A 2-STEP PROCESS FOR THE FORMATION OF A MO2C CONTACT ON POLYCRYSTALLINE DIAMOND FILMS

The various phases obtained after annealing of molybdenum films on dia mond free and encapsulated by Si3N4 are determined from Rutherford bac kscattering spectrometry and X-ray diffraction. Virgin molybdenum film s always contain some oxygen, which hinders carbon diffusion and preve nts the formation of Mo2C. Oxygen is removed by annealing of the free molybdenum films above 700 degrees C, and full formation of Mo2C is ob tained at 1000 degrees C. However, annealing at 1100 degrees C induces the formation of a superficial carbon layer, with carbon inclusions i n the carbide. A two-step process, with annealing of the molybdenum vi rgin film at 900 degrees C, then from 100 to 1100 degrees C after enca psulation with Si3N4, allows the formation of the suitable full Mo2C f ilm, with less stringent conditions. (C) 1997 Elsevier Science S.A.