Silicon Dry Etch Process for Shallow Trench Isolation

Shallow Trench Isolation (STI) holds many advantages to that of its predecessor isolation technology in that STI increases the packing density, has superior latch-up immunity, smaller channel-width encroachment, and better planarity, allowing for smaller and thus faster and/or less power hungry devices. The goal of this project was to develop an anisotropic silicon etch process for use in the Drytek Quad 482 Reactive Ion Etch system, yielding a depth of at least 0.5μm and steep sidewall angle of the trench. For this study, varying plasma chemistries of consisting sulfur hexafluoride, oxygen and argon are examined to etch the bulk silicon for formation of the trench using a 3000A silicon nitride and 500A pad oxide as a hard mask layer. Some anisotropy was seen in the etch process using a scanning electron microscope to examine the etch profile