As Extreme Ultra Violet lithography (EUVL) is becoming adopted into manufacturing, there is an ongoing need to identify and improve the EUV mask multilayer properties that impact reflectivity. Key properties include the roughness and inter-diffusion depth at the Mo-Si interfaces. During mask usage, on exposure to EUV, the interfaces are impacted during thermal cycling, so interfacial stability is key. We report on the use of X-ray reflectivity (XRR) to probe the interfacial depth and roughness of Mo/Si multilayers deposited via secondary ion beam deposition (IBD). We confirm top-surface roughness by AFM. We measure minimal impact of the underlying substrate on top-surface roughness of Mo-Si multilayer stacks. Mo and Si single-layer roughness are shown to be primarily dependent on deposition angle; with minimal roughness at intermediate angles and significant deterioration beyond a deposition angle of about 60 degrees. We use this angular dependence to systematically vary the interfacial roughness and monitor the impact on the XRR measurement. We demonstrate that XRR, with attention to the Fourier Transform, may also be used to quantify the inter-diffusion depth at the Mo-Si interfaces. We measure inter-diffusion depths of 0.5 - 1.8nm. A simulated model is developed, incorporating both interfacial depth and roughness, and the experimental data are compared with this model. The model could be applied to quantify the impact on the interfaces of: beam energy and flux; incidence angles; gas species and pressure; interfacial treatments; thermal treatment; or mask usage.

For future nodes, TaN-based absorber layers on EUV mask-blanks, may need to be replaced with thinner layers of new material systems. Ni and Co based materials are promising material candidates owing to their high EUV absorption. Ion Beam Etching (IBE) is being explored as an option for patterning these metallic systems that are hard to etch by Reactive Ion Etch. In this work we expand our initial work on the IBE of Ni absorber films to include the role of etch beam energy and alternative etch-masks for both Ni and Co based films. We present experimental film level data such as etch uniformity, angular-dependent etch rates, and surface roughness. We extend the modeling of IBE of line-space patterns, to narrower line widths and various etch-mask materials vis-a-vis side wall angle and CD fidelity, both as a function of beam energy and angle of etch.

Development progress and roadmap, for high-reflective Mo/Si multilayers for EUV mask-blanks, are reviewed. We outline the state-of-the-art in low-defect-density secondary ion beam deposition (IBD), and ongoing hardware development for performance improvement and high-volume manufacturing. We further discuss extension of ion beam technology to later steps in the EUV mask manufacturing: deposition of highly-uniform 2.5 - 3nm Ru capping layers; and patterning of novel Ni absorber structures. IBD-deposited Ru films are demonstrated with uniformity of 0.7% 3 sigma over a 188mm diameter area. By x-ray reflection with Cu K alpha radiation, we measure a film density of 12.4 g/cm(3), and a roughness of less than 1.0nm. Deposition rates of similar to 1 - 7 nm/min are demonstrated, implying a capping layer deposition time of 20 seconds - 3 minutes.. For advanced absorber patterning, we discuss Argon ion beam etch (IBE) of Ni films. Ni and Ru IBE etch rates of similar to 8 - 80 nm/min are demonstrated, implying absorber etch times of similar to 30 seconds - 5 minutes. IBE Ni: Ru etch selectivity is 1:1 to 1.3:1, so Ru is not a 'stopping layer', etch depth must be controlled by time, and Ni uniformity is a requirement. IBE Ni:Photoresist etch selectivity is 0.8:1 to 1.6:1. We simulate the IBE absorber pattern definition for mask features of half-pitch 96nm (24nm at wafer level). Ion beam incidence angle can be optimized to maintain critical dimension within 6% of the pre-etch value.

