Specific Process Knowledge/Lithography/EBeamLithography/Dose Testing

In E-beam lithography it is often necesarry to do a dose test in order to get the required result. In a dose test one will expose critical parts of a pattern with various doses and determine the best dose by SEM analysis of the final pattern. There are several ways to set up a dose test array on the JEOL system, in this section we will describe four different setups, each with their own benefits and drawbacks.

Simple SDF sequencing

The most straightforward method is to create one SDF sequence per dose and simply vary the dose with the RESIST command in the SDF as illustrated below. Each instance must of course be offset with the OFFSET command such that they are not exposed on top of each other. The pattern information in the referenced JDF can contain a PEC modulation table with this method and hence it is suited for proximity corrected designs.

The main benefit of this method is how easy it is to setup and that it supports PEC modulation.

The drawback is however that the system will perform initial calibration between each sequence, thus for each dose the system will run calibration as defined in the PATH of the JDF file, this can add several minutes of execution time to each sequence and for a large dose matrix it can cost a lot of additional time.

;SDF example
MAGAZIN    'DOSES'       

;--------Dose 1--------
#1                            
%4D                           
JDF     'dosetest',1   
ACC 100                       
CALPRM '6na_ap5'              
DEFMODE 2                     
RESIST 200                    
SHOT A,24                     
OFFSET(-100,0)                   

;--------Dose 2--------
#1                            
%4D                           
JDF     'dosetest',1   
ACC 100                       
CALPRM '6na_ap5'              
DEFMODE 2                     
RESIST 220                    
SHOT A,24                     
OFFSET(0,0)                   

;--------Dose 3--------
#1                            
%4D                           
JDF     'dosetest',1   
ACC 100                       
CALPRM '6na_ap5'              
DEFMODE 2                     
RESIST 240                    
SHOT A,24                     
OFFSET(100,0)                   
     
END