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We report on the properties of Aluminum Scandium Nitride (AlScN) thin films deposited by pulsed-DC co-sputtering. We present the impact of the nitrogen-to-argon gas ratio on the crystal growth orientation, film stress, surface roughness, scandium concentration, and deposition rate of 760-860 nm thick AlScN thin films on Ti/Pt (111). We utilize the optimized process conditions from this study to deposit thin layers of AlScN and to explore the nucleation and orientation of thin AlScN layers on Ti/Pt (111). We report on the ferroelectric properties of 100 nm thick AlScN materials.

The discovery of enhanced piezoelectricity in solid solutions of AlN and ScN is certainly one of the most important events in piezoelectric MEMS. As compared to pure AlN, it brought a crucial factor 2 to 3 improvement in a number of figures of merit governing the performance of MEMS devices. The aim of this contribution is to give a short overview on actual topics in processing, properties, and applications in RF filters and sensors.

Scandium doped aluminium nitride (ScAlN) gained much attention during last years, since its piezoelectric response is much enlarged as compared to pure AlN films. Above 30% Sc the films are of high interest for piezoMEMS sensing and actuation, ultrasound generation, as well as energy harvesting applications. In this work, piezo-performance uniformity maps are presented for 20% and 33% Sc containing films, sputter deposited on 200-mm wafers. Furthermore, we employ a new method to determine the electro-mechanical coupling k(t)(2). Coupling results for various Sc/(Sc+Al) concentration (0, 6, 20, 26, 33%) are shown. In addition, the dielectric constant epsilon(r) and dielectric loss tan delta, and the transversal and the longitudinal piezoelectric coefficients, e(31,f) and d(33,f,) were measured. The wafers show a high with-in-wafer uniformity (1 sigma uniformity < 2% for Sc20Al80N and < 1% for Sc33Al67N). The highest coupling k(t)(2) = 21.2% was achieved for a 33% Sc film. The presented Al-Sc property-uniformity maps provide a good foundation for ScAlN based MEMS device design and manufacturing.

Partial substitution of aluminium by scandium in the wurtzite structure of aluminium nitride (AlN) leads to a large increase of the piezoelectric response by more than a factor of 2. Therefore, aluminium scandium nitride (ASN) thin films attracted much attention to improve piezoelectric MEMS devices such as RF filters, sensors, micro actuators and energy harvesting devices. In this work, process-microstructure-property relationships of ASN thin films containing up to 42% Sc were investigated. Like AlN thin films, ASN films are sputter deposited at 300–350°C with pulsed DC powered magnetrons. The influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response was investigated in order to achieve optimal piezoelectric coefficients up to high Sc concentrations. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) were used to analyse the quality of c-axis texture. The films showed exclusively (002) texture with rocking-curve widths in the range of 1.3–2° (FHWM). The films were further analysed by scanning electron microscopy (SEM). The Sc content was determined by energy-dispersive X-ray spectroscopy (EDX). A good compositional homogeneity in the range of 0.5–1 at.% was achieved between border and centre of 200-mm wafers. So far, we obtained ASN films with transversal piezoelectric coefficients of up to e31,f = −2.77 C/m2, which is a factor 2.6 higher than in pure AlN thin films.

The enhancement of the electromechanical coupling coefficient caused by Sc substitution in AlN-based piezoelectric MEMS devices can be exploited successfully only if the dielectric losses remain confined to low values. While the magnitude of the piezoelectric activity in Al 1-x Sc x N thin films has been described widely in the literature, the impact of the Sc content on the loss tangent has not been studied extensively. In this work we discuss the dissipation factor obtained for x=0.095 and x=0.3 on Mo and Pt bottom electrodes, for full capacitor stacks deposited with an EVATEC Clusterline®200–II PVD tool equipped with single alloy targets 304mm in diameter.