High purity soft-magnetic cobalt films were grown by cyclic thermal–chemical vapor deposition (CVD) process using dicobalt octacarbonyl as metal organic precursor, at an optimum substrate temperature of 125 °C. Physical, electrical, and magnetic properties of CVD grown Co films were compared with physical vapor deposition (PVD) grown Co films. Films were analyzed by x-ray photoelectron spectroscopy, x-ray diffraction, four-point resistivity probe, scanning electron microscopy, hysteresis loop tracer, vibrating sample magnetometry, and atomic force microscopy. The authors observed in-plane uniaxial magnetic anisotropy in the CVD-grown cobalt film with cyclic pulse-purge technique. Typical film properties obtained were low volume resistivity (<20 μΩ cm), >99.5% purity, 100% growth linearity as a function of number of cycles, good step coverage in a SiO2 trench, low coercivity (<15 Oe), high saturation magnetization (∼1.5 T), and low root-mean-square surface roughness (7 Å). Compared to our PVD films, CVD Co films are magnetically softer, smoother, and less textured.

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 character of this process is demonstrated. The effects of key processing parameters including temperature, pulse time, and plasma power are investigated in terms of growth rate, stress, crystal morphology, chemical, electrical, and optical properties. Stoichiometric thin films with growth rates of 0.4–0.5 Å/cycle were achieved. Low electrical resistivity (<300 μΩ cm), high mass density (>4 g/cm3), low stress (<250 MPa), and >85% step coverage for aspect ratio of 10:1 were realized. Wet chemical etch data show robust chemical stability of the film. The properties of the film have been optimized to satisfy industrial viability as a Ruthenium (Ru) preseed liner in potential data storage and TSV applications.

A magnetron sputtered AlN buffer layer process has been developed using a batch PVD system capable of substrate temperatures above 800C. Epitaxial growth has been demonstrated and the film is suitable as a template for subsequent GaN growth to be utilized for LED and high power Si devices.

A novel method has been developed for synthesis of multi-element alloys by planetary magnetron sputter deposition techniques. The alloy is formed by alternating depositions of uniform ultra-thin component layers at a fraction of a mono-atomic layer, or atomic layer lamination. A minimal layer thickness of down to 0.1Å can be obtained such that the components can be mixed at atomic level forming a homogeneous alloy. A typical example is demonstrated here for the synthesis of Co x Fe 1−x alloys by alternating depositions of Co and Fe layers from pure element targets. The compositional dependence of the laminates basically reconstructs the well-known Slater-Pauling curve of the bulk Co x Fe 1−x alloys. The laminates exhibit a clear structural transition at Co compositions between 60 and 80 % from fcc phase to bcc phase, characteristic of bulk Co x Fe 1−x alloys. The novel atomic layer lamination has been successfully applied to the composition optimization of CoFe pinned layer with a best pinning strength at Co 70 Fe 30 for exchange biased spin-valve films.

In this work, we report a novel approach to facilitate the phase transformation, namely the introduction of ultrathin Ru and Cr nanolayers inside the PtMn layer. The concept is to bury one or more very thin (<1 monolayer) Ru or Cr layers in the PtMn at some distance from the interface. The effect of these insertion layers is to aid the FCC to FCT transformation by suppressing the constraining effect from the interface. Experimental results show an enhancement of the exchange bias field by adding these ultrathin insertion layers. The enhancement of the exchange bias field can be up to 10% compared to the structure without the insertion layer. From these results, it can be seen that significant exchange bias field enhancement can indeed be obtained with as little as 2 Å of Ru insertion at 10 Å from the interface. Similar results have been obtained with 1 Å Cr insertion at the same PtMn layer position. These results illustrate the potential of nano-lamination of antiferromagnets as an avenue toward creation of novel spin valve and spintronic materials.

NiFe films with different thicknesses as were etched under several Ar+-ion-beam energy conditions. The functional dependence of the saturation magnetic flux on the remaining NiFe film thickness was used to determine the magnetic dead layer (MDL) thickness (tMDL). A tMDL of 24Å was generated in the NiFe films etched using a 1200-eV Ar+-ion beam. A dual-energy (1200eV∕400eV) etching process was found to be effective in reducing tMDL to 16Å without much throughput loss. A combination of optimal etching depth with an appropriate ion-beam energy is necessary in minimizing tMDL. The mechanism of MDL formation is discussed in terms of oxidation and surface roughening of the NiFe films.

