1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a fine pattern in a semiconductor device using a photolithography. 2. Description of the Related Art Photolithography processes are used to form micro patterns in semiconductor devices such as a NAND type flash memory or a non-volatile memory. A photolithography process is carried out in such a manner that a photoresist pattern is formed on a material layer and an etching process is carried out to the material layer using the photoresist pattern as an etching mask, thereby forming a pattern. In general, a photolithography process includes a photoresist coating process for forming a photoresist layer over the material layer, an exposure process for selectively exposing the photoresist layer to light according to predetermined patterns, and a development process for removing only the light-exposed portion of the photoresist layer. The photoresist layer is formed of a chemically amplified photoresist (CAP) which is formed of a polymer with acid functional group. However, a CAP has a low etching resistance compared to other types of photoresist. Also, the acid functional group of the CAP reacts with amine compound during the photoresist coating process to cause a decrease in line width. Moreover, in the development process, line width is further decreased. FIG. 1 is a schematic diagram of a conventional photolithography process, wherein a photoresist layer 20 formed over a semiconductor substrate 10 includes portions A which are left un-developed (FIG. 1A). When the semiconductor substrate 10 is dry-etched using the photoresist layer 20 as an etching mask, the remaining portions A are etched as well (FIG. 1B). As a result, the semiconductor substrate 10 may have a decreased line width compared to that desired. The present invention was made to overcome the above described problems. An object of the present invention is to provide a method of manufacturing a semiconductor device, which forms a fine pattern by providing a hard mask with good etching resistance over the photoresist pattern. Another object of the present invention is to provide a method of manufacturing a semiconductor device, which controls a photoresist pattern in a horizontal direction while it is being formed and also prevents the photoresist pattern from being decreased in line width. To achieve these and other objects of the present invention, the present invention provides a method of manufacturing a semiconductor device. The semiconductor device has a material layer formed on a semiconductor substrate. The method includes forming a photoresist pattern on the material layer using a photolithography process. The photoresist pattern has a first region, wherein a desired line width of the material layer is reduced by an etching process, and a second region, wherein no etch selectivity exists. An antireflection coating (ARC) is formed over the first region of the photoresist pattern and the second region is left uncovered. Thereafter, the second region of the photoresist pattern is removed. To further achieve these and other objects of the present invention, the present invention provides a method of manufacturing a semiconductor device. The semiconductor device has a material layer formed on a semiconductor substrate. The method includes forming a first photoresist pattern on the material layer using a photolithography process. The first photoresist pattern is formed with an antireflective coating (ARC) over a first region, a portion of which is removed to expose the material layer, and is formed without the ARC over a second region. The first region is selectively etched using the ARC in the first photoresist pattern as an etching mask. The ARC in the first photoresist pattern is removed. An ARC is formed over a third region of the material layer and the second photoresist pattern is formed on the material layer, wherein the second region of the second photoresist pattern has a shape identical to that of the ARC. The ARC in the first photoresist pattern is composed of a tri-layer structure of an antireflection coating, a nitride layer and a top antireflection coating (TARC). The first photoresist pattern is formed of a novolac resin. To further achieve these and other objects of the present invention, the present invention provides a method of manufacturing a semiconductor device. The semiconductor device has a material layer formed on a semiconductor substrate. The method includes forming a first photoresist pattern on the material layer using a photolithography process. The first photoresist pattern is formed with an antireflective coating (ARC) over a first region, which is etched to have a desired line width, and is formed without the ARC over a second region, which is not etched. An ARC is formed over a third region of the material layer and the second photoresist pattern is formed on the material layer, wherein the second photoresist pattern is formed with a negative photosensitive material, which has an acid functional group, in the first region. The first photoresist pattern is removed and the second photoresist pattern is developed using a developer containing an amine compound. To further achieve these and other objects of the present invention, the present invention provides a method of manufacturing a semiconductor device. The semiconductor device includes a first photoresist pattern formed over a material layer of a semiconductor substrate. The method includes coating a photoresist film over the material layer using an inorganic ARC formed of silicon carbide (SiC) and a top antireflective coating (TARC) formed of a novolac resin. The first photoresist pattern includes an anti-reflection coating (ARC) over a first region of the photoresist film and is not etched, a second region of the photoresist film, wherein the first photoresist pattern is exposed, and a third region of the photoresist film, wherein the first photoresist pattern is not exposed. The first photoresist pattern is formed of a negative photosensitive material and the ARC is composed of a tri-layer structure of an ARC, a nitride layer and a top ARC. The top ARC is composed of a silicon nitride (SiN) layer. The first photoresist pattern is formed using an ArF light source. The method of manufacturing a semiconductor device according to the present invention provides the ARC in the first photoresist pattern over the second region of the material layer. Thus, the first photoresist pattern has a high etching resistance. When the second region of the first photoresist pattern is etched using the ARC in the first photoresist pattern as an etching mask, an ARC is formed over the third region of the material layer by the ARC in the first photoresist pattern, which serves to prevent the first photoresist pattern from being decreased in line width. Also, the ARC in the first photoresist pattern prevents the second region of the first photoresist pattern from being decreased in line width during the development process. Also, the method of manufacturing a semiconductor device according to the present invention provides the ARC in the first photoresist pattern over the first region of the first photoresist pattern and then removes the second region of the first photoresist pattern to expose the material layer. The ARC is formed over the third region of the material layer using a second photoresist pattern having a negative photosensitive material and containing an amine compound in the first region, thereby preventing the first photoresist pattern from being decreased in line width. According to the method of manufacturing a semiconductor device of the present invention, a hard mask is formed over the photoresist pattern, thereby preventing the photoresist pattern from being decreased in line width. Therefore, it is possible to obtain a fine pattern without a decrease in line width.