Abstract:
Among the multiple OES data wavelengths, an analysis device identifies the wavelength of light emissions from a substance contained in the plasma from among multiple light emission wavelengths within the chamber by way of the steps of: measuring the light emission within the chamber during etching processing of the semiconductor wafer; finding the time-based fluctuation due to changes over time on each wavelength in the measured intensity of the light emissions in the chamber; comparing the time-based fluctuations in the wavelength of the light emitted from the pre-specified substance; and by using the comparison results, identifying the wavelength of the light emitted from the substance caused by light emission within the chamber.

Description:
BACKGROUND 
     The present invention relates to a method for selecting a wavelength to affect the etching processing results, from light emission data measured during plasma etching processing (hereafter called etching processing) in etching devices that machine the semiconductor wafer by using plasma. 
     In order to achieve a microscopic shape such as for a semiconductor device formed over a wafer, plasma is utilized to ionize a substance, and by using the effect from that substance, (reaction with wafer surface) etching is performed to remove a substance over the wafer. There are a variety of substances for ionizing and there are also many types and forms of substances over the wafer material used according to the required product performance. 
     Moreover, in order to form a shape over the wafer, an organic substance resist is coated over the wafer, a shape is formed by photolithography, and etching performed. A substance is also placed whose reaction speed can be adjusted in order to obtain a specified shape. A variety of types and forms of substances that react with each other can be placed within the chamber for performing the etching process. 
     The ionizing phenomenon implemented by plasma is accompanied by a light emission phenomenon, so etching devices that utilize plasma in the etching process include a spectroscope (OES: Optical Emission Spectroscope) capable of monitoring the plasma emission status. 
     Data measured by a spectroscope is hereafter called OES data. 
     The OES data contains two dimensional spatial and temporal elements and expresses the emission intensity values respectively measured at each time and wavelength. 
     The light emission intensity values fluctuate according to the state of the etching process so the etching process is controlled by using the OES data. In one example of this control, the etching process is terminated or the inflow gas quantity is reduced when a specified wavelength value among the OES data has exceeded the threshold. 
     Japanese Unexamined Patent Application Publication No. Hei9 (1997)-306894 discloses a method for identifying the wavelength used for controlling the etching from the OES data. 
     Japanese Unexamined Patent Application Publication No. Hei9 (1997)-306894 discloses a method to analyze the emitted light occurring along with the plasma processing by the plasma device, and automatically setting an optimal wavelength for detecting a pre-established endpoint prior to executing plasma processing based on fluctuations over accumulated time in the light emission intensity on the specified wavelength. More specifically, a method is disclosed for setting a wavelength whose maximum value is the differential detected by an intensity differential detector circuit, as the optimal wavelength. 
     SUMMARY 
     The advances in recent years in making ever tinier and detailed patterns on the semiconductor wafer serving as the object for etching have created a need for higher accuracy when performing the etching process. 
     The state of the substance contained in the plasma is strongly related to the results obtained in the etching process. An important element required for performing a high-accuracy etching process is observing the light emission from the plasma within the chamber during the etching process, and identifying the wavelength exhibiting the light emitted from the substance contained in the plasma during observation of the light emission. The etching process can be improved to a high degree of accuracy by monitoring the etching state through using information (light emission intensity values and fluctuation quantities) on the light emissions from the substance contained in the plasma, and supervising and controlling the processing. 
     Among the etching processes, Japanese Unexamined Patent Application Publication No. Hei9 (1997)-306894 discloses a method to detect the endpoint as the timing at which etching ends in the etching process. However, the method disclosed in Japanese Unexamined Patent Application Publication No. Hei9 (1997)-306894 selects the wavelength after evaluating the light emission intensity at two specified time points and therefore has the problem of being incapable of selecting an effective wavelength when controlling the etching process with the light emission intensity at time points (such as an intermediate time point in the etching process) other than those two time points. 
     Another problem was that determining whether or not the light emission intensity at the selected wavelength was caused by the substance contained in the plasma. 
     Whereupon the present invention has the object of providing an OES data analysis method, analysis program, analysis device, and analysis system to identify the wavelength that exhibits light emission from the substance contained in the plasma from OES data from observation of light emissions during etching, and monitor, supervise, and control the etching process. 
     In order to achieve the above object, a representative mode of the present invention is featured in including the following configuration in an etching device containing an analysis unit to process the OES data. 
     The present invention has the unique feature of including the steps of: measuring the light emission within the chamber during the semiconductor wafer etching process; finding the time-based fluctuations for each wavelength due to variations over time in the measured light emission intensity of the light emissions in the chamber; comparing the time-based fluctuations corresponding to the wavelength of the light emission by the pre-specified substance; and based on the compared results, identifying the specified wavelength of light emitted from the substance contained in the plasma within the chamber. 
     The present invention is capable of identifying the wavelength where light is emitted from the substance contained in the plasma within the chamber, from the plurality of wavelengths in the OES data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing the configuration of the etching device of the first embodiment of the present invention; 
         FIG. 2  is a block diagram showing the configuration of the etching unit of the first embodiment of the present invention; 
         FIG. 3  is a drawing for describing an example of the OES data; 
         FIG. 4  is a graph for describing time-based fluctuations in OES data at a specified wavelength; 
         FIG. 5  is a drawing for showing an example of a substance and matching wavelength table; 
