Abstract:
A system and method are provided for automatic dose-correction recipe generation, the system including a dose-correction recipe generator, a reticle data unit in signal communication with the recipe generator, a slit data unit in signal communication with the recipe generator, a process data unit in signal communication with the recipe generator, a wafer data unit in signal communication with the recipe generator, a control unit in signal communication with the recipe generator, and an output unit or a storage unit in signal communication with the control unit; and the method including receiving a current reticle data set and a previous reticle data set, receiving a current slit data set and a previous slit data set, receiving a process condition, receiving a wafer condition, automatically generating a dose-correction recipe in accordance with the received reticle, slit, process and wafer information, and controlling a dose in accordance with the generated recipe.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present disclosure generally relates to semiconductor manufacturing and lithography methods. More particularly, the present disclosure relates to methods for intra-field dose mapping and correction in semiconductor devices. 
       SUMMARY OF THE INVENTION 
       [0002]    The present disclosure teaches an automatic dose-correction recipe generation system for adaptation of a semiconductor intra-field (e.g., chip or die) dose correction map to new photolithography masks. Exemplary embodiments are provided. 
         [0003]    An exemplary embodiment automatic dose-correction recipe generation system comprises: a dose-correction recipe generator; at least one reticle data unit in signal communication with the recipe generator; at least one slit data unit in signal communication with the recipe generator; a process data unit in signal communication with the recipe generator; a wafer data unit in signal communication with the recipe generator; a control unit in signal communication with the recipe generator; and at least one of an output unit or a storage unit in signal communication with the control unit. 
         [0004]    A further embodiment sets forth that the reticle data unit subtracts current reticle data from previous reticle data. A further embodiment sets forth that the current reticle data corresponds to a current mask and the previous reticle data corresponds to a previous mask. 
         [0005]    A further embodiment sets forth that the slit data unit subtracts current slit data from previous slit data. A further embodiment sets forth that the current slit data corresponds to a current condition of a slit and the previous slit data corresponds to a previous condition of the slit. 
         [0006]    A further embodiment sets forth that the process unit includes at least one of resist conditions, process conditions, or mask error enhancement factor conditions. A further embodiment sets forth that the wafer unit includes wafer conditions and topography information. A further embodiment sets forth that the control unit includes twenty-nine fingers. A further embodiment sets forth that the output unit is indicative of detected critical dimension uniformity. A further embodiment provides a sub-recipe unit for generating a sub-recipe for each combination of reticle and scanner data. 
         [0007]    An exemplary embodiment method for automatic dose-correction recipe generation comprises: receiving at least one current reticle data set and at least one previous reticle data set; receiving at least one current slit data set and at least one previous slit data set; receiving at least one process condition; receiving at least one wafer condition; automatically generating a dose-correction recipe in accordance with the received reticle, slit, process and wafer information; and controlling a dose in accordance with the generated recipe. 
         [0008]    A further embodiment includes subtracting current reticle data from previous reticle data. A further embodiment sets forth that the current reticle data corresponds to a current mask and the previous reticle data corresponds to a previous mask. 
         [0009]    A further embodiment includes subtracting current slit data from previous slit data. A further embodiment sets forth that the current slit data corresponds to a current condition of a slit and the previous slit data corresponds to a previous condition of the slit. 
         [0010]    A further embodiment sets forth that the process conditions include at least one of resist conditions, process conditions, or mask error enhancement factor conditions. A further embodiment sets forth that the wafer conditions include wafer topography information. A further embodiment includes at least one of storing or outputting information indicative of detected critical dimension uniformity. A further embodiment includes generating a sub-recipe for each combination of reticle and scanner data. 
         [0011]    A further embodiment sets forth a computer-readable storage medium tangibly embodying a program of instructions executable by a computer to perform program steps for automatic dose-correction recipe generation, the program steps comprising: receiving at least one current reticle data set and at least one previous reticle data set; receiving at least one current slit data set and at least one previous slit data set; receiving at least one process condition; receiving at least one wafer condition; automatically generating a dose-correction recipe in accordance with the received reticle, slit, process and wafer information; and controlling a dose in accordance with the generated recipe. 
         [0012]    The present disclosure will be further understood from the following description of exemplary embodiments, which is to be read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The present disclosure provides a method for adapting a semiconductor intra-field dose correction map from a first photolithography mask to a second photolithography mask in accordance with the following exemplary figures, in which: 
           [0014]      FIG. 1  shows a schematic block diagram of a method for intra-field dose correction; 
           [0015]      FIG. 2  shows a schematic graphical diagram of mask uniformity; 
           [0016]      FIG. 3  shows a schematic graphical diagram of slit uniformity variation in a scanner; 
           [0017]      FIG. 4  shows a schematic block diagram of an automatic recipe generation system for intra-field dose correction in accordance with an exemplary embodiment of the present disclosure; 
           [0018]      FIG. 5  shows a schematic block diagram of an automatic recipe generation system, adapted to the case where a new mask is re-ordered without any change, in accordance with an exemplary embodiment of the present disclosure; and 
           [0019]      FIG. 6  shows a schematic block diagram of an automatic recipe generation system, adapted for multi-reticle and/or multi-scanner sets, in accordance with an exemplary embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    An automatic dose correction recipe generation system is provided for improving intra-field critical dimension (CD) uniformity. The recipe generation system is applicable to lithography, dose correction, dose mapping and slit uniformity. 
