CN-116246953-B - Method for forming semiconductor device

Abstract

The method includes forming an etch mask to cover the mandrels, the first spacers, and the second spacers, and the first spacers and the second spacers are in contact with opposing sidewalls of the mandrels. The etch mask is then patterned and includes a first portion overlying the first spacer, a second portion overlying the second spacer, and a bridge portion connecting the first portion to the second portion. The bridge portion has a first sidewall. A first etching process is performed on the mandrels using the etch mask to define a pattern, and after the first etching process, the mandrels include second bridge portions having second sidewalls vertically aligned with the corresponding first sidewalls. After etching through the mandrel, a second etching process is performed to laterally recess the second bridge portion of the mandrel. Embodiments of the present application also relate to methods of forming semiconductor devices.

Inventors

• CHEN WENYAN

Assignees

• 台湾积体电路制造股份有限公司

Dates

Publication Date

20260512

Application Date

20230110

Priority Date

20220524

Claims (20)

1. 1. A method of forming a semiconductor device, comprising: Forming a first etch mask to cover the mandrels, first spacers, and second spacers, wherein the first spacers and the second spacers are in contact with opposing sidewalls of the mandrels; patterning the first etch mask, wherein after the patterning, the first etch mask comprises: A first portion covering the first spacer; A second portion covering the second spacer, and A bridge portion connecting the first portion to the second portion, wherein the bridge portion includes a first sidewall; Performing a first etching process on the mandrels using the first etching mask to define a pattern, wherein after the first etching process the mandrels comprise second bridge portions having second sidewalls vertically aligned with the corresponding first sidewalls, and After etching through the mandrel, a second etching process is performed to laterally recess the second bridge portion of the mandrel.
2. 2. The method of claim 1, wherein the first and second spacers are not etched in the second etching process.
3. 3. The method of claim 1, wherein the first etching process is for a first duration and the second etching process is for a second duration, and wherein the second duration is longer than the first duration.
4. 4. The method of claim 1, wherein in the second etching process, the mandrel has a first etching rate, the first and second spacers have a second etching rate, and wherein a ratio of the first etching rate to the second etching rate is greater than 10.
5. 5. The method of claim 1, wherein the first etching process and the second etching process are performed using the same process conditions.
6. 6. The method of claim 5, wherein the first etching process and the second etching process are both anisotropic etching processes.
7. 7. The method of claim 1, wherein the first etching process and the second etching process are performed using different process conditions.
8. 8. The method of claim 7, wherein the first etching process and the second etching process are performed using the same etching gas and different parameters.
9. 9. The method of claim 8, wherein the second etching process is more isotropic than the first etching process.
10. 10. The method of claim 8, wherein the first etching process is performed using a first bias power and the second etching process is performed using a second bias power that is lower than the first bias power.
11. 11. The method of claim 7, wherein the first etching process and the second etching process are performed using different etching gases.
12. 12. A method of forming a semiconductor device, comprising: Forming a mandrel between the first spacer and the second spacer; Forming an etch mask comprising: A first portion overlapping the first spacer; A second portion overlapping the second spacer, and A bridge portion overlapping the mandrel, wherein the mandrel includes a portion between the first and second spacers, the portion exposed through an etch mask, and The mandrel is etched using the etch mask to define a pattern for the mandrel, wherein after etching the mandrel, a remaining portion of the mandrel that directly overlaps the bridge portion includes a first sidewall that is laterally recessed from a second sidewall of the bridge portion, and wherein when the mandrel is etched, both the first sidewall and the second sidewall are exposed to an etching gas for the etching.
13. 13. The method of claim 12, wherein the first sidewall is recessed from the corresponding second sidewall by a recess distance greater than 1 nm.
14. 14. The method of claim 12, wherein during etching the mandrels, additional sidewalls of the first and second spacers are also exposed to the etching gas, and wherein the first and second spacers have third sidewalls that are vertically aligned with corresponding fourth sidewalls of the etch mask.
15. 15. The method of claim 12, further comprising: Etching a mask layer underlying the mandrels, the first spacers, and the second spacers, wherein the second portions of the mandrels, the first spacers, and the second spacers collectively function as a second etch mask; transferring the pattern of the mask layer into a dielectric layer located under the mask layer, and A conductive material is filled into the dielectric layer to form a metal line.
16. 16. The method of claim 12, further comprising: Depositing spacer layers on the top surface and opposite sidewalls of the mandrel, and An anisotropic etching process is performed on the spacer layer to form the first and second spacers.
17. 17. A method of forming a semiconductor device, comprising: forming a first spacer and a second spacer parallel to each other, wherein the first spacer and the second spacer have a distance from each other; Forming a mandrel comprising a bridging portion between the first and second spacers, wherein the bridging portion comprises first opposing sidewalls that physically contact the first and second spacers, and wherein the bridging portion has a first width measured in a direction perpendicular to a longitudinal direction of the first spacer, and The first opposing sidewalls of the mandrel are laterally recessed using an etching gas such that the mandrel has a second width that is less than the first width, wherein during the lateral recessing, the sidewalls of the first and second spacers are exposed to the etching gas, and wherein after the lateral recessing, the first and second spacers are a distance from each other.
18. 18. The method of claim 17, wherein forming the bridge portion of the mandrel comprises a first anisotropic etching process.
19. 19. The method of claim 18, wherein the lateral recess comprises a second anisotropic etching process.
20. 20. The method of claim 19, wherein the second anisotropic etching process has a longer duration than the first anisotropic etching process.

