- Email: [email protected]
7521. Preparation of cubic boron nitride film by CO2 laser physical vapour deposition with simultaneous nitrogen ion supply
Classified abstracts 7515-7523
23 7515. Infrared absorption analysis of films deposited by glow-discharge of silane/helium mixtures Using infrared (ir) absorption measurements, it is proposed that amorphous hydrogenated silicon films obtained from plasma-enhanced chemical vapor deposition of Silane (Sill4) highly diluted in helium at high rfpower densities, consist of an amorphous tissue in which a columnar microstructure is embedded. The evolution of the ir spectrum with dilution evidences a remarkable tendency to the substitution of monohydrides by dihydrides. The films show high transparency and good conductivity. These properties make them suitable to be used as window layers for thin-film solar cells when conveniently doped. M T Guti6rrez et al, J Appl Phys, 67, 1990, 7031-7033. 23 7516. Electromigration lifetime and crystal structure of thin aluminum film connectors for microelectronic devices deposited by the ionized cluster beam technique A comparison of electromigration failure in aluminum films deposited by conventional means and by the 'ionized cluster beam' technique on silicon and on SiO2 is presented. The crystal structures of the respective films have been investigated utilizing transmission electron microscopy (TEM), electron diffraction, and X-ray diffraction. An elemental analysis was performed by Auger spectroscopy. The electromigration resistance in some of the films has been found to increase considerably. Possible reasons for this larger lifetime under dc stressing are discussed on the basis of the crystal structures of the films. R E Hummel et al, J Vac Sci Technol, A8, 1990, 1437 1442. 23 7517. Interference method for monitoring the refractive index and the thickness of transparent films during deposition An interferometric method is described for simultaneous measurement o f the refractive index and the thickness of transparent isotropic films during the deposition process. Two laser beams are focused impinging at two different angles onto the film. The intensity of the beams reflected from the growing film shows minima and maxima, which are counted and evaluated to determine the refractive index n and the thickness d of the film in the range of some I00 nm up to several micrometers using 633-nm laser light, n and d can be determined within an accuracy better than 1%, if the thickness is larger than three times the vacuum wavelength of the laser. The measurements are well in accordance with the calculations of the intensity modulation. The method can easily be extended to multilayer systems. H Alius and R Schmidt, Rev Scient Instrum, 61, 1990, 1200-1203. 23 7518. Selected-area deposition of diamond films Diamond film patterns with line/space dimensions of a few #m were accomplished on Si substrates prepared by reactive-ion etching (RIE) and amorphous-Si masking (ASM) methods, both including a photolithography process. For diamond deposition, microwave plasma CVD and electron-assisted CVD were used. Furthermore, a growth of diamond particles at selective sites was attained using the RIE method. K Kobashi et al, Vacuum, 41, 1990, 1383-1386. 23 7519. Role of nitrogen ions in ion-beam reactive sputtering of NbN Using ion-beam reactive sputtering of a niobium target, we have studied the effects of energetic-nitrogen-ion bombardment on the target reaction and on the resulting N b N film properties. Nitrogen is either added into the ion source with the noble gas to obtain a beam of nitrogen and argon ions, or injected directly into the chamber as neutral molecules so the ion beam is composed of essentially all argon. The target reaction rate is seen to be controlled by the adsorbed thermal nitrogen, and only minimally affected by the presence of ionized nitrogen. Thus, argon-ion bombardment of the target is responsible for stimulating the reaction between the adsorbed nitrogen and the metal target producing the N b N layer. However, the film properties are affected by the presence of nitrogen ions. Films grown with N2 added in the ion source have a higher resistivity and lower superconducting transition temperature than films grown with N2 injected directly into the chamber. These differences increase with N2 flow; the differences are attributed to damage of the growing film by energetic nitrogen reflecting from the target, as measured by an energeticneutral-particle detector. D J Lichtenwahaer et ai, J Vac Sci Technol, A8, 1990, 1283-1287. 676
