Patent Application
20060129263
The present invention relates to tool control and particularly to a control system for manipulating tool process parameters capable of controlling a tool without over-burdening a manufacturing execution system (MES) of a manufacturing system.
Manufacturing process control is conventionally accomplished by analyzing product parameters after a process run is finished. The product parameters are obtained through inspecting the product or work-in-process using various metrology tools, such as metrology tools for film thickness and critical dimension measurement. Tool process parameters are seldom taken into account in conventional process control methods and systems. According to the conventional process control, errors in the manufacturing process are corrected only after the mistake has been made, and the resulting yield loss has been incurred. As optical lithography pushes to smaller and smaller dimensions, patterned features smaller than the wavelength of light must be routinely manufactured. In such system, tiny deviations of tool process parameters make up an increasingly large share of manufacturing errors. The MES of the conventional system manipulates few, if any, tool process parameters. Additionally, MES is already burdened by control functions other than tool process parameter control. Therefore, in the conventional system very little capacity remains for controlling tool process parameters. In order to achieve real-time control of tools by means other than the conventional post-process correction, efficient control over tool process parameters is necessary.
Hence, there is a need for a control system for tool process parameters that addresses the problems arising from the existing technology.
It is therefore an object of the invention to provide a tool control system and method capable of efficient, real-time control of tool process parameters.
Another object of the present invention is to provide a tool control system and method capable of controlling tool process parameters without burdening the MES in a manufacturing system.
To achieve the above objects, the present invention provides a system and method capable of analyzing tool process parameters off-line and adjusting tool process parameters in real-time to achieve efficient tool control. By manipulating the enormous number of tool process parameters offline outside the MES, the tool control system and method enhances product yield and relieves the MES of the heavy burden of manipulating tool process parameters.
According to the present invention, a system for controlling process parameters of a plurality of tools is provided. The system contains first and second storage devices, and first and second processors. The first storage device stores first process parameters for the tools. The first processor retrieves the first process parameters from the first storage device and calculates a control limit for each of the tools accordingly. The second storage device stores the control limit information. The second processor receives second process parameters for the tool, retrieves corresponding control limit information from the second storage device, performs a statistical process control analysis accordingly, and generates an alarm signal when direct adjustment of the tool process parameter is required.
The present invention also provides a method of controlling tool process parameters, which is implemented in the aforementioned system. First, process parameters for a plurality of tools are received. Second, a first database is established for storing the process data. Then the process parameters are analyzed to determine control information for each of the tools. A second database is established for storing the control information. Next, a statistical process control analysis is performed to analyze the process parameters according to the control information. Then, an alarm signal is issued according to the statistical process control analysis for directing adjustment of the tool process parameters.
The above-mentioned method may take the form of program code embodied in a tangible media. When the program code is loaded into and executed by a machine, the machine becomes an apparatus for practicing the invention.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The present invention will now be described with reference to FIGS. 2 to 5, which in general relate to a tool control system.
The second processor 213 further comprises buffer cache 2135 storing recently used control information. The buffer cache is refreshed according to a least recently used (LRU) mechanism.
First, historical process parameters of a plurality of tools are provided (step S41). The historical process parameter mainly comprises information regarding tool process parameters, such as temperature and pressure, collected during a plurality of preceding process runs. The historical process parameter is collected by corresponding tool controller 27 and relayed to the second processor 215. The second processor 215 then stores the historical process parameter in the first storage device 211, which is connected directly to the first and second processors 213 and 215.
Second, the historical process parameters are analyzed to determine control information for each of the tools (step S42). The control information comprises information regarding control specifications, control charts, and control rules for process parameters of each tool. The control information determination is performed offline outside the MES, thus the capacity of the MES can be preserved for overall tool control operations. According to this embodiment, the control information is stored in the second storage device 217.
Next, process parameters for a current process run of a tool are received (step S43). The current process parameters comprise information regarding tool process parameters, such as temperature and pressure, collected during a current process run. The current process parameters are collected by corresponding tool controller 27 and relayed to the second processor 215.
After the current process parameter is received, a statistical process control analysis is performed. The statistical process control analysis is performed by the second processor 215, analyzing the current process parameter according to the control information. After being analyzed, the current process parameters are stored in the first storage device 211 and assessed as historical process data. In step S44, it is determined whether the current process parameters conform to the control specification information, and if not, an out-of-specification alarm signal is issued (step S441). In step S45, it is determined whether the current process parameters conform to the control chart information, and if not, an out-of-control alarm signal is issued (step S451). The out-of-specification and out-of-control alarm signals are sent to a corresponding tool controller and direct the adjustment of process parameters for the corresponding tools (step S46). The threshold for determining the conformation between the current process parameters and the control specification and control chart information is specified in the control rule information. The control rule information comprises a percentage setting rule and wafer-to-wafer and lot-to-lot gating rules. In order to facilitate the calculation, buffer cache 2135 stores recently used control information. The buffer cache is refreshed according to a least recently used (LRU) mechanism.
The method of the present invention, or certain aspects or portions thereof, may take the form of program code (i.e. instructions) embodied in a tangible media, such as floppy diskettes, CD-ROMS, hard drives, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The methods and apparatus of the present invention may also be embodied in the form of program code transmitted over some transmission medium, such as electrical wiring or cabling, through fiber optics, or via any other form of transmission, wherein, when the program code is received and loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates analogously to specific logic circuits.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