         FIG. 6  is a drawing for showing an example of an OES data table; 
         FIG. 7  is a drawing for showing an example of an identical substance correlating information table; 
         FIG. 8  is a drawing for showing an example of a peripheral wavelength correlating information table; 
         FIG. 9  is a drawing for showing an example of a threshold information table; 
         FIG. 10  is a drawing for showing an example of a recommended wavelength information table; 
         FIG. 11  is a drawing for showing an example of a light emission intensity average information table; 
         FIG. 12  is a flow chart for showing the process flow in the analysis device for the first embodiment of the present invention; 
         FIG. 13  is a graph for showing an example of the case of a correlation in time-based fluctuations among wavelengths; 
         FIG. 14  is a graph for showing an example of the case where there is no correlation in time-based fluctuations among wavelengths; 
         FIG. 15  is a drawing for showing an example of the display screen of the first embodiment of the present invention; and 
         FIG. 16  is a drawing for showing an example of the display screen of the first embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments of the present invention are described next while referring to the accompanying drawings. In all drawings for describing the embodiments, the same reference numerals are generally attached to the same members, and their redundant descriptions are omitted. 
     [Etching Device] 
     In the present invention, the etching device  1  as shown in the block diagram in  FIG. 1 , includes an etching unit  10 , analysis unit  20 , input unit  30 , output unit  31 , and communication IF unit  32 , and also a bus  33  to mutually connect these components. 
     The etching unit  10  includes a plasma machining unit  11 , a spectroscope (OES)  12 , a control unit  13 , and an IF unit  14 . The plasma machining unit  11  generates the plasma and machines the wafer, and while the etching is being performed, the spectroscope (OES)  12  obtains the light emission data from the plasma serving as the OES data. The OES data is stored by way of the IF unit  14 , into the storage unit  22  contained in the analysis unit  20 . The control unit  13  controls the processing by the plasma machining unit  11 . The etching unit  10  is described in detail later while referring to  FIG. 2 . 
     The analysis unit  20  contains an arithmetic logic unit  21  to process the collected OES data, a storage unit  22  to store OES data, data showing the wavelength of the light emitted from each substance, and the processed results, and an IF unit  210 . The arithmetic logic unit  21  obtains time-based data on the plural light emission intensities from the OES data, calculates the degree of similarity such as the correlation coefficient among the obtained time-based data, and performs processing to identify the wavelength required for monitoring, supervising, and controlling the etching process, from the extent of the degree of similarity. The processing by the arithmetic logic unit  21  is described in detail while referring to  FIG. 13 . 
     The input unit  30  is for example a mouse or keyboard that receives information input by user operation. The output unit  31  is a display or printer for outputting information to the user. The communication IF unit  32  is an interface connectable to other systems (also connectable to currently used production control systems etc.) by way of the bus  33  and an external network, and for sending and receiving information. The bus  33  couples each component ( 10 ,  20 ,  30 ,  31 , and  32 ). Each IF unit ( 14 ,  29 , etc.) are interfaces for sending and receiving information by way of the bus  33 . The analysis unit  20  may also be connected as an analysis device outside of the etching device  1 . 
     [Etching Unit] 
     The etching unit  10  is comprised of the plasma machining unit  11 , a spectroscope (OES)  12 , a control unit  13 , and an IF unit  14 . The plasma machining unit  11  includes a chamber  111 , electrode  112   a  and  112   b , a window  115 , and a gas supply device  117 . In response to instructions from the control unit  13 , the plasma machining unit  11  stores the wafer  114  inside the chamber ill, supplies the etching gas from the gas supply device  117 , and causes the gas  113  made into plasma to strike the wafer  114  by applying a voltage using the electrode  112   a  and  112   b , to machine the wafer  114 . The gas  113  contains substances in the etching gas supplied from the gas supply device  117  and substances generated in the wafer  114  from the machining process. A light  116  is emitted at a wavelength according to the substance contained in the gas. The emitted light passes through the window  115  and is measured by the spectroscope (OES)  12 . 
     [OES Data] 
       FIG. 3  is a drawing for describing an example of the OES data measured by the spectroscope (OES)  12 . The OES data contains two dimensional spatial and temporal elements, and expresses the light emission intensity value respectively measured at each wavelength and time.  FIG. 4  is a graph for describing time-based fluctuations in light emission intensity at a specified wavelength. The light emission intensity value varies with the time as shown in  FIG. 4 . The locus of the time-based fluctuations varies with the wavelength. 
     [Analysis Unit] 
     The analysis unit  20  as shown in  FIG. 1 , includes an arithmetic logic unit  21 , a storage unit  22 , and an IF unit  210 . The storage unit  22  contains a substance and matching wavelength table storage region  23 , OES data storage region  24 , identical substance correlating information storage region  25 , peripheral wavelength correlating information storage region  26 , threshold information storage region  27 , and recommended wavelength information storage region  28 . 
     Information specifying the wavelength of light  116  from the substance possible contained in the gas  113  is stored in the substance and matching wavelength table storage region  23 . The substance is a single element or coupled from plural elements, and the wavelength of the light emitted from each substance is identified by measurements made beforehand. The substances as described here are not constantly contained in the gas  113 . Moreover, if the wavelengths of light emitted from each substance are the same then the substances are identical even if the conditions for the etching device  1  are different. 
       FIG. 5  shows a substance and matching wavelength table  23   a  serving as the first embodiment of the substance and matching wavelength table storage region  23 . This table contains respective fields such as the substance field  23   b , and wavelength field  23   c , etc. 
     Information for identifying the substance possibly contained in the gas  113  is stored in the substance field  23   b.    
     Information for identifying the wavelength of light emitted from the substance specified in substance field  23   b  is stored in the wavelength field  23   c . The wavelength specified by the wavelength field  23   c  is made to correspond to one or a plurality of substances. 
