Deposition and characterization of Ta, TaN/sub x/, and Ta/sub 4/B films for NGL mask application

Next generation lithography (NGL) masks are mainly divided into three categories by pattern transfer method - reflective type, membrane type and stencil type. Among these types of masks, the reflective and membrane type masks require the metal patterns for contrast formation through scattering or absorption. It is important to control the stress and microstructure of the metal film to ensure the pattern placement accuracy of the masks. Among the several kinds of metal pattern materials, Ta-based materials show advantages in compatibility with dry etching and cleaning process with acidic solutions. However, it is known that the columnar structure of the sputter deposited film provides paths for oxygen, resulting in the in-plane distortion of the masks. In this experiment, TaN/sub x/ and Ta/sub 4/B films are deposited by using the same deposition system and their properties as pattern materials have been compared with those of pure Ta film.