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 Data Analysis Sheet RS.1

Data analysis sheet for residual strain measurements

Top view of fixed-fixed beam used to measure residual strain.

Figure RS.1.1.  Top view of fixed-fixed beam used to measure residual strain.

To obtain the following measurements, consult ASTM standard test method E 2245 entitled
"Standard Test Method for Residual Strain Measurements of Thin, Reflecting Films
Using an Optical Interferometer."


date data taken (optional) = / /
identifying words (optional)   =   
instrument used (optional)   =   
fabrication facility/process (optional)   =   
test chip name/number (optional)   =   
filename of 3-D data set (optional)   =   
filename of 2-D data traces (optional) =
    
    
 

Table 1 - Preliminary ESTIMATES

Description

1 material =  
   
 
 
 
   

material

2 t = µm beam thickness
3 design length = µm

design length

4 which beam?    
   
Third    
  
which fixed-fixed beam on the test chip ? 
5 magnification = × magnification
6 orientation = 0 
90
Other
orientation of the fixed-fixed beam on the chip
7 calx = x-calibration factor (for the given magnification)
8 interx = µm maximum field of view (for the given magnification)
9 σxcal = µm one sigma uncertainty in a ruler measurement (for the given magnification)
10 xres = µm resolution of the interferometer in the x-direction
11 calz = z-calibration factor (for the given magnification)
12 cert = µm certified value of physical step height used for calibration
13 σzcal = µm standard deviation of step height measurements (on double-sided physical step height)
14 zres = µm resolution of the interferometer in the z-direction
15 Rtave = µm peak-to-valley roughness of a flat and leveled surface of the sample material calculated to be the average of three or more measurements, each measurement of which is taken from a different 2-D data trace
16 aligned?      alignment ensured ?
17 leveled?      data leveled ?
18 stiction?      Is this fixed-fixed beam exhibiting stiction ?  
(
If it is exhibiting stiction, do not fill out the remainder of this form.)


     
                                     


Table 2 - INPUTS (uncalibrated values from Trace "a" or "e")

Notes

19 x1max (i.e., x1upper) = µm  
20 x1min (i.e., x1lower)  = µm (x1min > x1max)
21 x2min (i.e., x2lower)  = µm (x2min > x1min)
22 x2max (i.e., x2upper) = µm (x2max > x2min)
 

Table 3 - INPUTS (uncalibrated values from Trace "b")

Notes

23 x1F = µm z1F = µm (x1ave < x1F * calx)
24 x2F = µm z2F = µm (inflection point)
( x1F < x2F < x3F )
25 x3F = µm z3F = µm (most deflected point) 
( x1S = x3F ; z
1S = z3F )
26 x2S = µm z2S = µm (inflection point)
27 x3S = µm z3S = µm ( x3S * calx < x2ave )
( x1S < x2S < x3S )

Table 4 - INPUTS (uncalibrated values from Trace "c")

Notes

28 x1F = µm z1F = µm (x1ave < x1F * calx)
29 x2F = µm z2F = µm (inflection point)
( x1F < x2F < x3F )
30 x3F = µm z3F = µm (most deflected point)
( x1S = x3F ; z1S = z3F )
31 x2S = µm z2S = µm   (inflection point)
32 x3S = µm z3S = µm   ( x3S  * calx < x2ave )
( x1S < x2S < x3S )

Table 5 - INPUTS (uncalibrated values from Trace "d") 

Notes

33 x1F = µm z1F = µm (x1ave < x1F * calx)
34 x2F = µm z2F = µm   (inflection point)
( x1F < x2F < x3F )
35 x3F = µm z3F = µm (most deflected point)
( x1S = x3F ; z1S = z3F )
36 x2S = µm z2S = µm  (inflection point)
37 x3S = µm z3S = µm ( x3S  * calx < x2ave )
( x1S < x2S < x3S )

                                      

OUTPUTS (calibrated values):
   
        
x1ave µm            x2ave µm
             L     
µm
 
                        Lmax = ( x2max x1max ) * calx
                         L
min = ( x2min
x1min ) * calx
                         uLL  =  ( Lmax Lmin ) / 6 = 
µm
                         uLxcal  = ( σxcal / interx ) * ( L / calx ) =
µm

                         uLxres  = xres* calx / 1.732 = 
µm

             u
cL   =  
SQRT[uLL2 + uLxcal2 + uLxres2]  µm
             s         
           from Trace "c"
                         s = 1       (for downward bending fixed-fixed beams)
                         s =
−1     (for upward bending fixed-fixed beams)

                             AF    µm      from Trace "b"
                            w1F      
        from Trace "b"
                             AS  
µm      from Trace "b"
                           w3S   =              
from Trace "b"

             xeF   
µm            from Trace "b"
             xeS   
µm   
         from Trace "b"
           
 εr0    × 10-6       from Trace "b"
             εr     =    
× 10
-6       from Trace "b"

