This invention relates to methods and apparatus for deriving substantially correct parameter data for processing workpieces, more particularly, processing workpieces for electronic device fabrication.
The most successful processing of materials for electronic devices typically requires optimization and precise control of the processing environment at all process steps. Many of these process steps are performed under conditions that make it difficult or impossible to measure the desired process variables. In those cases where an important process variable cannot be readily measured, an attempt is made to correlate the parameter of interest to other measurable or controllable parameters. The accuracy and stability of these correlations, also called equipment response models, are a critical factor in determining the process capability and device yield at any given process step.
Descriptions of some of the available technologies and sensor apparatus for measuring process variables are available in the technical and patent literature. Examples of some of the technologies are described in United States patents U.S. Pat. Nos. 6,244,121, 6,051,443, 6,033,922, 5,989,349, 5,967,661, 5,907,820, and Patent Corporation Treaty application WO 02/17030.
Some of the available technologies are tethered systems in which sensors exposed to the process conditions that are to be measured have physical connections to remote facilities such as power sources and information processors, and electronic components. Other technologies use an electronics module that is coupled to the detectors on a support; the sensors and electronics module are part of a single unit that is exposed to the process conditions that are to be measured. The electronics module is necessary for a sensor apparatus with capabilities such as autonomous information processing capability, wireless communication capability, and other electronically controlled on-board capabilities.
In some applications, the presence of the tether or electronics module can introduce an unacceptable error in the measurement data. For the case of measuring temperatures using a sensor apparatus, the mere presence of the electronics module will distort the temperature field being measured. It is possible to reduce the distortion by using very small components in the module, thereby reducing the module""s overall size and thermal mass.
Of course, for some applications the module distortion effect may be ignored if a high degree of measurement accuracy is unnecessary. However, some of the critical process steps required for processing high-value workpieces such as semiconductor wafers for electronic device and optical device fabrication and substrates for flatpanel display fabrication do indeed require high accuracy for the values of the process conditions. For such applications, measurements of a parameter such as temperature need to be extremely accurate, particularly for the temperature uniformity across the area of the workpiece. Furthermore, applications involved with the manufacture, calibration, research, and development of process equipment for processing high value substrates require high accuracy measurements since the operation of the equipment can be limited by the accuracy of the measurements. Inaccurate data can result in the loss of millions of dollars of product in some instances. Alternatively, the inaccurate data can result in the production of products having poorer performance because the process conditions were optimized based on the inaccurate data.
Clearly, there are numerous applications requiring high accuracy methods and apparatus by which spatially resolved and time resolved equipment response models can be easily and economically developed and maintained. An example of an important application is the uniform processing of workpieces such as semiconductor wafers, flatpanel displays, and other electronic devices. Furthermore, there is a need for high accuracy methods and apparatus capable of collecting data for response models in a nonperturbing manner on unmodified process equipment running realistic process conditions. Still further, there is a need for methods and apparatus capable of correcting measurements errors that can be caused by the methods and apparatus used for the measurements.
This invention seeks to provide methods and apparatus that can improve the accuracy of measured parameter data used for processing workpieces. One aspect of the present invention includes methods of deriving substantially correct data for applications such as generating data for monitoring, controlling, and optimizing processes and process tools. Another aspect of the present invention includes apparatus for deriving substantially correct data for applications such as generating data for monitoring, controlling, and optimizing processes and process tools.
It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out aspects of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
The above and still further features and advantages of the present invention will become apparent upon consideration of the following detailed descriptions of specific embodiments thereof, especially when taken in conjunction with the accompanying drawings.