Polycrystalline aluminum nitride material and method of production thereof
Methods of preparing polycrystalline aluminum nitride materials that have high density, high purity, and favorable surface morphology are disclosed. The methods generally comprises pressing aluminum nitride powders to form a slug, sintering the slug to form a sintered, polycrystalline aluminum nitride boule, and optionally shaping the boule and/or polishing at least a portion of the boule to provide a finished substrate. The sintered, polycrystalline aluminum nitride materials beneficially are prepared without the use of any sintering aid or binder, and the formed materials exhibit excellent density, AlN purity, and surface morphology.
1. A polycrystalline aluminum nitride substrate, said substrate being prepared according to a method comprising:
pressing aluminum nitride powder to form a pressed aluminum nitride slug;
sintering the pressed aluminum nitride slug material by heating to a maximum temperature of at least about 1,500° C. at a heating rate that does not exceed 0.1° C./minute to 10° C./minute in a non-oxidizing atmosphere to form a sintered aluminum nitride boule with a thickness of at least 5 cm and with a diameter or length or width of at least 5 cm; and
mechanically polishing at least a portion of the sintered aluminum nitride boule to form a polycrystalline aluminum nitride substrate,
such that the so-formed substrate has a relative density of at least about 98%, an aluminum nitride purity of at least about 98% by weight, an rms surface roughness of less than about 80 nm, and a defect density of less than about 1,000 cm −2 .
2. An article of manufacture comprising a polycrystalline aluminum nitride substrate according to claim 1 .
3. The article of manufacture according to claim 2 , wherein the article is selected from the group consisting of heat sinks, electrical insulator parts, handle wafers, carrier wafers, and layer transfer substrates.
4. The article of manufacture according to claim 2 , wherein the article is selected from the group consisting of electronic devices, microelectronic devices, optoelectronic devices, and telecommunication devices.
5. A polycrystalline aluminum nitride substrate having a relative density of at least about 98%, an aluminum nitride purity of at least about 98% by weight, an rms surface roughness of less than about 80 nm, and a defect density of less than about 1,000 cm −2 .
6. The polycrystalline aluminum nitride substrate according to claim 5 , wherein the substrate is substantially free of any sintering aids and binders.
7. A product of manufacture comprising a polycrystalline aluminum nitride substrate according to claim 6 .
8. The product of manufacture according to claim 7 , wherein the article is selected from the group consisting of heat sinks, electrical insulator parts, handle wafers, carrier wafers, and layer transfer substrates.
9. The article of manufacture according to claim 7 , wherein the article is selected from the group consisting of electronic devices, microelectronic devices, optoelectronic devices, and telecommunication devices.
10. A polycrystalline aluminum nitride boule having a relative density of at least about 98%, an aluminum nitride purity of at least about 98% by weight, a thickness of at least 5 cm, and a diameter or length or width of at least 5 cm.
11. The polycrystalline aluminum nitride boule of claim 10 , wherein the boule has a thickness of at least about 5.0 cm and a diameter of at least about 5.0 cm.
12. The polycrystalline aluminum nitride boule of claim 10 , wherein the boule is substantially free of any sintering aids and binders.