US20080070485A1

US20080070485A1 - Chemical mechanical polishing process

Info

Publication number: US20080070485A1
Application number: US11/532,090
Authority: US
Inventors: Chien-Hsuan Chen; Ho-Da Jiang; Chih-Yueh Li; Chih-Chin Yang; Cheng-Hsun Wu
Original assignee: United Microelectronics Corp
Current assignee: United Microelectronics Corp
Priority date: 2006-09-14
Filing date: 2006-09-14
Publication date: 2008-03-20

Abstract

A chemical mechanical polishing (CMP) process at least includes a polishing step and an ex-situ conditioning step, and the ex-situ conditioning step must be immediately performed after the polishing step. Therefore, it can save the process time. Furthermore, when applying to a CMP apparatus with several polishing regions, it can integrate these polishing regions having different polishing time in order to shorten total manufacturing time, thereby improving throughput.

Description

BACKGROUND OF THE INVENTION

1. Field of Invention
The present invention relates to chemical mechanical polish (CMP) process. More particularly, the present invention relates to a CMP process, capable of improve the throughput.
2. Description of Related Art
As the device size is continuously reduced, the exposure-light resolution for the photolithography is required to be relatively high. As the depth of the exposure-light is reduced, it is required more strictly for the varying degree of altitude on the wafer surface. Thus, when the manufacturing process is down to the sub-micron, the planarization of the wafer is accomplished, based on CMP process. The unique property of anisotropic polishing CMP process not only can be used to planarize the profile of the wafer surface, but also can be used in fabricating the metallic vertical or horizontal interconnect in damascene damacene structure, the shallow trench isolation of device during the first manufacturing stage and the advance manufacturing of device, the planarization of the microelectromechanical system, and the flat display panel etc..
The CMP apparatus usually uses a polishing head to hold the wafer, an then the front surface of the wafer is pressed onto a polishing platen, which has a polishing pad with a slurry layer thereon, for performing polishing process.
However, after the polishing process is performed for a certain period, the polishing pad of the CMP apparatus would have the residual particles. These particles may come from the polishing particles of the slurry or the film material on the wafer while polishing away. Therefore, in order to maintain the clean condition on polishing pad, a polishing pad conditioner is needed to remove the residual particles on the polishing pad, so as to maintain the polishing rate and stability for the polishing pad on the wafer.
In general, the conditioner is used in two ways. One way is in-situ condition, that is, the polishing process is performing while the conditioner is using for conditioning process. Another way is ex-situ condition, that is, the conditioner is using for conditioning process after or before the polishing process is performed on each batch of wafers.
However, during the in-situ conditioning process, since the slurry is usually acid, the diamond particles on the conditioner is easily dropped and scattered over the polishing pad. This results in occurrence of the scratch or the micro-scratch on the wafer after polishing. Therefore, the ex-situ conditioning process is taken in place, so as to prevent the foregoing situation from occurring. However, since the ex-situ conditioning process needs to wait to perform on the polishing pad, until all of the wafers in the CMP apparatus have been polished in completion and moved outside. This therefore is time consuming.

SUMMARY OF THE INVENTION

In an objective of the present invention, a CMP process is provided, capable of saving the processing time.
In another objective of the present invention, a CMP process is provided, capable of improving the throughput.
The present invention provides a CMP process, at least comprising a polishing process and an ex-situ conditioning process. The characteristic of the present invention includes performing the ex-situ conditioning process immediately after the polishing process.
According to an embodiment of the CMP process in the present invention, the polishing process includes pressing a wafer over a polishing platen with a polishing pad for polishing, and removing the wafer from the polishing pad.
According to an embodiment of the CMP process in the present invention, the ex-situ conditioning process includes using a conditioner for conditioning the polishing pad.
The present invention further provides a CMP process, suitable for performing in a CMP apparatus. The CMP apparatus includes multiple polishing regions and a mechanical (robot) arm, wherein each of the polishing regions at least includes a polishing head, a polishing platen, a slurry supplier and a conditioner. The polishing head of each polishing region hold a wafer, and the mechanical arm can drive the polishing head of each of the polishing regions. The operation steps include:

- (a) pressing the polishing pad, causing the wafer in touch with the polishing pad of the polishing platen;
- (b) performing a polishing process;
- (c) moving up the polishing head, causing the wafer away from the polishing pad;
- (d) after the step (c), via a conditioner, immediately performing an ex-situ conditioning process on the polishing pad; and
- (e) rotating the mechanical arm, to drive the wafer to the next polishing region.

