opposite of the plan view side of sample 300 and second side 342 is the plan view side 340 first side 340 is created by cutting off a portion of the silicon substrate 330 so that the overall thickness less than the original thickness of the sample 200 and is approximately 100 u03bcm to 160 u03bcm after forming first side 340 a first thinned surface 360 is formed by cutting or mask etching a portion of layer 330 to result in sample 300 having a thickness b which is less than thickness a e g approximately 35 u03bcm in the area of sample 300 near the site of interest 350 in the present embodiment site of interest 350 is within layer 320 of sample 300 but in other embodiments site 350 may be in another layer or other layers of sample 300 second thinned surface 370 is created by two consecutive steps designed to further thin site of interest 350 to a thickness c which is less than thickness b in the first step focused ion beam milling is used to thin site of interest 350 at first thinned surface 360 to a roughly uniform thickness of approximately 2 u03bcm it is not of uniform thickness due to the well known slope variation generated by fib milling from the edge of a sample to the thicker portions of a sample.