ICMCTF2015 Session B2-1: CVD Coatings and Technologies

Monday, April 20, 2015 10:00 AM in Room Golden West

Monday Morning

Time Period MoM Sessions | Abstract Timeline | Topic B Sessions | Time Periods | Topics | ICMCTF2015 Schedule

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10:00 AM B2-1-1 Chemical Vapor Deposition of Diamond Coatings on Cu-W Alloys
Boqian Wan, Yuanshi Li, Qiaoqin Yang, Xiaoyu Sun (University of Saskatchewan, Canada)
Due to the large difference of thermal expansion coefficient between diamond and copper, diamond thin films on Cu substrate surfer from cracking and delamination. In this study, three Cu-W alloys containing 30 ~ 50 wt % Cu were synthesized by powder metallurgy and used as substrates for diamond coating in a microwave plasma enhanced chemical vapor deposition reactor. Optical microscopy, scanning electron microscopy, Raman spectroscopy, X-ray diffraction, synchrotron X-ray absorption spectroscopy, and indentation testing were used to investigate the morphology, composition, microstructures and adhesion of diamond films. The results show that the adhesion of diamond coatings on these Cu-W alloy substrates are much higher than on Cu substrate. The adhesion improvement is primarily attributed to the reduced thermal expansion coefficient mismatch and the formation of WC phase on the sub-surface of the substrate which strengthens the coating-substrate interfacial bonding.
10:20 AM B2-1-2 Advanced CVD-Diamond Coatings on Cutting Tools for Machining of CFRP
Michael Woda, Biljana Mesic, Martin Frank, Christoph Schiffers, Werner Kölker, Oliver Lemmer (CemeCon AG, Germany)
Composite materials - carbon reinforced fiber plastics (CFRP) and CFRP stacked with aluminum and titanium - are used in aerospace and automotive industry as an important and emerging material. Milling and drilling of the workpiece material CFRP is facing new challenges for high-end cutting tools including fiber delamination, parasitic chatter-marks and rapid tool wear due to the abrasive behavior of CFRP. Diamond coated tools made of cemented carbides are well suited to enable sufficient tool performance. In particular multilayer nano-crystalline diamond layers grown by Hot Filament CVD (HF-CVD) with very smooth surfaces and excellent adhesion reveal beneficial properties for CFRP cutting applications.
10:40 AM B2-1-3 Surface Reactions during Ammonia-Plasma-Assisted Atomic LayerDeposition of Silicon Nitride
Sumit Agarwal, Rafaiel Ovanesyan (Colorado School of Mines, USA); Dennis Hausmann (Lam Research Corporation, USA)

The advent of FinFETs with high-aspect-ratio 3-D geometries increases demands on conformality of SiNx films. These stringent requirements on conformality and low thermal budget can be simultaneously met usingatomic layer deposition (ALD). While there are a few reports in the literature that show that SiNxcan beconformally deposited via ALD at <400 °C, these films are not sufficiently dense to serve as moisture oroxidation barriers. Hence, improvements in this area are needed via a fundamental understanding of the surfacereaction processes. Recently, we have developed a novel ALD processes for the growth of Si3N4 thin films using trisilylamine (Si(NH3)3, TSA) and silane precursors, and an NH3 plasma. This ALD process with these precursors providesdense films with a conformal coverage over aspect ratios typical for the above applications; 10:1. To understand theunderlying film growth mechanism, the specific surface reactions involved during each half-reaction cycle of thisALD process were monitored with in situ attenuated total reflection Fourier transform infrared (ATR-FTIR)spectroscopy. ZnSe internal reflection crystals were used as substrates since ZnSe is transparent in the infrared upto 700 cm-1. This spectral range, combined with the high sensitivity achieved with ATR-FTIR spectroscopy,allows us to identify and monitor in real time the different surface species generated and consumed due tosequential exposure of the growth surface to Si-containing precursors and an NH3 plasma. The vibrational modesthat were monitored include the surface SiHx (x = 1,2,3)and NHx(x = 1,2)stretching modes in the 2100 and 3400 cm-1 region, respectively, NHx(x = 1,2)bending modes in the 1100-1600 cm-1 region, and Si3N4 phonon modes, which appear in the 800-900 cm-1 region. Further, these films were extensively characterized using a suite of ex situ diagnostic tools such as ellipsometry, transmission electron microscopy, and Rutherford backscattering.

11:00 AM B2-1-4 Microstructural Investigation of CVD Titanium Aluminium Nitride Multilayer Coatings
Samira Mousavi Nik (Chalmers University of Technology, Sweden); Dirk Stiens, Thorsten Manns, Sakari Ruppi (Walter AG, Germany); Mats Halvarsson (Chalmers University of Technology, Sweden)
Coatings of alumina and TiN are widely used in metal cutting applications. Alumina is an excellent material due to its chemical inertness and hot-hardness and is generally deposited by CVD (Chemical Vapour Deposition). Various phases, such as alpha, kappa and gamma can be produced. With the addition of Al to TiN, the material is capable of forming an alumina scale for oxidation resistance, and improved wear behaviour is observed in many applications. Such TiAlN coatings are commonly produced with different PVD (Physical Vapour Deposition) techniques. More recently also CVD has been used for deposition of TiAlN coatings. The desired fcc phase of TiAlN is metastable and can be produced by CVD processes using ammonia (NH3) as a precursor. The maximum Al/Al+Ti ratio in TiAlN is around 0.7 for PVD, while values up to 0.9 or even higher is possible by CVD. This is thought to be beneficial for the oxidation resistance and performance of such coatings in metal cutting applications.

