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Study on the experimental nucleation of plasma chemical vapor deposition diamond film

Study on the experimental nucleation of plasma chemical vapor deposition diamond film

Study on the experimental nucleation of plasma chemical vapor deposition diamond film: The diamond film prepared by this technology is a technology with the ability of plasma chemical vapor accumulation. Because thin-film diamond is of great significance in super-hard maintenance coatings, light windows, heat sink data, microelectronics, etc., when mankind has mastered the preparation technology of diamond thin films, especially the preparation technology of single crystal diamond thin films, they rely on The history of data will quickly move from the age of silicon materials to the age of diamonds. However, the mechanism of plasma chemical vapor deposition of diamond films is still unclear, especially for heteroepitaxial single crystal diamond films. The difficulty lies in the fact that the low-temperature plasma is in a thermally unbalanced state, and the reaction gas used is also polyatomic molecules. , The reaction system is complex and lacks basic data support. However, after more than 20 years of theoretical and experimental research, people have not only developed many plasma chemical vapor deposition techniques for preparing diamond films, but also have a certain understanding of the factors affecting the growth of diamond films through the analysis and summary of experimental data. For the growth of polycrystalline diamond film, nucleation is the key, and there are many factors that affect nucleation, including plasma conditions, matrix data, and temperature. Using plasma chemical vapor deposition of diamond film, we must first understand the nucleation process of diamond, which is generally divided into two stages: carbon-containing groups reach the surface of the substrate, and then dispersed into the interior of the substrate; the second stage is the carbon reaching the surface of the substrate The nucleation and growth of atoms on the surface of the matrix centered on defects, diamond crystals, etc.; therefore, the factors that determine the diamond nucleation include: 1. Matrix data: because the nucleation depends on the saturation of the surface of the matrix and the amount of carbon reaching the core The critical concentration, therefore, the carbon dispersion coefficient of the matrix data has an important influence on nucleation. The larger the dispersion coefficient, the less likely it is to reach the critical concentration required for nucleation. It is very difficult for metal substrates such as iron, nickel, titanium to directly nucleate on this type of data; and for data with a lower carbon dispersion coefficient , Such as tungsten, silicon, etc., diamonds can quickly nucleate. 2. Surface grinding: Generally, the nucleation of diamond can be advanced by grinding the surface with diamond powder. Grinding using SiC, c-BN, Al2O3 and other data can also promote the formation of nucleation. There are two main mechanisms for grinding to promote nucleation formation: one is that after grinding, the diamond particles remain on the surface of the substrate and act as a seed; the other is that grinding can produce many tiny defects on the surface of the substrate. These defects are favorable directions for spontaneous nucleation. The closer the lattice point constant of the grinding data is to diamond, the better the effect of enhancing nucleation. Therefore, the general grinding data are diamond powder prepared by the high temperature and high pressure method. 3. Plasma parameters: In the early stage of diamond nucleation, due to the dispersion of carbon to the substrate, an interface layer was formed on the surface of the substrate. Therefore, the study pointed out that plasma parameters also have an important effect on the interface layer. For example, when a diamond film is deposited on the surface of a silicon substrate At this time, the methane concentration has a direct effect on the formation of the SiC interface layer. 4. Bias enhanced nucleation: In microwave plasma chemical vapor deposition, the substrate is generally negatively biased, that is to say, the potential of the substrate is related to the low potential of the plasma. The effect of the negative bias is to increase the ion concentration on the substrate surface. When the bias voltage is too high, because too many ions sputter the outer layer of the substrate and the precursor nuclei, a nucleation is formed. Therefore, when the bias voltage is enhanced, the size of the bias voltage is more appropriate.

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Plasma etching cleaning machine ICP etching technology is widely used in SiC etching applications

Plasma etching cleaning machine ICP etching technology is widely used in SiC etching applications

