Fabrication and Characterization of FeNiCr Matrix-TiC Composite for Polishing CVD Diamond Film

Dynamic friction polishing （DFP） is one of the most promising methods appropriate for polishing CVD diamond film with high efficiency and low cost. By this method CVD diamond film is polished through being simply pressed against a metal disc rotating at a high speed utilizing the thermochemical reaction occurring as a result of dynamic friction between them in the atmosphere. However, the relatively soft materials such as stainless steel, cast iron and nickel alloy widely used for polishing CVD diamond film are easy to wear and adhere to diamond film surface, which may further lead to low efficiency and poor polishing quality. In this paper, FeNiCr matrix-TiC composite used as grinding wheel for polishing CVD diamond film was obtained by combination of mechanical alloying （MA） and spark plasma sintering （SPS）. The process of ball milling, composition, density, hardness, high-temperature oxidation resistance and wear resistance of the sintered piece were analyzed. The results show that TiC was introduced in MA-SPS process and had good combination with FeNiCr matrix and even distribution in the matrix. The density of composite can be improved by mechanical alloying. The FeNiCr matrix-TiC composite obtained at 1273 K was found to be superior to at 1173 K sinterin8 in hardness, high-temperature oxidation resistance and wearability. These properties are more favorable than SUS304 for the preparation of high-performance grinding wheel for polishing CVD diamond film.

A CVD diamond film detector for pulsed proton detection

A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection efficiency of the detector increases with increasing electric field intensity and reaches to 9.44% at 5 V/μm with the charge collection distance of 15.9 μm. The relationship between the sensitivity of the detector and proton energy is consistent with the Monte Carlo （MC） simulation result. Its plasma time for a pulse with 4.85×10^5 protons is 1l.2ns. The dose threshold for onset of damage under 9MeV proton irradiation in the detector is about 10^13 cm^-2. All of the results show that a CVD diamond detector has fast time response and high radiation hardness, and can be used in pulsed proton detection.

Optical and electronic performances of CVD diamond film andits applications in radiation detectors

The outstanding properties of CVD diamond film such as electronic, optical, thermal and mechanical and the high radiation hardness have made it an ideal candidate material for radiation detectors in severe environments. Fabrication of ＇detector grade＇ CVD diamond films and development of CVD diamond detectors have been leading edge subjects. Micro-strip gas chamber （MSGC） fabricated on CVD diamond substrate would overcome the charge-up effect and the substrate instability, which has been a hotspot in the research of gas detectors.

Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature—Part I Simulation of CVD diamond film growth under Joe-Badgwell-Hauge model

The growth of (100} oriented CVD (Chemical Vapor Deposition) diamond film under Joe-Badgwell-Hauge (J-B-H) model is simulated at atomic scale by using revised KMC (Kinetic Monte Carlo) method. The results show that: (1) under Joe's model, the growth mechanism from single carbon species is suitable for the growth of (100) oriented CVD diamond film in low temperature; (2) the deposition rate and surface roughness (Rq) under Joe's model are influenced intensively by temperature (Ta) and not evident bymass fraction W of atom chlorine; (3)the surface roughness increases with the deposition rate, i.e. the film quality becomes worse with elevated temperature, in agreement with Grujicic's prediction; (4) the simulation results cannot make sure the role of single carbon insertion.

Atomic scale KMC simulation of {100} oriented CVD diamond film growth under low substrate temperature-Part Ⅱ Simulation of CVD diamond film growth in C-H system and in Cl-containing systems

The growth of {100}-oriented CVD diamond film under two modifications ofJ-B-H model at low substrate temperatures was simulated by using a revised KMC method at atomicscale. The results were compared both in Cl-containing systems and in C-H system as follows: (1)Substrate temperature can produce an important effect both on film deposition rate and on surfaceroughness; (2) Aomic Cl takes an active role for the growth of diamond film at low temperatures; (3){100}-oriented diamond film cannot deposit under single carbon insertion mechanism, which disagreeswith the predictions before; (4) The explanation of the exact role of atomic Cl is not provided inthe simulation results.

