Systems and methods for the production of highly tetrahedral amorphous carbon coatings
View Patent ↗The invention provides systems and methods for the deposition of an improved diamond-like carbon material, particularly for the production of magnetic recording media. The diamond-like carbon material of the present invention is highly tetrahedral, that is, it features a large number of the sp 3 carbon-carbon bonds which are found within a diamond crystal lattice. The material is also amorphous, providing a combination of short-range order with long-range disorder, and can be deposited as films which are ultrasmooth and continuous at thicknesses substantially lower than known amorphous carbon coating materials. The carbon protective coatings of the present invention will often be hydrogenated. In a preferred method for depositing of these materials, capacitive coupling forms a highly uniform, selectively energized stream of ions from a dense, inductively ionized plasma. Such inductive ionization is enhanced by a relatively slow moving (or “quasi-static”) magnetic field, which promotes resonant ionization and ion beam homogenization.
1. A method of forming a layer of diamond like carbon with an ion stream, the method comprising:
generating a plasma;
varying a DC bias voltage to selectively control an ion impact energy of the ion stream;
applying the DC bias voltage to the plasma to generate the ion stream; and
forming the layer of diamond like carbon having a thickness of less than about 75 Å with the ion stream having the controlled energy.
2. The method of claim 1 method further comprising measuring the ion impact energy with a detector.
3. The method of claim 2 wherein the ion impact energy is measured near a substrate plane.
4. The method of claim 2 wherein the ion impact energy comprises a distribution of ion impact energies and the distribution of ion impact energies is measured with the detector to characterize the distribution of ion impact energies.
5. The method of claim 1 wherein the DC bias voltage is selectively controlled with an effective area of a capacitor.
6. The method of claim 1 wherein the controlled energy of the ion stream comprises a sharp distribution of ion impact energies.
7. The method of claim 1 wherein the layer of diamond like carbon provides a plasmon energy peak in a range from about 25.5 eV to about 31.4 eV.
8. The method of claim 1 wherein the layer of diamond like carbon comprises between about 15% and about 85% sp 3 carbon-carbon bonds.