Monitoring system and method for verifying measurements in pattened structures

Abstract

A method and system are presented for monitoring measurement of parameters of patterned structures based on a predetermined fitting model. The method comprises: (a) providing data indicative of measurements in at least one patterned structure; and (b) applying at least one selected verification mode to said data indicative of measurements, said at least one verification mode comprising: I) analyzing the data based on at least one predetermined factor and classifying the corresponding measurement result as acceptable or unacceptable, II) analyzing the data corresponding to the unacceptable measurement results and determining whether one or more of the measurements providing said unacceptable result are to be disregarded, or whether one or more parameters of the predetermined fitting model are to be modified.

What is claimed is: 
     
         1 . A method for monitoring measurement of parameters of patterned structures, said measurement of the parameters of patterned structures being based on a predetermined fitting model, the method comprising:
 (a) providing data indicative of measurements in at least one patterned structure;   (b) applying at least one selected verification mode to said data indicative of measurements said at least one verification mode comprising: analyzing the data based on at least one predetermined factor and classifying corresponding measurement result as acceptable or unacceptable, thereby enabling to determine whether one or more of the measurements providing said unacceptable result are to be disregarded, or whether one or more parameters of the predetermined fitting model are to be modified.   
     
     
         2 . The method of  claim 1 , wherein said data indicative of measurements includes at least one of the following types of data: raw measured data, measurement health data, data corresponding to a desired degree of fit with the fitting model, and measurement result in the form of one or structure parameters calculated from a fitting procedure. 
     
     
         3 . The method of  claim 2 , wherein said desired degree of fit is defined by a merit function or goodness of fit factor. 
     
     
         4 . The method of  claim 3 , wherein said applying of the selected verification mode comprises analyzing multiple values of the merit function determined for multiple measurement sites respectively, and upon determining that said multiple values of the merit function include at least one value that differs from other of said multiple values by a value exceeding certain threshold, classifying the corresponding measurement as unacceptable result. 
     
     
         5 . The method of  claim 4 , wherein said multiple measurement sites comprise at least one control site having a configuration corresponding to at least one other measurement site and being characterized by a smaller number of floating parameters of the structure. 
     
     
         6 . The method of  claim 4 , wherein said applying of the selected verification mode comprises analyzing at least two merit functions determined for a control site and at least one measurement site respectively, and upon determining that a difference between the merit functions of the control site and said at least measurement site differs by a value exceeding certain threshold, classifying the corresponding measurement as the unacceptable result. 
     
     
         7 . The method of  claim 4 , further comprising utilizing and the merit function and determining a measurement result in the form of at least one parameter of the patterned structure, for each of a control site and at least one measurement site, wherein the control site has a configuration corresponding to said at least one measurement site and being characterized by a smaller number of floating parameters of the structure. 
     
     
         8 . The method of  claim 2 , wherein the raw measured data comprises at least two data pieces corresponding to at least two different measurement conditions respectively. 
     
     
         9 . The method of  claim 8 , comprising, for each of said at least two data pieces, utilizing at least one model based measured parameter corresponding to a predetermined degree of fit with the raw measured data piece and determining the at least one parameter of the patterned structure; said applying of the selected verification mode comprising analyzing at least two values of said at least one parameter of the patterned structure corresponding to said at least two different measurement conditions, and upon determining that a difference between said at least two values exceeds a certain threshold, classifying the corresponding measurement as unacceptable result. 
     
     
         10 . The method of  claim 9 , wherein said data indicative of measurements comprise spectral data, said at least two data pieces corresponding to at least two different sets of wavelengths respectively. 
     
     
         11 . The method of  claim 9 , wherein said at least two data pieces correspond to at least two different angles of incidence of radiation onto the structure, and/or angles of radiation propagation from the structure, utilized in the measurements. 
     
     
         12 . The method of  claim 9 , wherein said at least two data pieces correspond to at least two different polarizations of radiation utilized in the measurements. 
     
     
         13 . The method of  claim 2 , wherein said raw measured data is in the form a multi-point function of a measured response of the structure to incident radiation, said applying of the selected verification mode comprises comparing the multi-point function of a measured response with a theoretical model-based function corresponding to a predetermined degree of fit with the measured response, and upon determining that said multi-point function includes at least one function value for at least one measurement point that differs from the function values at other measurement points by a value exceeding certain threshold, classifying the measured data as the unacceptable data. 
     
     
         14 . The method of  claim 3 , wherein said applying of the selected verification mode comprises determining a number of iteration steps applied to reach the desired goodness of fit condition, and upon identifying that said number exceeds a certain threshold, classifying the corresponding measurement as the unacceptable result. 
     
     
         15 . The method of  claim 2 , wherein said raw measured data corresponds to the measurements performed on the same measurement site and comprising measured signals successively obtained from said measurement site. 
     
     
         16 . The method of  claim 15 , wherein said raw measured data further comprises an integrated measured signal formed by said serious of measured signals successively measured on the same measurement site. 
     
     
         17 . The method of  claim 15 , wherein said selected verification mode comprises comparing the measured signals of said serious of measured signals with one another, and upon determining that said measured signals include at least one measured signal that differs from other measured signals by a value exceeding certain threshold, classifying the corresponding measurement as the unacceptable result. 
     
     
         18 . The method of  claim 16 , wherein said selected verification mode comprises comparing the measured signals of said serious of measured signals with the integrated measured signal, and upon determining that said measured signals include at least one measured signal that differs from the integrated measured signal by a value exceeding certain threshold, classifying the corresponding measurement as the unacceptable data. 
     
     
         19 . A monitoring system for controlling measurements of parameters of patterned structures, the system comprising:
 (a) data input utility for receiving data indicative of measurements in at least one patterned structure;   (b) a memory utility for storing at least one fitting model; and   (c) a processor utility comprising:
 a fitting utility configured and operable for using said at least one fitting model to determine a measurement result in the form of at least one parameter of the patterned structure; 
 a verification module comprising one or more error indicator utilities each configured and operable for applying at least one verification mode to data indicative of measurements, said at least one verification mode comprising: 
 analyzing said data based on at least one predetermined factor and classifying corresponding measurement as acceptable or unacceptable and generating output data indicative thereof, thereby enabling to determine whether one or more of the unacceptable measurements are to be disregarded, or whether one or more parameters of the predetermined fitting model are to be modified. 
   
     
     
         20 . A measurement system comprising an optical measurement unit and the monitoring system of  claim 19  connectable to the measurement unit, said measurement unit being configured and operable to apply one or more optical measurements to a patterned structure and generate measured data indicative thereof, said measured data comprising raw data in the form of one or more measured signals and/or measurement health data.