Alan V. Hayes

Diamond-like carbon films deposited using a broad, uniform ion beam from an RF inductively coupled CH4-plasma source

Abstract Diamond-like carbon (DLC) films with 12–25 GPa hardnesses and 3–400 nm thicknesses were deposited on silicon, Al2O3-TiC substrates, and permalloy coated with Al2O3-TiC substrates using a broad, uniform ion beam from an RF, inductively coupled, CH4-plasma (ICP) source (30 cm). The deposition process represents a significant advance in the ability to: (1) accomplish the desired balance between mechanical, optical and electrical properties by utilizing different RF powers to vary the plasma density and electron temperature; (2) improve step coverage when the film is deposited on patterned or rough substrates; (3) carry out reliable fault-free and long duration operation. The RF inductively coupled ion beam source can be operated with highly reactive ion beam processes for long periods of time. In particular, the source demonstrates excellent compatibility with pure oxygen. The ability of an O2-plasma to etch hydrocarbon precipitates allowed us to utilize this procedure as an effective “on-line” ion source clean-up. Highly reproducible deposition rates (

Low-temperature (≤200 °C) plasma enhanced atomic layer deposition of dense titanium nitride thin films

Titanium nitride (TiN) has been widely used in the semiconductor industry for its diffusion barrier and seed layer properties. However, it has seen limited adoption in other industries in which low temperature (<200 °C) deposition is a requirement. Examples of applications which require low temperature deposition are seed layers for magnetic materials in the data storage (DS) industry and seed and diffusion barrier layers for through-silicon-vias (TSV) in the MEMS industry. This paper describes a low temperature TiN process with appropriate electrical, chemical, and structural properties based on plasma enhanced atomic layer deposition method that is suitable for the DS and MEMS industries. It uses tetrakis-(dimethylamino)-titanium as an organometallic precursor and hydrogen (H2) as co-reactant. This process was developed in a Veeco NEXUS™ chemical vapor deposition tool. The tool uses a substrate rf-biased configuration with a grounded gas shower head. In this paper, the complimentary and self-limiting ch...

Field electron emission from diamond-like carbon films deposited using RF inductively coupled CH4-plasma source

Abstract Diamond-like carbon (DLC) films 4–400 nm thick were deposited on conductive n -Si and metal substrates using direct ion beam deposition from an RF inductively coupled CH 4 -plasma (ICP) source. The field electron emission of the films was examined as a function of deposition conditions and post-deposition surface modification by Ni ultrathin coatings. Electrical properties of the films were studied as well. A specially designed high vacuum scanning tunnelling-field emission microscope was employed for simultaneous mapping of the topography, work function and local field electron emission intensity. Stable, low voltage emission was observed after the emission electric field/current activation process. The activation mechanism was probably the formation of conductive channels in the films to supply electrons for emission from low work function surface areas. Deposition of ultrathin metal coatings on the DLC films reduced both the effective barrier height and the field emission threshold. The DLC films surface coated with ultrathin Ni films resulted in electron emission at fields as low as 20–25 V μm −1 . It was shown that DLC films with thicknesses in the range 5–15 nm demonstrated efficient field emission long-term stability. The results are interpreted based on the reduced electrical resistivity of nanometer scale thick films, and deviation of resistivity over the surface.

Ion beam deposition of diamond-like carbon from an r.f. inductively coupled CH4-plasma source

Abstract In this paper, we describe a robust process for depositing diamond-like carbon (DLC) films from an r.f. inductively coupled CH4-plasma source (18 cm in diameter). This process represents a significant improvement in ability to carry out reliable fault-free and long duration operation. A pure Maxwellian distribution of discharge electrons (homogeneity) and a wide range of electron temperatures are important attributes of the r.f. plasma source. By variation of r.f. power the composition and plasma density were optimized to minimize the source contamination and provide enhanced deposition stability and reproducibility. Beam energy was varied in the range 100–900 eV to obtain different combinations of sp 3 sp 2 ratio and level of hydrogenation. Hard coatings with high electrical resistivity and moderate stress were deposited on the silicon, silicon dioxide, glass, and Al2O3TiC substrates. Deposition rate and coatings thickness ranges were 10–40 nm/min and 5–1000 nm, respectively. The deposition uniformity was within 3% over 16.5 cm.

Modeling the EUV multilayer deposition process on EUV blanks

Extreme ultraviolet lithography (EUVL) is the leading next generation lithography (NGL) technology to succeed optical lithography at the 22 nm node and beyond. EUVL requires a low defect density reflective mask blank, which is considered to be the most critical technology gap for commercialization of the technology. At the SEMATECH Mask Blank Development Center (MBDC), research on defect reduction of EUV mask blanks is being pursued using the Veeco Nexus deposition tool. Its defect performance is one of the factors limiting the availability of defect-free EUVL mask blanks. SEMATECH has identified better understanding of the physics of the deposition process as one of the keys to improving the defect performance of Nexus tools. SEMATECH is therefore undertaking an effort to model the physics of the tool backed with an experimental program to characterize the process. The goal is to be able to predict defect performance and defect improvement to direct new tool design. In this paper, we present the results of simulating the deposition rate and uniformity of deposited multilayers and growth of the multilayer on a given defect profile.