Scandium doped aluminium nitride (ScAlN) exhibits an overall greater piezoelectric response as compared to pure aluminium nitride (AlN). Films with a Sc/(Sc+Al)content above 30% or more are of high interest for MEMS sensing and actuation, ultrasound generation, and energy harvesting applications. In this work we present the uniformity of the material properties of (002)-axis oriented $\text{Sc}_{33}\text{A}1_{67}\text{N}$ films deposited on 200-mm wafers. For this purpose, the dielectric constant $\varepsilon_{\text{r}}$ and dielectric loss tanδ, as well as the transversal and the longitudinal piezoelectric coefficients, $e_{31,\text{f}}$ and $d_{33,\text{f}}$ , were measured. Wafers exhibiting a great in-wafer uniformity of the piezoelectric coefficients up to $d_{33,\text{f}}=11.8\text{pm}/\text{V}$ and $e_{31,\text{f}}=-2.3 \text{C}/\text{m}^{2}$ were obtained ( $1\sigma$ uniformity $\approx$ 1-2%). The results are very promising for the fabrication and designing of devices, as well as for volume manufacturing.

Aluminium scandium nitride (ASN) exhibits a largely enhanced piezoelectric response as compared to aluminium nitride (AlN), which makes it an upcoming piezoelectric material for use in next generation RF filters, sensors, actuators and energy harvesting devices. In this work, process-microstructure-property relationships of such sputtered ASN films containing up to 42 at% Sc were investigated. Hereby, the influence of the process parameters on the film structure, the intrinsic stress and the piezoelectric response were carefully investigated. A high piezoelectric response (e(31),(f) = -2.67 C/m(2) and d(33,f) = 10.3 pm/V) was measured for films with 42 at% and 34 at% Sc, respectively. The results are very promising towards industrial applications.

Recent literature has focused on improving piezoelectric coupling coefficients by alloying aluminum nitride (AlN) with scandium (Sc). Akiyama et al. showed the highest d_33 piezoelectric coefficient increase of >4x at a 41% Sc substitution for Al. Thus far, studies mainly focus on material measurements such as x-ray diffraction or piezoelectric constants to assess the material quality. Although these measurements are useful to assess the improvement in the piezoelectric performance of the material, they do not address improvements in the figure-of-merit (FOM) of resonators (i.e., coupling coefficient times quality factor). Resonator structures are needed to directly extract these key performance parameters for film assessment. Fabrication integration, however, must be minimized to avoid obscuring film performance by extrinsic device effects.

Recent literature has focused on improving piezoelectric coupling coefficients by alloying aluminum nitride (AlN) with scandium (Sc). Akiyama et al. showed the highest piezoelectric coefficient increase of nearly four times for a 41% Sc substitution for Al. Thus far, studies mainly focus on material measurements such as x-ray diffraction or piezoelectric constants to assess the material quality. Although these measurements are useful to assess the improvement in the piezoelectric performance of the material, they do not address changes in the coupling coefficient and quality factor. Resonator structures are needed to directly extract these key performance parameters for film assessment. Fabrication integration, however, must be minimized to avoid obscuring film performance by extrinsic device effects. In this work, we assess a film evaluation tool using contour mode resonators (CMRs) to directly extract resonator performance for film comparison. Resonators formed from AlN, Sc 0.06 Al 0.94 N, and Sc 0.125 Al 0.875 N films are compared to demonstrate the method.

Aluminium scandium nitride (Al 1−x Sc x N) with its strongly enhanced piezoelectric response is the upcoming piezoelectric material of choice in next generation RF filters, sensors, actuators and energy harvesting devices. This paper will concentrate on the deposition technology for Al 1−x Sc x N films with high Sc content. Films with Sc concentrations close to 43 at% have been grown on 200-mm substrates using a cluster type sputter deposition tool. The piezoelectric response will be discussed and correlated with the deposition parameters and film structural properties. The steps required to deliver a high-volume production solution for high Sc concentration will be described.