Description

Method for forming semiconductor device Technical Field Embodiments of the present application relate to methods of forming semiconductor devices. Background The integrated circuit includes an interconnect structure that may include metal lines and vias to function as a three-dimensional wiring structure. The function of the interconnect structure is to properly connect the densely packed devices together. Metal lines and vias are formed in the interconnect structure. Metal lines and vias are typically formed by damascene processes. The damascene process may include forming trenches and via openings in a dielectric layer, depositing a barrier layer, and then filling the trenches and via openings with a conductive material. After a Chemical Mechanical Polishing (CMP) process, the top surfaces of the metal lines are level, leaving the metal lines and vias in the trench and via openings, respectively. Reducing the scale of metal lines and vias in a controlled manner is a challenging task. Disclosure of Invention Some embodiments of the present application provide a method of forming a semiconductor device comprising forming a first etch mask to cover mandrels, first spacers, and second spacers, wherein the first spacers and the second spacers are in contact with opposing sidewalls of the mandrels, patterning the first etch mask, wherein after the patterning the first etch mask comprises a first portion to cover the first spacers, a second portion to cover the second spacers, and a bridge portion to connect the first portion to the second portion, wherein the bridge portion comprises a first sidewall, performing a first etch process on the mandrels using the first etch mask to define a pattern, wherein after the first etch process the mandrels comprise a second bridge portion having a second sidewall vertically aligned with the corresponding first sidewall, and performing a second etch process to recess the second bridge portion of the mandrels laterally after etching through the mandrels. Further embodiments of the present application provide a method of forming a semiconductor device comprising forming a mandrel between a first spacer and a second spacer, forming an etch mask comprising a first portion overlapping the first spacer, a second portion overlapping the second spacer, and a bridge portion overlapping the mandrel, wherein the mandrel comprises a portion between the first spacer and the second spacer, the portion being exposed through the etch mask, and etching the mandrel using the etch mask to define a pattern for the mandrel, wherein after etching the mandrel, a remaining portion of the mandrel directly overlapping the bridge portion comprises a first sidewall laterally recessed from a second sidewall of the bridge portion, and wherein both the first sidewall and the second sidewall are exposed to an etching gas for the etching when etching the mandrel. Still further embodiments of the present application provide a method of forming a semiconductor device comprising forming first and second spacers parallel to each other, wherein the first and second spacers have a distance from each other, forming a mandrel comprising a bridging portion between the first and second spacers, wherein the bridging portion comprises first opposing sidewalls that physically contact the first and second spacers, and wherein the bridging portion has a first width measured in a direction perpendicular to a longitudinal direction of the first spacers, and laterally recessing the first opposing sidewalls of the mandrel using an etching gas such that the mandrel has a second width that is less than the first width, wherein during the lateral recessing the sidewalls of the first and second spacers are exposed to the etching gas, and wherein after the lateral recessing the first and second spacers have a distance from each other. Drawings The various aspects of the invention are best understood from the following detailed description when read in connection with the accompanying drawings. It should be noted that the various components are not drawn to scale according to standard practice in the industry. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. Fig. 1, 2A, 2B, 3, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 7C, 8A, 8B, 8C, 8D, 9A, 9B, 9C, 10A, 10B, 10C, 11A, 11B, 12A, 12B, 13A, 13B, 13C, and 14 illustrate cross-sectional, top, and perspective views of intermediate stages in forming an interconnect structure including metal lines and vias according to some embodiments. Fig. 15 illustrates a process flow for forming metal lines and vias, in accordance with some embodiments. Detailed Description The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and ar