US-20260130186-A1 - SUBSTRATE WETTABILITY FOR PLATING OPERATIONS

Abstract

Various embodiments include methods and apparatuses to moisturize a substrate prior to an electrochemical deposition process. In one embodiment, a method to control substrate wettability includes placing a substrate in a pre-treatment chamber, controlling an environment of the pre-treatment chamber to moisturize a surface of the substrate; and placing the substrate into a plating cell. Other methods and systems are disclosed.

Inventors

• Zhian He
• Shantinath Ghongadi
• Hyungjun Hur
• Ludan Huang
• Jingbin Feng
• Douglas Hill
• Thomas Burke
• Manish Ranjan
• Andrew James PFAU

Assignees

• LAM RESEARCH CORPORATION

Dates

Publication Date

20260507

Application Date

20251218

Claims (20)

1. 1 . A system to reduce oxidation and increase wettability of a substrate, the system comprising: a substrate environment configured to hold the substrate for a predetermined period of time, the substrate environment being oxygen-free, deionized (DI)-moisturized and comprising nitrogen; a pre-treatment chamber configured to subject the substrate to a hydrogen, plasma-based process under vacuum; a vacuum-to-atmospheric transition module configured to receive the substrate subsequent to the hydrogen, plasma-based process and to supply water vapor to increase water-vapor adsorption on a surface of the substrate; a plating cell configured to perform a plating operation on the substrate; and an anneal chamber configured to, subsequent to the plating operation, post-anneal the substrate.
2. 2 . The system of claim 1 , wherein the substrate includes a metal-seed layer formed thereon.
3. 3 . The system of claim 1 , wherein the substrate environment is a front-opening, unified pod (FOUP).
4. 4 . The system of claim 1 , further comprising: a controller configured to control a relative-humidity (RH) range within the substrate environment in a range of between about 20% and about 100%.
5. 5 . The system of claim 1 , wherein the plating operation comprises an electrochemical deposition.
6. 6 . The system of claim 1 , further comprising: a post-plating chamber configured to perform cleaning and drying of the substrate subsequent to the plating operation.
7. 7 . A system to reduce oxidation and increase wettability of a substrate, the system comprising: a nitrogen-based substrate environment to hold the substrate for a predetermined amount of time; a pre-treatment chamber configured to subject the substrate to a hydrogen, plasma-based process under vacuum; a vacuum-to-atmospheric transition module configured to hold the substrate for a predetermined period of time to transition the substrate from vacuum conditions of the pre-treatment chamber to approximately atmospheric pressure; a delay station configured to supply water vapor to increase water-vapor adsorption on a surface of the substrate; a plating cell configured to perform a plating operation on the substrate; and an anneal chamber configured to, subsequent to the plating operation, post-anneal the substrate.
8. 8 . The system of claim 7 , wherein the delay station is configured to rotate the substrate.
9. 9 . The system of claim 8 , wherein a rotational rate of the substrate is between 0 revolutions per minute (RPM) and about 1300 RPM.
10. 10 . The system of claim 7 , wherein the system is configured to form a hydroxide layer on a surface of the substrate to facilitate the water-vapor adsorption.
11. 11 . The system of claim 7 , wherein the substrate includes a metal-seed layer formed thereon.
12. 12 . A system to reduce oxidation and increase wettability of a substrate, the system comprising: a substrate environment to hold the substrate for a predetermined amount of time; a pre-anneal module configured to perform a pre-anneal process on the substrate with a forming gas including hydrogen; a pre-treatment chamber configured to subject the substrate to a hydrogen, plasma-based process under vacuum; a vacuum-to-atmospheric transition module configured to supply water vapor to increase water-vapor adsorption on a surface of the substrate; a plating cell configured to perform a plating operation on the substrate; and an anneal chamber configured to, subsequent to the plating operation, post-anneal the substrate.
13. 13 . The system of claim 12 , further comprising: a delay station located in the pre-treatment chamber and configured to rotate the substrate prior to the plating operation while supplying water vapor to increase water-vapor adsorption on a surface of the substrate.
14. 14 . The system of claim 12 , wherein the system is configured to form a hydroxide layer on a surface of the substrate to facilitate the water-vapor adsorption.
15. 15 . The system of claim 13 , wherein a rotational rate of the substrate is between 0 revolutions per minute (RPM) and about 1300 RPM.
16. 16 . The system of claim 12 , wherein the pre-anneal module and the anneal chamber are each configured to: anneal the substrate at a temperature range of between about 30° C. and about 400 ° C. for between about 30 seconds and about 600 seconds; and cool the substrate for between about 30 seconds and about 600 seconds.
17. 17 . A system to reduce oxidation and increase wettability of a substrate, the system comprising: a substrate environment to hold the substrate for a predetermined amount of time, the substrate environment comprising at least one of nitrogen and hydrogen; a pre-treatment chamber configured to perform a hydrogen-plasma under vacuum at an elevated temperature; a vacuum-to-atmospheric transition module configured to supply water vapor to increase water-vapor adsorption on a surface of the substrate; a plating cell configured to perform a plating operation on the substrate; and an anneal chamber configured to, subsequent to the plating operation, post-anneal the substrate.
18. 18 . The system of claim 17 , further comprising: a delay station located in the pre-treatment chamber and configured to rotate the substrate prior to the plating operation while supplying water vapor to increase water-vapor adsorption on a surface of the substrate.
19. 19 . The system of claim 17 , wherein the system is configured to form a hydroxide layer on the substrate to facilitate the water-vapor adsorption.
20. 20 . The system of claim 17 , further comprising: a controller configured to control an environment of the pre-treatment chamber to moisturize a surface of the substrate, the moisturizing not adding an oxidizing layer on the surface of the substrate.

