應用在砷化鎵單質微波積體電路上各種不同的連接線製程之研究

Abstract

本實驗使用低介電材料Benzocyclobutene（BCB）或是空氣做為金屬層間的介質，進行各種不同金屬連接線技術，以應用於砷化鎵微波積體電路製程。論文中詳述各個製程步驟的技術，並將銅製程應用於其中，以得到更佳的電性及降低製造成本。 在本論文中論及了低介電物質應用於銅製程中製造銅空氣橋。銅製程的使用可降低成本及獲得較小之電阻值；在本論文中首度使用銅/鎢薄金屬技術，並利用H2O2/HNO3蝕刻W/Cu以做為銅空氣橋製造之電鍍基層膜，此製程適用於GaAs MMIC製程。此外，更將低介電物質應用於傳統金製程中，以比較其與銅製程之差異。實驗結果顯示銅製程所得之銅膜片電阻值為4.6 ~ 5.6 mΩ/□，較傳統金製程所得之金膜片電阻值14.1 ~ 16.0 mΩ/□更低。 實驗結果顯示銅薄金屬經H2O2/HNO3溶液蝕刻後，可將銅薄金屬去除，也保有結構之完整性並以此製程製作出低介電介質之銅空氣橋製程。本計劃中，Au Airbridge、Au BCB Bridge和Cu BCB Bridge之製程流程已設計完成並成功做出各類取代傳統金空氣橋之連接線之各類連接線，等待應用於元件上作電性之量測。

In this study, the low k material Benzocyclobutene (BCB) is used as the inter-metal dielectric, and Cu is used as the conducting metal to form the alternative interconnect technology for GaAs MMICs. Technologies of these processes are described in detail in the thesis. The low k material BCB and copper are integrated to form Cu BCB bridge. The use of copper metal as conducting metal has the advantages of low cost and low sheet resistance, however, W is deposited as barrier layer to prevent interdiffusion of Cu and under-layer metals; the H2O2 / HNO3 is used to etch copper thin metal W/Cu and the whole process is compatible with GaAs MMICs process. BCB is also applied to form Au BCB bridge and compare with Cu BCB bridge. The sheet resistance of the electroplated Cu is 4.6 ~ 5.6 mΩ/□ which is lower than that of electroplated Au which is 14.1 ~ 16.0 mΩ/□. In this work, physical structures of Au airbridge, Au BCB bridge, and Cu BCB bridge are developed and ready for process integration with GaAs MMICs.