Jyrki Molarius

Summa Semiconductor Oy · Process development

Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated,self-terminating gas–solid reactions, has become the method of choice in semiconductormanufacturing and many other technological areas for depositing thin conformal inorganic mate-rial layers for various applications. ALD has been discovered and developed in...

We present a computational study of spontaneous polarization and piezoelectricity in ScxAl1-xN alloys in the compositional range from x = 0 to x = 0.5, obtained in the context of density functional theory and the Berry-phase theory of electric polarization using large periodic supercells. We report composition-dependent values of piezoelectric coef...

In this chapter, the thin film piezoelectric materials were reviewed from the point of view of RF-BAW technology used in all mobile smart devices. It discusses not only Zinc oxide (ZnO) piezoelectric film but also the materials science of piezoelectric film growth applied for BAW resonators. Chemical mechanical polishing (CMP) is an enabling techno...

The fabrication, electrical characterization and reliability study of copper through-silicon via (TSV) is reported. All the fabrication steps needed in this process have a process temperature < 250°C. The copper TSVs have two distinct features: tapered via profile and partial filling of the vias. Besides the single Kelvin cell TSVs, daisy chains ha...

Contacts to GaAs substrates with n-type epilayers formed by GaAs/Ni/Ge/WN/Au, GaAs/Ni/Ge/Ni/WN/Au and GaAs/Ge/ Ni/WN/Au systems were investigated. Ohmic contacts in these systems were formed by a solid-phase reaction between Ni/Ge and GaAs. Interfacial reaction and electrical properties of these contacts are characterized by backscattering spectrom...

Ti-N films were deposited by reactive ion plating on various substrates. The N/Ti-ratio was systematically varied in order to produce films of varying structure and properties from pure titanium to overstoichiometric TiN. Broad diffraction peaks typical of PVD Ti-N films were found. Metastable ct-titanium was observed over a wide range up to about...

The relationship between microstructure of tungsten thin films and plasma etching properties has been studied. Rutherford backscattering, nuclear reaction analysis 16O(α,α)16O, X-ray diffraction, and resistivity measurements have been used to characterize the sputter deposited films. Independent of deposition pressure, the films were all high densi...

During heat treatment of GaAs there is a tendency for arsenic to evaporate. This process can have deleterious consequences and must be controlled during the annealing of GaAs by using encapsulants. In this work we use a Cr collector to catch the evaporated atoms. This collector is placed on top of GaAs or GaAs/cap during annealing. We survey the ef...

The reaction mechanisms in the Si|Ta|Cu and Si|TaC|Cu metallization systems are discussed based on the experimental results and the assessed ternary Si-Ta-Cu, Si-Ta-C and Ta-C-Cu phase diagrams. The ternary Si-Ta-N and Ta-N-Cu phase diagrams were also assessed in order to compare the thermodynamic properties of the TaC diffusion barriers to more wi...

Three series of Ti-N films with varying nitrogen contents from about 8 to 52 at.% N were deposited by triode ion plating at temperatures of 773, 623 and 373 K, respectively.Marked changes in the structures of the films with decreasing temperature were observed by x-ray diffraction.Stoichiometric δ-TiN which showed (220) preferred orientation at 773...

During thermal annealing of GaAs there is a tendency for arsenic to evaporate. This process can have deleterious consequences and must be controlled during annealing by encapsulants. We survey conducting electrically, sputtered tantalum-based encapsulants as capping materials for thermal annealing of GaAs in the temperature range 550-900-degrees-C....

The growth of high-quality AlN films has been studied by reactive sputtering onto Mo electrodes with Ni, Ti, and TiW seed layers and subsequent integration into thin film bulk acoustic wave resonators. The crystalline structure and morphology of the Mo and c-axis oriented AlN films were found to vary strongly with seed layer material and thickness....

High permittivity oxide thin film capacitors for RF components should be integrated on the chip to form a complete miniaturized module, with other semiconductor or thin film components such as inductors, isolation capacitors, and bias resistors. The quality factor (Q) values of the RF capacitors are strongly dependent on electrode conductivity. Ala...

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IntroductionExperimentalResults and DiscussionConclusions

Interfacial reactions in the Si/TaC/Cu metallization system were investigated by utilizing transmission electron microscopy and a combined kinetic and thermodynamic analysis. The formation of an amorphous Ta[C,O] layer was observed at the TaC/Cu interface at 600 °C. After annealing at the same temperature a thin amorphous layer was detected also at...

The aim of this work was to develop a deposition process for a high-dielectric constant tantalum pentoxide for integrated capacitors. Thin films were deposited reactively on glass wafers using a radio-frequency magnetron sputtering cluster tool at 4 1 various O /Ar flow ratios. By using 2 MeV He backscattering spectroscopy and X-ray diffraction, th...

