Etching Method to Form Spacers Having Multiple Film Layers

摘要

Methods herein can be used for removing silicon nitride around fins and other structures without damaging underlying silicon structures. Methods herein also include forming dual layer spacers and L-shaped spacers, as well as other configurations. Techniques include a multi-step process of anisotropic etching of low-k material with high selectivity to silicon nitride, followed by isotropic etching of SiN with high selectivity to the low-k material. Such techniques, for example, can be used to form an L-shaped spacer on a 3-D gate structure, as well as providing a method for completely removing silicon nitride without damaging surrounding or underlying materials.

主权项

1. A method of forming a spacer, the method comprising:
positioning a substrate on a substrate holder in a plasma processing chamber, the substrate having a silicon nitride film covering structures on the substrate and a low-k film covering the silicon nitride film, the silicon nitride film and the low-k film substantially conforming to geometry of structures on the substrate; executing an anisotropic etch process that etches a portion of the low-k film using plasma products from a halogen-containing process gas mixture such that the low-k film is removed from first structures while remaining on second structures that are taller than the first structures, executing the anisotropic etch process deposits a CFy-based polymer on exposed silicon nitride surfaces; and executing an isotropic etch process that etches silicon nitride using plasma products from an oxygen-based process gas.