Table 2.

Comparison of machining capabilities of the major SPL nanolithography approaches.

Items	Close-to-Atomic Scale SPL	T/tc-SPL	O-SPL	M-SPL	D-SPL	B-SPL
Resolution	Atomic scale [3]	10 nm [85]	4 nm [60]	10 nm [165]	10 nm [74]	10 nm [166]
Throughput	-	~104 μm2 h−1 [167]	~102 μm2 h−1 [66]	~2.4 × 103 μm2 h−1 [112]	~104 μm2 h−1 [98]	~10 μm2 h−1 [168]
Machining capability	-	2D, 3D	2D, 3D	2D, 3D	2D	2D
Machinable materials	Molecular, atoms, electrons	PMMA, PC PPV film, copolymer film	Metal, semiconductors, graphene, polymer	Polymer, metal, ceramics and semiconductors, graphene	Transporting organic molecules, polymers, DNA, proteins and metal ions	Graphene, metal, semiconductors, Si, polymer
Environmental conditions	Vacuum	Liquid, Air	20%–80% relative humidity	Air	34% relative humidity	High electric fields
Processing speed	Super slow 80 nm/s [169]	Super fast 20 mm/s [170]	Moderate 10 μm/s [74]	Fast 50 μm/s [2]	Slow 2 μm/s [171]	Slow 0.1 μm/s [172]
Control	Difficult	Good	Excellent	Excellent	Complicated	Difficult
Principle	Physico-chemistry process	Physico-chemistry process	Chemical process	Physical process	Chemical process	Physico-chemistry process
Tip wear	Negligible	Not serious	Negligible	Serious	Negligible	Negligible
Advantages	Atomic-scale precision	Super fast	Robust oxide formation	Easy to implement and various substrates materials	Very suitable for biological materials	Negligible probe wear
Disadvantages	Extreme slow	Requires heated probes	Requires oxidizability of the workpiece	Probe wear and burr formation	Requires ink	Requires extra electric circuits to control current