In the production of semiconductor devices, fine processing by lithography using a photoresist has been performed. The fine processing is a processing method for forming fine convexo-concave shapes corresponding to a pattern on the surface of a substrate by: forming a thin film of a photoresist on a semiconductor substrate such as a silicon wafer; irradiating the resultant thin film with an active ray such as an ultraviolet ray through a mask pattern in which a pattern of a semiconductor device is depicted for development; and subjecting the substrate to etching processing using the resultant photoresist pattern as a protecting film. Recently, however, the high integration of semiconductor devices has progressed and the adopted active ray tends to have a shorter wavelength, such as an ArF excimer laser (193 nm) replacing a KrF excimer laser (248 nm). Following such a tendency, the influence of reflection of an active ray on a semiconductor substrate has become a large problem. Thus, in order to solve this problem, widely studied is a method of providing a bottom anti-reflective coating between the photoresist and the substrate. For such a bottom anti-reflective coating, many investigations on an organic bottom anti-reflective coating composed of a polymer having a light absorbing group and the like are performed due to easiness of its use and so on. Examples thereof include: an acrylic resin-based bottom anti-reflective coating having both a hydroxy group as a crosslinkable group and a light absorbing group within one molecule thereof; and a novolac resin-based bottom anti-reflective coating having both a hydroxy group as a crosslinkable group and a light absorbing group within one molecule thereof.
As a characteristic required for the bottom anti-reflective coating, there can be mentioned a large absorbance to light or radiation, no intermixing with a photoresist (being insoluble in a photoresist solvent), no diffusion of low molecule substances from the bottom anti-reflective coating to the photoresist as an upper layer during heating and baking, a higher dry etching rate than that of the photoresist, and the like.
Further, recently, in order to solve a problem of the wiring delay which has become apparent as the miniaturization of a pattern rule of the semiconductor device has progressed, it is studied to use copper as a wiring material. Then, together with it, a dual damascene process is studied as a wiring forming method for the semiconductor substrate. Then, in the dual damascene process, a bottom anti-reflective coating is formed on a substrate having a large aspect ratio in which a via hole is formed. Therefore, for the bottom anti-reflective coating used in this process, filling characteristics capable of filling holes without a void, planarization characteristics capable of forming a planar film on the substrate surface, and the like are required.
In addition, as an underlayer film between the semiconductor substrate and the photoresist, the use of a film known as a hardmask containing a metal element such as silicon and titanium (see, for example Patent Document 1) is performed. In this case, the resist has components largely different those of the hardmask, so that the removal rates of the resist and the hardmask by dry etching largely depend on the type of gas used for dry etching. Then, by appropriately selecting the type of gas, the hardmask can be removed by dry etching without a large decrease in the film thickness of the photoresist. Therefore, when both of the photoresist and the hardmask are used, it is considered that even when the photoresist is a thin film, the protective film (composed of the photoresist and the hardmask) can secure a film thickness satisfactory as a protective film for processing a semiconductor substrate.
Thus, in the production of semiconductor devices in recent years, for achieving various effects such as the reflection preventing effect, a resist underlayer film has become disposed between the semiconductor substrate and the photoresist. Then, also until today, the studies of a composition for a resist underlayer film have been performed, however, due to the diversity of characteristics required for the composition and so on, the development of a novel material for the resist underlayer film is desired.
For example, there is disclosed a composition or a pattern forming method using a compound having a silicon-silicon bond (see, for example Patent Document 2).
In addition, there is disclosed a reflection preventing layer forming composition containing a novolac-shaped silane-containing polymer. This polymer has a novolac group in the backbone and has a cluster-shaped silane in side chains and can contain an acid generator and a crosslinkable compound (see Patent Document 3).
Further, there is also disclosed a hardmask material using a polycarbosilane-containing resin (for example, Patent Document 4 and Patent Document 5).    [Patent Document 1]
Japanese Patent Application Publication No. JP-A-11-258813    [Patent Document 2]
Japanese Patent Application Publication No. JP-A-10-209134    [Patent Document 3]
Japanese Patent Application Publication No. JP-A-2005-115380    [Patent Document 4]
Japanese Patent Application Publication No. JP-A-2001-93824    [Patent Document 5]
Japanese Patent Application Publication No. JP-A-2005-70776