Self-aligned, over etched hard mask fabrication method and structure

• US 10,679,853 B2
• Filed: 02/08/2018
• Issued: 06/09/2020
• Est. Priority Date: 02/08/2018
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Libsch, Frank Robert, Shahidi, Ghavam G., Lee, Ko-Tao, Rossnagel, Stephen M.
• Primary Examiner(s): Nguyen, Thanh T
• Application Number:
  US15/892,395
• Publication Number:
  US 20190244815A1
• Time in Patent Office: 852 Days
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0273 characterised by the treatment of photoresist layers
• CPC Class Codes: H01L 21/0332 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/0337 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
• CPC Class Codes: H01L 21/0338 Process specially adapted to improve the resolution of the mask
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01M 10/0436 Small-sized flat cells or batteries for portable equipment
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0562 Solid materials
• CPC Class Codes: H01M 10/0585 of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0421 involving vapour deposition
• CPC Class Codes: H01M 4/049 Manufacturing of an active layer by chemical means
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A hard mask and a method of creating thereof are provided. A first layer is deposited that is configured to provide at least one of a chemical and a mechanical adhesion to a layer immediately below it. A second layer is deposited having an etch selectivity that is faster than the first layer. A third layer is deposited having an etch selectivity that is slower than the first and second layers. The third layer has a composite strength that is higher than the first and second layers. A photoresist layer is deposited on top of the third layer and chemically removed above an inner opening. The third layer and part of the second layer are anisotropically etched through the inner opening. The second layer and the first layer are isotropically etched to create overhang regions of the third layer.

Claims

1. A patterning hard mask for fabricating a self-aligned structure, the hard mask comprising:

a first layer of the patterning hard mask configured to provide at least one of a chemical and a mechanical adhesion to a layer immediately below it and having an etch selectivity that is faster than the layer immediately below it;

a second layer of the patterning hard mask located on top of the first layer and having an etch selectivity that is faster than the first layer; and

a third layer of the patterning hard mask located on top of the second layer, the third layer having;

an etch selectivity that is slower than the second and first layers;

a composite strength that is higher than the first and second layers; and

overhang regions extending over a cavity,

wherein the second layer is isotropically etched to create the overhang regions of the third layer.

2. The patterning hard mask of claim 1, wherein:

the etch selectivity of the first layer is faster by at least a 10 to 1 ratio with respect to the layer immediately below it; and

the etch selectivity of the second layer is faster by at least a 3 to 1 ratio with respect to the first layer.

3. The patterning hard mask of claim 1, wherein the second layer has a thickness that at least 2 times the height of the self-aligned structure.

4. The patterning hard mask of claim 1, wherein the thickness of the third layer is smaller than each of the first and second layers.

5. The patterning hard mask of claim 1, wherein:

the first layer comprises polysilicon (poly-Si);

the second layer comprises silicon dioxide (SiO₂); and

the third layer comprises silicon nitride (SiN).

6. The patterning hard mask of claim 1, wherein:

the first layer comprises silicon nitride (SiN);

the second layer comprises silicon dioxide (SiO₂); and

the third layer comprises silicon nitride (SiN).

7. The patterning hard mask of claim 1, wherein the second layer is at least twice the total height of all the layers used in the fabrication of the self-aligned structure.

8. The patterning hard mask of claim 1, wherein the self-aligned structure is at least one of:

a solid state thin film battery (SSTFB);

an integrated circuit;

a Micro-Electro-Mechanical System (MEMS);

a Nano-Electro-Mechanical (NEM) device; and

a photonic device.

9. The patterning hard mask of claim 1, wherein the second layer has material properties that allow it to delaminate more readily than the first and third layers during a hard mask removal etch, such that the hard mask floats away from the fabricated self-aligned structure.

10. The patterning hard mask of claim 1, wherein a compressive strength of a material of the second layer substantially cancels out a tensile stress of the third layer.

11. The patterning hard mask of claim 1, wherein the hard mask has an inner opening and an outer opening.