High accuracy beam placement for local area navigation

摘要

An improved method of high accuracy beam placement for local area navigation in the field of semiconductor chip manufacturing. Preferred embodiments of the present invention can also be used to rapidly navigate to one single bit cell in a memory array or similar structure, for example to characterize or correct a defect in that individual bit cell. High-resolution scanning is used to scan only a “strip” of cells on the one edge of the array (along either the X axis and the Y axis) to locate a row containing the desired cell followed by a similar high-speed scan along the located row (in the remaining direction) until the desired cell location is reached. This allows pattern-recognition tools to be used to automatically “count” the cells necessary to navigate to the desired cell, without the large expenditure of time required to image the entire array.

主权项

1. An apparatus for accurately locating a feature of interest on a sample, comprising:
a moveable sample stage for supporting the sample; a particle beam column for producing a beam of particles to image the sample; and a computer-readable non-transitory memory storing computer instructions, the instructions including a program for controlling the apparatus and causing the apparatus to carry out the steps of:
(i) loading a sample into a particle beam system;(ii) navigating to the portion of the array containing the feature of interest;(iii) forming at least one fiducial on the sample surface at a location near the estimated location of the feature of interest;(iv) obtaining an image of an edge strip along an edge of the array, said edge strip image having a resolution high enough that the pixel size is less than half of the minimum repeating dimension of the cells in the array, and the edge strip image being at least X cells in length and substantially smaller than the field of view in the first image;(v) analyzing the image data to automatically count X cells along the edge of the array to determine the location of the desired row containing the feature of interest;(vi) obtaining a row strip image along the desired row, said row strip image having a resolution high enough that the pixel size is less than half of the minimum repeating dimension of the cells in the array, and the row strip image being at least Y cells in length and substantially smaller than the field of view in the first image, and the row strip image including at least one fiducial and the feature of interest;(vii) analyzing the image data to automatically count Y cells along the desired row to determine the location of cell address X, Y containing the feature of interest; and(viii) determining the offset between the at least one fiducial and the location of cell address X, Y containing the feature of interest.