High resolution energy analyzer for broad ion beam characterization

Characterization of the ion energy distribution function (IEDF) of low energy high current density ion beams by conventional retarding field and deflection type energy analyzers is limited due to finite ion beam emittance and beam space charge spreading inside the analyzer. These deficiencies are, to a large extent, overcome with the recent development of the variable-focusing retarding field energy analyzer (RFEA), which has a cylindrical focusing electrode preceding the planar retarding grid. The principal concept of this analyzer is conversion of a divergent charged particle beam into a quasiparallel beam before analyzing it by the planar retarding field. This allows analysis of the beam particle total kinetic energy distribution with greatly improved energy resolution. Whereas this concept was first applied to analyze 5-10 keV pulsed electron beams, the present authors have adapted it to analyze the energy distribution of a low energy (<or=1 KeV) broad ion beam. In this paper we describe the RFEA design, which was modified from the original, mainly as required by the specifics of broad ion beam energy analysis, and the device experimental characterization and modeling results. Among the modifications, an orifice electrode placed in front of the RFEA provides better spatial resolution of the broad ion beam ion optics emission region and reduces the beam plasma density in the vicinity of analyzer entry. An electron repeller grid placed in front of the RFEA collector was found critical for suppressing secondary electrons, both those incoming to the collector and those released from its surface, and improved energy spectrum measurement repeatability and accuracy. The use of finer mesh single- and double-grid retarding structures reduces the retarding grid lens effect and improves the analyzer energy resolution and accuracy of the measured spectrum mean energy. However, additional analyzer component and configuration improvements did not further change the analyzed IEDF shape or mean energy value. This led us to conclude that the optimized analyzer construction provides an energy resolution considerably narrower than the investigated ion beam energy spectrum full width at half maximum, and the derived energy spectrum is an objective and accurate representation of the analyzed broad ion beam energy distribution characteristics. A quantitative study of the focusing voltage and retarding grid field effects based on the experimental data and modeling results have supported this conclusion.

THIRTY-FIVE CENTIMETER DIAMETER RADIO FREQUENCY ION-BEAM SOURCE

A 35 cm diam inductively coupled rf ion source and its applications for material processing is described. This is the largest commercial rf ion-beam source presently available for ion-beam etching and deposition. It has been used to generate beams of different ions (Ne+, Ar+, Kr+, Xe+, O2+, Cl2+, CH4+,…) at 50–1000 eV of ion energy and corresponding beam currents of 0.15–1.5 A. A presentation of the ion source operation characteristics, along with performance results for various etching and deposition applications are given. Etch uniformities of less than 3% for etch diameters of up to 250 mm are obtained. Etch rates in excess of 100 nm/min for NiFe or silicon dioxide are achievable.

Reactive ion beam etching of lithium tantalate and its application for pyroelectric infrared detectors

Abstract The properties of reactive ion beam etching (RIBE) of single crystalline lithium tantalate (LiTaO 3 ) and photoresist are reported, with particular attention given to the dependence on the gas flow, the ion beam current, the accelerating voltage as well as the angle of incidence. For the experiments a filamentless r.f. ion beam source and gas mixtures containing C 2 F 6 , CF 4 , Ar and O 2 were applied. Compared with Ar ion beam etching (IBE) the LiTaO 3 /photoresist etch rate selectivity was found to be three times higher. High selective RIBE of LiTaO 3 and photoresist is an efficient process for the production of one- and two-dimensional pyroelectric IR detectors: The thickness of a LiTaO 3 wafer patterned with photoresist must be reduced by etching by about 10–15 μm.

Recent advances in Veeco’s radio frequency ion sources for ion beam materials processing applications (abstract)

In this article we describe an advanced inductively coupled plasma ion source being developed at Veeco for applications in data storage and active optical device fabrication. The new source design minimizes rf capacitive coupling. Capacitive coupling is responsible for erosion of the quartz discharge chamber and high transverse ion energies. Suppression of capacitive coupling, however, can be problematic for some applications due to the fact that, without it, conductive coatings that shield the transfer of inductive power to the plasma can accumulate inside the source. The authors have developed a simple and unique protective device that when installed on the quartz hardware effectively inhibits rf losses in the deposited films, greatly extending the quartz maintenance cycle and overcoming the above problem. Reduction of capacitive coupling is achieved using a slotted Faraday shield inserted between the low-frequency 1.8 MHz rf antenna and the plasma. It is found that the rf power loss to this shield is e...

Ion beam deposition of permanent magnet layers for liftoff processes

Thin film permanent magnet layers of Cr/CoCrPt were prepared by ion beam deposition in a Veeco IBD-350 tool. The magnetic properties were measured as a function of deposition angle, deposition energy, assist energy, and the underlayer and permanent magnet thicknesses. It was found that higher deposition energies and angles (from normal) resulted in larger coercivities. Increasing the assist energy also helped increase the coercivity. The coercivities were in the range of 1400–2100 Oe depending on the deposition conditions, for a Cr-50 A/CoCrPt-250 A film. The squareness, S (the ratio of remnant magnetization to saturation magnetization) and Mrt (remnant magnetization and film thickness product) for these films were about 0.85 and 1.3 memu/cm2, respectively. It was found that underlayers of Cr as thin as 25 A could be used, without significant degradation of magnetic properties. The coercivity had a broad peak between 100 and 200 A of CoCrPt, above which the coercivity gradually decreased. θ–2θ x-ray diffr...