Paper HI-WeA3
FIB Platform Employing a Low-Temperature Ion Source

Wednesday, November 1, 2017, 3:00 pm, Room 7 & 8

We present a demonstration of a new high-performance ion source retrofitted to a commercial FIB platform. Spot sizes as small as (2.1 ± 0.2) nm (one standard deviation) are observed with a 10 keV, 1.0 pA beam. Brightness values as high as (2.4 ± 0.1) × 10⁷ A m^-2 sr^-1 eV^-1 are observed near 8 pA [1]. The measured peak brightness is over 24 times higher than the highest brightness observed in a Ga liquid metal ion source (LMIS); the spot size obtained by operating our source at 10keV is significantly smaller than the spot size achievable with the replaced LMIS operating at 40 keV.

The FIB platform utilizes a Low Temperature Ion Source (LoTIS). As previously described [2], this source is composed of a several discrete stages that collect, compress, cool and finally photoionize a cesium atomic beam. High brightness and small spot sizes are achieved owing to the extremely low (10 uK) temperatures that may be achieved in the neutral atomic beam prior to photoionization. The atomic beam transmits over 5×10¹⁰ atoms s^-1, which would be equivalent to an ion beam with over 8 nA if ionized completely; extraction of currents up to 5 nA have been demonstrated to date.

We will present a description of the Cs⁺ LoTIS-FIB system, together with an examination of the brightness and spot size measurement methodology at beam currents up to a nanoampere. Images acquired using the system will also be shown. Finally, we will describe outcomes of some preliminary milling, gas assisted etching and deposition experiments performed with the system.

[1] A. V. Steele, A. Schwarzkopf, J. J. McClelland, and B. Knuffman. Nano Futures. 1, 015XXX (2017). (to be published 5/2017)

[2] B. Knuffman, A. V. Steele, and J. J. McClelland. J. Appl. Phys. 114, 044303 (2013).