According to another embodiment of the CMP process in the present invention, the step (d) and step (e) are simultaneously performed.
According to another embodiment of the CMP process in the present invention, the step (e) is performed after the step (d).
In the present invention, since the ex-situ condition process is performed immediately after the wafer is polished in completion, the manufacturing can be saved. Also and, when the present invention is applied to a CMP apparatus with several polishing regions. These polishing regions having different polishing time can be integrated, in order to the total manufacturing time and thereby increase throughput.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

FIG. 1 is a drawing, schematically illustrating the CMP process, according to an embodiment of the present invention.

FIG. 2 is a drawing, schematically illustrating the CMP process, according to another embodiment of the present invention.

FIG. 3 is a drawing, schematically illustrating the polishing timing of the CMP process of the present invention in comparing with a convention CMP process, according to a first embodiment of the invention.

FIG. 4 is a drawing, schematically illustrating the polishing timing of the CMP process of the present invention in comparing with a convention CMP process, according to a second embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present invention, the ex-situ condition process is performed immediately after the wafer is polished in completion, so as to save the manufacturing time. Multiple embodiments are provides for describing the present invention but are not used to limit the present invention.
FIG. 1 is a drawing, schematically illustrating the CMP process, according to an embodiment of the present invention.
In FIG. 1, the embodiment starts from the step 100 for performing polishing process. The polishing process includes pressing a wafer over a polishing platen with a polishing pad to perform polishing, and then moving the wafer away from the polishing pad. After then, the step 110 is immediately performed for ex-situ conditioning process. Here, “immediately” means that a conditioner is used to condition the polishing pad at the time when the wafer is moved away from the polishing platen. It is different from the conventional way that it is necessary to wait until the wafer has been moved to the polishing platen at the next polishing region. After then, the conditioner is used to condition the polishing pad.
In addition, the present invention can be applied to a CMP apparatus with several polishing regions, as shown in FIG. 2.
FIG. 2 is a drawing, schematically illustrating the CMP process, according to another embodiment of the present invention. The embodiment is suitable for use in a usual CMP apparatus. The CMP apparatus includes a plurality of polishing regions and a mechanical arm. Each of the polishing regions at least includes a polishing head, a polishing platen with a polishing pad, a slurry supplier, and a conditioner. The polishing head of each polishing region can hold a wafer, and the mechanical arm can drive the polishing head of each polishing region.
Referring to FIG. 2, the step 200 is performed for pressing the polishing head, so as to cause the wafer in touch with the polishing pad of the polishing platen. After then, the step 210 is performed for polishing. In step 220, the polishing head is moved up and moves away from the polishing pad. In step 230, the conditioner is used to perform ex-situ conditioning process on the polishing pad. Then, in step 240, the mechanical arm is rotated, so as to drive the wafer to a next polishing region.
Since the polishing time on each polishing region can be set to be the same or different, in this embodiment, if the polishing time on each polishing region are the same, then the step 230 and step 240 can be simultaneously performed. Contrarily, if the polishing time on each polishing region are different, then the polishing region with longer polishing time is still performed with the step 210 (performing polishing) while the polishing region with shorter polishing time has been performing the step 230 performing ex-situ conditioning). In this consideration, for the point of view from the polishing region with shorter polishing time, at this moment, the step 240 (rotating the mechanical arm) is not performed, and should wait to perform until the step 220 (moving the wafer away from the polishing pad) in the polishing region with longer polishing time is accomplished. In addition, when the process shown in FIG. 2 is repeated, then it is suitable for use in a mass production.
In the following, two embodiments are provided to shown the improved effect when the invention is plied in the CMP apparatus having several polishing regions.