FeCo films and their lamination with ultrathin NiFe layers down to 5Å were deposited using dc magnetron sputtering techniques. Soft magnetic FeCo films were obtained at an optimal target power of 500W and an optimal deposition pressure of 2mTorr with high saturation flux density, Bsat>2.4T, and low easy-axis coercivity, Hce⩽15Oe, and hard-axis coercivity, Hch⩽3Oe, at a film thickness of 2000Å. While the magnetostriction remains at ∼4×10−6 the stress was further optimized by applying substrate bias at a controlled level ⩽50V without sacrificing film magnetic softness.

In this paper, we present data comparing three different in-situ beam treatment (smoothing) techniques for enhancement of GMR properties. The three techniques were radio-frequency bias (RFB), gas cluster ion beam (GCIB), and ion beam (IB). All three were optimized for maximum enhancement of properties and resulted in an increase of GMR of about 0.5 to 1% (> 13.5% to > 14.5%) and a reduction in interlayer coupling of about 15 to 30 Oe (5 Oe to -25 Oe) when treating the CoFe/Cu interface of a synthetic pinned bottom spin valve. Smoothing the Ru/CoFe interface resulted in enhancement of GMR, but no change in the interlayer coupling. The optimum conditions for all three techniques corresponded to ion bombardment energies in the range of 10-60 eV. For RFB, the substrate bias voltage was optimized at 60 V, for IB, the extraction energy was 30 eV, and for GCIB, the equivalent energy/atom was in the same range. Our results indicate that all three smoothing methods are effective in improving the GMR properties with no fundamental advantage of any particular technique.

In this article, we present data on the critical dependence of the magnetic, electrical and microstructural properties of spin-valves (SV) on seed-layer thicknesses. The SV structure is: seed-layer/PtMn 140 /spl Aring//CoFe 16 /Ru 8.5 /spl Aring/ /CoFe 21 /spl Aring/ /Cu 20 /spl Aring//CoFe 12 /spl Aring//NiFe 30 /spl Aring//Ta 30 /spl Aring/, where the seed layer is NiFeCr-CoFe or NiFeCr/NiFe. As the thickness of the bilayer seed layer is varied, it is found that a critical thickness boundary exists across which the film properties are radically different. The GMR ratio increased from 7% to 14% (a 100% change), the sheet resistance decreased by about 4 ohms/square and the crystalline texture transitioned from weak to extremely strong (111) texture. The critical thickness boundary is at a combined thickness of 37 /spl Aring/ to 40 /spl Aring/. These results suggest a mechanism at the boundary between NiFeCr and CoFe during film growth. A better lattice match between NiFeCr-CoFe, for example, NiFeCr 33 /spl Aring/ and CoFe 7 /spl Aring/, generates a strong (111) texture, which enhances the MR% as compared to NiFeCr 33 /spl Aring//CoFe 6 /spl Aring/. The H/sub 50/ (the field at 50% MR) also exceeds 2000 Oe. This also indicates enhancement of the PtMn fcc to fct transition based on the specifically combined thicknesses of NiFeCr-CoFe. With the NiFeCr-NiFe seed layer, the critical thickness effect is not observed within these thickness ranges.

We have studied the effect of low energy (20–100eV) Ar bombardment on the surface roughness of (111) oriented Cu films both experimentally and by molecular-dynamics simulations. We found, in good agreement between the experiments and the simulations, that a significant reduction of the surface roughness can be induced at all energies in this range. However, the angle of incidence for optimal smoothing depends strongly on the ion energy, whereby the lower energies used are more efficient at near normal incidence, and the higher energies are more efficient for off-normal angles (e.g., >45degrees).