Magnetic etching process, especially for magnetic or magnetooptic recording

1. A writing process for forming a pattern on a multi-layer material composed of thin layers deposited on a substrate, in which said multi-layer material is irradiated by means of a beam of light ions, having an energy of the order of or less than a hundred keV, wherein one or more regions of the multi-layer material having individual sizes of the order of 1 micrometer or less are selectively irradiated, the irradiation dose being controlled so as to be a few 10 16 ions/cm 2 or less, the irradiation modifying the composition of atomic planes in the material around an interface between two layers of the multi-layer material, wherein said light ions are ions having a mass less than 16 units of atomic mass.

2. Process according to claim 1 , wherein the irradiation is carried out through a mask.

3. Process according to claim 2 , wherein the writing process is adapted for the magnetic or magnetooptic recording of binary information, for the production of discrete magnetic materials, of magnetic memory circuits or of magnetically-controllable logic circuits, or for the production of sensors.

4. Process according to claim 2 , wherein the writing process is adapted for optical recording process of a read-only memory type.

5. Process according to claim 2 , wherein the writing process is adapted for producing magnetically-controllable optical circuits using a controlled variation of the optical index component associated with magnetism.

6. Process according to claim 1 , wherein the writing process is adapted for the magnetic or magnetooptic recording of binary information, for the production of discrete magnetic materials, of magnetic memory circuits or of magnetically-controllable logic circuits, or for the production of sensors.

7. Process according to claim 1 , wherein the writing process is adapted for optical recording process of a read-only memory type.

8. Process according claim 1 , wherein the recording material is a magnetic multi-layer material, the individual layers of which are pure metals or transition metal alloys or rare earth alloys.

9. Process according to claim 1 , wherein the writing process is adapted for producing magnetically-controllable optical circuits using a controlled variation of the optical index component associated with magnetism.

10. Process according to claim 1 , wherein the beam of light ions comprises He + ions.

11. Process according to claim 1 , wherein said irradiation is capable of modifying the composition around said interface between two layers without measurably increasing the surface roughness of the multi-layer material.

12. A process for performing irradiation on a multi-layer material having a buried layer disposed between at least one top layer and at least one bottom layer, said process comprising:

selecting one or more regions of the multi-layer material having a width in the order of 1 micrometer or less; and

irradiating the selected regions of the multi-layer material with (1) a beam of light ions having an energy of the order of or less than a hundred keV and (2) irradiation dose controlled so as to be a few 10 16 ions/cm 2 or less such that the irradiation modifies the buried layer of the multi-layer material, wherein said light ions are ions having a mass less than 16 units of atomic mass.

13. Process according to claim 12 , wherein the irradiation modifies a magnetic property of the buried layer.

14. Process according to claim 12 , wherein the irradiation is capable of modifying the buried layer of the multi-layer material without significantly affecting the optical reflectivity of the at least one top layer of the multi-layer material.

15. Process according to claim 12 , wherein said irradiation is capable of modifying the magnetic property of the buried layer without measurably increasing the surface roughness of the multi-layer material.