenuated phase-shift mask (APSM) applications

We have developed a novel Si-based composite thin film for attenuated phase shift mask(APSM) applications at 193/157 nm wavelength. The fabrication involved sputtering deposition, either with dual target or a single composite target. At 193 nm, these thin films show tunable optical transmission and good stability against long term radiation, common chemicals used to strip photoresist, and exhibit good dry etch selectivity to quartz. Specifically, a film with initial transmission of 5.72%,the total increase oftransmission was 0.27% for doses up to 5.4 kJ/cm2. Also, the increase of transmission was 0.19% after 60 mm of cleaning treatment in acid based solution (H2S04H20210:1 at 95°C). The dry etch selectivity over fused quartz was greater than 5:1. The transmission of the films at 193 nm can be tuned from 0 % to 20 % by varying the thin film composition, process gas flow and composition, and deposition pressure. This wide transmission window provides the possible extension down to 157 nm wavelength.

High Density Amorphous Carbon Films and the Preparation of Diamond Membranes for X-Ray Lithography

Abstract Trends in recently reported data on high sp 3 fraction (up to 85%), non-hydrogenated amorphous diamond-like carbon films deposited by ion beam sputtering and laser vaporization are examined. The degree of diamond-like film character is found to depend upon the deposition technique as well as the substrate temperature and thermal diffusivity. The data suggest that the combination of incident particle kinetic energy and surface accommodation determine the physical properties of the resultant film. A model is proposed for the condensation of energetic carbon atoms into diamond-like films in which a quench-type surface accommodation mechanism is operative. Diamond Membranes are being developed for x-ray lithographic masks. Typically, these 1-3 micron thick membrane films are deposited onto silicon substrates using microwave driven plasmas. To obtain smooth films with uniform tensile stress, spray and electrophoretic deposition of 0.1 micron diamond seeds were used to control the initial nucleation and growth of the diamond films. The films have a room temperature tensile stress of 25 to 125 MPa. The temperature dependence of the stress is due to the tensile growth stress of the diamond film and the thermal stress of the diamond-silicon layer structure. The films have a biaxial modulus of 800 GPa. X-ray lithography masks have been made and used to print patterns with x-rays from a synchrotron source.