以田口方法改善金屬導線之片電阻值的探討

Abstract

隨著電子元件尺寸逐步的微小化，蝕刻特性必須被精確的控制，其中包含︰非等向性、選擇比、蝕刻率和均勻性等等。不僅如此，更要能夠處理相當複雜且相互抵觸的製程特性。本論文將針對在反應性離子蝕刻系統，利用實驗計畫法最佳化以氯化物為氛圍的鋁合金之電漿蝕刻製程，主要目的在於改善晶圓廠內蝕刻製程金屬導線之電性，吾人利用田口方法來規劃實驗設計，以期能有效讓製程條件最佳化。 在本論文中，將探討影響金屬蝕刻的製程條件，包括8個實驗的製程參數，其中有主要蝕刻步驟中的BCl3、Cl2、N2及CF4氣體流量和過度蝕刻步驟中之壓力、射頻功率、N2及BCl3氣體流量。將可調整的製程參數分別列入田口方法L18直交表中，選取適當水準範圍。另外在主要蝕刻步驟中固定射頻功率575 W和壓力 250 mTorr，過度蝕刻步驟中蝕刻時間固定在135秒。 將所得的數據結果利用STATISTICA軟體進行分析，順利找出對鋁合金蝕刻特性的重要因子並完成各實驗因子對製程的效應，最後求得最佳條件組合為：A1B1C1D2E2F1G2H1，其先後順序分別代表在過度蝕刻步驟N2流量為60 sccm、在主要蝕刻步驟BCl3流量為54 sccm、Cl2流量為16 sccm、N2流量為60 sccm、CF4流量為5 sccm、在過度蝕刻步驟壓力為450 mTorr、射頻功率為575 W及BCl3流量為50 sccm，根據最佳條件組合運用於量產產品上，並使得產品的良率有顯著的提升。

The scale of the electrical device is tiny gradually, not only the etching characteristic that included anisotropy, selectivity, etching rate and uniformity and so on be must controlled precisely, but we must be able to handle the characteristic of the process which was quite complex and mutually conflicts. This thesis will aim at the system of reactivity ion etching, I use the design of experiment to fine tune the etching process of plasma of aluminum alloy in the atmosphere of the chloride, The main purpose consist in improving the electrical property of the metallic wire of etching process in wafer factory. Considering this issue, we scheme the experimental design using the Taguchi method, and expect to modulate the parameters of the process effectively and to optimize the property of the process. In this thesis, there are 8 variables of the experimental process that include the BCl3, Cl2, N2 and CF4 gas flow rate in the main etch step and pressure, radio frequency power, N2 and BCl3 gas flow rate in the over etch step. Therefore we listed the adjustable parameters of the process respectively into the L18 table in Taguchi method, selecting suitable level. Moreover the radio frequency power is fixed 575 W and the pressure is fixed 250 mTorr in the main etch step, the etching time is fixed 135 sec in the over etch step. After completed the experiment, we analyzed the experimental result by the software of the STATISTICA, found out the important factors smoothly for the etching property of the metallic Wire, and completed the effect of the process for each experimental factors, we finally got the combination of the optimum parameters that is A1B1C1D2E2F1G2H1, which represent N2 flow rate 60 sccm in over etching step. BCl3 flow rate 54 sccm, Cl2 flow rate 16 sccm, N2 flow rate 60 sccm and CF4 flow rate 5 sccm in main etching step. Pressure 450 mTorr, radio frequency 575 W and BCl3 flow rate 50 sccm in the over etching step, according to the combination of the optimum parameters which be applied to mass-production products on productive line, and the yield of the products is raised.