A MONTE CARLO SIMULATION OF THE CVD DIAMOND FILM

A Monte Carlo algorithm has been developed by the authors to simulate the chemical vapor deposition (CVD) processes of diamond films. The method considers both the diffusion and the incorporation of the growth radicals on the growing surface in simulating the evolution of the morphology and microstructure. The calculation of configuration energy is used to determine the orientation of adsorbed growth radicals. The effect of processing variables such as nucleation density and substrate temperature on the morphology and microstructure is discussed. It is found that competitive characteristic and coarsening effect exist in the simulation results, which agree with the experimental observations.

A review on polishing technology of large area free-standing CVD diamond films

Recently,with the rapid development of chemical vapor deposition(CVD)technology,large area free-standing CVD diamond films have been produced successfully.However,the coarse grain size on the surface and the non-uniform thickness of unprocessed CVD diamond films make it difficult to meet the application requirement.The current study evaluates several existing polishing methods for CVD diamond films,including mechanical polishing,chemical mechanical polishing and tribochemical polishing technology.

The glass roller cutter made of CVD diamond film

As a cutting tool,diamond films made by chemical vapor deposition(CVD) outperformed polycrystalline diamond(PCD) sintered under ultrahigh pressure.For example,the longevity of the CVD tools may be 2～5 times that of PCD inserts.In addition,the former cutting paths are strainghter with less chipping on the edge.However,there have been no report on CVD diamond films that were used as a roller scriber for splitting large glass panels.Our research demonstrated that the CVD diamond film could concentrate the energy in a smaller area(about 1/4),so the glass compressed by the tip of the diamond film was under a larger tensile stress in perpendicular to the direction of compression.The tensile stress then initiated the microcracks that were more in line with the direction of the compression. The reason that CVD diamond film could concentrate the compressive stress was due to its 100%diamond content.The high diamond content could allow the tip to be polished sharper.In contrast,the PCD cutting tip contained micro grains of cobalt that were softer than glass.As a result,the compressional stress was spreading out due to the larger area of contact.Consequently,the microcracks initiated at the PCD tip were random and they might not propagate along the direction of cutting.

C-H-F氛围下金刚石薄膜的低温CVD生长过程分析

基于第一性原理的密度泛函理论对C-H-F氛围下低温CVD金刚石薄膜的生长过程进行仿真分析,计算H、F原子在氢终止金刚石表面发生萃取反应的吸附能、反应热与反应能垒,并分析CF_(3)、CF_(2)、CF 3种生长基团在带有活性位点基底上的吸附。结果表明:与H原子相比,F原子更容易在氢终止金刚石表面萃出H,并以HF形式脱附,且在C-H-F氛围下有利于在低温时产生更多的活性位点;CF_(3)、CF_(2)、CF基团在吸附后的结构和吸附能绝对值都更有利于金刚石相的生成,适当提高CF_(3)、CF_(2)、CF基团的浓度有助于实现金刚石相的更高速率生长。

Growth behavior of CVD diamond films with enhanced electron field emission properties over a wide range of experimental parameters

In this study, diamond films were synthesized on silicon substrates by microwave plasma enhanced chemical vapor deposition（CVD） over a wide range of experimental parameters. The effects of the microwave power,CH;/H;ratio and gas pressure on the morphology, growth rate, composition, and quality of diamond films were investigated by means of scanning electron microscope（SEM）, X-ray diffraction（XRD）, Raman spectroscopy and X-ray photoelectron spectroscopy（XPS）. A rise of microwave power can lead to an increasing pyrolysis of hydrogen and methane, so that the microcrystalline diamond film could be synthesized at low CH;/H;levels. Gas pressure has similar effect in changing the morphology of diamond films, and high gas pressure also results in dramatically increased grain size. However,diamond film is deteriorated at high CH;/H;ratio due to the abundant graphite content including in the films. Under an extreme condition of high microwave power of 10 kW and high CH;concentration, a hybrid film composed of diamond/graphite was successfully formed in the absence of N;or Ar,which is different from other reports. This composite structure has an excellent measured sheet resistance of 10-100 Ω/Sqr. which allows it to be utilized as field electron emitter. The diamond/graphite hybrid nanostructure displays excellent electron field emission（EFE） properties with a low turn-on field of 2.17 V/μm and β= 3160, therefore it could be a promising alternative in field emission applications.