Embodiment 1

FIG. 3 is a drawing, schematically illustrating the polishing timing of the CMP process of the present invention in comparing with a convention CMP process, according to a first embodiment of the invention.
Referring to FIG. 3, when the CMP apparatus has three polishing regions, indicated by P1, P2 and P3 as the first polishing platen, the second polishing platen, and the third polishing platen in the polishing regions. Each polishing region has a polishing time period by 60 seconds. In addition, a transferring time for the wafer being moved to the next polishing region, equivalent to the rotation time of the mechanical arm, is set to 6 seconds. The polishing platens P1 and P2 have the ex-situ conditioning time by 20 seconds while the polishing platen P3 does not have the ex-situ conditioning.
As known from FIG. 3, when the polishing step at P1 finishes (at time point 0 of the time coordinate of FIG. 3), in the embodiment of the invention, the ex-situ conditioning step and the transferring step are performed simultaneously. Therefore, when the wafer being polished at P1 is moved to the P2 for polishing by 14 seconds, at time point 20 in FIG. 3, the ex-situ conditioning step at P1 has finished and it is ready for polishing the next wafer. Likewise, the rest steps can be performed. On contrary, the ex-situ conditioning step of prior art 1 has to wait to start until the transferring step is finished. In prior art 1, after moving the wafer from P1 to P2 and starting polishing by 20 seconds, at time point 26 of the time coordinate, the ex-situ conditioning step at P1 finishes. As a result, the invention can save 6 second for each wafer in CMP process 6. It is 6 sec/wafer.

Embodiment 2

FIG. 4 is a drawing, schematically illustrating the polishing timing of the CMP process of the present invention in comparing with a convention CMP process, according to a second embodiment of the invention.
The difference of embodiment 2 from embodiment 1 is that the polishing time for P1 and P2 is set to 60 second while the P3 is set to 70 seconds. When the polishing step for the first wafer at P1 has finished, at time point 0 of the time coordinate, the ex-situ conditioning step and the transferring step are performed at the same time. After the first wafer, being moved to P2, is polished by 14 second, at time point 20 of the time coordinate, P1 has finished the ex-situ conditioning step and performed the polishing step for the second wafer. In addition, when the first wafer being moved to P2 finishes the polishing step, at time point 80 of time coordinate. After waiting for 14 seconds, the first wafer and the second wafer can be simultaneously transferred to P3 for polishing step by 70 seconds, at time period 6-76 of the time coordinate. Comparing embodiment 2 with prior art 2, in the prior art 2, it still has to wait for 20 seconds after the polishing step for the first wafer being moved to P2 has finished, at time point 86 of time coordinate, so as to simultaneously transfer with the second wafer. This takes longer time in process.
In summary, the features of the present invention include performing the ex-situ conditioning process immediately after polishing the wafer in completion. In addition, when the present invention is applied to the CMP apparatus with several polishing regions, the present invention can integrate these polishing regions having different polishing time in order to shorten total manufacturing time, thereby improving throughput.
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 present invention. In view of the foregoing descriptions, it is intended that the present invention covers modifications and variations of this present invention if they fall within the scope of the following claims and their equivalents.

Claims

1. A chemical mechanical polishing (CMP) process comprising:

providing a CMP apparatus having a plurality of polishing pads and a mechanical arm;

pressing a first wafer and a second wafer onto a first pad and a second pad respectively to perform a first polishing process of the first wafer and a second polishing process of the second wafer without pad conditioning;

finishing the second polishing process of the second wafer while the first polishing process of the first wafer still under performing;

moving up the second wafer away from the second pad, then performing a conditioning process to the second pad;

finishing the first polishing process of the first wafer and moving up the first wafer away from the first pad while the second pad still under the pad conditioning process; and

simultaneously rotating the mechanical arm to remove away the first wafer and the second wafer while the second pad still under the pad conditioning process.

2. (canceled)

3. (canceled)

4. A chemical mechanical polishing (CMP) process, comprising:

finishing the first polishing process of the first wafer and the second polishing process of the second wafer simultaneously;

moving up the first wafer and the second wafer away from the first pad and the second pad respectively, then performing a conditioning process to the first pad and the second pad; and

simultaneously rotating the mechanical arm to remove away the first wafer and the second wafer while the first and the second pad still under the pad conditioning process.

5. (canceled)

6. (canceled)

7. The CMP process of claim 1, further comprising:

performing the conditioning process to the first pad after moving up the first wafer away from the first pad.

8. The CMP process of claim 1, further comprising:

performing the conditioning process to the first pad when simultaneously rotating the first wake and the second wafer.