Method for production of selective growth masks using underfill dispensing and sintering
The present invention discloses a method for production of selective growth masks using underfill dispensing and sintering. The method includes steps of: providing a sapphire substrate, growing a gallium nitride base layer on the sapphire substrate, coating a photoresist layer, performing imprint lithography, exposure and development, performing underfill dispensing, and performing sintering. The production method of the present invention can be applied in the atmosphere, and vacuum chambers as known production approaches are unnecessary. The selective growth masks produced by the method of the present invention make the growth of nanowires cylindrical and perpendicular to the gallium nitride base layer, and each nanowire is parallel to one another.
1. A method for production of selective growth masks using underfill dispensing and sintering, comprising following steps of:
providing a sapphire substrate, wherein the sapphire substrate is a base for growing subsequent films;
growing a gallium nitride base layer on the sapphire substrate;
coating a photoresist layer, wherein the photoresist layer is formed by coating a photoresist material on the gallium nitride base layer formed on the sapphire substrate;
performing imprint lithography, exposure and development, wherein the imprint lithography is to imprint a pattern of holes on the photoresist layer, and the exposure and development is to illuminate the imprinted photoresist layer by a light source so as to transfer the pattern of the holes to the photoresist layer and form a protruding dam of the photoresist layer;
performing underfill dispensing, wherein an insulating material is filled into a plurality of gaps exposed from the underlying gallium nitride base layer and disposed outside the protruding dam of the photoresist layer; and
performing sintering, wherein a heating process is applied to remove the photoresist layer, and the insulating material disposed outside the protruding dam of the photoresist layer forms an insulating layer and acts as a selective growth mask on the gallium nitride base layer.
2. The method of claim 1 , wherein the gallium nitride base layer is formed by Metal-Organic Chemical Vapor Deposition (MOCVD).
3. The method of claim 1 , wherein the thickness of the photoresist layer is between 20 nm and 2,000 nm.
4. The method of claim 1 , wherein the imprint lithography is a nanoscale imprint lithography or a microscale imprint lithography.
5. The method of claim 1 , wherein the light source is a 248 nm KrF light source, a 193 nm ArF light source, or a 13.5 nm EUV light source.
6. The method of claim 1 , wherein the insulating material is silicon dioxide (SiO 2 ) or silicon nitride (SiN x ).
7. The method of claim 1 , wherein the sintering is performed by using a high temperature oxygen-based heating furnace (O 2 furnace).
8. The method of claim 1 , wherein plural nanowires are grown in the selective growth mask.