In the present work CVD TiAlN multilayer coatings were produced on standard WC/Co cemented carbide substrates. The coatings were characterized by X-ray diffraction (XRD), scanning and trans­mis­sion electron microscopy (STEM and TEM) and energy dispersive X-ray analysis (EDX). The detailed microstructure, such as grain size, grain shape and possible twinning is reported. The texture and presence of local epitaxy between layers are described using XRD pole figures and electron diffraction techniques, such as selected area electron diffraction (SAED) and convergent beam electron diffraction (CBED). The local composition changes are described using EDX linescans and maps. The possible grain boundary changes in TiAlN due to prolonged deposition times are also investigated.

11:20 AM B2-1-5 Amorphous Phase Mixed α-Al2O3 Hard Coatings by Plasma-Enhanced Chemical Vapor Deposition
Naoyuki Iwasaki, Sho Tatsuoka, Kenichi Sato, Kenji Yamaguchi (Mitsubishi Materials Corporation, Japan)
Chemical Vapor Deposition (CVD) method has been used for the industrial production of wear resistant coatings on cutting tools and Al2O3 coatings have been widely used to maintain high hardness and excellent oxidation resistance under such a severe cutting condition. We have reported that growth mechanism of amorphous phase mixed α-Al2O3 thin films deposited by thermal CVD using gas mixtures of trimethylaluminium, as aluminum precursor and O2 instead of conventional gas mixtures, such as AlCl3 and CO2 [1].

In this work, we investigated growth mechanism of amorphous phase mixed α-Al2O3 thin films deposited by Plasma-Enhanced Metal Organic CVD (MOCVD) using gas mixtures of trimethylaluminium, as aluminum precursor and O2. Due to the plasma activation, high growth rate of 15μm/h for amorphous phase mixed α-Al2O3 and 45μm/h for amorphous-Al2O3 are obtained. Plasma-Enhanced MOCVD Al2O3 film shows unique lenticular morphology and much higher deposition rate makes more amorphous-like Al2O3.

[1] S. Tatsuoka, et al., ICMCTF2014, B2-12.

11:40 AM B2-1-6 Novel Transparent Silicon Nitride Film Synthesis at Room Temperature by Radical and Plasma Control with RF/UHF Hybrid Plasma Processes
JeonG Han (Sungkyunkwan University, Korea); B.B. Sahu, KyungSik Shin (Sungkyunkwan University, Republic of Korea); Kenji Ishikawa, M. Hori (Nagoya University, Japan)

Hydrogenated silicon nitride (SiNx: H) films have shown many useful industrial applications. Conventionally, PECVD method offers the possibility of producing high-quality dielectrics at relatively low temperatures (200-400ºC) in comparison to thermal oxidation or low-pressure CVD, which take place at temperatures approaching several hundreds to few thousands of ºC. Due to the utilization of process gases like silane (SiH4) and ammonia (NH3), there is the issue of the incorporation of high content of hydrogen in the films that can affect the characteristics of the SiNx: H films, such as high residual stress, Si-H bond concentration, etc. This drawback together with the high deposition temperature can also limit the deposition of films on polymer substrates. Moreover, low temperature SiNx: Hfilm deposition with low hydrogen content by PECVD is of special interest for barrier films for flexible substrates. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to very high frequency (VHF) and in the range of microwave.

High quality SiNx: H films with very low content of hydrogen are prepared at low temperature using the mixture of N2/SiH4/NH3, by utilizing ultrahigh frequency plasma (UHF) source at 320 MHz along with a low frequency RF CCP source at 13.56 MHz. The primary goal of the former one is to assist and enhance the dissociation of nitrogen radicals along with the RF. Thus, one of the major goals of this work is also to investigate dissociation and control of the nitrogen radicals during the deposition process and their role in the film property and structure control, using radical monitor diagnostic by vacuum ultraviolet absorption spectroscopy (VUVAS). Moreover, different operating parameters can affect deposition rates along with other physical and optical properties of the film. To investigate the radical and plasma formation and their control for the growth of the film, we have systematically used other plasma diagnostic tools like optical emission spectroscopy (OES), RF compensated Langmuir probe (LP) and ICCD camera diagnostics, at different process conditions.

This paper will discuss on low temperature and high rate synthesis of high quality and transparent SiNx: H films using the RF/UHF hybrid plasma process with integrated plasma diagnostics. The films properties such as refractive index, composition, and microstructure are discussed with the analyzed data using Ellipsometry, FTIR and UV-visible spectroscopy, etc.
Time Period MoM Sessions | Abstract Timeline | Topic B Sessions | Time Periods | Topics | ICMCTF2015 Schedule