Using FIB processes that enable the geometrical modification of straight and aligned CNT tips, it is possible to fabricate CNT tips that are tailored for CD-AFM applications. Some examples developed by KRISS are the platinum ball-capped (B-tip) and the bent CNT tip (J-tip), which can reach re-entrant sidewalls and enter very narrow trenches or holes. The B-tip geometry more closely resembles the functional geometry of conventional CD-AFM tips and so is more generally applicable than the J-tip. However, as discussed more in the Appendix, the J-tip may be useful for cases of sidewall re-entrance exceeding 10 nm, which is the approximate limit of most conventional CD-AFM tips. Using two different instruments, KRISS and NIST evaluated the performance of these two tip types for CD-AFM metrology, and the initial results were promising.