氮化鋁是一種具有高絕緣、高熱傳的材料，但由於氮化鋁同時具有高的化學惰性，再加上現有的拋光技術最好只能將多晶氮化鋁基板表面拋至RMS=16nm，因此要實現多晶氮化鋁/氮化鋁晶圓鍵合是非常困難的。本研究利用氧氣電漿活化粗糙的氮化鋁基板表面，以增加其表面親水功能基密度，使表面毛細管作用力提升。用AFM量測電漿活化前與電漿活化後的表面粗糙度差異，發現電漿活化三分鐘後表面被電漿清潔因此粗糙度會下降，但電漿活化五分鐘後表面被電漿破壞，因此粗糙度上升。用接觸角量測儀量測電漿活化前與活化後潤濕性的差異，發現電漿活化後接觸角由85度下降到16度，證實了電漿活化後，表面親水功能基密度會提升。之後在兩片氮化鋁間滴入一滴去離子水後進行晶圓鍵合，將鍵合好的試片加壓並放在室溫下一天後，再放入烘箱中進行退火以提升鍵合強度。由SEM的結果得知，鍵合後的氮化鋁/氮化鋁鍵合對介面無微米等級的孔洞產生，由TEM結果發現在鍵合處有30nm厚的過渡層，利用EDS分析及XPS分析得知此過渡層的成分為氧化鋁。;Aluminum nitride is a material with high insulation and high heat transfer. However, due to the high chemical inertness of aluminum nitride, in addition to the existing polishing technology, the surface of aluminum nitride substrate can only be polished to RMS=16nm at best, so it is very difficult to realize aluminum nitride/aluminum nitride wafer bonding. In this study, the rough aluminum nitride substrate surface was activated by oxygen plasma to increase the density of hydrophilic functional groups on the surface of aluminum nitride and enhance the surface capillary force. The difference of surface roughness before and after plasma activation was measured by AFM. It was found that after three minutes of plasma activation, the surface was cleaned by plasma, so the roughness decreased. However, after five minutes of plasma activation, the surface was damaged by plasma, so the roughness increased. The difference in contact angle between before and after plasma activation was measured by Contact Angle Meter. The difference in wetting properties before and after plasma activation was measured by Contact Angle Meter. It was found that the contact angle decreased from 85 degrees to 16 degrees after plasma activation. It is confirmed that the density of hydrophilic functional groups on the surface will increase after plasma activation. After oxygen plasma activation, a drop of DI water was added between the two aluminum nitride pieces and then wafer bonding was performed. Finally, the bonded pairs were pressed and placed at room temperature for one day, and then annealed in an oven to improve the bonding strength. The SEM results showed that the AlN/AlN bonding pair had no micron-level holes at the bonding interface. From the TEM results, a 30 nm thick transition layers was found at the bonding interface. The composition of the transition layers was found to be aluminum oxide by EDS analysis and XPS analysis.
