B. Ivanov

Chemical vapour deposition of BC2N films and their laser-induced etching with SF6

Abstract Thin BC 2 N films have been obtained by chemical vapour deposition (CVD) from BCl 3 and CH 3 CN. The layers were two types according to their appearance: metallic and black. The differences in their morphology, structure and composition were studied by scanning electron microscopy. X-ray diffraction and X-ray photoelectron spectroscopy. Metallic BC 2 N films were subjected to laser-induced etching with SF 6 using copper bromide vapour laser. The etch depths increased with the increase of laser power and SF 6 pressure, and with the decrease of scanning speed. The maximum etch rate was 120 μm s −1 at 2 W laser power. 100 kPa SF 6 and 400 μm s −1 scanning speed.

Laser chemical vapour deposition of thin aluminium coatings

Abstract Laser chemical vapour deposition has recently become an attractive area of research. A maskless configuration of aluminium has been grown utilizing visible light from a copper laser which induces pyrolytical decomposition of trimethylaluminium (TMA). The process was carried out in vacuum or argon and hydrogen atmosphere at partial TMA pressures of 0.05, 0.1 and 0.5 kPa. A silicon monocrystalline wafer was used as a substrate. The layer was investigated by scanning electron microscopy, Auger electron spectroscopy, Talystep and electrical resistance measurements. The crystalline structure of the coating shows well-defined grains. This morphology was observed for the first time by using a pulsed visible laser. The Auger electron spectra indicate the presence of bonded oxygen and carbon incorporated into the aluminium. These elements cannot be totally avoided but their concentration can be reduced at the established optimum conditions to obtain a low specific resistance for the layer.

Low-Pressure CVD of Carbon Nitride Using Triazine-Containing Precursors†

Carbon nitride (CxNy) layers with N/C ratios of 0.76–1.26 have been grown under low pressure from two organic chemical systems, namely 2,4-dichloro-6-bis(trimethylsilyl)imido-1,3,5-triazine [C3N3Cl2N(SiMe3)2] and tetramethylguanidine (C5H13N3) + 2,4,6-trichloro-1,3,5-triazine (C3Cl3N3). The films synthesized are transparent, well-adhered on silicon, homogeneous in morphology, and uniform in thickness. In addition, a technology has been developed for the deposition of carbon nitride powders with a N/C ratio of 1.3 as starting materials for further thermal treatment attempts in order to synthesize crystalline C3N4. At deposition temperatures between 400 and 800 °C and high supersaturation of reagents in the reactor, the powders obtained exhibit nuclei of crystalline phases.

Laser‐induced chemical vapor deposition of aluminum from trimethylamine alane

Maskless patterning of aluminum has been achieved by using visible light from a copper bromide vapor laser for pyrolytic decomposition of trimethylamine alane (TMAA) on silicon monocrystalline wafer. The analysis of the resultant stripes included scanning electron microscopy, Auger electron spectroscopy, Talystep, and electrical resistance measurements. The crystalline structure of the layers showed well‐defined grains. The Auger electron spectra indicated pure aluminum layers with small quantities of oxygen and carbon. The low resistivities of aluminum stripes deposited from TMAA (up to 4.0 μΩ cm) make it a promising precursor for metallization with aluminum and especially for chemical vapor deposition enhanced with a pulsed visible laser.

Inductively coupled plasma and laser-induced chemical vapour deposition of thin carbon nitride films

