A new bilayer bottom antireflective coating (BARC) layer composed of hexamethyldisiloxane film stack is demonstrated for both KrF and ArF lithographies. By simply adjusting the gas flow rate ratio, the materials of the bilayer can be varied to have suitable optical constants as BARC materials working at both 248 and 193 nm wavelengths. The swing effect is experimentally shown to be reduced significantly on both silicon and Al-Si substrates. The bilayer scheme is also demonstrated to be capable of providing large thickness-controlled tolerance;