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US 8,525,137 B2Granted
Method for creating S/TEM sample and sample structure
AssigneeFEI Company
InventorsJeff Blackwood, Stacey Stone, Jason Arjavac
Life of this patent
Estimating the term…
Abstract
An improved method and apparatus for S/TEM sample preparation and analysis. Preferred embodiments of the present invention provide improved methods for TEM sample creation, especially for small geometry (<100 nm thick) TEM lamellae. A novel sample structure and a novel use of a milling pattern allow the creation of S/TEM samples as thin as 50 nm without significant bowing or warping. Preferred embodiments of the present invention provide methods to partially or fully automate TEM sample creation, to make the process of creating and analyzing TEM samples less labor intensive, and to increase throughput and reproducibility of TEM analysis.
Claims26
A method of thinning a sample section for TEM analysis, the method comprising:
- loading the sample to be thinned into an ion beam system;
- thinning the sample section by directing a substantially normal ion beam at a first side of the sample section in a milling pattern that thins the sample section in a series of passes, each pass having a scan speed and comprising moving the beam in a raster pattern from the outside of the sample section inward to the desired sample face and then returning to the outside of the sample section, the series of passes continuing until the first side of the sample section has been thinned to a desired depth wherein said scan speed decreases as it gets closer to said desired depth;
- and
- automatically thinning the sample section by directing a substantially normal ion beam at the opposite second side of the sample section in a milling pattern that thins the sample section in a series of passes, each pass having a scan speed and comprising moving the beam in a raster pattern from the outside of the sample section inward to the desired sample face and then returning to the outside of the sample section, the series of passes continuing until the second side of the sample section has been thinned to a desired depth wherein said scan speed decreases as it gets closer to said desired depth.
1 more element
A method of extracting a microscopic sample from a substrate, the method comprising:
- defining a sample section to be extracted on a substrate;
- directing a substantially normal ion beam at the substrate surface, said beam being scanned in a rectangular area to form a first rectangular hole having a predetermined depth, said first rectangular hole being adjacent to the sample section to be extracted;
- directing said beam at the substrate surface, said beam being scanned in a rectangular area to form a second rectangular hole having a predetermined depth, said second rectangular hole being adjacent to the sample section to be extracted but on the opposite side of said sample section from the first rectangular hole so that the remaining material between the two rectangles forms a thin vertical wafer that includes the sample section to be extracted;
- directing the ion beam at the remaining material at a non-normal angle in order to undercut the remaining material;
- rotating the sample by 180 degrees;
- directing the ion beam at the remaining material at a non-normal angle from the opposite side of the sample section in order to free the bottom of the sample section from the substrate;
- directing the ion beam at the remaining material at a non-normal angle in order to free the sides of the sample section leaving at tab of material on either side of the sample section connecting the sample section to the substrate;
- thinning the sample section by directing a substantially normal ion beam at a first side of the sample section in a milling pattern that thins the sample section in a series of passes, each pass having a scan speed and comprising moving the beam in a raster pattern from the outside of the sample section inward to the desired sample face and then returning to the outside of the sample section, the series of passes continuing until the first side of the sample section has been thinned to a desired depth wherein said scan speed decreases as it gets closer to the desired depth;
- thinning the sample section by directing a substantially normal ion beam at the opposite second side of the sample section in a milling pattern that thins the sample section in a series of passes, each pass having a scan speed and comprising moving the beam in a raster pattern from the outside of the sample section inward to the desired sample face and then returning to the outside of the sample section, the series of passes continuing until the second side of the sample section has been thinned to a desired depth wherein said scan speed decreases as it gets closer to the desired depth;
- severing the tabs of material on either side of the sample section connecting the sample section to the substrate in order to free the sample;
- and
- removing the sample from the substrate.
9 more elements
Dependencies are inferred from the claim text.