Plasma Anisotropic CVD for Cu Interconnects in LSI

利用h辅助等离子体化学气相沉积技术，实现了铜的各向异性沉积，即铜优先从沟槽底部填充而不沉积在沟槽的侧壁上。各向异性沉积有两个有趣的特征。一是沟槽宽度越窄，沟槽底部沉积速率越快。另一种是自限特性，即充填完全后，沟槽内的沉积会自动停止。这种类型的沉积有可能克服与适形填充相关的常见问题：小于沟槽宽度一半的小晶粒尺寸，以及形成具有相对高浓度残留杂质的缝。

We have realized anisotropic deposition of Cu, for which Cu is filled preferentially from the bottom of trenches without being deposited on their sidewall, using H-assisted plasma chemical vapor deposition. The anisotropic deposition has two interesting features. One is the fact that the narrower the width of trench is, the faster the deposition rate on its bottom becomes. The other is the self-limiting characteristic that the deposition in the trench stops automatically just after filling completely it. Such type of deposition has a potential to overcome common problems associated with conformal filling : a small crystal grain size below a half of the trench width, and formation of a seam with residual impurities of relatively high concentration.