23 7520. Selected-area deposition of diamond films Selected-area deposition of diamond film has been accomplished on Si substrates prepared by two different methods: reactive-ion etching (RIE) and amorphous-Si masking (ASM). In the RIE method, a Si substrate polished by a diamond paste was patterned with a photoresist mask, and the unprotected areas were etched by RIE, followed by a complete removal of the photoresist films. The diamond deposition was done by electron-assisted chemical-vapor deposition (CVD), and diamond films grew only in the areas once covered with the photoresist films and not etched by RIE. In the ASM method, a polished Si substrate was also photolithographically masked with photoresist, followed by a uniform deposition of a hydrogenated amorphous silicon (a-Si:H) film. The photoresist film was then lifted off together with the overlay of deposited a-Si : H, leaving the polished Si surface patterned with an a-Si : H mask. In this case, the diamond deposition was done by microwave plasma CVD, and diamond films grew only in the areas not covered with a-Si : H. In both cases, well-defined diamond patterns with line/space dimensions of a few micrometers were formed on the substrates. T Inane et al, J Appl Phys, 67, 1990, 7329-7336. 23 7521. Preparation of cubic boron ultride film by C02 laser physical vapour deposition with simultaneous nitrogen ion supply Hard cubic boron nitride (c-BN) rich films have been prepared by a newly developed CO2 laser physical vapour deposition process assisted by a simultaneous nitrogen ion supply. A high power CO2 laser of 200-1000 W was focused and irradiated onto the peripheral surface of a rotating sintered hexagonal boron nitride (h-BN) ring and the vapour was deposited on a substrate. N2 gas ionized in a Kaufman-type ion source was accelerated at a bias voltage of 0-2.0 kV and irradiated onto the substrate simultaneously with the laser evaporation process. The films were characterized by electron spectroscopy for chemical analysis, thin film X-ray diffraction, Auger electron spectroscopy, ir spectroscopy and scanning electron microscopy. Mechanical properties were also evaluated by Knoop hardness measurements, scratch tests and wear experiments. The composition ratio N : B of the films prepared from high purity 99% h-BN increased as the accelerating voltage increased and neared unity at about 1 kV. Cubic boron nitride (c-BN) was clearly identified at accelerating voltages over 0.5 kV. The higher the accelerating voltage was, the greater was the proportion of the cubic phase. The c-BN-rich films were found to have extremely high Knoop hardness of 3800-4600 kgf mm -2 and sufficient wear resistance against N i - M o steel (SAE 4620). S Mineta et al, Thin Solid Films, 189, 1990, 125-138. 23 7522. Crystal forms and their orientation in poly(vinylidene fluoride) films prepared by an ionized-vapour deposition method Poly(vinylidene fluoride) (PVDF) films were deposited on substrates by an ionized-vapour deposition method under various conditions in which the acceleration voltage and ionization current were changed. IR spectra of the PVDF films were measured by ir reflection absorption spectroscopy methods with polarized light, and the crystal forms and their orientation in the films were investigated. It was found that the films containing form I crystals, which are known to possess ferroelectricity, were able to be obtained when ionization and acceleration were carried out. The contents of form I depended on both acceleration voltage and ionization current. The wattage supplied to the substrate (ion current multiplied by the acceleration voltage) seems to be a dominant factor in determining the crystal forms. From the result of ir dichroic measurements, it was found that the form I crystals were oriented; the molecular chain axes were parallel to the substrate surface, and the CF2 dipole was perpendicular to the surface and along the applied field. The film showed pyroelectricity, and its pyroelectric coefficient was about 1 nC cm -2 K - ' which was a third of that of an authentic PVDF pyroelectric film. J Sakata and M Mochizuki, Thin Solid Films, 189, 1990, 123-132. 23 7523. Structure of ion-plated amorphous hydrogenated carbon films investigated by electron energy loss spectroscopy Thin ion-plated amorphous hydrogenated carbon films were investigated by electron energy loss spectroscopy. From an analysis of the dielectric function, information on the film structure could be obtained. The results will be compared with those of electron diffraction studies. Differences between insulating and conducting substrates could be verified in the film