Sputter deposited Al(1-x)ScxN thin films with a Sc content from x = 0 to 43 at% are investigated by electron microscopy in order to study and explain the formation and growth of abnormally oriented grains (AOG). It is found that the latter did not nucleate at the interface with the substrate, but at high energy grain boundaries, at which systematically higher Sc concentrations are detected. The AOGs are thus formed during the growth of c-textured grains. They grow faster than those, and finally protrude from the c-textured film surface, having at their end a pyramidal shape with three facets of a hexagonal wurtzite crystal: one (0001) and two (112 over bar 0) facets. Process conditions favoring less compact grain boundaries, and lower surface diffusion across grain boundaries are thought to promote nucleation of AOGs. Finally, a 4-step growth mechanism explaining the nucleation from a Sc-rich complexion and proliferation of AOGs with increasing film thickness is proposed.

Organic passivated silicon wafers, composite substrates such as silicon on glass or Fan-out Wafer-Level Package (FOWLP) technology all pose new challenges for UBM and RDL processes [1]-[5]. Materials used in these substrates must be adequately degassed for subsequent plasma processing under vacuum but their heat-sensitive nature necessitates careful thermal management. Selecting the proper technology for each individual step enables the definition of a high yield process, minimizing contamination from the organic materials. This paper discusses the preferred degas principles for different substrates and applications. Temperature simulation data and experimental results are presented for various heating methods including single wafer and batch processes. It illustrates the effectiveness of an atmospheric batch degasser for removal of volatile water and organic compounds (VC) at moderate temperatures below 150°C. The results will be compared with standard vacuum degas technologies and the resulting contact resistance (Rc) values after subsequent low temperature ICP etch will be reported. The paper also addresses the etch process requirements to ensure efficient pumping of remaining volatile contaminants, the required temperature management of the substrates and the particle containment and cleanliness of the process environment.

In this work high quality ferroelectric PZT films have been prepared in-situ by hot RF magnetron sputtering. 200 mm wafer were coated with PZT films of 1 μm and 2 μm thickness at sputter rates of 45 nm/min in a high volume production sputtering tool. The films were grown on oxidized Si substrates prepared either with sputtered Ti/TiO2/Pt, sputtered Ti/TiO2/Pt/TiO2 or evaporated Ti/Pt bottom electrodes at substrate holder temperatures in the range from 550 °C to 700 °C. At these temperatures, the material nucleates in the requisite piezoelectric perovskite phase without need of an additional post annealing treatment.The films were investigated with respect to their chemical composition and their crystallographic, piezoelectric and dielectric properties. At an intermediate chuck temperature of 600 °C the PZT thin films were characterized by a minimum volume fraction of secondary nonpiezoelectric phases. A Zr/(Zr+Ti) ratio of 0.53 has been achieved matching the morphotropic phase boundary. By improving the deposition process and poling procedure, a notable high e31,f coefficient of -17.3 C/m2 has been obtained. The corresponding longitudinal piezoelectric constant was determined to have an effective longitudinal piezoelectric coefficient d33,f of 160 pm/V.

In the present study, high quality PZT films were deposited by RF magnetron sputtering onto 200mm thermally oxidized silicon substrates at substrate holder temperatures (T h ) between 550°C – 700°C using PbO-enriched single ceramic PZT targets. The high substrate temperatures used here allowed direct growth of the piezoelectric perovskite phase and rendered an additional post annealing step unnecessary. The PZT layers were grown on (111) oriented Pt bottom electrodes, which were covered by thin TiO 2 seed layers. Over the temperature range investigated here, there was a monotonic reduction in the Pb/(Zr+Ti) atomic ratio with increasing Th; the stoichiometry of the morphotropic phase boundary Pb/(Zr+Ti) ∼ 1 and Zr/(Zr+Ti) ∼ 0.53 was obtained at 700°C. However, the XRD patterns indicated that the films prepared at intermediate T h = 600°C exhibited the minimum volume fraction of the spurious pyrochlore phase in addition to tetragonal and rhombohedral piezoelectric PZT structures. All PZT films contained mixed (110), (111) and (200) crystallographic orientations whose relative intensities were significantly influenced by T h . The highest piezoelectric coefficients d 33,f = 120 pm/V and e 31,f = −12.6 C/m2 were obtained for the films deposited at T h = 600°C.

