Title: CF4電漿前置處理在超大型積體電路上的相關應用
Applications of CF4 plasma pretreatment in the ULSI technology
Authors: 曾泓棋
Tzeng Hung Chi
Lee Chung Len
Keywords: CF4電漿;前置處理;能障下降;Ni矽化物;漏電流;CF4 plasma;pretreatment;barrier height;EEPROM;SILC;Ni silicide;leakage current
Issue Date: 2000
Abstract: 隨著可攜帶式電子產品的普及化,帶動系統整合晶片(SOC, System-on-a-chip)與非揮發性記憶體(Nonvolatile EEPROM memory)兩項技術的發展。在系統整合晶片中需要不同厚度的閘極氧化層,而非揮發性記憶體則需要降低操作電壓與功率消耗,這對氧化層的成長上都是相當困難且複雜的技術,有待進一步的研究。 在本論文中,我們提出一種經CF4電漿前置處理步驟來成長的閘極氧化層的方法。由電漿引進氟至氧化層中可以大大降低載子入射能障(Barrier height),繼而產生較大的F-N穿遂電流,達成降低操作電壓的需求。實驗中也證明了在氧化層成長中加入N2O回火可以維持上述特性,並改善氧化層的Qbd、減少漏電流。 在最後一個部分是研究氟化處理對金屬矽化物可靠度的影響,尤其是對半導體元件在漏電流的影響。我們發現了CF4電漿前置處理可以有效地改善此現象。
As the portable electronic products becoming more and more popular, the SOC (System-on-a-chip) and nonvolatile EEPROM memory technologies are developed naturally. However, SOC technology is extremely complicated due to the fact that multiple thickness of gate oxide was needed. EEPROMs with lower operation voltages were also needed to save power consumption, but it is impractical to achieve by scaling down thickness of tunnel oxides. In this thesis, we propose a new kind of fluorinated oxides by CF4 plasma pretreatment. Barrier heights are reduced greatly, and then larger F-N tunneling currents are generated. Additional N2O annealing maintains those properties; by the way, the Qbd’s and the leakage currents characteristics are improved. Finally, Ni silicide formed on the CF4 fluorinated polysilicon was also studied. In forming silicide, Ni atom penetration will degrade the characteristics of devices. Especially in ULSI circuits, larger leakage currents produce excess heat to influence the reliability. In our experiments, CF4 plasma pretreatment could suppress the Ni penetration and decreases leakage currents of the oxides.
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