Fabrication Of Oxide Film And Investigation Of Growth Mode Using Modified Si Substrate

In this dissertation, anisotropic wet etching method was used to modify the surface pattern of single Si(100) substrate; Liquid phase deposition and RF magnetron sputtering were adopted to obtain STO film; Spin-coating sol-gel method was employed to prepare Bi-2212 film. The main contents of the dissertation are as follows:1. The fabrication of V-grooves on single Si(100) substrate. In this paper, parallel and continuous V-grooves along the Si[010] direction with sidewalls of Si(110) were formed on Si(100) substrate using KOH/IPA solution as etchant, and the TiO2 film was deposited on the Si(100) as resist mask by RF-magnetron sputtering. The investigation on different etching time and thickness of mask showed that the depth and width of V-grooves decreased gradually with the increase of etching time, and the mask was also consumed continuously. Top of the grooves were corroded and the structure were deteriorated when the mask was exhausted. So the substrate cannot be well protected if the mask was too thin, while the mask tended to fall off from the substrate if the mask was too thick. V-grooves with smooth sidewalls were obtained when the etching time was 30 min and the thickness of TiO2 mask was 200 nm. In the meanwhile, V-grooves could also be obtained using isotropic wet etching method based on anisotropic etching method, while the quality is undesirable. The modified substrate with V-grooves is the base for the preparation of films with different orientation.2. Liquid phase deposition and RF magnetron sputtering were adopted to obtain STO film. STO film was deposited on Si(100) substrates with V-grooves. Results revealed that quality of STO films prepared via LPD depended on the wettability of substrate surface, and the wettability was desirable when the hydrophilic treatment for the substrates was 10 min. Smooth film was obtained when the deposition temperature was 40℃, followed by annealing at 650℃for 4 h, and large grains occurred when increasing the deposition temperature. STO film with [e00)] preferred orientation was obtained when the substrate temperature is 300℃via RF magnetron sputtering, followed by post annealing at 700℃. The increase and decrease of substrate temperature or annealing temperature would deteriorate the preferred orientation, while the decrease of sputtering power and pressure improved the degree of preferred orientation of STO film. 3. Spin-coating sol-gel method was employed to prepare Bi-2212 film. Nitrates were used as the reactor, ethylenediaminetetracetic acid (EDTA) as chelating agent and triethanolamine (TEA) as polymerizing agent. Results revealed that the attachment of sol film and substrate is optimal when the time of water bath is 9h, which the viscosity of sol was 55mPa.s. In the meanwhile, the optimization of drying process showed that the rapid drying at 600℃can decrease both the partition of film brought by the assembling of precursor gel film and the ingredient segregation brought by the different dissolvability of every ingredient.In addition,830℃was the optimal heat treatment temperature to form Bi-2212 single phase, and Bi-2212 thin film with high quality can be obtained when the heating-up time and holding time are 5 h and 3 h, respectively. At last, the times for spin-coating were also investigated, and 5 times was desirable to obtain films with smooth surface and better superconductivity property. The Bi-2212 film was c-axis epitaxial on flat Si(100) substrate, but the impurity should be reduced, and the surface morphology need to be improved. For the film grown on modified substrate, the a, b-axis epitaxial film could be found on sidewall of V-grooves, but the result need to be confirmed.