A frequent problem encountered by photoresists during the manufacturing of semiconductor device is that activating radiation is reflected back into the photoresist by the substrate. So, it is necessary that the light reflection is reduced from the substrate. One approach to reduce the light reflection is the use of bottom anti-reflective coating (BARC) applied to the substrate beneath the photoresist layer. The BARC technology has been utilized for a few years to minimize the reflectivity. As the chip size is reduced to sub 0.13 micron, the photoresist thickness has to decrease with the aspect ratio being less than 3.0. Therefore, new Organic BARC is strongly required which has the minimum reflectivity with thinner BARC thickness and higher etch selectivity toward resists. Nissan Chemical Industries, Ltd. and Brewer Science, Inc. have developed the advanced Organic BARC for achieving the above purpose. As a result, the suitable high performance NCA3000 series 248nm Organic BARCs were developed. Using CF4 gas as etchant, the plasma etch rate of NCA3000 series is about 1.4-1.6 times higher than that of conventional 248nm resists and 1.1-1.2 times higher than that of the existing product. The NCA3000 series can minimize the substrate reflectivity at below 45nm BARC thickness, shows excellent litho performance and coating properties.
Dyed photo resist and/or Top Anti-Reflective Coatings (TARC) has been used as mold in ion doping layer. However, in sub 0.25-micron pattern, this system is difficult to apply due to their poor CD control ability. As the chip size is shrunk to sub 0.25-micron in ion doping layer, the use of Organic Bottom Anti-Reflective Coatings (BARC) is strongly required. On the other hand, current Organic KrF BARCs does not dissolve in alkaline developer, and the dry etching process is indispensable in order to remove Organic BARCs. For this reason, it is difficult to apply the current Dry type Organic BARCs to the ion doping layer. To solve this problem, Wet Developable Organic BARCs to be applied to sub 0.25-micron, which have alkaline solubility have been required. NCA800 series that are the suitable alkaline developable KrF Organic BARCs, has been developed and achieved. Alkaline solubility of these BARCs was controllable by baking temperature. NCA800 series show the excellent litho performance and coating property.