There have been a number of efforts to develop a model that could be used to predict and to describe phase formation in the case of thin film diffusion couples. In this report, thermodynamic and kinetic frameworks as well as some of the proposed models for interface reactions have been critically reviewed. The following conclusions have been made:...

Piezoelectric zinc oxide films are used in microelectromechanical systems (MEMS) applications, where they can be used in sensors to detect, e.g., pressure or acceleration. Beside sensors, ZnO films are applied in activation devices, where force is needed. Conductive-doped zinc oxide (most often with aluminum) is also used in optoelectronics. Piezoe...

The aim of this work was to evaluate tantalum nitride thin films fabricated using reactive sputtering with adjusted deposition parameters. Thin TaxN films were deposited reactively on Si wafers using reactive RF magnetron sputtering at various N2/Ar gas ratios. The films were investigated by four-point probe sheet resistance measurement, profilomet...

The effect of oxygen on the reactions in the Si/Ta/Cu and Si/TaC/Cu metallization systems was investigated by utilizing the assessed Ta–O binary and the evaluated ternary Ta–C–O phase diagrams together with detailed transmission electron microscopy (TEM) and secondary ion mass spectrometry analyses (SIMS). The presence of some form of amorphous tan...

The reaction mechanisms and related microstructures in the Si/TaC/Cu metallization system have been studied experimentally and theoretically by utilizing ternary Si–Ta–C and Ta–C–Cu phase diagrams as well as activity diagrams calculated at 800 °C. With the help of sheet resistance measurements, Rutherford backscattering spectrometry, x-ray diffract...

An amorphous Ta(O,C)(x) layer was found to form at the TaC/Cu interface in the Si/TaC/Cu metallization system. The formation of the layer was induced by oxygen trapped in the as-deposited films, since on the basis of thermodynamic evaluation of the ternary Ta-C-O system, the dissociation of the TaC layer and the formation of the Ta2O5 and graphite...

The effect of oxygen on the reaction mechanisms in the Si/Ta/Cu metallization system was studied experimentally and by utilizing the thermodynamically assessed Ta–O binary system. It was presented that an interfacial tantalum oxide was formed between Cu and Ta and that it established an additional barrier layer for Cu diffusion. The formation of ad...

We present results for a ZnO based filters for the mobile Extended GSM (EGSM) Rx band centered at 942.5 MHz. Our devices are of the SMR type. The acoustical isolation from the glass substrate is achieved by a tungsten-silicon dioxide quarter wavelength mirror. Resonators with an effective coupling coefficient of 0.236 and Q~800 have been achieved....

The reactions in the Si/TaC/Cu and Si/Ta 2 N/Cu metallisation systems were investigated by x-ray diffraction, Rutherford backscattering, scanning electron microscope and the transmission electron microscopy. The results were then combined with the assessed ternary Si-Ta-C, Ta-C-Cu, Si-Ta-N and Ta-N-Cu phase diagrams. It was found that both barriers...

The reaction mechanisms in the Si/Ta/Cu metallization system and their relation to the microstructure of thin films are discussed on the basis of experimental results and the assessment of the ternary Si–Ta–Cu phase diagram at 700 °C. With the help of sheet resistance measurements, Rutherford backscattering spectroscopy, x-ray diffraction, a scanni...

The reactions in the Si/Ta/Cu metallization system produced by the sputtering process were investigated by means of sheet resistance measurements, X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM) and optical microscopy. In particular, the reaction sequence was emphasized. The reaction mechani...

The use of a scanning tunneling microscope (STM) for microroughness measurements of polished silicon wafers has been restricted to well cleaned surfaces. In this work it is shown that the water bound to the native oxide layer, not the oxide layer itself, causes the difficulties associated with STM work. Using prolonged scanning with a high bias vol...

There is clear need to apply copperfor metallisation in integrated mcircuits and micropackaging, but its usage has been hindered by chemical incompatibility of copper with silicon. However, tantalum-based diffusion barriers, like tantalum nitrides (Ta2N and TaN), seem to provide a feasible solution. In this study the effects of the reactive r.f spu...

The radial distribution of grown-in microdefects in eight Czochralski-grown silicon crystals was measured by counting the flow pattern (FP) defects revealed by preferential etching. At the center of the crystal, the FP-defect density increased from 5.2 to 6.7 × 105 1/cm3, when the pulling speed was increased from 0.8 to 1.1 mm/min. The magnitude of...

