Reduction of substrate alkaline contamination by utilizing multi-layer bottom antireflective coating structures in ArF lithography

Demonstrates a new multilayer BARC structure for ArF lithography. The BARC is composed of a TEOS oxide / silicon nitride / silicon nitride film stack deposited by the conventional PECVD process. Silicon nitride films of different composition and optical properties at 193 nm can be easily obtained by varying the gas flow rate ratio of SiH/sub 4/ and NH/sub 3/. A TEOS oxide film is alkaline contamination free and can be used as NH/sub 3/ capping layer, which also has suitable optical characteristics as the top layer of a multi-layer BARC structure. Thermal stability of BARC layers is performed by thermal desorption spectroscopy to see if there is alkaline contamination from BARC films. Results show that this multi-layer BARC would reduce reflectance of these highly reflective substrates to less than 2%. Therefore, this multi-layer BARC structure is expected to have great potential for various highly reflective materials with no alkaline contamination.