     The light emission intensity value for wavelengths stored in the wavelength field  23   c  among OES data might not necessarily always be determined by the light emission from a substance (stored on the same row) linked to the substance field  23   b . Therefore, monitoring, supervision, and control of the plasma machining unit  11  requires identifying a substance whose light emission intensity is determined by light emission from a substance linked to the substance field  23   b  among the wavelengths stored in the wavelength field  23   c.    
     The OES data storage region  24  contains information specifying OES data measured by the spectroscope (OES)  12 . 
       FIG. 6  shows the OES data table  24   a  serving as the first embodiment of the OES data storage region  24 . This table contains each field such as a wavelength field  24   b , time field  24   c , light emission intensity field  24   d , etc. 
     Information for identifying the wavelength of the measured OES data is stored in the wavelength field  24   b . Rows storing values identical to the values stored in wavelength field  23   c  of the previously described substance and matching wavelength table  23   a  are present in the wavelength field  24   b.    
     Information specifying the time of the measured OES data is stored in the time field  24   c.    
     Information for specifying the light emission intensity of the OES data for the wavelength specified via the wavelength field  24   b  and the time specified via the time field  24   c  is stored in the light emission intensity field  24   d.    
     Results from calculating the correlation coefficient serving as the degree of similarity for time-based data of light emission intensity for items applicable to the wavelength stored in the substance and matching wavelength table storage region  23  among OES data stored in the OES data storage region  24 , are stored in the identical substance correlating information storage region  25 . 
       FIG. 7  is a drawing showing an example of an identical substance correlating information table  25   a  serving as the first embodiment of the identical substance correlating information storage region  25 . This table contains each field such as a substance field  25   b , a wavelength field (column direction)  25   c , a wavelength field (row direction)  25   d , a light emission intensity correlation 1 field  25   e , etc. 
     Names for each substance emitting light on a wavelength specified by the values stored in wavelength field (column direction)  25   c  and wavelength field (row direction)  25   d  are stored in the substance field  25   b.    
     The substance specified by the value stored in the substance field  25   b , is stored in the wavelength field (column direction)  25   c  as information specifying the wavelength linked via the substance and matching wavelength table  23   a.    
     Substances specified by the value stored in the substance field  25   b  are stored in the wavelength field (row direction)  25   d , in the same way as the wavelength field (column direction)  25   c , as information specifying the wavelength linked via the substance and matching wavelength table  23   a.    
     The light emission intensity correlation 1 field  25   e  stores information specifying the correlation coefficient serving as the degree of similarity for both time-based fluctuations in light emission intensity at a wavelength specified by a value stored in the wavelength field (column direction)  25   c ; and time-based fluctuations in light emission intensity at a wavelength specified by a value stored in the wavelength field (row direction)  25   d . The above described time-based fluctuations in light emission intensity are values specified by way of the OES data table  24   a.    
     Results from calculating the correlation coefficient serving as the degree of similarity for time-based data for light emission intensity for an applicable wavelength stored in the substance and matching wavelength table storage region  23  among the OES data stored in the OES data storage region  24 , are stored in the peripheral wavelength correlating information storage region  26 . 
       FIG. 8  shows the peripheral wavelength correlating information table  26   a  serving as the first embodiment of the peripheral wavelength correlating information storage region  26 . This table contains each table such as a substance field  26   b , a wavelength field  26   c , a peripheral wavelength field  26   d , and a light emission intensity correlation 2 field  26   e.    
     The substance field  26   b  stores each substance name corresponding to the value stored in the substance field  23   b  of the substance and matching wavelength table  23   a.    
     The wavelength field  26   c  stores values for wavelengths corresponding to values stored in the wavelength field  23   c  of the substance and matching wavelength table  23   a.    
     The peripheral wavelength field  26   d  stores information showing the peripheral range of the wavelengths, with wavelengths specified by values stored in the wavelength field  26   c  utilized as a reference standard. In the example in  FIG. 8 , a value where 50 was subtracted from the value stored in wavelength field  26   c , up to a value where 50 was added to the value stored in the wavelength field  26   c  are stored in the peripheral wavelength field  26   d , however a value other than 50 may be utilized, and the subtracted value and the added value may be mutually different values. 
     The light emission intensity correlation 2 field  26   e  stores information specifying the correlation coefficient serving as the degree of similarity, for time-based fluctuations for light emission intensity in the wavelength specified by the value stored in the wavelength field  26   c ; and the averaged time-based fluctuations for light emission intensity in the wavelength range specified by the value stored in the peripheral wavelength field  26   d . The above described time-based fluctuations in light emission intensity are values specified via the OES data table  24   a . The above described averaged time-based fluctuations for light emission intensity are values specified via the light emission intensity average information table  29   a  described later on. 
     Conditions for selecting a wavelength suitable for use in monitoring, supervision, and control of the etching unit  10  are stored in the threshold information storage region  27 . 
       FIG. 9  shows the threshold information table  27   a  serving as the first embodiment of the threshold information storage region  27 . This table contains each field such as the threshold value 1 field  27   b , threshold value 2 field  27   c , and threshold value 3 field  27   d , etc. 
     The threshold value 1 field  27   b  stores information for specifying the cell storing a large correlation coefficient for the light emission intensity correlation 1 field  25   e  of the identical substance correlating information table  25   a.    
     The threshold value 2 field  27   c  stores information for specifying the wavelength to serve as the recommended wavelength, by using information stored in the identical substance correlating information table  25   a.    
