Exposure mask and method for divisional exposure
View Patent ↗An exposure mask and a method for divisional exposure are provided to advantageously reduce or eliminate stitch defects in displays. In one embodiment, an exposure mask comprises a masking panel and a slit for selectively transmitting light from a light source, the slit including a taper portion such that an area proximate the taper portion transmits less than full light intensity onto a substrate to be masked. In one example, the area proximate the taper portion is bounded between an inner corner and an outer corner of the taper portion. In a further example, the area proximate the taper portion transmits substantially one-half the light intensity onto the substrate to be masked. A method of divisional exposure utilizing the advantageous exposure mask is also disclosed.
1. A divisional exposure method, comprising:
providing a masking panel including an arc-shaped slit for selectively transmitting light from a light source, the slit including taper portions such that an area proximate a taper portion transmits less than full light intensity onto a photoresist layer, wherein the end of each of the taper portions has a linear edge, and wherein the exposure mask has one single arc-shaped slit in one masking panel;
providing a pattern mask below the exposure mask, the pattern mask selectively transmitting light corresponding to a thin film pattern;
providing a substrate below the pattern mask, the substrate to be provided with the thin film pattern;
dividing the substrate into a plurality of shots;
exposing the photoresist layer in the area corresponding to a first shot of light;
moving the pattern mask and the substrate relative to the masking panel and the light source; and
exposing the photoresist layer in an area corresponding to a second shot of light;
wherein the area corresponding to a boundary area of the first shot and the second shot is covered by an overlap of taper portions of the slit and the portion of the photoresist disposed at the boundary area of the first shot and the second shot are twice exposed to light, resulting in the twice exposed boundary areas being exposed with the same intensity as the other exposed areas.
2. The method as in claim 1 , wherein the area proximate the taper portion is bounded between an inner corner and an outer corner of the taper portion.
3. The method as in claim 1 , wherein the area proximate the taper portion transmits substantially one-half the light intensity onto the photoresist layer.
4. The method as in claim 1 , wherein the portion twice exposed is exposed to substantially full light intensity.
5. The method as in claim 1 , further comprising etching through the photoresist pattern to form a thin film pattern.
6. The method as in claim 1 , wherein an angle of the taper portion formed between a line from an inner corner to an outer corner of the taper portion and an arc tangent at the outer corner is between about 70 degrees and about 110 degrees.
7. The method as in claim 1 , wherein the width of the slit is variable.
8. The method as in claim 1 , wherein the width of the slit ranges between about 20 mm and about 120 mm.
9. The method as in claim 1 , wherein the width of the slit ranges between about 80 mm and about 100 mm.
10. The method as in claim 1 , wherein the thin film pattern is selected from the group consisting of a gate line, a data line, a pixel electrode, an insulating layer, and a light blocking member.