Methods of forming photonic devices

• US 10,641,958 B2
• Filed: 04/08/2019
• Issued: 05/05/2020
• Est. Priority Date: 03/26/2018
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Liu, Tao-Cheng, Hung, Tsai-Hao, Kuo, Shih-Chi
• Primary Examiner(s): Ho, Anthony
• Application Number:
  US16/378,313
• Publication Number:
  US 20190293867A1
• Time in Patent Office: 393 Days
• CPC Class Codes: G02B 5/1819 Plural gratings positioned on the same surface, e.g. array of gratings plural diffractive elements positioned sequentially along the optical path G02B27/4272
• 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 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/136 by etching
• CPC Class Codes: H01L 21/30608 Anisotropic liquid etching H01L21/3063 takes precedence
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment

Abstract

A method includes: forming a first plurality of tiers that each comprises first and second dummy layers over a substrate, wherein within each tier, the second dummy layer is disposed above the first dummy layer; forming a second plurality of recessed regions in the first plurality of tiers, wherein at least one subgroup of the second plurality of recessed regions extend through respective different numbers of the second dummy layers; and performing an etching operation to concurrently forming a third plurality of trenches with respective different depths in the substrate through the at least one subgroup of the second plurality of recessed regions.

Claims

1. A method, comprising:

forming a first etch stop layer over a substrate;

forming a first mask layer over the first etch stop layer;

forming a second etch stop layer over the first mask layer;

forming a second mask layer over the second etch stop layer;

forming two or more first recessed regions that each extends through the second mask layer;

forming a second recessed region, directly below a first one of the two or more first recessed regions, that further extends through the second etch stop layer and the first mask layer; and

concurrently forming first and second trenches with respective different depths in the substrate according to a second one of the two or more first recessed regions and the second recessed region.

2. The method of claim 1, further comprising:

masking the second one of the two or more first recessed regions while forming the second recessed region.

3. The method of claim 1, further comprising:

removing remaining first etch stop layer, first mask layer, second etch stop layer, and second mask layer; and

filling the first and second trenches with a dielectric material.

4. The method of claim 1, further comprising:

forming the first and second trenches by etching the substrate through the second one of the two or more first recessed regions and the second recessed region, respectively.

5. The method of claim 4, wherein the depth of the second trench is greater than the depth of the first trench.

6. The method of claim 3, further comprising:

forming a first grating structure in the first trench, the first grating structure extending into the substrate to a first depth; and

forming a second grating structure in the second trench, the second grating structure extending into the substrate to a second depth greater than the first depth.

7. The method of claim 6, wherein forming the first and second grating structures comprises performing a polishing operation on the dielectric material formed above a top surface of the substrate and any remaining portions of the first and second etch stop layers and the first and second mask layers.

8. The method of claim 7, further comprising performing a wet etching process to remove any remaining portions of the first and second etch stop layers and the first and second mask layers.

9. A method, comprising:

forming a first tier over a substrate, the first tier including a first etch stop layer and a first mask layer formed over the etch stop layer;

forming a second tier over first tier, the second tier including a second etch stop layer and a second mask layer formed over the second etch stop layer;

forming a third tier over second tier, the third tier including a third etch stop layer and a third mask layer formed over the third etch stop layer;

forming a first recessed region that extends through the first mask layer;

forming a second recessed region that extends through the first mask layer, the first etch stop layer and the second mask layer;

forming a third recessed region that extends through the first mask layer, the first etch stop layer, the second mask layer, the second etch stop layer and the third mask layer;

forming a first trench through the first recessed region, the first trench extending into the substrate to a first depth;

forming a second trench through the second recessed region, the second trench extending into the substrate to a second depth greater than the first depth; and

forming a third trench through the third recessed region, the third trench extending into the substrate to a third depth greater than the second depth.

10. The method of claim 9, wherein the first, second and third trenches are formed by performing an etching process through the first, second and third recessed regions, respectively.

11. The method of claim 9 further comprising:

masking the first recessed region while forming the second recessed region; and

masking the first and second recessed regions while forming the third recessed region.

12. The method of claim 9, further comprising filling the first, second and third trenches with a dielectric material.

13. The method of claim 12, further comprising removing portions of the dielectric material above a top surface of the substrate and any remaining portions of the first, second and third mask layers and the first, second and third etch stop layers, thereby forming a first grating structure in the first trench, a second grating structure in the second trench and a third grating structure in the third trench, the first grating structure extending into the substrate to the first depth, the second grating structure extending into the substrate to the second depth and the third grating structure extending into the substrate to the third depth.

14. The method of claim 13, wherein removing comprises performing a polishing operation on the dielectric material formed above the top surface of the substrate and any remaining portions of the first, second and third mask layers and the first, second and third etch stop layers.

15. The method of claim 14, further comprising performing a wet etching process to remove any portions of the dielectric material remaining above the top surface of the substrate and any remaining portions of the first, second and third mask layers and the first, second and third etch stop layers.