TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The BSF layer comprises at least one film including an aluminum oxide (AlO) film, aluminum nitride (AlN) film and aluminum oxynitride (AlON) film. The BSF layer comprises: AlO film, and a protective layer formed with oxide is further placed between the p-type semiconductor substrate and the BSF layer; or AlN film or AlON film, and the AlN film or AlON film is formed on the p-type semiconductor substrate. The aluminum source gas comprises at least one trimethylaluminum (TMA), aluminum trichloride, triethylaluminum, chlorodimethylaluminum, aluminum ethoxide, aluminum isopropoxide, triisobutyl aluminum, dimethylaluminum hydride, trimethylamine alein (sic), triethylamine alein (sic) or dimethylethylamine alien (sic). The oxidizing agent gas comprises ozone, nitrous oxide, oxygen and hydrogen peroxide, and the nitriding agent gas is ammonia or nitrogen. Preferred Method: In the method: the AlO film, AlN film or AlON film is formed by performing deposition at 150-400 degrees C using an atomic layer deposition (ALD) or chemical vapor deposition (CVD) process. The step of forming the BSF layer comprises: either (a) loading at least one substrate on a substrate support disposed or placed in a processing chamber, and (b) repeatedly performing a process of sequentially injecting an aluminum source gas, a first purge gas, an oxidizing or nitriding agent gas, and a second purge gas from over the substrate support to deposit the AlO film or the AlN film; or step (a) as above per se, and repeatedly performing a process of sequentially injecting the aluminum source gas, first purge gas, one of an oxidizing agent gas and a nitriding agent gas, a second purge gas, the other one of the oxidizing agent gas and the nitriding agent gas, and a third purge gas from over the substrate support to deposit the AlON film; or step (a) as above per se, and repeatedly performing a process of sequentially injecting the aluminum source gas, first purge gas, one of an oxidizing agent gas and a nitriding agent gas, the second purge gas, the aluminum source gas, a third purge gas, the other one of the oxidizing agent gas and the nitriding agent gas, and a fourth purge gas from over the substrate support to deposit the AlON film; or (a1) loading many substrates on a substrate support placed in the processing chamber along a circumference of the substrate support, and repeatedly performing a process of simultaneously injecting the aluminum source gas, first purge gas, oxidizing or nitriding agent gas and second purge gas from a shower head provided over the substrate support while relatively rotating the substrate support with respect to the shower head including many gas injection units, to deposit the AlO film or the AlN film; or step (a1) as above per se, and repeatedly performing a process of simultaneously injecting the aluminum source gas, first purge gas, one of the oxidizing agent gas and nitriding agent gas, second purge gas, the other one of the oxidizing agent gas and the nitriding agent gas, and third purge gas from a shower head provided over the substrate support while relatively rotating the substrate support with respect to the shower head to deposit the AlON film; or step (a1) as above per se, and repeatedly performing a process of simultaneously injecting the aluminum source gas, first purge gas, one of the oxidizing agent gas and nitriding agent gas, second purge gas, the aluminum source gas, third purge gas, the other one of the oxidizing agent gas and the nitriding agent gas, and a fourth purge gas from a shower head provided over the substrate support while relatively rotating the substrate support with respect to the shower head, the shower head to deposit the AlON film.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The shower head assembly: has a structure in which different kinds of process gases are sequentially injected through the injection holes; and further comprises a central purge gas injection unit disposed in a center of the shower head assembly to supply a purge gas. The substrate processing apparatus further comprises: a rotation driver to rotate at least one of the substrate support and the shower head assembly such that the substrate support and the shower head assembly rotate with respect to each other. The shower head assembly comprises: many raw material gas injection units arranged along a circumference of the substrate support to supply different kinds of raw material gases on the substrate support; and many purge gas injection units respectively disposed between raw material gas injection units for injecting different kinds of raw material gases among the raw material gas injection units, to purge a raw material gas injected on the substrate support. In the apparatus: the shower head assembly and the gas injection blocks are configured in such a manner that adjacent at least two injection units among the raw material gas injection units and the purge gas injection units, the adjacent gas injection units injecting the same kind of gas, are grouped into a gas injection block; and the buffer units which inject no gas are respectively disposed between the raw material gas injection units and the purge gas injection units. EXAMPLE - No suitable example given.