1. Field of the Invention
The present invention relates to a method and an apparatus for coating an object with a photosensitive material, and more particularly to a method and an apparatus for uniformly coating an object with a photosensitive material.
2. Description of the Related Art
As a conventional method for coating a semiconductor substrate with a photosensitive material in a sheet form, a spin coating method is used. In the spin coating method, the photosensitive material is dropped and coated on a substrate that is being quickly rotated. That is, the photosensitive material is coated by a centrifugal force that is applied to the substrate. The spin coating method is proper to coat a small substrate such as a wafer with the photosensitive material. However, the spin coating method may be improper to coat a large and heavy substrate such as an LCD panel with the photosensitive material.
In order to coat a large and heavy substrate with a photosensitive material, a slit coating method has been proposed. In the slit coating method, the photosensitive material is supplied through a slit nozzle having a length thereof longer than a width thereof and is coated in a sheet form.
FIG. 1 is a schematic view showing a conventional slit coater.
Referring to FIG. 1, a slit coater 10 changes a photosensitive material having an indeterminate form into a photosensitive material having a band form, which has a length thereof longer than a width thereof. The slit coater 10 is aligned at a designated position “A” so as to supply the photosensitive material onto a substrate 40.
FIGS. 2A and 2B are views showing a silt coater and a substrate partially coated with photosensitive material.
Referring to FIG. 2A, the slit coater 10 supplies the photosensitive material 20 from a photosensitive material supply apparatus 30 to the substrate 40. The photosensitive material 20 supplied from the slit coater 10 has a band form as shown in FIG. 2B. The slit coater 10 coats the substrate 40 with the photosensitive material 20 in a first direction and at a first speed.
FIGS. 3A and 3B are views showing the substrate totally coated photosensitive material by the slit coater.
Referring to FIGS. 3A and 3B, the slit coater 10 coats the substrate 40 with the photosensitive material 20 from the first position “A” to a second position “B”. In the slit coating method, the photosensitive material may be easily coated on an area of substrate greater than that of a wafer.
FIG. 4 is a sectional view showing a profile of the photosensitive material coated on the substrate according to the slit coating method.
Referring FIG. 4, in the slit coating method, a thickness T1 at the first position “A” and a thickness T2 at the second position “B” are different from a thickness T3 at a center of the substrate 40, which is unpreferable. Also, the slit coating method causes coating failure as wave patterns or scratch patterns in the coated photosensitive material. Accordingly, the slit coating and spin coating methods are successively performed so as to coat the photosensitive material on the substrate.
When both the slit coating method and the spin coating method are performed on the same substrate, the time for coating the substrate with the photosensitive material may greatly increase. Also, since equipments for performing the slit coating method and the spin coating method are respectively required, cost of equipments may increase.