A method for providing an alignment surface for liquid crystal molecules in a liquid crystal display, comprising depositing on an optically transparent substrate an optically transparent film; and irradiating the film with nitrogen ions sufficiently to produce a pretilt angle of preferably greater than ten degrees. The film is preferably comprised of diamond like carbon. A liquid crystal display formed in accordance with the method.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein:
FIG. 1 illustrates pretilt angle as a function of N ion dose for various samples.
Claims
1. A method for providing an alignment surface for liquid crystal molecules in a liquid crystal display, comprising:
depositing a film on a substrate; andirradiating the film with nitrogen ions sufficiently to produce a pretilt angle of greater than ten degrees.
2. The method of claim 1, wherein the film is comprised of diamond like carbon and wherein the nitrogen ions have an energy which causes carbon rings of said film with a larger interaction cross section with the ions to have a higher probability of being destroyed than carbon rings with smaller interaction cross sections with the ions, and the nitrogen forms carbon-nitrogen bonds in the film, whereby an asymmetry in the orientation of remaining carbon rings is created by the ions.
3. The method of claim 1, wherein the film is comprised of diamond like carbon deposited by PECVD.
4. The method of claim 3, wherein the film is deposited on the substrate at an RF power density of substantially 30 mW/cm2.
5. The method of claim 3, wherein deposition temperature is between room temperature and 280° C.
6. The method of claim 1, wherein the film is comprised of diamond like carbon and wherein a gas precursor of the diamond like carbon film comprises approximately 5% C2H2 and 95% He.
7. The method of claim 6, further comprising adding hydrogen to the gas precursor to increase light transmittance of the film.
8. The method of claim 1, wherein thickness of the film is between substantially 20 and 100 A.
9. The method of claim 1, wherein the film is comprised of an inorganic material.
10. The method of claim 1, wherein the inorganic material is selected from the group consisting of CaF2 and MgF2, and Al2O3.
11. The method of claim 1, wherein the film is comprised of silicon, carbon, oxygen and hydrogen.
12. The method of claim 11, wherein the film is formed by using tetramethylcyclotetrasiloxane as a precursor.
13. The method of claim 1, wherein the energy of the nitrogen ions is less than 200 electron volts, but sufficient to break bonds in the film.
14. The method of claim 1, wherein the energy of the nitrogen ions is 100 electron volts.
15. The method of claim 1, wherein an incident angle of irradiation of the film by the nitrogen ions is within ten degrees to eighty degrees with respect to a normal to the substrate on which the film is deposited.
16. The method of claim 1, wherein the incident angle of irradiation of the film by the nitrogen ions is thirty five degrees.
17. The method of claim 1, wherein the pretilt angle of the alignment layer is greater than fifteen degrees.
18. The method of claim 1, wherein the pretilt angle of the alignment layer is greater than forty five degrees.
19. A method for providing an alignment surface for liquid crystal molecules in a liquid crystal display, comprising:
depositing on a substrate a film comprised of a material selected from the group consisting of CaF2, MgF2 and a film containing silicon, carbon, oxygen and hydrogen; andirradiating the film with nitrogen ions sufficiently to produce a pretilt angle.
20. A liquid crystal display comprising:
a first substrate;a second substrate;liquid crystal material disposed between said first substrate and said second substrate; andan alignment layer of diamond like carbon disposed on at least one of said first substrate and said second substrate, said alignment layer having a pretilt angle greater than ten degrees.
21. A liquid crystal display comprising:
a first substrate;a second substrate;liquid crystal material disposed between said first substrate and said second substrate;an alignment layer disposed on at least one of said first substrate and said second substrate, said alignment layer including carbon rings, wherein carbon rings of said film with a larger interaction cross section with bombardment ions have a higher probability of being destroyed than carbon rings with smaller interaction cross sections with the ions, further comprising carbon-nitrogen bonds in the film, whereby an asymmetry in the orientation of remaining carbon rings is created by the ions.
Patent Application
20070224365