     The threshold value 3 field  27   d  stores information for specifying the wavelength to serve as the recommended wavelength, by using information stored in the peripheral wavelength correlating information table  26   a.    
     The recommended wavelength information storage region  28  stores information used for specifying the wavelength to be utilized for monitoring, supervision, and control of the etching unit  10  from among the wavelengths stored in the substance and matching wavelength table storage region  23 . 
       FIG. 10  shows the recommended wavelength information table  28   a  serving as the first embodiment of the recommended wavelength information storage region  28 . This table includes each field such as the substance field  28   b , the wavelength field  28   c , and the recommended wavelength field  28   d , etc. 
     The substance field  28   b  stores the name of the substance corresponding to the values stored in the substance field  23   b  in the substance and matching wavelength table  23   a.    
     The wavelength field  28   c  stores the value of the wavelength corresponding to the value stored in the wavelength field  23   c  of the substance and matching wavelength table  23   a.    
     The recommended wavelength field  28   d  stores information for specifying the wavelength ideal for use in monitoring, supervision, and control of the etching unit  10  from the wavelengths specified by way of the value stored in the wavelength field  28   c.    
     The light emission intensity average information storage region  29  stores information for specifying the value that the OES data stored in the OES data storage region  24  is averaged in the specified wavelength zone. 
       FIG. 11  shows the light emission intensity average information table  29   a  serving as the first embodiment of the light emission intensity average information storage region  29 . This table contains each field such as peripheral wavelength field  29   b , time field  29   c , and light emission intensity average field  29   d , etc. 
     The peripheral wavelength field  29   b  stores information specifying the peripheral range of the wavelength whose calculated light emission intensity average was specified by way of a value stored in the light emission intensity average field  29   d.    
     The time field  29   c  stores information for specifying the measured time of the light emission intensity average specified by way of the value stored in the light emission intensity average field  29   d.    
     Information specifying averaged results in a range specified by way of a value stored in the peripheral wavelength field  29   b , from values stored in the light emission intensity field  24   d  of OES data table  24   a  is stored in the light emission intensity average field  29   d.    
     [Analysis Process by Analysis Unit  20 ] 
       FIG. 12  shows analysis processing (expressed in processing steps such as S 101 ) performed mainly by the arithmetic logic unit  21  in the analysis unit  20 . The analysis process is described while referring to  FIG. 12 . 
     The arithmetic logic unit  21  implements the analysis processing shown in  FIG. 12  when the etching processing by the etching unit  10  ends or the user inputs a command to execute the analysis process. The respective values are stored in the substance and matching wavelength table  23   a , the OES data table  24   a , and the threshold information table  27   a , at the stage where executing the analysis process. The values measured in past testing is stored in the substance and matching wavelength table  23   a , the values measured by the spectroscope (OES)  12  is stored in the OES data table  24   a , and the values set by the designer is stored in the threshold information table  27   a.    
     (S 101 ) 
     In S 101 , the arithmetic logic unit  21  stores the required data for calculation in each data table. 
     First of all, the arithmetic logic unit  21  stores the value stored in the substance field  23   b  in the substance and matching wavelength table  23   a , into the substance field  26   b  of the peripheral wavelength correlating information table  26   a , and stores the value stored in the wavelength field  23   c  of the substance and matching wavelength table  23   a , into the wavelength field  26   c.    
     The arithmetic logic unit  21  also stores the value stored in the substance field  23   b  in the substance and matching wavelength table  23   a , into the substance field  28   b  of the recommended wavelength information storage table  28   a , and stores the value stored in the wavelength field  23   c  of the substance and matching wavelength table  23   a , into the wavelength field  28   c.    
     The arithmetic logic unit  21  further stores the value stored in the time field  24   c  of the OES data table  24   a  into the time field  29   c  of the light emission intensity average information table  29   a.    
     When step S 101  ends, the arithmetic logic unit  21  stores a in the value i showing a row number in the substance and matching wavelength table  23   a.    
     (S 102 ) 
     In S 102 , the arithmetic logic unit  21  calculates the correlation of the time-based data for light emission intensity between identical substances, using information in the OES data table  24  as input, and stores the calculated correlation in the identical substance correlating information table  25   a.    
     First of all, the arithmetic logic unit  21  deletes all data in the identical substance correlating information table  25   a.    
     The arithmetic logic unit  21  loads the value (substance i) stored in the i-th row of the substance field  23   b  in the substance and matching wavelength table  23   a , and stores the value in the substance field  25   b  of the identical substance correlating information table  25   a.    
     The arithmetic logic unit  21  scans the substance field  23   b  in the substance and matching wavelength table  23   a  from the first row to the final row, and for the row storing a value identical to substance i, stores the value stored on the applicable row of wavelength field  23   c  into the final column of wavelength field (column direction)  25   c , and final row of wavelength field (row direction)  25   d . If there is already a value stored in the final column then one column is added to the final column, and the value stored in the applicable column. Also, if there is already a value stored in the final row, one row is added to the final row in the same way, and the value stored in the applicable row. This process stores a value identifying a wavelength corresponding to substance i, in the wavelength field (column direction)  25   c  and wavelength field (row direction)  25   d  of the identical substance correlating information table  25   a.    
     The arithmetic logic unit  21  further stores the value in the light emission intensity correlation 1 field  25   e . By setting the column number of wavelength field (column direction)  25   c  as j, and the row number of wavelength field (row direction) as k, the value (r 1 ) stored in k row j column of light emission intensity correlation 1 field  25   e  can be calculated by way of the following formula (1). 
     
