US-12628573-B2 - Trimming intermediate carbon layer to achieve nanometer scale patterning

Abstract

Embodiments of include a technique for trimming an intermediate carbon layer by hydrogen (H 2 ) plasma to achieve nanometer scale critical dimension patterning with high selectivity to metals and dielectrics. The technique includes providing a structure as a stack having at least one metal layer, a carbon layer, and at least one phase change material layer, the stack extending in a first dimension. The technique includes etching the carbon layer to a first width in a second dimension, the second dimension being perpendicular to the first dimension. The technique includes applying hydrogen plasma to laterally etch the carbon layer to a second width in the second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the at least one metal layer and the at least one phase change material layer.

Inventors

• Luxherta Buzi
• Robert L. Bruce
• Hiroyuki Miyazoe

Assignees

• INTERNATIONAL BUSINESS MACHINES CORPORATION

Dates

Publication Date

20260512

Application Date

20231204

Claims (20)

1. 1 . A method comprising: providing a structure as a stack comprising at least one metal layer, a carbon layer, and at least one phase change material layer, the stack extending in a first dimension; etching the carbon layer to a first width in a second dimension, the second dimension being perpendicular to the first dimension; and applying hydrogen plasma to laterally etch the carbon layer to a second width in the second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the at least one metal layer and the at least one phase change material layer.
2. 2 . The method of claim 1 , wherein the substantially no bias power is a zero bias power.
3. 3 . The method of claim 1 , wherein the applying the hydrogen plasma laterally etches the carbon layer by creating volatile hydrocarbons from the carbon layer.
4. 4 . The method of claim 1 , wherein a hardmask layer is utilized to etch the carbon layer to the first width in the second dimension.
5. 5 . The method of claim 4 , wherein the applying the hydrogen plasma laterally etches the carbon layer to the second width less than the first width without etching the hardmask layer.
6. 6 . The method of claim 1 , wherein a hardmask layer is utilized to etch the carbon layer to the first width that is less than 100 nanometers (nm) in the second dimension.
7. 7 . The method of claim 1 , wherein the hydrogen plasma comprises substantially pure hydrogen applied at a predetermined temperature.
8. 8 . A method comprising: providing a structure as a stack comprising a first metal layer, a first carbon layer, a phase change material layer, a second carbon layer, and a second metal layer, the stack extending in a first dimension; applying hydrogen plasma to laterally etch the second carbon layer to a width in a second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the first and second metal layers and the phase change material layer, the second dimension being perpendicular to the first dimension; and etching, using the second carbon layer having the width as a pattern, the phase change material layer and the first carbon layer to the width of the second carbon layer.
9. 9 . The method of claim 8 , wherein the substantially no bias power is a zero bias power.
10. 10 . The method of claim 8 , wherein the applying the hydrogen plasma laterally etches the second carbon layer by creating volatile hydrocarbons from the second carbon layer.
11. 11 . The method of claim 8 , wherein a hardmask layer is utilized to initially etch the second carbon layer to an initial width greater than the width.
12. 12 . The method of claim 11 , wherein the applying the hydrogen plasma laterally etches the second carbon layer to the width less than the initial width without etching the hardmask layer.
13. 13 . The method of claim 8 , wherein a hardmask layer is utilized to initially etch the second carbon layer to an initial width that is less than 100 nanometers (nm) in the second dimension.
14. 14 . The method of claim 8 , wherein the hydrogen plasma comprises substantially pure hydrogen applied at a predetermined temperature.
15. 15 . The method of claim 8 , wherein the first and second carbon layers act as a thermal source to the phase change material layer, in response to electrical current being applied to the stack.
16. 16 . The method of claim 8 , wherein the stack comprises another phase change material layer above the phase change material layer.
17. 17 . A method comprising: providing a structure as a stack comprising a first metal layer, a first carbon layer, a phase change material layer, a second carbon layer, and a second metal layer, the stack extending in a first dimension, wherein the second carbon layer is an intermediate layer in the stack and is above the phase change material layer and the first carbon layer; etching the first carbon layer to a first width in a second dimension, the second dimension being perpendicular to the first dimension; applying hydrogen plasma to laterally etch the second carbon layer to a second width in the second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the first and second metal layers and the phase change material layer, wherein the phase change material layer and the first carbon layer comprise a different width greater than the first width; and etching, using the second carbon layer having the second width as a pattern, the phase change material layer and the first carbon layer to the second width of the second carbon layer.
18. 18 . The method of claim 17 , wherein the substantially no bias power is a zero bias power.
19. 19 . The method of claim 17 , wherein the applying the hydrogen plasma laterally etches the second carbon layer by creating volatile hydrocarbons from the second carbon layer.
20. 20 . The method of claim 17 , wherein: a hardmask layer is utilized to initially etch the second carbon layer to the first width that is greater than the second width; the applying the hydrogen plasma laterally etches the second carbon layer to the second width less than the first width without etching the hardmask layer; and the first width is less than 100 nanometers (nm) in the second dimension.