Plasma etching cleaning machine ICP etching technology is widely used in SiC etching applications: Reaction-bonded silicon carbide (RB-SiC), as a new type of ceramic material, has the characteristics of high strength, specific stiffness, large thermal conductivity and small expansion coefficient. With the rapid development of optical technology, optical systems are moving towards large-diameter, low-caliber The development of loss and lightweight requires optical components with high resolution, wide field of view, and high-quality surface topography RB-SiC material has been widely used due to its superior performance, which puts forward higher requirements on the optical quality of the surface of the material. There are many methods for processing SiC, mainly including electrochemical corrosion, mechanical processing, ultrasonic processing, laser etching and plasma dry etching. The plasma dry etching technology of plasma etching cleaner mainly includes reactive ion etching (RIE), electron cyclotron resonance (ECR) and inductively coupled plasma (ICP). ICP etching equipment has the advantages of selectivity and anisotropic structure, simple operation, convenient control, etc. Therefore, ICP etching technology is widely used in SiC etching applications. 　　 Plasma Etching Cleaner ICP etching technology is mainly used in the processing and production of SiC semiconductor devices and micro-electromechanical systems (MEMS) devices, etching the surface quality, and improving the performance and quality of SiC microwave power devices. The complete etching process of ICP etching technology can be divided into three steps: ① adsorption of etched substances; ② formation of volatiles; ③ desorption. It includes two processes, chemical and physical: in the chemical process, the etching gas generates active radicals, metastable particles and electrons through inductive coupling through glow discharge, and the neutral particles diffuse to the surface of the substrate and are etched. The atoms on the material surface chemically react to produce volatile substances, and these by-products are drawn out of the chamber by the vacuum system to achieve gas chemical etching. In addition, the physical process is through ion bombardment of the etched substrate surface. Unlike sputter etching, the physical bombardment here is mainly to destroy chemical bonds and lattice sequences, accelerate the desorption of reactants, and promote the chemical reaction process. Carry out and remove non-volatile products on the surface. In the etching process of the plasma etching cleaner ICP, the substrate bias voltage provides energy for the plasma, enabling active particles to act on the surface of the substrate. The power determines the kinetic energy of the plasma. These high-energy active particles are in the etching process. , Plays an important role. Compared with the etching before and after the etching, the surface quality has declined. Analyze the reason. The active particles generated by the ICP etching glow discharge diffuse to the surface of the substrate and the chemical reaction will generate some non-volatile products, which is too late for desorption and deposition. To the surface of the substrate. In addition, some ions have physical bombardment on the substrate, destroying the surface lattice array, causing holes and pits on the surface of the substrate, resulting in a decrease in the surface quality of the material. At the same time, the structure of the original substrate is not uniform due to the presence of two-phase components of silicon and silicon carbide. The non-uniformity of the two-phase boundary, holes and pits on the surface of the material after plasma etching by the plasma etching cleaner will cause the scattering of light on the surface of the material, and the holes will also increase the absorption of light by the material. The surface reflectivity decreases and the surface roughness increases.

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The importance of plasma plasma processor cleaning organic field effect transistor (OFET) materials

The importance of plasma plasma processor cleaning organic field effect transistor (OFET) materials

The importance of plasma plasma processor cleaning organic field effect transistor (OFET) materials: Organic Field Effect Transistor (OFETS) is an active device that can change the conductivity of the semiconductor layer by changing the gate voltage, and then manipulate the current flowing through the source and drain. As the basic element in the circuit, the organic field effect transistor has received extensive attention and has been developed rapidly due to its advantages of low power consumption, high impedance, low cost, and large area production. Its components are mainly composed of electrodes, organic semiconductors, heat insulation layers and substrates. These components have a great influence on the performance of OFETs. The electrode, organic semiconductor, insulating layer and substrate are processed by a plasma plasma processor to improve the function of the material. 1. The substrate substrate-plasma plasma treatment machine plasma treatment, remove the substrate surface impurities, improve surface activity The substrate is generally on the bottom layer of the transistor, and the header plays a supporting role. It can be used as the substrate material of OFET: glass, silicon wafer, quartz, polycarbonate (PC), polyethylene naphthalene (PEN), polyimide (PI), polyethylene (PET), etc. Inorganic substrates have the advantages of high melting point and smooth surface, such as glass, silicon wafer, and quartz. Although the surface looks rough, these data show elastic and flexible materials like polyethylene naphthalene (PEN) and polyethylene (PET). The substrate processed by plasma plasma processing machine needs to be processed in the preparation stage to remove impurities on the surface of the substrate and improve surface activity. 2. Electrode treatment-plasma plasma treatment machine plasma treatment In organic field-effect transistors (OFETs), electrodes are another important component. It is generally believed that when the electrical barrier height of the organic semiconductor layer/electrode interface is △E<0.4eV, an ohmic contact can be formed between the electrode and the organic semiconductor layer. For P-type OFETs, the occupied orbital energy level is -4.9 eV to -5.5eV, and a higher work function is required. Commonly used ones are Au (-4.8eV-5.1eV) and ITO (-5.1eV). Ordinary ITO requires an improved work function due to its low work function, so it can be improved with a quasi 13.56MHz frequency VP-R3 plasma processor. 3. Insulation layer treatment-PLASMA plasma retouches the silicone surface to improve the compatibility of materials When the plasma plasma processor is running, the charge is first accumulated and transferred on the contact surface between the semiconductor and the insulating layer. In order to ensure that the gate leakage current between the gate electrode and the organic semiconductor is small, the insulating layer data is required to have a higher resistance. It requires better insulation. At present, the commonly used insulating layer data is first of all inorganic insulating layers, such as oxide layers. During this period, silicon dioxide is the insulating layer generally used in organic field-effect transistors. However, due to the existence of certain defects on the surface of silicon dioxide, in addition to its Number with organic semiconductors