       
         
           
             
               
                 
                   
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     The significance of each symbol in formula (1) is given as follows. 
     Here in wavelength field  24   b  of OES data table  24   a , the symbol p denotes the column number storing a value identical to the value stored in the j column of wavelength field (column direction)  25   c.    
     In wavelength field  24   b  of OES data table  24   a , the symbol q denotes the column number storing a value identical to the value stored in the k row of the wavelength field (row direction)  25   d.    
     The symbol xlp denotes the value stored in l row p column, among the values stored in the light emission intensity field  24   d  of the OES data table  24   a.    
     The symbol x mp  denotes the value stored in m row p column among the values stored in the light emission intensity field  24   d  of the OES data table  24   a.    
     The symbol x lq  denotes the value stored in l row q column among the values stored in the light emission intensity field  24   d  of the OES data table  24   a.    
     The symbol x mq  denotes the value stored in m row q column among the values stored in the light emission intensity field  24   d  of the OES data table  24   a.    
     The symbol n expresses the number of rows of the light emission intensity field  24   d  in the OES data table  24   a.    
     The symbol r 1  is the value (correlation coefficient) calculated in formula (1). The symbol r 1  expresses the extent of the degree of similarity of the time-based fluctuation for the value stored in the p column of light emission intensity field  24   d , and the value stored in the q column of light emission intensity field  24   d.    
       FIG. 13  is graphs of the time-based fluctuations in light emission intensity, and shows the value for correlation coefficient r 1  among the time-based fluctuations expressed in these two graphs. The time-based fluctuations in the two graphs are similar, and a large correlation coefficient r 1  can also be observed. 
     The formula (1) utilizes a correlation coefficient but other indices for evaluating the degree of similarity may also be utilized. 
     The arithmetic logic unit  21  calculates the correlation coefficient using formula (1) for all combinations of rows and columns in light emission intensity correlation 1 field  25   e , and stores the calculated value. 
     (S 103 ) 
     In S 103 , the arithmetic logic unit  21  inputs information from OES data table  24   a , calculates the average value of light emission intensity on wavelengths peripheral to the wavelength of the i-th row, and stores that average value in the light emission intensity average information table  29   a.    
     The arithmetic logic unit  21  first of all loads the value stored in the i-th row of wavelength field  23   c  into the substance and matching wavelength table  23   a , and sets the peripheral range of the wavelength using the loaded value as a reference. In the present embodiment, a value where 50 is subtracted from the loaded value is set as the minimum value, and a value where 50 is added to the loaded value is set as the maximum value. 
     The arithmetic logic unit  21  stores the set range in a “Minimum value range to maximum value range” format in the i-th row of peripheral wavelength field  26   d  in the peripheral wavelength correlating information table  26   a , and in the peripheral wavelength field  29   b  of the light emission intensity average information table  29   a.    
     The arithmetic logic unit  21  next calculates the average value for light emission intensity on the peripheral wavelength using the following formula (2), from the first row to the final row of the light emission intensity field  24   d  in the OES data table  24 , and stores the calculated value (AVE o ) in the light emission intensity average field  29   d  of the light emission intensity average information table  29   a . 
     
       
         
           
             
               
                 
                   
                     
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                             u 
                           
                           ⁢ 
                           
                             g 
                             ⁡ 
                             
                               ( 
                               
                                 x 
                                 os 
                               
                               ) 
                             
                           
                         
                         ) 
                       
                     
                   
                   ⁢ 
                   
                     
 
                   
                   ⁢ 
                   
                     
                       f 
                       ⁡ 
                       
                         ( 
                         
                           x 
                           os 
                         
                         ) 
                       
                     
                     = 
                     
                       { 
                       
                         
                           
                             
                               
                                 
                                   
                                     x 
                                     os 
                                   
                                   , 
                                 
                               
                               
                                 
                                   
                                     λ 
                                     s 
                                   
                                   ≥ 
                                   
                                     
                                       λ 
                                       min 
                                     
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     and 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     
                                       λ 
                                       s 
                                     
                                   
                                   ≤ 
                                   
                                     
                                       λ 
                                       max 
                                     
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     and 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     
                                       λ 
                                       s 
                                     
                                   
                                   ≠ 
                                   
                                     λ 
                                     i 
                                   
                                 
                               
                             
                             
                               
                                 
                                   0 
                                   , 
                                 
                               
                               
                                 
                                   other 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   than 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   those 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   above 
                                 
                               
                             
                           
                           ⁢ 
                           
                             
 
                           
                           ⁢ 
                           
                             g 
                             ⁡ 
                             
                               ( 
                               
                                 x 
                                 os 
                               
                               ) 
                             
                           
                         
                         = 
                         
                           { 
                           
                             
                               
                                 
                                   1 
                                   , 
                                 
                               
                               
                                 
                                   
                                     λ 
                                     s 
                                   
                                   ≥ 
                                   
                                     
                                       λ 
                                       min 
                                     
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     and 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     
                                       λ 
                                       s 
                                     
                                   
                                   ≤ 
                                   
                                     
                                       λ 
                                       max 
                                     
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     and 
                                     ⁢ 
                                     
                                         
                                     
                                     ⁢ 
                                     
                                       λ 
                                       s 
                                     
                                   
                                   ≠ 
                                   
                                     λ 
                                     i 
                                   
                                 
                               
                             
                             
                               
                                 
                                   0 
                                   , 
                                 
                               
                               
