| Summary: | 碩士 === 長庚大學 === 電子工程學研究所 === 97 === The cold\hot Al plug process is widely used to apply in gap filling of metal interconnect in the Trench DRAM product. In order to obtain better electrical performances, higher product yields, and excellent reliability in AlCu metal interconnect; it is necessary to promote aluminum gap fill capability, purify process gas and reduce down chamber gas leakage rate. In this thesis, at first, we investigate the influences of Ti glue layer and cold Al seed layer, and the Al-deposition temperature in the two-step cold/hot Al PVD reflow technology for via filling. It can be found obviously that the void formations are related to the factors including Ti glue layer, cold Al seed layer and reflow hot Al deposition temperature from SEM analysis. Furthermore, the performance and reliability are also impacted from the electrical and wafer level reliability test. Besides, we also demonstrated that the temperature of hot Al process can impact aluminum alloy orientation and analyze N2 partial pressure in Ar gas process and gas leakage effects in electrical properties and product yields.
On the other hand, we have adopted the ionized physical vapor deposition and long throw sputtering in titanium and titanium nitride contact metal process. In order to reduce contact leakage current and improve product performance and reliability, it is important to modify TiSix formation and suppress leakage current such as reducing contact resistance and decreasing subsequent annealing temperature. Furthermore, finally in the thesis, some process technologies are proposed to reduce bit-line contact leakage current in contact metal process. Those technologies include adding nitrogen ambient for metal target nrtridation, applying Electro-Magnet coil at chamber wall for ion trajectory change, and lowering RF bias power to reduce ion bombardment for leakage improvements, which can be implemented effectively in bit-line contact process to reduce leakage current and improve product performance and reliability.
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