         [0021]    Dose correction methods have been used to improve constrained minimum variance (CMV). In-field or intra-field CD uniformity relates to single chip or die uniformity. Much of the non-uniformity comes from mask error and/or deteriorated scanner slit conditions. Unfortunately, previous dose correction methods did not use mask data and/or slit uniformity information from a scanner. 
         [0022]    An exemplary automatic dose correction recipe generation system is provided to compensate for the non-uniformity resulting from mask processes and exposure processes on a scanner. Mask data is sent when a mask is delivered. Slit uniformity is monitored regularly, such as bi-weekly or weekly. A Mask Error enhancement Factor (MEF) is used to correct the mask process error on a wafer. 
         [0023]    As shown in  FIG. 1 , a method for intra-field dose correction is indicated generally by the reference numeral  100 . Here, a reticle unit  110  passes reticle information to an exposure tool  120 . The exposure tool passes exposure information to a detected critical dimension (DCD) unit  130  for measuring CD uniformity in the slit direction, without dose correction. In addition, the exposure tool  120  passes exposure information to a control unit  140 , which has  29 -finger portions  148 . Moreover, the DCD unit  130  passes a sub-recipe to the control unit  140 . The control unit, in turn, passes information to a DCD unit  150 , which exhibits improved uniformity with dose correction. Unfortunately, this method requires a great deal of data. Notably, the method uses no mask information, no scanner information, and no wafer information. 
         [0024]    When a new mask is reordered without any change, this method requires setup of another dose correction recipe for the new mask, which may take up to four additional weeks. In addition, the recipe requires another set of wafer CD data, regardless of mask CD data and scanner condition. 
         [0025]    Turning to  FIG. 2 , plots of mask uniformity are indicated generally by the reference numeral  200 , with units in nanometers. A first intra-field 
         [0026]    CD uniformity map  210  shows intra-field uniformity for a wafer with a first mask, and a second intra-field CD uniformity map  220  shows intra-field uniformity for a wafer with a second mask. The first mask map  210  includes areas  212  having CDs greater than a mean CD value, and areas  214  having CDs smaller than a mean CD value. Similarly, the second mask map  220  includes areas  222  having CDs greater than a mean CD value, and areas  224  having CDs smaller than a mean CD value. 
         [0027]    A table  230  indicates vertical and horizontal data resulting from the first and second masks. Here, the first mask yields a vertical mean of 315.10 nanometers, a vertical target of 312.00 nanometers, a vertical difference (DFN) of 3.10 nanometers, a vertical 3-sigma value of 2.05 nanometers, a vertical range of 3.97 nanometers, and an X-Y value of −0.31. The first mask yields a horizontal mean of 315.42 nanometers, a horizontal target of 312.00 nanometers, a horizontal DFN of 3.42 nanometers, a horizontal 3-sigma value of 2.31 nanometers, and a horizontal range of 4.36 nanometers. 
         [0028]    In comparison, the second mask yields a vertical mean of 312.92 nanometers, a vertical target of 312.00 nanometers, a vertical DFN of 0.92 nanometers, a vertical 3-sigma value of 2.22 nanometers, a vertical range of 3.66 nanometers, and an X-Y of 1.33. The second mask yields a horizontal mean of 311.59 nanometers, a horizontal target of 312.00 nanometers, a horizontal DFN of −0.41 nanometers, a horizontal 3-sigma value of 2.36 nanometers, and a horizontal range of 3.81 nanometers. 
         [0029]    Turning now to  FIG. 3 , a plot of slit uniformity variation in a scanner is indicated generally by the reference numeral  300 . The plot  300  includes dose ratio percentage on the vertical axis, shown here in a range from 99.8% to 101.2%, and slit position in millimeters on the horizontal axis, shown here from −15 to +15 millimeters. Data  310  was collected on November 16 th , and follows a curve  312 . Data  320  was collected about three months later on February 19 th , and follows a curve  322 . As illustrated, slit variation that only reached about 100.5% in November, reached about 101.0% in February. Thus, scanner condition changes over time, and can also be affected by regular preventative maintenance (PM). It is much more difficult to improve CD uniformity without this slit uniformity information from the scanner. 
         [0030]    Therefore, an improved method may use both mask CD and scanner condition to correct the mask CD non-uniformity. In this case, the mask CD may be delivered from a mask house. The scanner condition, which affects slit uniformity, may be measured with regular automatic monitoring. In addition, the mask error enhancement factor (MEF) may be measured during resist evaluation. A system embodiment of the present disclosure produces outputs from calculations using input data, such as reticle information, scanner information such as slit conditions, wafer information such as topography, and material information such as n and k values. 
