CN-122013273-A - Pre-wetting method for electrochemical plating

Abstract

The invention provides a pre-soaking method for electrochemical plating, which comprises the following steps of providing a wafer, forming a through hole on the wafer, sequentially depositing a diffusion barrier layer and a seed crystal layer in the through hole, placing the wafer in a process chamber, performing a hot baking process, vacuumizing the process chamber to remove residual gas in the process chamber, introducing ammonia gas into the process chamber, adjusting the air pressure in the process chamber to the pre-soaking process pressure, stopping introducing the ammonia gas, and introducing water vapor into the process chamber to pre-soak the through hole. The presoaking method provided by the invention uses ammonia as a medium, utilizes the property that ammonia is very soluble in water, solves the contradiction that high vacuum exhaust and water are easy to vaporize under high vacuum in the prior art by the steps of high vacuum exhaust, ammonia replacement, water vapor dissolution and the like, obviously improves the filling reliability and the product yield, and has simple method operation and strong process compatibility.

Inventors

• LI QIAODAN
• YU WEIGUO
• YANG KUI
• WANG PING

Assignees

• 上海华力集成电路制造有限公司

Dates

Publication Date

20260512

Application Date

20260227

Claims (10)

1. 1. A method of pre-wetting for electrochemical plating comprising the steps of: providing a wafer, wherein a through hole is formed in the wafer, and a diffusion barrier layer and a seed crystal layer are sequentially deposited in the through hole; Placing the wafer in a process chamber for a thermal baking process; Vacuumizing the process chamber to remove residual gas in the process chamber; Introducing ammonia into the process chamber, and adjusting the air pressure in the process chamber to the presoaked process pressure; And stopping introducing ammonia gas, and introducing water vapor into the process chamber to pre-infiltrate the through holes.
2. 2. The method for pre-soaking in electrochemical plating according to claim 1, wherein the pre-soaking process pressure is 20-50 torr.
3. 3. The method of claim 1, wherein the vacuum is applied to the process chamber at a pressure of 10 -12 ~10 -5 torr.
4. 4. The method of pre-wetting for electrochemical plating of claim 1, further comprising maintaining a pressure within the process chamber for a first time prior to introducing ammonia gas into the process chamber.
5. 5. The method of pre-wetting for electrochemical plating of claim 4, wherein the first time is configured to be greater than 10s.
6. 6. The method for pre-wetting electrochemical plating according to claim 1, wherein the flow rate of the ammonia gas is 10-500 sccm.
7. 7. The method for pre-wetting electrochemical plating according to claim 1, wherein the temperature of the heat treatment is 100-400 ℃.
8. 8. The method of claim 1, wherein depositing the diffusion barrier and seed layer comprises one of atomic layer deposition, chemical vapor deposition, and physical vapor deposition.
9. 9. The method of claim 1, wherein the aspect ratio of the through hole is 5-25.
10. 10. The method of pre-wetting for electrochemical plating according to claim 1, further comprising performing an electrochemical plating process and an edge washing process on the wafer after pre-wetting the through hole.

Description

Pre-wetting method for electrochemical plating Technical Field The invention relates to the technical field of semiconductor manufacturing, in particular to a pre-soaking method for electrochemical plating. Background In TSV fabrication processes, metallization filling is a critical step, and copper is typically filled into high aspect ratio vias using an electrochemical plating (ECP) process. However, unlike the shallow trench filling in the back-end-of-line (BEOL) damascene process, the high aspect ratio of the TSV has a capillary phenomenon, which can leave gas at the bottom, resulting in a problem that the plating solution cannot contact the bottom of the Via, and a hole (Void) or Open Via (Via Open) is easily formed after filling. In order to overcome this problem, a thermal baking and pre-soaking process is usually introduced before electroplating, the thermal baking is aimed at removing the water and part of the gas adsorbed in the through holes, and the subsequent pre-soaking process is to introduce steam (H 2 O) into the chamber under a controllable pressure, so that it condenses on the inner wall of the through holes to form a water film, so as to replace the residual gas and facilitate the entry of the subsequent electroplating solution. However, the vacuum degree required by the process is contradictory to the physical properties of the pre-wetting medium (H 2 O), namely, in order to thoroughly remove the residual gas at the bottom of the through hole as much as possible, the process chamber needs to be pumped to the vacuum degree as high as possible (far below 20 torr), but when the pressure of the chamber is below 20torr, the introduced H 2 O is quickly vaporized, and the pre-wetting effect cannot be realized. Therefore, the existing pre-wetting process is forced to maintain the pressure at a lower vacuum level above 20torr, so that the gas in the through hole cannot be completely removed, and the residual gas is wrapped during the electroplating, which is still a main cause of TSV electroplating filling defects (such as Via Open). There is a need for a new pre-wetting method that completely eliminates the gas in the through holes without causing vaporization of the water. Disclosure of Invention The invention aims to provide a device for solving the problem that residual gas exists in a through hole during pre-infiltration. In order to solve the technical problems, the invention provides a pre-soaking method for electrochemical plating, which comprises the following steps: providing a wafer, wherein a through hole is formed in the wafer, and a diffusion barrier layer and a seed crystal layer are sequentially deposited in the through hole; Placing the wafer in a process chamber for a thermal baking process; Vacuumizing the process chamber to remove residual gas in the process chamber; Introducing ammonia into the process chamber, and adjusting the air pressure in the process chamber to the presoaked process pressure; And stopping introducing ammonia gas, and introducing water vapor into the process chamber to pre-infiltrate the through holes. Optionally, the presoaking process pressure is 20-50 torr. Optionally, the vacuum is pulled on the process chamber at a pressure of 10 -12~10-5 torr. Optionally, the method further comprises maintaining the pressure in the process chamber for a first time prior to introducing ammonia into the process chamber. Optionally, the first time is configured to be greater than 10s. Optionally, the flow rate of the ammonia gas is 10-500 sccm. Optionally, the temperature of the heat treatment is 100-400 ℃. Optionally, the means for depositing the diffusion barrier and seed layer includes one of atomic layer deposition, chemical vapor deposition, and physical vapor deposition. Optionally, the depth-to-width ratio of the through hole is 5-25. Optionally, after pre-wetting the through hole, the method further comprises performing an electrochemical plating process and a trimming process on the wafer. In summary, the invention provides a pre-soaking method for electrochemical plating, which comprises the steps of providing a wafer, forming a through hole on the wafer, sequentially depositing a diffusion barrier layer and a seed crystal layer in the through hole, placing the wafer in a process chamber for performing a thermal baking process, vacuumizing the process chamber to remove residual gas in the process chamber, introducing ammonia gas into the process chamber, adjusting the air pressure in the process chamber to the pre-soaking process pressure, stopping introducing the ammonia gas, and introducing water vapor into the process chamber to pre-soak the through hole. Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects: During infiltration, the residual gas in the through hole is discharged at a high vacuum degree, then ammonia gas is introduced, the vacuum degree is maintained at a level that water cannot