Description

CLAIM OF PRIORITY This application is a continuation of and claims the benefit of priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 17/051,432, filed on Oct. 28, 2020, which is a U.S. National Stage Filing under 35 U.S.C. 371 from International Application No. PCT/US 2019/029728, filed on Apr. 29, 2019, and published as WO 2019/212986 A1 on Nov. 7, 2019, which claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 62/664,938, filed on Apr. 30, 2018, each of which is incorporated by reference herein in its entirety. TECHNICAL FIELD The subject matter disclosed herein relates to treating various types of substrates (e.g., silicon wafers or other elemental or compound wafers, or “wafers” in general) that have poor wettability, as a result of other process steps encountered prior to plating. Specifically, the disclosed subject matter improves wetting during substrate immersion into a plating bath and improves performance during an electrochemical plating process onto the substrate. BACKGROUND An electrochemical deposition process is commonly used for the metallization of an integrated circuit. In various processes, the deposition process involves depositing metal lines into trenches and vias that have been pre-formed in previously-formed dielectric layers. In this dependent process, a thin adherent metal diffusion-barrier film is generally pre-deposited onto the surface by utilizing physical vapor deposition (PVD) or chemical vapor deposition (CVD) processes. Depending on the target metal film, a metal-seed layer will subsequently be deposited on top of the barrier film. The features (vias and trenches) are then electrochemically filled with a target metal through an electrochemical deposition process. However, the performance of an electrochemical deposition onto substrates is impacted by many factors. For example, the plating bath composition, including both inorganic component concentrations and additive concentrations, have a significant role in ensuring void-free gap fill. The way in which the substrates enter into the plating solution (e.g., a time it takes to fully immerse the cathode/substrate into the plating solution, an angle at which the cathode/substrate enters the solution, a rotating speed of the cathode/substrate during immersion, etc.), as well as the current and voltage applied to the substrate, can play significant roles in the gap-fill quality and gap-fill uniformity across the substrate. Various aspects regarding the initial immersion of cathode/substrate into the plating solution are known to a person of ordinary skill in the art. One aspect that plays a significant role is the wettability of the substrate by the plating bath during entry. Without proper wetting, air bubbles, for example, could stick to the surface of the substrate at certain areas, and the electrodeposition thereafter in the area impacted by the bubbles would be difficult to achieve due to an electrical discontinuity. The end result is missing plating in these areas. The defects associated with this poor wettability is referred to generally as “missing metal” defects. The missing metal defects frequently produce “killer defects” to areas containing active devices on the substrate. For example, FIGS. 1A and 1B show typical defect maps as a result of poor wetting of the substrate under methods of the prior art. The darker areas of FIGS. 1A and 1B indicate high areal-concentrations of defects. FIGS. 2A through 2C show typical defect shapes at progressively smaller fields-of-view (FOV) on a surface of a substrate as a result of poor wetting. FIG. 2A shows defects at an FOV of about 98 μm, FIG. 2B shows defects at an FOV of about 11.25 μm, and FIG. 2C shows defects at an FOV of about 3 μm. As described above, for an electrochemical plating process, a thin adherent metal diffusion-barrier film is generally pre-deposited onto the surface by utilizing, for example, physical vapor deposition (PVD) or chemical vapor deposition (CVD) techniques. Depending on the target metal film, a metal-seed layer may then be deposited on the top of the barrier film. In general, a period of time from when the barrier layer and seed layer are deposited on the substrate to a time when the substrate is to be electrochemically deposited creates a time difference (Δt, referred to as “queue time”). During the queue time, a surface condition of the substrate is expected to change over time. One of the most widely perceived surface changes is the oxidation of the metal layer on the substrate. The oxidation of the surface metal increases the sheet resistance of the seed layer, thereby making it more difficult to plate uniformly onto the seed layer due to a stronger terminal effect. The oxide layer changes the additive absorption behavior on the seed layer and could lead to various plating problems. The oxide layer also changes the wetting behavior during substrate immersion. The oxide, if not reduced back to metal b