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The energy range of the plasma is very wide. There is no choice for the excitation or ionization of electrons

The energy range of the plasma is very wide. There is no choice for the excitation or ionization of electrons

The energy range of the plasma is very wide. There is no choice for the excitation or ionization of electrons: Chemical reactions can only occur when the energy of the molecule exceeds the activation energy. In conventional chemistry, energy is transferred by collisions between molecules or between molecules and walls. In plasma, on the one hand, the vibrational energy is increased to a small response energy in a certain order; on the other hand, the collision of electrons and molecules can transfer more energy, which makes neutral molecules become multiple active components, or makes moderately active The components are ionized, and the new components mainly include super-active neutral particles, cations and anions. Traditional chemical reactions cannot produce many new components, but plasma has become a very powerful means of chemical manipulation, which is burdened with catalysis. Generally speaking, reactions with lower temperatures, and perhaps reactions with faster reaction speeds at a certain temperature, are all affected by the plasma. But in a plasma with a wide energy range, the excitation or ionization of electrons is not selective. In a plasma system, many different types of active particles can cause a large number of reactions. During the reaction process, it is almost impossible for the particularly important and significant particles to be manipulated. High-energy particles can destroy the covalent bonds of molecules in the plasma environment. The use of a strong local field to participate in the tail of the strong electron scattering function in high-energy electrons and non-equilibrium plasma may produce new chemical reactions. The plasma environment is conducive to many chemical reactions. Process parameters such as gas type, flow rate, pressure, input power, etc. determine whether a reaction can produce the primary input process parameters. There will also be multiple reactions between the border and the bottom. Ablation rate and accumulation rate are obtained through related surface treatment. When organic vapor is used as the working gas, polymerization and aggregation of plasma will occur. During the etching and accumulation process, the surface of the material reacts with the original or newly generated components in the plasma, that is, the surface conditions, such as pollutants, polymerization inhibitors, barrier layers, gas adsorption, etc., will affect the process dynamics and the accumulation of the film. Characteristics have an impact. The molecules in the plasma are decomposed into highly active components, which then react with organic matter. Hydrogen can be connected to double bonds and can be separated from other molecules. In oxygen-based plasma, there are many components of ionization and dissociation energies. Others can also constitute metastable components like O2(1△g). For the oxygen atom, the important reaction is to add a double bond, and the CH bond becomes a hydroxyl or carboxyl group. Nitrogen can react with saturated or unsaturated molecules. An interesting development of plasma chemistry is the decomposition of original simple molecules into chaotic molecular structures. Typical reactions include: isomerization, elimination of atoms or small groups, dimerization/polymerization, and destruction of original data, etc., for example, the mixture of methane, water, nitrogen, and oxygen through the glow discharge, and finally obtained from The substance of life-amino acids. There is cis-trans isomerization, ring formation, and ring-opening reactions in the plasma. In addition to single-molecule reactions, bimolecular reactions can also occur.

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Several points to be noted in the planning of low-temperature plasma power integrity power system

Several points to be noted in the planning of low-temperature plasma power integrity power system

