The study of compensative structure assisted convex and concave corner structures etching by inductively coupled plasma-reactive ion etch (ICP-RIE)

In this paper, the compensative structure assisted the convex and concave corner structures etch in inductively coupled plasma reactive ion etch (ICP-RIE) have been studied. In anisotropic silicon etching, under the Bosch patent, sequentially alternating etch and passivation cycles can easily achieve high aspect ratio silicon structures. But, the feature size of the convex and concave corner structures are difficult to maintain as original design at the bottom position in deep etch, due to non-vertical movement plasma etch. A compensative structure can obstruct the non-vertical plasma to etch the convex corner structures and reduce the etch lag effect during the etch process leading to better profile at deep etch. The current study systematically investigates plasma condition to verify feasibility of the proposed method, and discusses effect of the gap between compensative structure and convex and concave corner structures at three different gaps of 15, 10, 5μm. It demonstrate the compensative structure with small gap in front of the convex and concave corner structures have better profile at deep ICP-RIE etching.