Charged particle beam system and methods

Abstract

Disclosed is a charged particle beam system comprising a charged particle beam column having a charged particle source forming a charged particle beam, an objective lens and a first deflection system for changing a position of impingement of the charged particle beam in a sample plane. The system further comprises a sample chamber comprising a sample stage for holding a sample to be processed, and a controller configured to create and store a height map of a sample surface. The controller is further configured to dynamically adjust the objective lens of the charged particle beam in dependence on a position of impingement of the charged particle beam according to the height map.

1 .- 20 . (canceled) 
     
     
         21 . A method, comprising:
 a. generating an image of a surface a sample in a sample chamber using a light optical imaging system or an electron beam system;   b. identifying reference marks in the image;   c. determining positions of the reference marks on the surface of the sample based on the identified reference marks;   d. determining a location of a first region of the surface of the sample to be processed based on the positions of the reference marks and design data of the sample;   e. biasing a deflection system of a charged particle beam system according to the location determined in d, the charged particle beam system being selected from the group consisting of the electron beam system and an ion beam system; and   f. scanning a charged particle beam generated by the charged particle beam system over the first region of the surface of the sample and simultaneously detecting products of the interaction of the charged particle beam with the sample to determine and record a location of an alignment mark in the surface of the sample, the alignment mark being different from the reference marks.   
     
     
         22 . The method of  claim 21 , further comprising recording a height map of the sample surface. 
     
     
         23 . The method of  claim 22 , further comprising using an electron beam or a gas field ion beam to record the height map of the sample. 
     
     
         24 . The method of  claim 22 , further comprising, based on the height map, adjusting a focus position of the charged particle beam during f. 
     
     
         25 . The method of  claim 21 , further comprising:
 measuring a number of interaction products of the charged particle beam with the sample while the charged particle beam impinges on the first region; and   dynamically adjusting a dwell time during which the charged particle beam impinges on the first region either based on the measured number of interaction products by comparing the measured number of interaction products with a predefined number of interaction products or by measuring the beam current of the charged particle beam.   
     
     
         26 . The method of  claim 25 , further comprising recording a height map of the sample surface. 
     
     
         27 . The method of  claim 21 , wherein the charged particle beam system comprises an objective lens, and the method further comprises:
 focusing the charged particle beam with the objective lens to generate a focused charged particle beam spot at a first distance from the objective lens; and   positioning the sample relative to the charged particle beam so that the surface of the sample has a second distance from the objective lens, the first distance being different from the second distance.   
     
     
         28 . The method of  claim 27 , wherein the first distance is at least one micrometer different from the second distance. 
     
     
         29 . The method of  claim 28 , wherein the first distance is at most  100  micrometers different from the second distance. 
     
     
         30 . The method of  claim 27 , wherein the charged particle beam system comprises an ion optical column which comprises a beam limiting aperture, and the method further comprising adjusting the objective lens to project the beam limiting aperture onto the surface of the sample. 
     
     
         31 . The method of  claim 27 , further comprising recording a height map of the sample surface. 
     
     
         32 . The method of  claim 21 , further comprising, during c, biasing the sample with a voltage which is negative or positive with respect to a voltage of the objective lens. 
     
     
         33 . The method of  claim 21 , further comprising repeating e and f for a first number of first regions without moving the sample relative to the ion beam column. 
     
     
         34 . The method of  claim 33 , further comprising:
 moving the sample relative to the ion beam column; and   thereafter repeating e and f for a second number of first regions.   
     
     
         35 . The method of  claim 34 , further comprising measuring a movement of the sample stage relative to the ion beam column. 
     
     
         36 . The method of  claim 33 , further comprising recording a height map of the sample surface. 
     
     
         37 . The method of  claim 21 , wherein:
 the charged particle beam comprises an ion beam; and   the method further comprises:
 using ion beam sputtering or ion beam induced gas chemical deposition to write a system alignment mark into the sample; and 
 periodically recording an image of the system alignment mark. 
   
     
     
         38 . The method of  claim 37 , further comprising adjusting parameters of the charged particle beam system based on the recorded image of the alignment mark. 
     
     
         39 . The method of  claim 37 , further comprising recording a height map of the sample surface. 
     
     
         40 . A system, comprising:
 a light optical imaging system configured to generate an image of a surface of a sample;   a charged particle beam system configured to generate a charged particle beam, the charged particle beam system comprising a deflection system configured to change a position of impingement of the charged particle beam on the surface of the sample;   a detector configured to detect interaction products caused to leave the sample during impingement of the charged particle beam onto the sample surface; and   a controller configured to:
 a. identify reference marks in an image of the surface of the sample generated by the light optical imaging system; 
 b. determine positions of the reference marks on the surface of the sample based on the identified reference marks; 
 c. determine a location of a first region of the surface of the sample based on the determined positions of the reference marks and design data of the sample; 
 d. bias the deflection system according to the determined location of the first region of the surface of the sample; 
 e. simultaneously:
 i. scan a charged particle beam generated by the charged particle beam system over the first region of the surface of the sample; and 
 ii. detect products of the interaction of the charged particle beam with the sample to determine and record a location of an alignment mark in the surface of the sample, 
 
   wherein:
 the alignment mark being different from the reference marks; and 
   the charged particle beam system selected from the group consisting of an electron beam system and an ion beam system.