Abrading – Precision device or process - or with condition responsive... – Computer controlled
Reexamination Certificate
1998-06-26
2001-01-09
Banks, Derris H. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
Computer controlled
C451S041000, C451S287000
Reexamination Certificate
active
06171174
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the planarization of semiconductor wafers and, more specifically, to a system and method for controlling a polishing tool having multiple arms.
BACKGROUND OF THE INVENTION
Chemical-mechanical polishing (CMP) is a widely used means of planarizing silicon dioxide as well as other types of layers on semiconductor wafers. Chemical mechanical polishing typically utilizes an abrasive slurry disbursed in an alkaline or acidic solution to planarize the surface of the wafer through a combination of mechanical and chemical action. A typical chemical mechanical polishing tool includes a rotatable circular platen or table on which a polishing pad is mounted and a polishing device is positioned above the pad. The polishing device includes one or more rotating carrier heads to which wafers can be secured typically through the use of vacuum pressure. In use, the platen is rotated and an abrasive slurry is disbursed onto the polishing pad. Once the slurry has been applied to the polishing pad, a downforce is applied to each rotating carrier head to press its wafer against the polishing pad. As the wafer is pressed against the polishing pad, the surface of the wafer is mechanically and chemically polished.
As semiconductor devices are scaled down, the importance of chemical-mechanical planarization to the fabrication process increases. In particular, it becomes increasingly important to control removal rate variations between wafers. Variations in removal rates effect the thicknesses of layers being polished. Variations in layer thicknesses deleteriously impact subsequent fabrication steps, such as lithography, and degrade device performance. To further complicate matters, the complexity of polishing tools is also increasing. For example, chemical mechanical polish tools have moved from single-arm polishing tools to multi-arm polishing tools which can, for example, polish five wafers simultaneously. The use of multiple polishing arms further contributes to variations in removal rates between wafers. As a result of the increasing importance and complexity of chemical mechanical planarization, semiconductor manufacturers seek systems and methods for controlling chemical mechanical polish tools.
SUMMARY OF THE INVENTION
The present invention provides a system and method of controlling a polishing tool having multiple arms. A method, in accordance with one embodiment, includes determining a first removal rate for each arm based on a first wafer run, determining a downforce adjustment input for each arm based on a process model, for the arms, which relates a removal rate for a given arm to downforce adjustments on each of the arms and using each first removal rate, and providing the downforce adjustment input for each arm to the polishing tool for polishing a subsequent run. In this manner, the method takes into account each arm's removal rate dependency on the downforce adjustments for all of the arms. This can reduce removal rate variations between arms as well as between wafers and improve the characteristics of the ultimately formed semiconductor devices.
A polishing system, in accordance with another embodiment of the invention, includes a polishing tool having multiple arms and one or more metrology tools, connected to the polishing tool, for measuring pre- and post-polish thicknesses of layers on wafers. The polishing system further includes a controller coupled to the polishing tool and the one or more metrology tools. The controller is configured to receive measured pre-polish thicknesses and post-polish thicknesses of wafers of a first wafer run and determine a removal rate for each arm using the measured pre-polish and post-polish thicknesses, determine a downforce adjustment input for each arm based on a process model, for the arms, which relates a removal rate for a given arm to downforce adjustments on each of the arms and using each first removal rate, and provide the downforce adjustment input for each arm to the polishing tool for polishing a subsequent run.
The above summary of the present invention is not intended to describe each illustrated embodiment or implementation of the present invention. The Figures and the detailed description which follow more particularly exemplify these embodiments.
REFERENCES:
patent: 5653622 (1997-08-01), Drill et al.
patent: 5655951 (1997-08-01), Meikle et al.
patent: 5665199 (1997-09-01), Sahota et al.
patent: 5696601 (1997-12-01), Kodera et al.
patent: 5730642 (1998-03-01), Sandhu et al.
patent: 5827111 (1998-10-01), Ball
patent: 5865666 (1999-02-01), Nagahara
patent: 0 770 455 A1 (1997-05-01), None
Campbell William Jarrett
Miller Michael Lee
Raeder Christopher Henry
Advanced Micro Devices
Banks Derris H.
LandOfFree
System and method for controlling a multi-arm polishing tool does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for controlling a multi-arm polishing tool, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for controlling a multi-arm polishing tool will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2443817