Method for lowering the phase transformation temperature of a metal silicide

THE PHASE TRANSFORMATION TEMPERATURE OF A FORMED METAL SILICIDE LAYER IS REDUCED BY COVERING A SILICON LAYER ON A SEMICONDUCTIVE CRYSTALLINE SHEET. FIRST, A REFRACTORY METAL IS PROPOSED NEAR THE SURFACE OF THE SILICON LAYER, A PRECURSOR METAL IS DEPOSITED IN A LAYER COVERING THE REFRACTORY METAL, AND THE CRYSTALLINE SHEET IS HEATED TO A SUFFICIENT TEMPERATURE TO FORM THE METAL SILICIDE. PRECURSORY. THE PRECURSORY METAL MUST BE A REFRACTORY METAL, AND IS PREFERABLY TITANIUM, TUNGSTEN, OR COBALT. THE CONCENTRATION OF THE REFRACTORY METAL ON THE SURFACE OF THE SILICON LAYER IS PREFERABLY LESS THAN 1017 ATOMS / CM3. THE REFRACTORY METAL MUST BE MO, CO, W, TA, NB, RU, O CR, AND MORE PREFERABLY MO, O CO. THE HEATING STEP USED TO FORM THE SILICIDE IS PERFORMED AT A TEMPERATURE LESS THAN 700 C, AND MORE PREFERABLY BETWEEN 600-700 C. OPTIONALLY, THE CRYSTALLINE SHEET IS ANNEALED BY FOLLOWING THE STEP OF DEPOSITING THE REFRACTORY METAL AND PRIOR TO THE STEP OF DEPOSITING THE PRECURSORY METAL LAYER. PREFERABLY, THIS ANNEALING STEP IS PERFORMED AT A TEMPERATURE OF THE CRYSTALLINE SHEET OF AT LEAST 900 C.