The present invention generally relates to semiconductor fabrication, and particularly to a method for cleaning a semiconductor device.
As usually known, the integrated circuit device is fabricated by semiconductor fabrication technology. In fabrication, a large number of semiconductor devices are formed on a wafer before cutting into dies. Various fabrication processes are performed to form the semiconductor structure as designed. Various chemical materials respectively are involved in the fabrication processes, such as etching process. A cleaning procedure is usually needed to remove the chemical residuals, which may be from the cleaning solution or the materials on the wafer to be cleaned. However, the cleaning procedure uses chemical agent, which may include water and/or acid, to clean dielectric, resulting in chemical residuals in the cleaning solution.
However, even if the cleaning procedure is performed, there is little amount of cleaning residuals may still remain at the edge of the wafer due to the semiconductor structure with uneven surface. After drying, the cleaning residuals would remain on the wafer as called the water mark. If the water mark is serious, the performance of the semiconductor device would degrade, resulting in poor performance.
How to reduce the water mark, or the cleaning residuals, is still an issue tp be concerned in semiconductor fabrication.
The invention provides a method for cleaning the semiconductor device, in which the water mark can be effectively removed, so to improve the cleaning quality.
In an embodiment, the invention provides a method for cleaning a semiconductor structure. The method comprises performing a rinse process of CO2 with water (CO2W) process over the semiconductor structure; and performing a standard clean (SC) process over the semiconductor structure with an overlapping period with the step of performing the rinse process of CO2W.
In an embodiment, as to the method, the SC process comprises a standard clean 1 (SC1) process or a standard clean 2 (SC2) process.
In an embodiment, as to the method, the semiconductor structure comprises a wafer or a wafer with a structure already formed on the wafer.
In an embodiment, as to the method, the semiconductor structure comprises a structure with a trench or a structure with a significant large aspect ratio.
In an embodiment, as to the method, the overlapping period is in a range of 0.5 s-2 s.
In an embodiment, as to the method, the overlapping period is 1 s.
In an embodiment, as to the method, the method further comprises a diluted hydrofluoric (DHF) process before performing the rinse process of CO2W.
In an embodiment, as to the method, during the rinse process of CO2W, a recipe of the SC process has been applied to the semiconductor structure by the overlapping period.
In an embodiment, as to the method, during the rinse process of CO2W, the substrate is in a rotating state.
In an embodiment, as to the method, the semiconductor structure has a hydrophobic surface under cleaning.
In an embodiment, the invention provides a method for processing a semiconductor device, comprising forming a semiconductor structure over a substrate. Performing a cleaning process of diluted hydrofluoric (DHF) acid over the semiconductor structure. Further, a rinse process of CO2 with water (CO2W) is performed over the semiconductor structure after the cleaning process of DHF acid. A standard clean (SC) process is performed over the semiconductor structure with an overlapping period with the step of performing the rinse process of CO2W.
In an embodiment, as to the method, the SC process comprises a standard clean 1 (SC1) process or a standard clean 2 (SC2) process.
In an embodiment, as to the method, the semiconductor structure comprises a wafer or a wafer with a structure already formed on the wafer.
In an embodiment, as to the method, the semiconductor structure comprises a structure with a trench or a structure with a significant large aspect ratio.
In an embodiment, as to the method, the overlapping period is in a range of 0.5 s-2 s.
In an embodiment, as to the method, the overlapping period is 1 s.
In an embodiment, as to the method, the method further comprises a drying process after the SC1 process.
In an embodiment, as to the method, during the rinse process of CO2W, a recipe of the SC process has been applied to the semiconductor structure by the overlapping period.
In an embodiment, as to the method, during the rinse process of CO2W, the substrate is in a rotating state.
In an embodiment, as to the method, the semiconductor structure has a hydrophobic surface under cleaning.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
The invention is directed to a technology for cleaning semiconductor device formed over a wafer. The invention proposes a cleaning procedure, so that the water mark as the cleaning residuals can be effectively reduced, so to improve the cleaning quality.
The invention has looked into the cleaning procedure to find the mechanism in causing the water mark. Then invention has also proposes the solution to reduce the water mark. Several embodiments are provided for describing the invention but not for limiting the invention.
The cleaning solution usually includes some chemical materials, such as acid or dielectric residuals. Most of the cleaning solution are driven away from the wafer due to the rotation of the wafer 50. However, the structure of the semiconductor 54 is not a smooth surface, so some cleaning solution may still remain at the edge of the wafer 50. After the cleaning solution is dried, the chemical residuals in the cleaning solution leaves on the semiconductor device 54 over the wafer 50, resulting in water mark.
The water mark 60 has been observed in the usual cleaning procedure.
Referring to
After looking into the cleaning procedure with the observation of the water mark leaving on the wafer in various samples, the invention has identified the factor, which may cause the water mark. The water mark may more seriously occur due to the residuals between the rinse process in step S102 and the SC1 process in step S104.
After investigating the issue in detail, the cleaning procedure may be modified by over lapping the rinse process in step S102 and the SC1 process in step S104 by a certain period, such as 1 second or even in range of 0.5 s to 2 s.
In step S204, the invention starts the SC1 process together with the rinse process of CO2W in step S202 by a time period by 1 second or even in range of 0.5 s to 2 s. In other words, the SC1 process starts before the rinse process of CO2W in step S202 has finished. The rinse process of CO2W in step S204 is the end part of the rinse process of CO2W in step S202.
In lower flow corresponding to
After the step S206 with completion of the SC1 process, the wafer 50 can be dried in step S208. An additional rinse process in an example may be applied again before drying the wafer 50. However, this is not the limitation. Also, the wafer 50 may be rotated with proper rotation speed, so to effectively remove the cleaning solution. However, the rotation of the wafer is also not the limitation. The wafer 50 can has no rotation in an example.
The invention proposes a new cleaning process to improve the wafer mark by overlapping the rinse process of CO2W after the DHF with the SC1 process by a short period, such as 1 second or 0.5 s-2 s. In other words, the recipes of CO2W and SC1 are mixed during this short period. In this situation, a hydrophobic surface can be created under cleaning process, the chemical residuals can be effectively rinsed away from the semiconductor device.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.