Repetitive circumferential milling for sample preparation
AssigneeFEI Company
InventorsLucille A. Giannuzzi, Paul Anzalone, Richard Young, Daniel W. Phifer, Jr.
Life of this patent
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Abstract
A method of sample extraction entails making multiple, overlapping cuts using a beam, such as a focused ion beam, to create a trench around a sample, and then undercutting the sample to free it. Because the sidewalls of the cut are not vertical, the overlapping cuts impinge on the sloping sidewalls formed by previous cuts. The high angle of incidence provides a greatly enhanced mill rate, so that making multiple overlapping cuts to produce a wide trench can requires less time than making a single, deep cut around the perimeter of a sample.
Claims31
A method of extracting a microscopic sample from a substrate, comprising:
- directing an ion beam at a substantially normal angle to the substrate surface along a first path, said first path defining a substantially complete perimeter around a sample, to produce a trench in the substrate;
- directing the ion beam at a substantially normal angle to the substrate surface along a second path, the second path defining a substantially complete perimeter around the sample and overlapping but offset from the first path essentially along the entire perimeter to enlarge the trench around the sample;
- and
- directing the ion beam at a substantially non-normal angle to the substrate to undercut the sample and free the sample from the substrate.
A method of extracting a microscopic sample from a substrate, the method comprising:
- directing a beam in a path to perform a series of overlapping cuts completely around the perimeter of a region of intrest containing a sample to be extracted and moving progressively toward the sample to be extracted to produce a trench around the sample, a portion of the trench becoming deeper in the direction toward the sample;
- severing the base of the sample;
- and
- removing the sample.
A method of extracting a microscopic sample, the method comprising:
- cutting a trench essentially completely around an area of interest including the sample by beam milling around the perimeter of the sample in a at least one continuous pass so that the sample is essentially freed on all sides except the bottom;
- and
- undercutting the sample to free it from the substrate.
A system for extracting a sample from a substrate, comprising:
- a beam source for producing a sub-micrometer diameter beam capable of milling a hole in a substrate, the beam having a non-uniform distribution for producing sloping sidewalls on the substrate;
- and
- a controller for controlling the movement of the beam relative to the substrate, the controller being programmed to make a series of overlapping cuts completely around the sample and moving inward toward the sample,the overlapping cuts being of increasing depth and creating a trench around the sample.
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 charged particle beam at the substrate surface at a first angle with respect to the substrate surface and then milling the substrate surface by directing a charged particle beam along a substantially complete perimeter around the sample section in one continuous pass in order to form a trench around the sample section;
- directing a charged particle beam at sample section at a second angle with respect to the substrate surface, and then milling the sample section in order to sever the base of the sample section from the substrate;
- and
- removing the sample section from the substrate.
A method of extracting a microscopic sample from a substrate, comprising:
- directing an ion beam at a substantially normal angle to the substrate surface along a first path substantially along a complete perimeter around a sample section to produce a trench in the substrate, wherein the ion beam is directed along the first path in one continuous pass around the sample perimeter without reversing the direction of the ion beam;
- directing the ion beam at a substantially normal angle to the substrate surface along a second path. wherein the ion beam is directed along the second path in one continuous pass around the sample perimeter without reversing the direction of the ion beam, the second path overlapping but offset inwardly toward the sample section from the first path essentially along the entire perimeter to enlarge the trench around the sample;
- and
- directing the ion beam at a substantially non-normal angle to the substrate to undercut the sample and free the sample from the substrate.
Dependencies are inferred from the claim text.