Ferroelectric PZT thin films have been in-situ deposited on 8-inch wafers by a high volume production sputtering tool. The films were grown on oxidized Si substrates covered either with sputtered Ti/TiO 2 /Pt, sputtered Ti/TiO 2 /Pt/TiO 2 or evaporated Ti/Pt bottom electrodes and investigated with respect to their chemical composition, crystallographic and dielectric properties. Moreover the d 33,f and the e 31,f coefficients have been examined. At a chuck temperature of 600 °C the intended chemical composition is achieved to nucleate and grow the ferroelectric perovskite phase with a minimum of secondary non-piezoelectric phases. A Zr/(Zr+Ti) ratio of 0.53 has been achieved matching to the morphotropic phase boundary. Notable high e 31,f and d 33,f coefficients of 101 pm/V and −13.8 C/m2, respectively, have been obtained

A spin coating technique for the 100 micron cover layer for Blu-Ray Disc production has been developed. The process includes a controlled manipulation of the viscosity of the lacquer with heat and UV light during spin coating. Stability and cost efficiency, two vital criteria for mass production, have been considered. Keywords: Optical Storage, Spin Coating, Blu-Ray Disc 1. INTRODUCTION With the Blu-Ray Disc, the 3rd generation of optical storage media is today appearing on the consumer market. While moulding and sputtering processes for substrate preparation and functional layer application are very similar to the currently used processes for CD and DVD production, the reliable and cost efficient application of a highly precise, 100 P m thick optical layer on top of the information layer is the challenging production step for this format. Since the very beginning of the Blu-Ray Disc, there have been two techniques discussed between media developers, equipment manufacturers, consumables suppliers and media producers for the 100 P m cover layer production: Spin coating of a UV curable resin is seen as one candidate, bonding a cover layer sheet stands as the alternative. Looking at the foil bonding technology one has to distinguish between PSA-sheet bonding and UV-resin bonding of a thin polycarbonate sheet. The PSA sheet bonding is a proven method which gives excellent cover layer thickness homogeneity. The PSA adhesive is supplied together with the foil and the manufacturing process of the disc is relatively simple. But due to the high cost per sheet it can only be seen as a start-up technology for the Blu-Ray Disc media family. It is not seen as an attractive solution for economic mass production because the cost per sheet cannot be reduced significantly. The foil bonding technology using UV-resin combines a spinning process and a bonding process similar to standard DVD bonding technology. A UV-curable resin is applied onto the BD substrate, spread over the disc in a spin coating process and combined with the foil, preferably in a vacuum bonding process, and finally the system is cured under UV irradiation. Like PSA-sheet bonding, foil bonding technology us ing UV-resin is a practical way to go. In both cases it is the quality of the foil which significantly de termines the quality of the cover layer. Using a spin coating process

Evaporated and sputtered tungstentrioxide (WO 3 ) films were bombarded with 300-keV He + and Ar + ions, respectively, and the resulting changes of the real [n(λ)] and imaginary [k(λ)] parts of the refractive index in the visible to infrared range of the wavelength λ were determined in situ. The primary effect of an ion-induced blue coloration is directly reflected by an absorption band centered at 1100 nm, which is growing for increasing ion fluences and exponentially approaching saturation. This monotonous increase of absorption is accompanied by changes of n(λ) with a characteristic fixed point n(λ*) independent of the ion bombardment, while for λ>λ* an ion-induced increase and for λ

Optical Discs are currently finding new mass applications in computing, web usage and entertainment. In only 5 years the CD-R consumption has grown from basically zero to over billion discs this year; the video DVD is very successful in the US and now starting in other regions; video recording on disc is on the horizon. Thin film deposition is among the key production technologies for the production of all of these formats. While in established fields such as CD-R production the emphasis is on productivity, other formats from DVD-9, SACD or the higher density rewritable formats require innovation in materials and process technology. This paper takes a closer look at these challenges for the different formats and discusses the current status of thin film processing of Optical Disc formats.