Methods and apparatus for digital material deposition onto semiconductor wafers

A method of forming a microelectronic device, comprising:

• providing a wafer having a first surface with a lateral perimeter, wherein lateral refers to a direction parallel to the first surface, wherein the first surface does not extend onto a curved surface of the wafer at a lateral perimeter of the wafer, the first surface having a coating area that does not extend to the lateral perimeter;
• providing droplet-on-demand sites configured to dispense droplets of a mixture of photoresist resin and solvents onto the wafer, the mixture having a viscosity of 2 centipoise (cp) to 20 cp and having a photoresist resin content of 10 weight percent to 20 weight percent, with a remainder of the mixture being substantially composed of solvents;
• heating the wafer to a temperature in a first temperature range;
• moving the wafer under the droplet-on-demand sites in a first direction while the wafer is in the first temperature range, and dispensing first discrete amounts of the mixture of photoresist resin and solvents from the droplet-on-demand sites onto the wafer to form a first photoresist sublayer of a photoresist layer on the wafer, the first photoresist sublayer being continuous, the first photoresist sublayer covering the coating area;
• removing a portion of the solvents from the first photoresist sublayer while the wafer is in the first temperature range, after dispensing the first discrete amounts of the mixture of photoresist resin and solvents;
• and
• after removing the portion of the solvents from the first photoresist sublayer, moving the wafer under the droplet-on-demand sites in a second direction that is opposite from the first direction while the wafer is in a second temperature range, and dispensing second discrete amounts of the mixture of photoresist resin and solvents from the droplet-on-demand sites onto the wafer to form a second photoresist sublayer of the photoresist layer on the first photoresist sublayer, the second photoresist sublayer being continuous, the second photoresist sublayer covering the coating area.