セルフスパッタ・リフローによる微細孔の埋込

Copper self-sputtering is investigated to fill deep holes in a Silicon wafer. The dimensions of the holes are 0.6 μm in diameter 1.2 μm in depth. The distance between the substrate and the target is 173 mm, 5.5 times the erosioncenter radius. This distance is chosen to attempt to improve the filling characteristics. The substrate temperature between 300°C and 550°C. The thickness of copper films deposited is in the range of 0.8 μm to 1.5μm. The base pressure of the sputtering process is a extremely high vacuum (XHV, less than 1×10−8 Pa). It is found that two-step self-sputtering of copper is very effective to fill up the contact holes without using a barrier metal However when using barrier metal films of TiN, the reflow processes after the deposition of total films at room temperature obtains good results.