                                 
                                   other 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   than 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   those 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   abov 
                                 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
     The meaning of each symbol in formula (2) is given as follows. 
     Here, the symbol o denotes the row number for the light emission intensity  24   d  in the OES data table  24 . 
     The symbol X os  denotes the value stored in o row s column among the values stored in the light emission intensity field  24   d  of the OES data table  24   a.    
     The symbol λ s  denotes the value stored in the s column, among the values stored in the wavelength field  24   b  of the OES data table  24   a.    
     The symbol λ min  denotes the minimum value stored in the above described range. 
     The symbol λ max  denotes the maximum value stored in the above described range. 
     The symbol λ i  denotes the value stored in the i-th row of the wavelength field  23   c  in the substance and matching wavelength table  23   a.    
     The symbol u denotes the number of columns in the wavelength field  24   c  of the OES data table  24   a.    
     The symbol AVE o  denotes the value stored in the o row of the light emission intensity average field  29   d  in the light emission intensity average information table  29   a.    
     The formula (2) signifies the calculation of the average of the light emission intensity for a wavelength, contained in the range of values stored on the i-th row of the peripheral wavelength field  26   d  in the peripheral wavelength correlating information table  26   a , and also not matching the value stored on the i-th row of the wavelength field  23   c  in the substance and matching wavelength table  23   a . The light emission intensity for a wavelength matching the value stored on the i-th row is here excluded from the calculation of the average value but may also be included in the calculation. 
     (S 104 ) 
     In step S 104 , the arithmetic logic unit  21  calculates the correlation of the time-based data for light emission intensity between information stored in the light emission intensity field  24   d  of the OES data table  24   a , and the information stored in the light emission intensity average field  29   d  of the light emission intensity average information table  29   a , and stores the calculated value in the light emission intensity correlation 2 field  26   e  of the peripheral wavelength correlating information table  26   a.    
     The arithmetic logic unit  21  stores the value (r 2 ) calculated by the following formula (3), into the i-th row of the light emission intensity correlation 2 field  26   e . 
     
       
         
           
             
               
                 
                   
                     r 
                     2 
                   
                   = 
                   
                     
                       [ 
                       
                         
                           
                             { 
                             
                               
                                 ∑ 
                                 
                                   l 
                                   = 
                                   1 
                                 
                                 n 
                               
                               ⁢ 
                               
                                 
                                   ( 
                                   
                                     
                                       x 
                                       lp 
                                     
                                     - 
                                     
                                       
                                         ∑ 
                                         
                                           m 
                                           - 
                                           1 
                                         
                                         n 
                                       
                                       ⁢ 
                                       
                                         
                                           x 
                                           
                                             m 
                                             ⁢ 
                                             
                                                 
                                             
                                             ⁢ 
                                             p 
                                           
                                         
                                         / 
                                         n 
                                       
                                     
                                   
                                   ) 
                                 
                                 ⁢ 
                                 
                                   ( 
                                   
                                     
                                       y 
                                       l 
                                     
                                     - 
                                     
                                       
                                         ∑ 
                                         
                                           m 
                                           - 
                                           1 
                                         
                                         n 
                                       
                                       ⁢ 
                                       
                                         
                                           y 
                                           l 
                                         
                                         / 
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                                   ) 
                                 
                               
                             
                             } 
                           
                           2 
                         
                         
                           
                             { 
                             
                               
                                 ∑ 
                                 
                                   l 
                                   = 
                                   1 
                                 
                                 n 
                               
                               ⁢ 
                               
                                 
                                   ( 
                                   
                                     
                                       x 
                                       lp 
                                     
                                     - 
                                     
                                       
                                         ∑ 
                                         
                                           m 
                                           - 
                                           1 
                                         
                                         n 
                                       
                                       ⁢ 
                                       
                                         
                                           x 
                                           
                                             m 
                                             ⁢ 
                                             
                                                 
                                             
                                             ⁢ 
                                             p 
                                           
                                         
                                         / 
                                         n 
                                       
                                     
                                   
                                   ) 
                                 
                                 2 
                               
                             
                             } 
                           
                           ⁢ 
                           
                             { 
                             
                               
                                 ∑ 
                                 
                                   l 
                                   = 
                                   1 
                                 
                                 n 
                               
                               ⁢ 
                               
                                 
                                   ( 
                                   
                                     
                                       y 
                                       l 
                                     
                                     - 
                                     
                                       
                                         ∑ 
                                         
                                           m 
                                           - 
                                           1 
                                         
                                         n 
                                       
                                       ⁢ 
                                       
                                         
                                           y 
                                           l 
                                         
                                         / 
                                         n 
                                       
                                     
                                   
                                   ) 
                                 
                                 2 
                               
                             
                             } 
                           
                         
                       
                       ] 
                     
                     
                       1 
                       2 
                     
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     3 
                     ) 
                   
                 
               
             
           
         
       
     
     The meaning of each symbol in formula (3) is given as follows. 
     Here, the symbol p denotes the column number storing a value identical to the value in the i-th row of the wavelength field  23   c  is stored in the wavelength field  24   b  of the OES data table  24   a.    
     The symbol X lp  denotes the value stored in l row p column among the values stored in the light emission intensity field  24   d  of the OES data table  24   a.    
     The symbol y l  denotes the value stored in l row among the values stored in the light emission intensity average field  29   d  of the light emission intensity average information table  29   a.    
     The symbol n expresses the number of rows of the light emission intensity field  24   d  in the OES data table  24   a.    
     The symbol r 2  is a value (correlation coefficient) calculated in formula (3). The symbol r 2  expresses the extent of the degree of similarity of the time-based fluctuation between the value stored in the p column of the light emission intensity field  24   d  in the OES data table  24   a , and the value stored in the q column in the light emission intensity field  24   d.    
     The formula (3) utilized a coefficient correlation but other indices for evaluating the degree of similarity may also be utilized. 
     (S 105 ) 
     In step S 105 , the arithmetic logic unit  21  utilizes the information stored in the identical substance correlating information table  25   a  to judge whether or not the wavelength specified by way of the value stored on the i-th row of wavelength field  23   c  in the substance and matching wavelength table  23   a  is the wavelength capable of being utilized for monitoring, supervision and control of the etching unit  10 . 
     The arithmetic logic unit  21  utilizes the value stored in the light emission intensity correlation 1 field  25   e  of the identical substance correlating information table  25   a  as an input, to calculate by way of the following formula (4) the percentage (R 1 ) by which the value stored in the light emission intensity correlation 1 field  25   e  is larger than the value stored in the threshold value 1 field  27   b  of the threshold information table  27   a . 
     
