Methods of producing optically-finished thin diamond substrates or windows of high aspect ratio
In a method of forming a diamond film, substrate, or window, a substrate is provided and the diamond film, substrate, or window is CVD grown on a surface of the substrate. The grown diamond film, substrate, or window has a thickness between 150-999 microns and an aspect ratio≥100, wherein the aspect ratio is a ratio of a largest dimension of the diamond film, substrate or window divided by a thickness of the diamond film. The substrate can optionally be removed or separated from the grown diamond film, substrate, or window.
1. A method of forming a free-standing diamond film comprising:
(a) CVD growing on a surface of a substrate a diamond film having an aspect ratio ≥100 and a thickness between 150-999 microns, wherein the grown diamond film has a nucleation side surface and a growth side surface opposite the nucleation side surface and the nucleation side surface of the grown diamond film has an optical finish having a surface roughness (Ra)≤50 nm;
(b) removing the substrate from the grown diamond film; and
(c) polishing the surface of the substrate to an optical finish having a surface roughness (Ra)≤20 nm wherein the polishing is completed prior to the CVD growing step,
wherein the method further comprises the step of polishing the growth side surface to an optical finish having a surface roughness (Ra)≤50 nm and the polishing the growth side surface step occurs after the growing step and prior to the removing step.
2. The method of claim 1 , wherein the substrate has a thickness ≥2 mm.
3. The method of claim 1 , wherein, prior to step (a), the surface of the substrate is seeded with diamond particles.
4. The method of claim 3 , wherein the substrate is seeded with diamond particles via at least one of the following processes: (1) ultrasonic treatment of the substrate in a ultrasonic bath comprised of a submicron or micron-sized diamond powder in a liquid suspension solution; and (2) ultrasonic treatment of the substrate in a ultrasonic bath comprised of nano-crystal diamond powder having an average particle size <100 nm in a liquid suspension solution.
5. The method of claim 4 , wherein the liquid suspension solution comprises one or more of the following: water, alcohol, hydrocarbon, and organic solvent.
6. The method of claim 5 , wherein the substrate is seeded with diamond particles via a least one of the following processes: (1) ultrasonic treatment of the substrate in a bath of aqueous diamond slurries or organic diamond slurries, or (2) rubbing the substrate with diamond powders.
7. The method of claim 1 , wherein the largest dimension of the substrate is a diameter of the substrate.
8. The method of claim 1 , wherein the substrate has a thickness ≥8 mm.
9. The method of claim 1 , further including, prior to step (a), polishing the surface of the substrate to an optical finish having a surface roughness (Ra)≤2 nm.
10. The method of claim 1 , wherein polishing the growth side surface includes polishing the growth side to an optical finish having a surface roughness (Ra)≤30 nm.
11. The method of claim 1 , wherein polishing the growth side surface includes polishing the growth side to an optical finish having a surface roughness (Ra)≤20 nm.
12. The method of claim 1 , wherein polishing the growth side surface includes polishing the growth side to an optical finish having a surface roughness (Ra)≤15 nm.
13. The method of claim 1 , wherein polishing the growth side surface includes polishing the growth side to an optical finish having a surface roughness (Ra)≤10 nm.
14. The method of claim 1 , wherein the diamond film has a diamond nucleation density ≥1.0×10 5 /cm 2 .
15. The method of claim 1 , wherein the surface of the substrate has a shape of at least one of a cone, a pyramid, an asphere, a parabola, a hyperbola, and a non-planar surface.
16. The method of claim 1 , wherein the surface of the substrate is planar.