Description

BACKGROUND The present invention generally relates to fabrication methods and resulting structures for integrated circuits (ICs), and more specifically, to fabrication methods and resulting structures for trimming an intermediate carbon layer by hydrogen (H2) plasma to achieve nanometer scale critical dimension (CD) patterning with high selectivity to metals and dielectrics. The relentless race for a reduction in the dimensions that characterize the microelectronics industry is achieved by innovations throughout decades of development. Pillars or stacks of different layers are utilized in the microelectronics, and the size of these pillars are becoming smaller as the size of microelectronics scales down. SUMMARY Embodiments of the present invention are directed to trimming an intermediate carbon layer by hydrogen plasma to achieve nanometer scale critical dimension patterning with high selectivity to metals and dielectrics. A non-limiting method includes providing a structure as a stack having at least one metal layer, a carbon layer, and at least one phase change material layer, the stack extending in a first dimension. The method includes etching the carbon layer to a first width in a second dimension, the second dimension being perpendicular to the first dimension. The method includes applying hydrogen plasma to laterally etch the carbon layer to a second width in the second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the at least one metal layer and the at least one phase change material layer. According to one or more embodiments, a non-limiting method includes providing a structure as a stack having a first metal layer, a first carbon layer, a phase change material layer, a second carbon layer, and a second metal layer, the stack extending in a first dimension. The method includes applying hydrogen plasma to laterally etch the second carbon layer to a width in a second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the first and second metal layers and the phase change material layer, the second dimension being perpendicular to the first dimension. The method includes etching, using the second carbon layer having the width as a pattern, the phase change material layer and the first carbon layer to the width of the second carbon layer. According to one or more embodiments, a non-limiting method is provided for forming a structure using an intermediate layer to etch layers below. The method includes providing the structure as a stack including a first metal layer, a first carbon layer, a phase change material layer, a second carbon layer, and a second metal layer, the stack extending in a first dimension, where the second carbon layer is the intermediate layer in the stack and is above the phase change material layer and the first carbon layer. The method includes etching the carbon layer to a first width in a second dimension, the second dimension being perpendicular to the first dimension. The method includes applying hydrogen plasma to laterally etch the second carbon layer to a second width in the second dimension, the hydrogen plasma being applied with substantially no bias power and to avoid etching the first and second metal layers and the phase change material layer, where the phase change material layer and the first carbon layer include a different width greater than the first width. The method includes etching, using the second carbon layer having the second width as a pattern, the phase change material layer and the first carbon layer to the second width of the second carbon layer. Other embodiments of the present invention implement features of the above-described devices/structures in methods and/or implement features of the methods in devices/structures. Additional technical features and benefits are realized through the techniques of the present invention. Embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed subject matter. For a better understanding, refer to the detailed description and to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS The specifics of the exclusive rights described herein are particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the embodiments of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 depicts a cross-sectional view of a flow of fabricating a structure according to one or more embodiments of the invention; FIG. 2 depicts a cross-sectional view continued from FIG. 1 of the flow of fabricating a structure according to one or more embodiments of the invention; FIG. 3 depicts a cross-sectional view continued from FIG. 2 of the flow of fabricating a structure according to one or more embodiments of the invention; FI