Preparation and Characterization of High Quality Diamond Films by DC ArcPlasma Jet CVD Method

Under optimal conditions free-standing high quality diamond films were prepared by DC arc plasma jet CVD method at a growth rate of 7-10 Pm/h. Surface and cross section morphologies of the diamond films were observed by SEM. Raman spectrometer wasused to characterize the quality of diamond films. The IR transmittivity measured by IR spectrometer is close to the theoretical value ofabout 71% in the far infrared band. The thermal conductivity measured by photothermal deflection exceeds 18 W/cm' K. <l 10> is thepreferential growth orientation of the films detected by X-ray diffractometer. As s result, the extremely high temperature of DC arc plasma jet can produce supersaturated atomic hydrogen, which played an important role in the process for the deposition of high quality diamond films.

Wear of CVD thick film diamond cutter while machining laminated flooring

The wide application of high pressure laminated (HPL) flooring has an insistent need for cutting tools with an excellent performance and fine cutting quality. Chemical vapor deposition (CVD) thick film diamond is a promising material for the machining of HPL flooring. In the present work, CVD thick film diamond tools were used to mill the wear resistance layer of HPL flooring. Wear volumes of flank face were examined by optical microscopy, and micro wear morphologies were observed by scanning electron microscopy (SEM). The experiments revealed that the predominant wear characteristics of CVD diamond tools were transgranular cleavage wear and intergranular peeling of the CVD diamond. Experimental results also showed that twin characteristic, cavity defect, micro crack and grain size of CVD thick film diamond contributed greatly to the wear process of CVD thick film diamond tools. The effects caused by the factors were also analyzed in detail in the paper.

Selective growth of diamond by hot filament CVD using patterned carbon film as mask

Selected-area deposition (SAD) of diamond films was achieved on silicon substrates with carbon film mask by hot filament chemical vapor deposition.Needle tip scraped lines were used to grow diamond films.Scanning electron microscope (SEM) investigation demonstrates that highly selective and sharp edged diamond films were produced.The results also demonstrate that the proper substrate temperature is very important for diamond selective growth in this deposition process.Since the enhancement of diamond growth was not observed on the needle tip scraped area of Si wafer with diamond powder scratching,the selective growth was considered to be closely correlated to silicon carbide formed during carbon film deposition and the residual carbon in the scraped area.

Growth of Diamond Film by Hot-filament CVD and Its Interface Research

1.IntroductionRecently,progress of vapour phasegrowth of diamond fihn under non-equilib-rium reaction condition has shown theprospect of its commercial production in re-spect of effectiveness and economy.Theprocess proceeds in the thermodynamical

OES study of the gas phase during diamond films deposition in high power DC arc plasma jet CVD system

This paper used optical emission spectroscopy （OES） to study the gas phase in high power DC arc plasma jet chemical vapour deposition （CVD） during diamond films growth processes. The results show that all the deposition parameters （methane concentration, substrate temperature, gas flow rate and ratio of H2/Ar） could strongly influence the gas phase. C2 is found to be the most sensitive radical to deposition parameters among the radicals in gas phase. Spatially resolved OES implies that a relative high concentration of atomic H exists near the substrate surface, which is beneficial for diamond film growth. The relatively high concentrations of C2 and CH are correlated with high deposition rate of diamond. In our high deposition rate system, C2 is presumed to be the main growth radical, and CH is also believed to contribute the diamond deposition.