       
         
           
             
               
                 
                   
                     R 
                     1 
                   
                   = 
                   
                     { 
                     
                       
                         
                           
                             
                               
                                 
                                   
                                     ∑ 
                                     
                                       w 
                                       = 
                                       1 
                                     
                                     a 
                                   
                                   ⁢ 
                                   
                                     
                                       h 
                                       ⁡ 
                                       
                                         ( 
                                         
                                           z 
                                           vw 
                                         
                                         ) 
                                       
                                     
                                     / 
                                     
                                       ( 
                                       
                                         a 
                                         - 
                                         1 
                                       
                                       ) 
                                     
                                   
                                 
                                 , 
                               
                             
                             
                               
                                 a 
                                 ≠ 
                                 1 
                               
                             
                           
                           
                             
                               
                                 0 
                                 , 
                               
                             
                             
                               
                                 a 
                                 = 
                                 1 
                               
                             
                           
                         
                         ⁢ 
                         
                           
 
                         
                         ⁢ 
                         
                           h 
                           ⁡ 
                           
                             ( 
                             
                               z 
                               vw 
                             
                             ) 
                           
                         
                       
                       = 
                       
                         { 
                         
                           
                             
                               
                                 1 
                                 , 
                               
                             
                             
                               
                                 
                                   z 
                                   vw 
                                 
                                 ≥ 
                                 
                                   
                                     Th 
                                     1 
                                   
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   and 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   
                                     λ 
                                     v 
                                   
                                 
                                 ≠ 
                                 
                                   λ 
                                   w 
                                 
                               
                             
                           
                           
                             
                               
                                 0 
                                 , 
                               
                             
                             
                               
                                 other 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 than 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 those 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 above 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     4 
                     ) 
                   
                 
               
             
           
         
       
