Epitaxial AlxGa1−xN films have been grown on c-cut sapphire substrates at 800 °C and 10−2 Torr N2 by pulsed laser deposition (PLD) using a KrF laser. Throughout the composition range from x=0 to 0.6, the films show epitaxial patterns in reflection high-energy electron diffraction, in agreement with the results from x-ray diffraction. The lattice constants of the films vary linearly with x. The composition dependence of the band gaps of the films deviates from linearity and bows downward. This letter reports the application of PLD to controlling the lattice constant and band gap by varying the proportion of AlN and GaN in the target mixture.
A CVD-based low κ film was evaluated for inter-metal dielectric in < 0.18 µm generation devices. The film was deposited by conventional rf PECVD method using organosilane compound and oxygen. The measured dielectric constant of the film was 2.7~2.75. The κ value of the film was stable over several weeks and the moisture absorption was minimal. The chemical composition was in the form of SiO x C y H z , where the carbon content was less than 5 atomic %. Blanket film integration study was conducted to find out the manufacturing compatibility. The largest increase in κ value occurred during etching and ashing steps. However, SIMS compositional analysis revealed that the damage from these steps were limited to within top 300 Å, and the initial low κ value was recovered after the top damaged layer was removed by CMP. The final integrated dielectric constant was less than 3.0. The film density was measured as 1.4, compared to 2.3 g/cm 3 of conventional SiO 2 . The low density of the film resulted from the termination of SiO 2 network structures by Si-CH 3 and Si-H.
INTRODUCTIONSilicon dioxide (SiO 2 ) has been dominantly applied as inter metal (IMD) and inter layer dielectric (ILD) throughout the history of microelectronics industry. The dominance is mainly attributed to its desirable electrical, thermomechanical characteristics as well as simplicity in integration with other materials. As the interconnection complexity required for high performance devices rapidly increases, however, several issues have arisen with traditional interconnection scheme, including enhanced RC delay effect, signal integrity due to cross talking and high power dissipation [1]. As part of the efforts to resolve these issues, new low dielectric constant material needs to be developed. Several approaches have been widely pursued in the past several years. Organic [2,3], inorganic [4,5] or hybrid[6,7,8] materials have been widely evaluated by either spin-on or chemical vapor deposition methods. Some of the issues with organic materials include thermal stability and reduced mechanical strength, which impose significant challenges on film integration. Inorganic low κ materials, in general, exhibit less integration issues, but κ stability still needs to be improved and there is difficulty in obtaining manufacturable materials with κ less than 3.0. Inorganic/organic hybrid material has received wide attention to obtain reliable low κ films while minimizing integration difficulties. In the development of hybrid low κ material, it is desirable to maintain low carbon content. High carbon content material has potential issues of via poisoning, etch and ash difficulties and thermomechanical instability. In this paper is presented the low carbon content low κ materials with carbon content less than 5%.
GaN films and ZnO buffer layers have been deposited on c-cut sapphire substrates by pulsed laser deposition (PLD) employing a KrF laser (X = 248 nm). The influence of the deposition parameters, such as substrate temperature and gas pressure during growth, have been studied. GaN films grown above 700 "C are single crystalline and the full width of half-maximum (FWHM) of the GaN (0002) peak decreases to 0.37' as the growth temperature increases to 800 *C. The optimum growth pressure for GaN is determined to be 0.01 torr N 2 . The optical transmission below the bandgap of the GaN film grown at this pressure is over 85%.
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