23 7515. Infrared absorption analysis of films deposited by glow-discharge of silane/helium mixtures Using infrared (ir) absorption measurements, it is proposed that amorphous hydrogenated silicon films obtained from plasma-enhanced chemical vapor deposition of Silane (Sill4) highly diluted in helium at high rfpower densities, consist of an amorphous tissue in which a columnar microstructure is embedded. The evolution of the ir spectrum with dilution evidences a remarkable tendency to the substitution of monohydrides by dihydrides. The films show high transparency and good conductivity. These properties make them suitable to be used as window layers for thin-film solar cells when conveniently doped. M T Guti6rrez et al, J Appl Phys, 67, 1990, 7031-7033. 23 7516. Electromigration lifetime and crystal structure of thin aluminum film connectors for microelectronic devices deposited by the ionized cluster beam technique A comparison of electromigration failure in aluminum films deposited by conventional means and by the 'ionized cluster beam' technique on silicon and on SiO2 is presented. The crystal structures of the respective films have been investigated utilizing transmission electron microscopy (TEM), electron diffraction, and X-ray diffraction. An elemental analysis was performed by Auger spectroscopy. The electromigration resistance in some of the films has been found to increase considerably. Possible reasons for this larger lifetime under dc stressing are discussed on the basis of the crystal structures of the films. R E Hummel et al, J Vac Sci Technol, A8, 1990, 1437 1442. 23 7517. Interference method for monitoring the refractive index and the thickness of transparent films during deposition An interferometric method is described for simultaneous measurement o f the refractive index and the thickness of transparent isotropic films during the deposition process. Two laser beams are focused impinging at two different angles onto the film. The intensity of the beams reflected from the growing film shows minima and maxima, which are counted and evaluated to determine the refractive index n and the thickness d of the film in the range of some I00 nm up to several micrometers using 633-nm laser light, n and d can be determined within an accuracy better than 1%, if the thickness is larger than three times the vacuum wavelength of the laser. The measurements are well in accordance with the calculations of the intensity modulation. The method can easily be extended to multilayer systems. H Alius and R Schmidt, Rev Scient Instrum, 61, 1990, 1200-1203. 23 7518. Selected-area deposition of diamond films Diamond film patterns with line/space dimensions of a few #m were accomplished on Si substrates prepared by reactive-ion etching (RIE) and amorphous-Si masking (ASM) methods, both including a photolithography process. For diamond deposition, microwave plasma CVD and electron-assisted CVD were used. Furthermore, a growth of diamond particles at selective sites was attained using the RIE method. K Kobashi et al, Vacuum, 41, 1990, 1383-1386. 23 7519. Role of nitrogen ions in ion-beam reactive sputtering of NbN Using ion-beam reactive sputtering of a niobium target, we have studied the effects of energetic-nitrogen-ion bombardment on the target reaction and on the resulting N b N film properties. Nitrogen is either added into the ion source with the noble gas to obtain a beam of nitrogen and argon ions, or injected directly into the chamber as neutral molecules so the ion beam is composed of essentially all argon. The target reaction rate is seen to be controlled by the adsorbed thermal nitrogen, and only minimally affected by the presence of ionized nitrogen. Thus, argon-ion bombardment of the target is responsible for stimulating the reaction between the adsorbed nitrogen and the metal target producing the N b N layer. However, the film properties are affected by the presence of nitrogen ions. Films grown with N2 added in the ion source have a higher resistivity and lower superconducting transition temperature than films grown with N2 injected directly into the chamber. These differences increase with N2 flow; the differences are attributed to damage of the growing film by energetic nitrogen reflecting from the target, as measured by an energeticneutral-particle detector. D J Lichtenwahaer et ai, J Vac Sci Technol, A8, 1990, 1283-1287. 676
