Reactivity enhancement in ion beam etcher

• US 10,684,407 B2
• Filed: 06/06/2018
• Issued: 06/16/2020
• Est. Priority Date: 10/30/2017
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Facebook Technologies, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Mohanty, Nihar Ranjan
• Primary Examiner(s): Ahmed, Shamim
• Application Number:
  US16/001,694
• Publication Number:
  US 20190129089A1
• Time in Patent Office: 741 Days
• Field of Search: None
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12176 Etching
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/4272 having plural diffractive elements positioned sequentially along the optical path
• CPC Class Codes: G02B 5/1842 Gratings for image generation G02B5/1847 takes precedence
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: H01J 2237/20207 Tilt
• CPC Class Codes: H01J 2237/20214 Rotation
• CPC Class Codes: H01J 2237/3174 Etching microareas
• CPC Class Codes: H01J 2237/3341 Reactive etching
• CPC Class Codes: H01J 37/3056 for microworking, e.g. etching of gratings, trimming of electrical components trimming of resistors H01C17/22
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/32715 : Workpiece holder
• CPC Class Codes: H05H 1/4652 : using inductive coupling means, e.g. coils

Abstract

Techniques for fabricating a slanted structure are disclosed. In one embodiment, a method of fabricating a slanted structure in a material layer includes injecting a first reactive gas into an reactive ion source generator, generating a plasma that includes reactive ions in the reactive ion source generator, extracting at least some of the reactive ions from the plasma to form a collimated reactive ion beam towards the material layer, and injecting a second reactive gas onto the material layer. The collimated reactive ion beam and the second reactive gas etch the material layer both physically and chemically to form the slanted surface-relief structure.

Claims

1. A method of fabricating a slanted surface-relief structure in a material layer, the method comprising:

injecting a first reactive gas into an reactive ion source generator;

generating a plasma using the first reactive gas in the reactive ion source generator, the plasma including reactive ions of the first reactive gas that are configured to react with the material layer to generate volatile materials;

extracting at least some of the reactive ions from the plasma to form a collimated reactive ion beam towards the material layer; and

injecting a second reactive gas onto the material layer, the second reactive gas configured to react with the material layer,

wherein the collimated reactive ion beam and the second reactive gas etch the material layer both physically and chemically to form the slanted surface-relief structure in the material layer.

2. The method of claim 1, further comprising:

rotating the material layer based on a desired slant angle of the slanted surface-relief structure.

3. The method of claim 1, wherein the first reactive gas comprises at least one of CF₄, CHF₃, N₂, O₂, SF₆, Cl₂, BCl₃, HBr, H₂, Ar, He, or Ne.

4. The method of claim 1, wherein the material layer includes a semiconductor substrate, a SiO₂ layer, a Si₃N₄ material layer, a titanium oxide layer, an alumina layer, a SiC layer, a SiO_xN_y layer, an amorphous silicon layer, a spin on carbon (SOC) layer, an amorphous carbon layer (ACL), a diamond like carbon (DLC) layer, a TiO_x layer, an AlO_x layer, a TaO_x layer, or a HFO_x layer.

5. The method of claim 1, wherein generating the plasma in the reactive ion source generator comprises:

applying an RF signal to an inductively coupled plasma generator of the reactive ion source generator.

6. The method of claim 1, wherein extracting at least some of the reactive ions from the plasma to form the collimated reactive ion beam comprises:

applying an extraction voltage on an extraction grid adjacent to the reactive ion source generator; and

applying an acceleration voltage on an acceleration grid to extract and accelerate at least some of the reactive ions,

wherein the extraction grid and the acceleration grid are aligned; and

wherein the acceleration voltage is lower than the extraction voltage.

7. The method of claim 1, wherein injecting the second reactive gas comprises:

injecting the second reactive gas onto the material layer using a gas ring.

8. The method of claim 1, wherein the second reactive gas comprises at least one of CF₄, CHF₃, N₂, O₂, SF₆, Cl₂, BCl₃, or HBr.

9. The method of claim 1, further comprising:

neutralizing the collimated reactive ion beam before etching the material layer using the collimated reactive ion beam and the second reactive gas.

10. The method of claim 9, wherein neutralizing the collimated reactive ion beam comprises:

injecting an electron beam into the collimated reactive ion beam.

11. The method of claim 1, wherein:

the slanted surface-relief structure comprises a slanted surface-relief optical grating.

12. The method of claim 11, wherein:

the slanted surface-relief optical grating comprises a plurality of ridges; and

a leading edge of each ridge is parallel to a trailing edge of the ridge.

13. The method of claim 12, wherein:

a slant angle of the leading edge and a slant angle of the trailing edge are greater than 30 degrees with respect to a surface normal of the material layer.

14. The method of claim 11, wherein:

a depth of the slanted surface-relief optical grating is greater than 100 nm.

15. The method of claim 11, wherein:

a duty cycle of the slanted surface-relief optical grating is greater than 60%.