The structural properties of epitaxial Si1 − xGex layers formed by high-dose germanium implantation have been studied. Transmission electron microscopy (TEM) and Rutherford backscattering channeling (RBS-C) were employed to evaluate the annealing behavior of radiation damage. The depth profiles of impurities and dopants of O, C, F, and Ge were meas...

(100) Si samples, amorphized by implanting with 50, 70 and 100 keV 74Ge+ ions at doses of the order of 1 × 1016cm−2, have been recrystallized by rapid thermal annealing (RTA) with different temperature-time (T−t) combinations. Monte Carlo calculations using TRIM-91 computer program were performed to estimate the depth of amorphized regions, implant...

Titanium nitride was reactively sputtered on silicon, silicon dioxide and sapphire wafers. Taguchi-method was used for the experimental design. TiN- and TiN/Al-films were patterned and etched in reactive ion etcher. Electrical and structural measurements of these TiN-films will be reported.

As-deposited tungsten silicide films have typically high resistivity and require annealing to lower the resistivity to practical values. Rapid thermal annealing (RTA) has emerged as the main method because impurity diffusion in silicides is extremely fast. In this study we have explored the possibility of reducing the required thermal budget for tu...

During thermal annealing of there is a tendency for arsenic to evaporate. This process can have deleterious consequences and must be controlled during annealing by encapsulants. We survey conducting electrically, sputtered tantalum‐based encapsulants as capping materials for thermal annealing of in the temperature range 550–900°C. Conducting cappin...

The loss of arsenic during reaction between GaAs (single crystal and thin film) and palladium (Pd) is reported. A chromium thin film was used as a collector for evaporating material during heat treatment. The amount of arsenic on the chromium collector was measured using backscattering spectrometry. It was found that more arsenic evaporates from th...

Arsenic has a tendency to evaporate during high temperature annealing of GaAs. This process can have deleterious consequences for electrical properties of the contact to GaAs and must be controlled during annealing by encapsulants. It would also be advantageous if this cap could be integrated in the contact metallization scheme for GaAs. In this wo...

Arsenic has a tendency to evaporate during high temperature annealing of GaAs. This process can have deleterious consequences for electrical properties of the contact to GaAs and must be controlled during annealing by encapsulants. It would also be advantageous if this cap could be integrated in the contact metallization scheme for GaAs. In this wo...

Amorphous Ta–Si–N thin films of a wide range of compositions were prepared by rf reactive sputtering of a Ta 5 Si 3 target in a N 2 /Ar plasma. The relationship between films’ composition and resistivity is reported. All obtained films were tested as diffusion barriers between Al and Si. Backscattering spectrometry combined with cross‐sectional tra...

The design of a metal/semiconductor contact must meet requirements of an electronic nature (I(V) characteristic) and of an atomic nature (metallurgical stability). A conceptual scheme is described that embodies these two requirements in two distinct elements of the contact. Empirically developed contact schemes now used in silicon-based devices con...

An ohmic contact to n-type GaAs of the configuration GaAs/Ni/Ge/W ₆₀N₄₀/Au has been investigated. The contacting layer in this metallization is formed by a solid-state reaction between Ni/Ge and GaAs. Backscattering spectrometry and electrical measurements show that the interposed W-N layer acts as an excellent diffusion barri...

Indium oxide (In 2 O 3 ) films were prepared by reactive rf sputtering of an In target in O 2 /Ar plasma. We have investigated the application of these films as diffusion barriers in 〈Si〉/In 2 O 3 /Al and 〈Si〉/TiSi 2.3 /In 2 O 3 /Al metallizations. Scanning transmission electron microscopy together with energy dispersive analysis of x ray of cross‐...

Electrical measurements on shallow n+ p junction diodes demonstrate that In2O3 films about 80 nm thick prepared by reactive sputtering of an indium target in an O2-Ar plasma are excellent diffusion barriers between aluminum and silicon for annealing at up to 650°C for 15 min. The performance of In2O3 barriers is compared with other conducting oxide...

The stability of r.f.-sputtered vanadium boride thin films is investigated for application as diffusion barriers between silicon and aluminum layers. The composition of VBx barriers is uniform in depth and varies from x = 1.5 to x = 2.7 depending on the sputtering power. The phase VB2 is present at all compositions. Metallurgical interactions in th...

We have deposited a thin-film of W60N40 as encapsulant to reduce the loss of arsenic from GaAs when this films of palladium (27 nm) and GaAs (55 nm) deposited on an inert substrate react with each other on thermal annealing in an argon ambient. Results from Rutherford backscattering spectrometry, scanning electron microscopy, and four-point probe s...

The principles of reactive triode ion plating will be briefly described and examples of new nitride coatings deposited on cutting tools will be given. The coatings discussed include TiN, (Ti, Al)N and ZrN. Their relative order of performance in turning tests will be discussed and microstructural details will be studied by means of scanning electron...