         [0031]    Each mask has a different CD distribution. Although wafer CD distribution data may be used to setup the dose correction recipe, the mask CD distribution data may be used instead. Directly using the mask data from a mask house for exposing wafers reduces the time required to set up the dose correction recipe. 
         [0032]    As shown in  FIG. 4 , an exemplary embodiment automatic recipe generation system for intra-field dose correction is indicated generally by the reference numeral  400 . The system  400  includes a reticle data unit  410  connected to an automatic recipe generation system unit  420 . A slit condition data unit  430  is connected to the automatic recipe generation system unit  420 . An MEF and process unit  440 , which tracks resist and process conditions, is also connected to the automatic recipe generation system unit  420 . In addition, a wafer condition unit  450 , which maintains topography information, is further connected to the automatic recipe generation system unit  420 . The automatic recipe generation system unit  420 , in turn, is connected to a control unit  460 , such as a 29-finger unit. The control unit  460  is connected to an output unit  470 , which indicates here that DCD uniformity is improved using this method of dose correction. Moreover, there is no need to take new measurements for recipe setup using this automatic recipe generation system for intra-field dose correction. 
         [0033]    Turning to  FIG. 5 , an automatic recipe generation system, adapted to the case where a new mask is reordered without any change, is indicated generally by the reference numeral  500 . The system  500  includes a reticle offset data unit  510  connected to an automatic recipe generation system unit  520 , where the reticle offset data unit subtracts new reticle data  512  from old reticle data  511 . A slit uniformity offset data unit  530  is connected to the automatic recipe generation system unit  520 . The slit uniformity offset data unit  530  subtracts new slit uniformity data  532  from old slit uniformity data  531 . An MEF and process offset unit  540 , which subtracts new resist and process conditions from old resist and process conditions, is also connected to the automatic recipe generation system unit  520 . In addition, a wafer condition offset unit  550 , which maintains a zero result for old topography information minus new topography information, is further connected to the automatic recipe generation system unit  520 . The automatic recipe generation system unit  520 , in turn, is connected to a control unit  560 , such as a 29-finger unit. The control unit  560  is connected to an output unit  570 , which indicates here that DCD uniformity is improved using this method of dose correction. Moreover, there is no need to take new measurements for recipe setup using this automatic recipe generation system for intra-field dose correction. 
         [0034]    Turning now to  FIG. 6 , an automatic recipe generation system, adapted for multi-reticle and multi-scanner sets, is indicated generally by the reference numeral  600 . The system  600  includes a reticle offset data unit  610  with data sets  611 ,  612  and  613  connected to an automatic recipe generation system unit  620 , where the reticle offset data unit subtracts each new reticle data set from the old (e.g., R 1 , R 2 , R 3  . . . Rx). A slit uniformity offset data unit  630  with data sets  631 ,  632  and  633  is connected to the automatic recipe generation system unit  620 . The slit uniformity offset data unit  630  subtracts each new slit uniformity data set from the old (e.g., S 1 , S 2 , S 3  . . . Sx). An MEF and process offset unit  640 , which subtracts new resist and process conditions from old resist and process conditions, is also connected to the automatic recipe generation system unit  620 . In addition, a wafer condition offset unit  650 , which subtracts new topography information from old topography information, is further connected to the automatic recipe generation system unit  620 . The automatic recipe generation system unit  620 , in turn, is connected to a control unit  660 , such as a 29-finger unit. The control unit  660  is connected to an output unit  670 , which indicates here that DCD uniformity is improved using this method of dose correction. Thus, before every exposure, a sub-recipe for each set of Reticle data (e.g., Rx) and Scanner data (e.g., Sx) is generated automatically. 
         [0035]    These and other features of the present disclosure may be readily ascertained by one of ordinary skill in the pertinent art based on the teachings herein. It is to be understood that the principles of the present disclosure may be implemented in various forms of hardware, software, firmware, special purpose processors, or combinations thereof. 
         [0036]    Most preferably, the principles of the present disclosure are implemented as a combination of hardware and software. Moreover, the software is preferably implemented as an application program tangibly embodied in computer-readable storage media. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPU”), a random access memory (“RAM”), and input/output (“I/O”) interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit, a printing unit, and a photolithography unit. 
         [0037]    It is to be further understood that, because some of the constituent system components and methods depicted in the accompanying drawings are preferably implemented in software, the actual connections between the system components or the process function blocks may differ depending upon the manner in which the present invention is programmed. Given the teachings herein, one of ordinary skill in the pertinent art will be able to contemplate these and similar implementations or configurations of the present invention. 
         [0038]    Although illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present disclosure is not limited to those precise embodiments, and that various other changes and modifications may be effected therein by those of ordinary skill in the pertinent art without departing from the scope or spirit of the present disclosure. All such changes and modifications are intended to be included within the scope of the present disclosure as set forth in the appended claims.