| Title |
A Study on the Properties of WS i_{x} Thin Film with Formation Conditions of Polycide |
| Keywords |
Tungsten hexafluoride (W F_{6} ) ; Dichlorosiliane (Si H_2C l_2) ; Tungsten Silicide (WS i_{x} ) ; Contact Resistance |
| Abstract |
We perform the physical analysis such that Si/W composition ratios and phosphorus distribution change in the W/S i_{x} thin films according to phosphorus concentration of polysilicon and W F_{6} flow rate for the formation of WS i_{x} polycide used as a gate electrode. We report that these physical characteristics have effects on the contact resistance between word line and bit line in DRAM devices. RBS measurements show that for the samples having phosphorus concentrations of 4.75 and 6.0×10^{2-} atoms/㎤ in polysilicon, by applying W F_{6} flow rates decreases from 4.5 to 3.5 sccm, Si/W composition ratio has increases to 2.05∼2.24 and 2.01∼2.19, respectively. SIMS analysis give that phosphorus concentration of polysilicon for both samples have decreases after annealing, but phosphorus concentration of WS i_{x} thin film has increases by applying W F_{6} flow rates decreases from 4.5 to 3.5 sccm. The contact resistance between word line and bit line in the sample with phosphorus concentration of 6.0 × 10^{20} atoms/㎤ in polysilicon is lower than the sample with 4.75 × 10^{20} atoms/㎤ After applying W F_{6} flow rates decreases from 4.5 to 3.5 sccm, the contact resistance has been improved dramatically from 10.1 to 2.3 μ Ω- textrm cm^2. |