Systems and methods for drying patterned OLED formulations
A drying chamber for drying a substrate patterned with display areas wetted by OLED materials dissolved or suspended in a volatile carrier liquid and separated from one another by dry boundary regions. A mask adjusts drying rate of the carrier liquid during vacuum extraction using vapor-transmissive areas opposite the wet areas and vapor-barrier regions opposite the dry boundary regions, or by confining the wet areas collectively in a chamber volume small enough to quickly saturate with the carrier liquid before vacuum extraction.
1. A drying chamber comprising:
a substrate support disposed within an enclosure, the substrate support having a support surface;
a gas source coupled to the enclosure;
a vacuum source coupled to a ceiling of the enclosure;
a movable mask having vapor-transmissive areas and vapor-barrier regions disposed across the support surface of the substrate support within the enclosure and spaced apart from a ceiling of the enclosure to provide an adjustable distance between the mask and the support surface; and
a gas distribution element disposed between the mask and the vacuum source, the gas distribution element comprising a vapor barrier surrounding a gap between the mask and the gas distribution element.
2. The drying chamber of claim 1 , wherein the mask has mask supports that extend outside the enclosure.
3. The drying chamber of claim 2 , wherein the mask supports are located on two opposite sides of the mask.
4. The drying chamber of claim 1 , wherein the gas source is coupled to the enclosure at a location that provides a gas flow outside the vapor barrier.
5. The drying chamber of claim 1 , wherein the mask includes a wall extending from a proximate surface of the mask toward the support surface.
6. The drying chamber of claim 1 , wherein the substrate support includes temperature-control elements.
7. The drying chamber of claim 1 , wherein the mask comprises a rigid material disposed over and spaced apart from the substrate.
8. The drying chamber of claim 1 , wherein each vapor-transmissive area has a single opening, a plurality of openings, a mesh, a screen, or a porous material.
9. A method for drying a substrate having wet areas wet with a carrier liquid separated by dry boundary regions, the method comprising:
orienting a mask and a gas distribution element having a vapor barrier relative to the substrate within an enclosure, the mask having vapor-transmissive areas and vapor-barrier regions;
supporting the mask on movable mask supports located on opposite sides of the mask to vary a gap between the mask and a ceiling of the enclosure;
positioning the vapor barrier to surround a gap between the mask and the gas distribution element; and
drawing the carrier liquid from the wet areas of the substrate through the vapor-transmissive areas of the mask using a vacuum port coupled to the ceiling of the enclosure.
10. The method of claim 9 , wherein orienting a mask relative to the substrate positions the vapor-transmissive areas opposite the wet areas and the vapor-barrier regions opposite the dry boundary regions.
11. The method of claim 10 , further comprising setting a gap between the substrate and the mask.
12. The method of claim 9 , wherein the gas distribution element is perforated, and the drawing the carrier liquid from the wet areas of the substrate comprises passing the carrier liquid through the perforated gas-distribution element.
13. The method of claim 12 , wherein each of the wet areas are of a first shape and each of the vapor-transmissive areas extend over a similar second shape, the method further comprising aligning the wet areas relative to the vapor-transmissive areas.