Several points to be noted in the planning of low-temperature plasma power integrity power system: Analysis of low-temperature plasma power integrity power system noise margin Most chips will give a normal operating voltage range, usually ±5%. The output voltage accuracy of the traditional voltage stabilizer is generally ±2.5%, so the peak amplitude of the power supply noise should not be greater than ±2.5%. Accuracy is conditional, including load conditions, working temperature and other restrictions, so there must be margin. Second, the calculation of the noise margin of the low-temperature plasma power supply of the whole machine. For example, the normal working voltage of the chip is 3.13V to 3.47V, and the nominal output of the voltage regulator chip is 3.3V. The whole machine is installed on the circuit board, and the power supply voltage regulator chip of the whole machine outputs 3.36V. Then, the allowable voltage change range is 3.47-3.36=0.11V=110 millivolts. The output accuracy of the voltage stabilizer is ±1%, that is, ±3.363*1%=±33.6 mV. The power system noise margin is 110-33.6=76.4 millivolts. 3. How does the power supply noise of the low-temperature plasma power supply rectifier generate? The output of the stabilized power supply chip itself is unstable and will fluctuate to a certain extent. The second is that the regulated power supply cannot respond to the rapid changes in the current requirements of the load in real time. The rectifier power supply stabilized power supply chip senses the change of its output voltage and adjusts its output current to return it to the rated output voltage. Third, the voltage drop caused by the load transient current on the impedance of the power path and the impedance of the ground path. The pins and pads themselves will have parasitic inductance. When the transient current flows through the channel, a voltage drop will inevitably occur. Therefore, power integrity Therefore, the voltage at the power supply pin of the load chip will fluctuate with the change of the transient current, which is the power supply noise generated when impedance occurs.

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The radio frequency plasma cleaner plays an important role in improving the working reliability of GaAs semiconductor devices

The radio frequency plasma cleaner plays an important role in improving the working reliability of GaAs semiconductor devices

The radio frequency plasma cleaner plays an important role in improving the working reliability of GaAs semiconductor devices: GaAs has excellent optoelectronic properties and is a widely used semiconductor material in II-V compound semiconductors. However, the dangling bonds on the surface of GaAs materials are easily combined with impurities or oxygen elements, forming impurity defects and oxide layers on the surface, becoming non-radiative recombination centers, affecting the light-emitting characteristics of the material, and can bring serious consequences to the optoelectronic characteristics of GaAs semiconductor devices. Influence. Passivating the GaAs surface can not only reduce the surface impurity concentration, eliminate non-radiative recombination centers, and improve its photoelectric performance, but also the passivation protective layer can prevent the GaAs surface from combining with oxygen in the atmosphere and being re-oxidized , It plays an important role in improving the working reliability of GaAs semiconductor devices. Sulfur passivation of GaAs semiconductor materials can form sulfur-containing compounds on the surface, which can significantly improve the physical and chemical properties of the GaAs surface. Using the plasma processing method of a radio frequency plasma cleaner, the sulfur-containing Ar plasma is guided to bombard the GaAs sample, so that the sulfur reacts with the GaAs to form a thicker sulfur-containing passivation layer, and the passivation effect can be maintained for a long time. The method has strong controllability, avoids the influence of the strong corrosion effect of wet sulfur passivation, and provides new technical means for improving the performance of GaAs-based semiconductor optoelectronic devices and increasing their working life. Use the Ar glow discharge of a radio frequency plasma cleaner to clean the surface of the sample with low power to remove the surface oxide layer. Then the sulfur element is heated, and the sulfur partial pressure in the vacuum chamber can be adjusted appropriately by changing the heating temperature. Then through Ar, using Ar plasma induction, the sulfur vapor is discharged to generate sulfur plasma, which reacts with the CaAs sample on the slide table to generate stable sulfur-containing compounds on the surface of the sample. In order to adjust the partial pressure of sulfur vapor in a wider range, we appropriately control the pumping rate of the vacuum system by adjusting the vacuum baffle to ensure that there is sufficient and stable sulfur vapor concentration in the cavity to participate in the surface reaction of the sample. After Ar plasma cleaning by a radio frequency plasma cleaner, the PL intensity is slightly higher than that of the untreated GaAs sample. This is because Ar plasma has a cleaning effect on the oxide layer on the GaAs surface, which reduces the non-radiative recombination of the GaAs surface and improves the efficiency of photoluminescence. The PL intensity of the sample treated with sulfur-containing plasma is 104% higher than that of the sample bombarded by Ar plasma alone, indicating that the sulfur plasma has a good surface passivation effect. Compared with the untreated sample, the PL peak intensity increased by 71%, and after annealing, the peak wavelength of the plasma sulfur passivated sample was restored. The passivation of GaAs samples by sulfur plasma will not cause obvious impurity pollution, especially the passivation effect is relatively stable, which is more suitable for the passivation process of GaAs optoelectronic devices. The surface of the GaAs substrate was subjected to dry sulfur passivation using a radio frequency plasma cleaner method. The passivation effect of radio frequency plasma is affected by substrate temperature, sputtering power, and degradation temperature. By optimizing the sulfur plasma passivation conditions, the PL intensity of the sample was increased by 71%, and it showed better PL stability.

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