Growth of mirror-like ultra-nanocrystalline diamond(UNCD)films by a facile hybrid CVD approach

In this study, growth of mirror-like ultra-nanocrystalline diamond（UNCD） films by a facile hybrid CVD approach was presented. The nucleation and deposition of UNCD films were conducted in microwave plasma CVD（MPCVD） and direct current glow discharge CVD（DC GD CVD） on silicon substrates, respectively. A very high nucleation density（about 1×10^11 nuclei cm^-2） was obtained after plasma pretreatment. Furthermore, large area mirrorlike UNCD films of Φ 50 mm were synthesized by DC GD CVD. The thickness and grain size of the UNCD films are 24 μm and 7.1 nm, respectively. In addition, the deposition mechanism of the UNCD films was discussed.

Adhesive strength of CVD diamond thin films quantitatively measured by means of the bulge and blister test

Large advancement has been made in understanding the nucleation and growth of chemical vapor deposition （CVD） diamond, but the adhesion of CVD diamond to substrates is poor and there is no good method for quantitative evaluation of the adhesive strength. The blister test is a potentially powerful tool for characterizing the mechanical properties of diamond films. In this test, pressure was applied on a thin membrane and the out-of-plane deflection of the membrane center was measured. The Young＇s modulus, residual stress, and adhesive strength were simultaneously determined using the load-deflection behavior of a membrane. The free-standing window sample of diamond thin films was fabricated by means of photolithography and anisotropic wet etching. The research indicates that the adhesive strength of diamond thin films is 4.28±0.37 J/m^2. This method uses a simple apparatus, and the fabrication of samples is very easy.

The fabrication of ideal diamond disk(IDD)by casting diamond film on silicon wafer

With the relentless densification of interconnected circuitry dictated by Moore’ s Law,the CMP manufacture of such delicate wafers requires the significant reduction of polishing pressure of integrated circuits,not only globally,but also locally on every tip of the pad asperities.Conventional diamond disks used for dressing the polyurethane pads cannot produce asperities to achieve such uniformity.A new design of diamond disk was fabricated by casting diamond film on a silicon wafer that contains patterned etching pits. This silicon mold was subsequently removed by dissolution in a hydroxide solution.The diamond film followed the profile of the etching pits on silicon to form pyramids of identical in size and shape.The variation of their tip heights was in microns of single digit that was about one order of magnitude smaller than conventional diamond disks for CMP production.Moreover,the diamond film contained no metal that might contaminate the circuits on polished wafer during a CMP operation.The continuous diamond film could resist any corrosive attack by slurry of acid or base.Consequently,in-situ dressing during CMP is possible that may improve wafer uniformity and production throughput.This ideal diamond disk(IDD) is designed for the future manufacture of advanced semiconductor chips with node sizes of 32 nm or smaller.

Effect of Substrate Temperature on the Selective Deposition of Diamond Films

Selective deposition of diamond film on patterned Si (100) substrates has been achieved by using microwave plasma chemical vapor deposition (MPCVD) method. The films have been characterized by scanning electron microscope (SEM) and Raman spectrum. The influence of substrate temperature on the nucleation behavior of diamond was discussed in detail and the optimized deposition condition has been obtained.

Growth of Free-standing Diamond Films on Graphite Substrates with Ti Interlayers

Free-standing diamond films, deposited using DC Arc Plasma Jet CVD method onto graphite substrates with titanium interlayers, have been investigated. The Ti interlayers were deposited by arc ion plating equipments. The thickness, morphology and composite phase of Ti interlayers were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The titanium carbide (TiC) was detected in both sides of the interlayers, which played an important role with respect to reasonable adhesion with film and diamond nucleation. The semi-translucent diamond films were characterized by SEM and Raman spectrum. The sharp diamond peak with low intensity of amorphous carbon shows that diamond films have very high quality. The overall results suggest that plating Ti interlayer on graphite substrate is an effective way to obtain optical grade free-standing diamond films.