     
     The meaning of each symbol in formula (4) is given as follows. 
     The symbol v denotes the row number storing a value identical to the value stored in the i-th row of the wavelength field period  23   c , into the wavelength field (row direction)  25   d  of the identical substance correlating information table  25   a.    
     The symbol w is the value for specifying the column number of the light emission intensity correlation 1 field  25   e  of the identical substance correlating information table  25   a.    
     The symbol a denotes the number of columns in the light emission intensity correlation 1 field  25   e  of the identical substance correlating information table  25   a.    
     The symbol Z VW  denotes the value stored in the v row w column among the values stored in the light emission intensity correlation 1 field  25   e  of the identical substance correlating information table  25   a.    
     The symbol Th 1  denotes the value stored in the threshold value 1 field  27   b  of the threshold information table  27   a.    
     The symbol λv denotes the value stored in the v row, among the values stored in the wavelength field (row direction)  25   d  in the identical substance correlating information table  25   a.    
     The symbol λw denotes the value stored in the w column, among the values stored in the wavelength field (column direction) in the identical substance correlating information table  25   a.    
     The symbol R 1  is a calculated value and indicates the percentage by which the correlation coefficient for light emission intensity of the wavelength specified by the value stored in the i-th row of the wavelength field  23   c  of the substance and matching wavelength table  23   a  is larger than the value specified in the threshold  1  field  27   b . A large R 1  value indicates that the light emission intensity on the wavelength linked to the identical substance has similar time-based fluctuations. The reason for the similar time-based fluctuations is likely caused by increases or decreases in the quantity of that corresponding substance (if the quantity of the substance is increased, then the light emission intensity on the wavelength linked to that substance will increase as the quantity of that substance increases). By making use of this type of light emission intensity for monitoring, supervision, and control of the etching unit  10 , the quantity of the substance contained in the gas  113  can be known, and monitoring, supervision, and control of the etching unit  10  can be effectively implemented. 
     Based on the above approach, the arithmetic logic unit  21  next compares the R 1  with the value stored in the threshold value 2 field  27   c , and if R 1  is a value equal to or larger than the value stored in the threshold value 2 field  27   c , then the arithmetic logic unit  21  judges that the wavelength identified by the value stored in the i-th row of the wavelength field  23   c  in the substance and matching wavelength table  23   a  is the wavelength capable of being utilized for monitoring, supervision, and control of the etching unit  10 , and the arithmetic logic unit  21  proceeds to the process in S 106 . 
     If R 1  is a value smaller than the value stored in the threshold value 2 field  27   c , then the arithmetic logic unit  21  proceeds to the process in S 107 . 
     (S 106 ) 
     In S 106 , the arithmetic logic unit  21  stores the value “recommend 1” showing the judgment that the wavelength is capable of being utilized for monitoring, supervision, and control of the etching unit  10 , into the i-th row of the recommended wavelength field  28   d  in recommended wavelength information table  28   a.    
     (S 107 ) 
     In S 107 , the arithmetic logic unit  21  utilizes the information stored in the identical substance correlating information table  25   a  to decide whether or not the wavelength specified by the value stored in the i-th row of wavelength field  23   c  in the substance and matching wavelength table  23   a  is the wavelength capable of being utilized for monitoring, supervision, and control of the etching unit  10 . 
     The arithmetic logic unit  21  compares the value stored in the light emission intensity correlation 2 field  26   e  of peripheral wavelength correlating information table  26   a , with the value stored in threshold value 3 field  27   d  of the threshold information table  27   a . If the value stored in the light emission intensity correlation 2 field  26   e  is smaller than the value stored in the threshold value 3 field  27   d , the waveform specified by the value stored in the i-th row of wavelength field  23   c  of the substance and matching wavelength table  23   a  is judged as the wavelength capable of being utilized for monitoring, supervision, and control of the etching unit  10 , and the arithmetic logic unit  21  proceeds to the process in S 108 . 
     However, if the value stored in the light emission intensity correlation 2 field  26   e  of the peripheral wavelength correlating information table  26   a  is small, the small value signifies that the degree of similarity between the time-based fluctuations in light emission intensity on the wavelength specified by the value stored in the i-th row of the waveform field  23   c  of the substance and matching wavelength table  23   a , and average of time-based fluctuations for light emission intensity on the peripheral wavelength is small as shown in  FIG. 14 . In this case, the increase or decrease in the light emission intensity on the applicable wavelength is likely caused by factors such as the temperature and amount of that corresponding substance. Using the light emission intensity on this type of wavelength to monitor, supervise, and control the etching unit  10  permits knowing factors such as the temperature and amount of the substance contained in the gas  113 , and the monitoring, supervision, and control of the etching unit  10  can be effectively implemented. 
     If the value stored in the light emission intensity correlation 2 field  26   e  is larger than the value stored in the threshold value 3 field  27   d , the arithmetic logic unit  21  proceeds to the process in S 109 . 
     (S 108 ) 
     In S 108 , the arithmetic logic unit  21  stores the value for “recommend 2” showing the judgment that the wavelength is capable of being utilized for monitoring, supervision, and control of the etching unit  10 , into the i-th row of the recommended wavelength field  28   d  in the recommended wavelength information table  28   a . If a value for “recommend 1” is already stored then “recommend 1” and “recommend 2” are both jointly recorded. 
     (S 109 ) 
     In S 109 , if the processing in S 106  or S 108  was executed, the arithmetic logic unit  21  performs processing to provide a wavelength capable of being utilized for monitoring, supervision, and control of the etching unit  10  to the user. 
     If there is a value for “recommend 1” stored in the i-th row in the recommended wavelength field  28   d  of the recommended wavelength information table  28   a , the arithmetic logic unit  21  displays information as shown for example in  FIG. 15  on the output unit  31 . 
     The arithmetic logic unit  21  displays the wavelength (value stored in the i-th row of the wavelength field  23   c  of the substance and matching wavelength table  23   a ) recommended for utilization in device control and quality analysis, that is judged as the wavelength exhibiting light emitted from a substance contained in the plasma within the chamber; and the name of the substance corresponding to that wavelength (value stored in the i-th row of the substance field  23   b  of the substance and matching wavelength table  23   a ). 
     The arithmetic logic unit  21  also displays the correlation coefficient (value stored in the light emission intensity correlation 1 field  25   e  of the identical substance correlating information table  25   a ) between the time-based fluctuations for light emission intensity in the recommended wavelength, and the time-based fluctuations for light emission intensity in the wavelength from the same substance as the recommended wavelength. 
     The arithmetic logic unit  21  further displays a graph of the time-based fluctuations for light emission intensity in the recommended wavelength, and the time-based fluctuations (value stored in the light emission intensity field  24   d  of the OES data table  24   a ) for light emission intensity in the wavelength from the same substance as the recommended wavelength. 
     If there is a value for “recommend 2” stored in the i-th row of the recommended wavelength field  28   d  of the recommended wavelength information table  28   a , the arithmetic logic unit  21  displays information as shown for example in  FIG. 16  on the output unit  31 . 
     The arithmetic logic unit  21  displays the recommended wavelength (value stored in the i-th row of the wavelength field  23   c  of the substance and matching wavelength table  23   a ) and the name of the substance corresponding to that wavelength (value stored in the i-th row of the substance field  23   b  of the substance and matching wavelength table  23   a ). 
     The arithmetic logic unit  21  also displays the correlation coefficient (value stored in the light emission intensity correlation 2 field  26   e  of the peripheral wavelength correlating information table  26   a ) between the time-based fluctuations for light emission intensity in the recommended wavelength, and the time-based fluctuations for the light emission intensity average on the recommended peripheral wavelength. 
     The arithmetic logic unit  21  further displays a graph of time-based fluctuations (value stored in the light emission intensity field  24   d  of OES data table  24   a ) for light emission intensity in the recommended wavelength; and the time-based fluctuations (value stored in light emission intensity average field  29   d  of the light emission intensity average information table  29   a ) for the light emission intensity in the wavelength from the same substance as the recommended wavelength. 
     (S 110 ) 
     In S 110 , the arithmetic logic unit  21  ends the process when the process has reached the final row of wavelength field  23   c  of the substance and matching wavelength table  23   a , and adds a 1 to if the process has not reached the final row, and executes the calculation for the next row of the wavelength field  23   c  in the substance and matching wavelength table  23   a.    
     As described above, in the etching device  1  (analysis unit  20 ) of the present embodiment, the data measured by the spectroscope (OES), and information on the wavelength of light emitted by each substance can be provided as input information to provide a wavelength that allows knowing properties (such as the temperature and amount of substance contained in the gas  113 ) of the gas  113 . By using the light emission intensity of the provided wavelength as an input, the control unit  13  of the etching unit  1  can perform the etching process with higher efficiency by appropriately controlling factors such as the quantity of gas, temperature, and voltage supplied to the chamber  111 . 
     Moreover, a wavelength utilizable for monitoring, supervision, and control is automatically be selected from many candidates among wavelengths in the OES data so that the large quantity of man-hours required for analyzing the etching data can be eliminated and monitoring, supervising, and control of the etching can be efficiently performed. 
     The embodiment of the present invention was specifically described above, however the present invention is not limited to the above embodiment and all manner of variations and adaptations not departing from the scope of the present invention are permissible.