Triode ion plated ZrN and (Ti,Al)N thin films were deposited on high‐speed steel and stainless‐steel substrates. The samples studied in this work were selected on the basis of their cutting performance in turning tests as reported earlier. In cutting tests (Ti,Al)N and ZrN both showed significantly increased wear life as compared to standard TiN. X...

Metallic composites with specifically defined properties may be produced by various techniques. Thus, for example, high temperature materials can be covered by MCrAIY coatings by means of low pressure plasma spraying. These coatings offer considerable advantages with regard to high temperature oxidation resistance and generally lead to a longer use...

Int. Conf. High Nitrogen Steels, HNS 88. Lille, France, 18 - 20 May 1988

Three binary nitrides of the refractory materials titanium, zirconium and niobium and ternary (Ti, Al)N as well as quaternary (Ti, Al, V)N coatings were deposited by reactive triode ion plating on powder metallurgically produced high-speed steel (PM-HSS) inserts. The coated tools were then tested by dry turning of hardened and tempered AISI 4140 st...

One effective way of enhancing ionization in ion plating is to use a negatively biased hot filament. Such triode ion-plating systems are currently used in industry to deposit wear-resistant thin film coatings on cutting tools, for example. In this work the effect of a negatively biased hot electron-emitting filament on ionization efficiency is stud...

A hot work tool wear test and friction coefficient determinations have been used to investigate how TiN- and TiAlN-coated tools start to fail under simulated hot-working conditions. The coatings were deposited by triode ion plating onto H13 steel discs representing the tool. In the test an induction-heated steel bar representing the workpiece recip...

The scratch test method was used to study the effect of nitrogen content on the critical normal force of TiN films on stainless steel and high speed steel substrates. The critical normal force decreased strongly with decreasing nitrogen concentration, which may be explained by the corresponding decrease in the elastic modulus which has recently bee...

Thin titanium nitride (TiN) and zirconium nitride (ZrN) films containing excess nitrogen up to 59 and 63 at. % N, respectively, were deposited on austenitic stainless‐steel substrates by reactive triode ion plating at about 823 K. The film structure and surface chemistry were studied using x‐ray diffraction, scanning Auger spectroscopy, and electro...

The ductility of high speed steel (HSS) coated with a thin layer of titanium nitride (TiN) was studied. The testing method was based on using a conventional Charpy impact testing hammer. The impact energy required to break the TiN-coated steel square rods used as test pieces was recorded. Uncoated HSS rods were used as a reference. The effects of t...

Ti–N coatings containing from 29 to 53 at. % nitrogen were deposited on high‐speed steel inserts by triode ion plating. The cutting performance of the inserts was compared in a standard turning test and distinct differences were observed between the individual coatings. No direct relation between the thickness and cutting performance was found alth...

The formation of nitrogen-rich surface layers in the ionitriding of steel and titanium at low pressures was studied. The phases, structures and morphologies formed when the process parameters were varied were analyzed by X-ray diffraction, optical and scanning electron microscopy, and the scanning Auger microprobe technique. The structure and morph...

Thin titanium nitride (TiN) and zirconium nitride (ZrN) films containing excess nitrogen up to 62 and 65 at. % N, respectively, were deposited on austenitic stainless steel sheet substrates by triode ion plating at about 823 K. The nitrogen content of the films was determined using the nuclear resonance broadening technique based on the 15N(p,αγ)12...

Auger‐depth profiling experiments of mechanically thinned samples were carried out with TiN films deposited on n‐type (100)silicon wafers, stainless steel, and high‐speed steel (HSS). The films were deposited between 700 and 800 K by triode ion plating based on the electron beam evaporation of titanium in an atmosphere containing both nitrogen and...

Thin Ti–N films were prepared by reactive triode ion plating. The nitrogen content was varied from 17 to 50 at. % nitrogen. Two series of experiments corresponding to differing values of deposition rate and cathode current density were carried out. The nitrogen depth profiles were analyzed using the nuclear resonance broadening (NRB) technique. The...

2nd Int. Conf. on Plasma Surface Engineering, PSE '90. Garmisch-Partenkirchen 10 - 14 Sept. 1990, 14

Advanced Ceramics and PM-materials. Hämeenlinna, 23 - 25 Sept. 1990, 105

Book of abstracts (abstrakti, esitelmä ja posteri) The manufacturing of Nb-doped SrTiO3 and different heterostructures will be investigated. The methods include thin film techniques (sputtering and ALD - atomic layer deposition) - and powder metallurgical (P/M) methods. ALD is based on saturating surface reactions of alternately supplied precursor...