||In this thesis, we propose low thermal budget laser technologies to form a homogenous and ultralow sheet resistance nickel silicide on the Source/Drain region of bulk silicon FinFET, thereby improves the device performance.|
Carbon dioxide laser is employed to replace the second annealing step of nickel silicide process. We investigate the effect of the chuck temperature and laser power on both physical and electrical characteristics of the blanket wafer. According to the experiment results, the sheet resistance doesn’t change after applying a laser annealing at the 2nd annealing step of nickel silicide which is on a room-temperature chuck. Moreover, the 3rd annealing by RTA can make the sheet resistance reduce from 100 ohm/sq. to 13 ohm/sq. However, when the heated chuck is applied, nickel silicide can be formed without the 3rd annealing and a lower sheet resistance about 9 ohm/sq. can be obtained. The physical mechanism between chuck temperature and laser absorption of silicon substrate will be detailed in this thesis as well.
We integrate the technologies mentioned above to the silicon bulk FinFET, and the highest drive current can be reached to 648 μA/um for n-type, which is 1.3 times to the device without silicide. Nickel silicide fabricated with laser spike annealing involvement has better electrical properties and also has lower thermal budget, thus it is beneficial to develop the device with smaller physical dimensions.
Finally, we apply multi-ring circular transmission line model to extract the specific resistivity. According to the experiment result, nickel silicide formed with laser has lower resistivity, which means that laser has a potential on reducing the contact resistance.