CHARACTERIZATION OF MATERIAL INTERACTION AND COMPOSITIONAL ANALYSIS OF NANOMACHINING AND NANODEPOSITION USING A Cs⁺ FOCUSED ION BEAM – A SOURCE TECHNOLOGY CANDIDATE FOR FUTURE CIRCUIT EDIT PLATFORMS

The use of focused ion beam (FIB) instruments has become essential for the semiconductor and microelectronic industries in recent years. Transmission electron microscopy (TEM) sample preparation [1,2], failure analysis (FA) [1,3], and nanofabrication of miniature prototypes [3,4] are all performed using FIBs. Another indispensable FIB application field is circuit edit (CE), where FIB has been used to fix faulty circuitry and verify layout modifications prior to lithography masks remanufacturing [5]. In addition, CE provides working chips prior to the next manufacturing round, thus expediting time to market of semicoductor products [6]. Frequent CE FIB activities are signal rerouting and device bypassing [5,6]. These involve FIB gas assisted etch to designated metal lines, followed by ion beam induced deposition (IBID) of oxides (for isolation where required) and metals (for connections). The requirements from the IBID material here are relatively low resistivity for conductors, and high resistivity for the insulators - both depend on the material purity of the deposit [5].

In order to enable the fine micro- and nano-machining required for the above applications, FIB source technologies have been developed over the past three decades. To date, the Ga⁺ liquid metal ion source (LMIS) and Xe⁺ plasma cusp ion sources provide the horsepower behind fine machining and bulk micro-machining, respectively [6,7]. Gas field ionization source (GFIS) based FIBs were introduced in the last decade, providing small probe-size and highly localized nano-machining solutions for mask-defect repairing and fine re-wiring [6]. These tools are in different development and comercialization phases.

Alternative emerging FIB source technologies based on the magneto-optical trap were recently introduced [8,9]. These “cold beam” technologies, involve the ionization of deep sub-Kelvin laser-cooled atoms, and formation of low energy spread focused ion beams. One of the most promissing candidates for cold beam is the Cs⁺ Low Temperature Ion Source (LoTIS), introduced by zeroK Nanotech [8].

In this talk we shall present and discuss our recent findings on gas assisted nano-machining and IBID using the proof of concept Cs⁺ LoTIS installed on zeroK’s test platform. TEM images of nano-mchining features will be shared, as well as energy dispersive spectroscopy (EDS) composition measurements taken from IBID lines. Further nano-machining attributes will be discussed.

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