Abstract Thin CN x films have been deposited on silicon substrates by inductively coupled plasma chemical vapour deposition (ICP-CVD) and by laser-induced chemical vapour deposition (LCVD) utilizing the focused beam of a copper bromide vapour laser. Different gas mixtures were used: CH 4 /N 2 and CCl 4 /N 2 /H 2 for ICP-CVD, and CCl 4 /NH 3 for LCVD. Plasma properties (electron temperature, electron and ion densities, plasma potential) were studied by Langmuir probe and optical emission spectroscopy. The growth rates ranged up to 80 nm min −1 for ICP-CVD and 700 μm min −1 for LCVD. The surface morphology was studied using atomic force microscopy for ICP-CVD, and scanning electron microscopy for LCVD. Beside carbon and nitrogen, silicon and oxygen for LCVD and chlorine for ICP-CVD (in the case of the CCl 4 /N 2 /H 2 system) was detected by Auger electron spectroscopy. Fourier transform infrared (FTIR) spectroscopy was used to determine the chemical bonding structure. Bands assigned to C=C and C=N (graphite-like domains) and to C=H bonds were detected in the films deposited by both processes. In addition, different bands attributed to other types of carbon nitride bonds or to due to the presence of impurity atoms were observed in the FTIR spectra of the CN x films deposited by the ICP-CVD and LCVD. The results of both deposition techniques were compared and discussed on the base of the processes peculiarities.

Pyrolytic Lcvd of Silicon Using A Pulsed Visible Laser - Experiment and Modelling

Maskless deposition of silicon from silane on Si monocrystalline wafer using copper bromide vapor laser (CBVL) is investigated. Morphology and geometric parameters of the stripes obtained are studied and some conclusions for the process mechanism are made. Applying Kirchoffs transform and Greens function analysis nonlinear heat diffusion problem for different pulse shapes was solved. The influence of pulse shape on the temperature distribution and its time evolution was studied. Nonisothermal and non-stationary deposition kinetic models using the obtained results were developed.

An experimental approach for growth rate determination of LCVD-written aluminium stripes

A new experimental approach for growth rate determination of microdimensional aluminium stripes written by laser-induced chemical vapour deposition (LCVD) was developed. The aluminium lines were obtained by pyrolysis of trimethylaluminium (TMA) on (100) silicon monocrystalline wafer using the focused beam of a copper bromide vapour laser. Quantitative determination of the deposit was performed by its chemical removal from the substrate into a solution and further analysis performed using inductively coupled plasma atomic emission spectroscopy. Using this analytical method, dependences of the aluminium quantity on the partial pressure of TMA and the laser power were obtained. The growth rate at direct writing with a pulsed visible laser was calculated on the basis of aluminium quantity determinations. It is demonstrated that the proposed experimental approach could be successfully used for kinetic studies of LCVD processes.

Sensor for temperature measurement of laser heated surfaces

Abstract A small area nickel-based sensor for surface temperature measurement has been developed on different insulating substrates. The dependence of resistance on temperature in the range 50–350°C was studied and the temperature coefficient of resistance was determined, which provided the high sensibility of the device. The sensor was successfully tested in laser irradiation and the promising results obtained made it applicable for surface temperature estimation with an accuracy of ± 1°C during laser processing.

Design of Injection Feed Multiwafer Low‐Pressure Chemical Vapor Deposition Reactors

A two-dimensional model has been developed for low-pressure chemical vapor deposition reactors with injection feeding of gas components. The classical methods for linear differential equations are applied to obtain analytical solutions of the model both with and without main gas flow in the system. Analysis of the model reveals a relationship between the reactor geometry and the process parameters for maintaining constant reagent concentration in the system. Injection design is determined by means of simulation study of definite deposition processes.

LCVD of CN x Layers from NH 3 ,/CCI 4 . Mixture using CuBr Vapor Laser

Amorphous CN x films were obtained on monocrystalline silicon substrates by direct writing laser induced chemical vapor deposition from CCI 4 and NH 3 using CuBr vapor laser. The main process parameters (scanning speed, laser power, background temperature) were varied in wide ranges. The deposition rates in the laser spot were in the range of 1 – 10 μm/s. Scanning electron microscopy showed that the layers had rather rough surface. The deposited films were composed of carbon, nitrogen, silicon and oxygen, as detected by AES and EDX analyses. Chemical bonding structure was investigated by FTIR and showed absorption bands corresponding to different chemical groups - CH, CH 2 , CH 3 , C=C, C=N, C=O, Si-O, Si-C, Si-N and C-N. The electrical measurements of the deposited films showed that their resistivity varied from 0.15 to 1.40 MΩ.cm and it was very sensitive to the deposition conditions.