23 7520. Selected-area deposition of diamond films Selected-area deposition of diamond film has been accomplished on Si substrates prepared by two different methods: reactive-ion etching (RIE) and amorphous-Si masking (ASM). In the RIE method, a Si substrate polished by a diamond paste was patterned with a photoresist mask, and the unprotected areas were etched by RIE, followed by a complete removal of the photoresist films. The diamond deposition was done by electron-assisted chemical-vapor deposition (CVD), and diamond films grew only in the areas once covered with the photoresist films and not etched by RIE. In the ASM method, a polished Si substrate was also photolithographically masked with photoresist, followed by a uniform deposition of a hydrogenated amorphous silicon (a-Si:H) film. The photoresist film was then lifted off together with the overlay of deposited a-Si : H, leaving the polished Si surface patterned with an a-Si : H mask. In this case, the diamond deposition was done by microwave plasma CVD, and diamond films grew only in the areas not covered with a-Si : H. In both cases, well-defined diamond patterns with line/space dimensions of a few micrometers were formed on the substrates. T Inane et al, J Appl Phys, 67, 1990, 7329-7336. 23 7521. Preparation of cubic boron ultride film by C02 laser physical vapour deposition with simultaneous nitrogen ion supply Hard cubic boron nitride (c-BN) rich films have been prepared by a newly developed CO2 laser physical vapour deposition process assisted by a simultaneous nitrogen ion supply. A high power CO2 laser of 200-1000 W was focused and irradiated onto the peripheral surface of a rotating sintered hexagonal boron nitride (h-BN) ring and the vapour was deposited on a substrate. N2 gas ionized in a Kaufman-type ion source was accelerated at a bias voltage of 0-2.0 kV and irradiated onto the substrate simultaneously with the laser evaporation process. The films were characterized by electron spectroscopy for chemical analysis, thin film X-ray diffraction, Auger electron spectroscopy, ir spectroscopy and scanning electron microscopy. Mechanical properties were also evaluated by Knoop hardness measurements, scratch tests and wear experiments. The composition ratio N : B of the films prepared from high purity 99% h-BN increased as the accelerating voltage increased and neared unity at about 1 kV. Cubic boron nitride (c-BN) was clearly identified at accelerating voltages over 0.5 kV. The higher the accelerating voltage was, the greater was the proportion of the cubic phase. The c-BN-rich films were found to have extremely high Knoop hardness of 3800-4600 kgf mm -2 and sufficient wear resistance against N i - M o steel (SAE 4620). S Mineta et al, Thin Solid Films, 189, 1990, 125-138. 23 7522. Crystal forms and their orientation in poly(vinylidene fluoride) films prepared by an ionized-vapour deposition method Poly(vinylidene fluoride) (PVDF) films were deposited on substrates by an ionized-vapour deposition method under various conditions in which the acceleration voltage and ionization current were changed. IR spectra of the PVDF films were measured by ir reflection absorption spectroscopy methods with polarized light, and the crystal forms and their orientation in the films were investigated. It was found that the films containing form I crystals, which are known to possess ferroelectricity, were able to be obtained when ionization and acceleration were carried out. The contents of form I depended on both acceleration voltage and ionization current. The wattage supplied to the substrate (ion current multiplied by the acceleration voltage) seems to be a dominant factor in determining the crystal forms. From the result of ir dichroic measurements, it was found that the form I crystals were oriented; the molecular chain axes were parallel to the substrate surface, and the CF2 dipole was perpendicular to the surface and along the applied field. The film showed pyroelectricity, and its pyroelectric coefficient was about 1 nC cm -2 K - ' which was a third of that of an authentic PVDF pyroelectric film. J Sakata and M Mochizuki, Thin Solid Films, 189, 1990, 123-132. 23 7523. Structure of ion-plated amorphous hydrogenated carbon films investigated by electron energy loss spectroscopy Thin ion-plated amorphous hydrogenated carbon films were investigated by electron energy loss spectroscopy. From an analysis of the dielectric function, information on the film structure could be obtained. The results will be compared with those of electron diffraction studies. Differences between insulating and conducting substrates could be verified in the film