                             AF    µm      from Trace "c"
                           w1F            
   from Trace "c"
                             AS  
µm      from Trace "c"
                           w3S   =            
  from Trace "c"

             xeF   
µm             from Trace "c"
             xeS   
µm             from Trace "c"
            
εr0    × 10-6        from Trace "c"
             εr    =    × 10-6        from Trace "c"                  (USE THIS VALUE)
                         usamp    =    × 10-6     from Trace "c"
                         uW    =    
× 10-6          from two or three traces
                         uxcal    =  
 × 10-6       from Trace "c"
                         uL    =    
× 10-6           from Trace "c"
                         uzcal    =    
× 10-6       from Trace "c"
                         uzres    =    
× 10-6       from Trace "c"
                         uxres    =    
× 10-6       from Trace "c"
                         uxresL    =    
× 10-6     from Trace "c"

             uc    
= SQRT[usamp2 + uW2 + uxcal2 + uL2 + uzcal2 + uzres2 + uxres2 + uxresL2]
             uc    =    × 10-6        from two or three traces

                             AF    µm      from Trace "d"
                           w1F       
        from Trace "d"
                             AS  
µm      from Trace "d"
                           w3S   =             
 from Trace "d"

             xeF   
µm             from Trace "d"
             xeS   
µm             from Trace "d"
             εr0    = 
× 10
-6        from Trace "d"
              εr     =    
× 10
-6        from Trace "d"

Report the results as follows:  Since it can be assumed that the possible estimated values are either
approximately uniformly distributed or Gaussian with approximate standard deviation uc
, the residual
strain is believed to lie in the interval er ± uc with a level of confidence of approximately 68 %
assuming a Gaussian distribution. 


Modify the input data, given the information supplied in any flagged statement below, if applicable, then recalculate:
1. Please fill out the entire form.
2.   The value for t should be between 0.000 µm and 10.000 µm.
3.   The value for the design length should be between 0 µm and 1000 µm. 
4.   The measured value for L is more than 3ucL from the design length.
5. Is the magnification appropriate given the design length ?
6. Magnifications at or less than 2.5× shall not be used.
7. Is 0.95 < calx < 1.05 but not equal to "1"?  If not, recheck your x-calibration.
8.   The value for interx should be between 0 µm and 1500 µm.
9.   The value for σxcal should be between 0 µm and 4 µm.
10.   The value for xres should be between 0 µm and 2.00 µm.
11. Is 0.95 < calz < 1.05 but not equal to "1" ?  If not, recheck your z-calibration.
12.   The value for cert should be greater than 0 µm and less than 25 µm.
13. The value for σzcal should be between 0 µm and 0.050 µm.
14. The value for zres should be greater than 0 µm and less than or equal to 0.005 µm.
15. The value for Rtave should be between 0 µm and 0.100 µm.
16. Alignment has not been ensured.
17. Data has not been leveled.
18. x1min should be greater than x1max.
19. x2min should be greater than x1min.
20. x2max should be greater than x2min.
21. The calibrated values for x1min and x1max are greater than 10 µm apart.
22. The calibrated values for x2min and x2max are greater than 10 µm apart.
23. In Traces "b," "c," and "d," the value for s is not the same.
24. x1ave should be < (x1F * calx) in all traces.
25. (x3S * calx) should be < x2ave in all traces.
26. In all traces, make sure ( x1F < x2F < x3F ).
27. In all traces, make sure ( x1S < x2S < x3S ).
28. For Trace "b," | [(x2F*calx) − xeF ] | = µm.  This should be < 5 µm.
If it is not, choose (x
2F, z2F) such that (x2F * calx) is closer to xeF = µm.
29. For Trace "b," | [(x2S*calx) − xeS ] | µm.  This should be < 5 µm.
If it is not, choose (x
2S, z2S) such that (x2S * calx) is closer to xeS = µm.
30. For Trace "c," | [(x2F*calx) − xeF ] | = µm.  This should be < 5 µm.
If it is not, choose (x
2F, z2F) such that (x2F * calx) is closer to xeF = µm.
31. For Trace "c," | [(x2S*calx) − xeS ] | =  µm.  This should be < 5 µm.
If it is not, choose (x
2S, z2S) such that (x2S * calx) is closer to xeS = µm.
32. For Trace "d," | [(x2F*calx) − xeF ] | µm.  This should be < 5 µm.
If it is not, choose (x
2F, z2F) such that (x2F * calx) is closer to xeF = µm.
33. For Trace "d," | [(x2S*calx) − xeS ] | µm.  This should be < 5 µm.
If it is not, choose (x
2S, z2S) such that (x2S * calx) is closer to xeS = µm.

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The MNT Project (http://www.eeel.nist.gov/812/MNT/index.html) is within the Enabling Devices and ICs Group.

Date created: 12/4/2000
Last updated: 6/2/2009