TABLE OF CONTENTS Under a strong magnetic field (1000 G), a high-voltage discharge (1000 V) is kept in the magnetron sputtering system. The sputtering system operates at a low gas pressure of 10 -4 to 10 -5 torr. The high sputtering voltage and low working pressure will cause the impingement of high-speed sputtered atoms on the substrates. This may result in the lowering of the growth temperature as described in the synthesis of PbTiO 3 thin films. Unusual properties are also observed in these sputtered films. This section presents some of the interesting phenomena observed in sputtered films prepared by magnetron sputtering under a strong magnetic field.
Polycrystalline ZnO films of hexagonal structure are prepared on a glass substrate by dc or rf sputtering from a zinc or ZnO target in an oxidizing atmosphere. Table 5.58 shows typical sputtering conditions and the crystallographic structure of ZnO films prepared in a conventional dc-sputtering system and in a dc-magnetron sputtering system. In the conventional sputtering system where the working pressure is 10 to 100 mtorr, it can be seen that the c-axis is preferentially oriented normal to the film surface, i.e., the (002) plane is parallel to the film surface. When ZnO films are prepared at a low working pressure of 1 mtorr or less in the magnetron sputtering system, the c-axis is predominantly parallel to the film surface, i.e., the (110) or (100) plane is parallel to the film...
