Local coinjection of a (H2–Ar) microplasma jet and Cu(O2C5F6H)2 molecules during focused electron beam-induced deposition (FEBID) was studied with respect to changes in the Cu:C ratio of deposits. Microplasma-assisted FEBID (30 keV and 1 nA) decreased codeposition of carbon, oxygen, and fluorine originating from the chamber background and the precursor molecule. The copper metal content could be increased to 41 at. %, being almost four times more than in conventional FEBID deposits without coinjection. Conventional FEB deposits from Cu(O2C5F6H)2 resulted in 11–12 at. % Cu content. Microplasma post-treatments of conventional FEB deposits resulted in volume changes, surface roughening, and an increase of the overall Cu content to 27 at. %. The removal mechanisms were of nonthermal nature. At repulsive bias potentials from 0 to +30 V, a pure chemical etching of the carbonaceous matrix by atomic hydrogen radials occurred. At attractive bias potentials of up to −30 V, a more efficient ion induced chemical sputtering regime prevailed where Ar+ ions break carbon bonds, which in turn will be passivated by atomic hydrogen radicals to form volatile hydrocarbon compounds.