Table 1.

A comparison of various lithographic techniques.

Category	DSA of BCPs	ASD of Polymer Brushes	EUV Lithography	Nano-Imprint Lithography	Optical Lithography
Principle of operation	Microphase separation produces self-assembled architectures [15]. Structural modulation by selection of molecular composition and weight [12,125].	Polymer brush’s metal binning sites facilitate deposition of inorganic films [18]. Thickness controlled by SVA and deposition process [124].	Relies on a wavelength of 13.5 nm instead of 193 nm used in conventional optical lithography [144]. Principle of operation relies on reflection [51].	Mask physically displaces photoresist to pattern it before cross linking [144,171]. Once resist is cured, mould is removed and patterned resist is used for manufacturing [171].	UV light and mask to transfer patterns. photosensitive substrate selectively exposed. Reactive ion etch transfers the pattern to the substrate [169].
Efficiency and energetic costs	Varies. Industrial SVA system requires development with fast, precise wafer scale processing [123,124,125].	Grafting of polymer brushes to substrates in seconds [18]. Requires standardised industrial process.	Recent EUV tools have productive capacity of 125 wafers per hour [164]. Hot plasma 20-50 eV or accelerator [154]. technology is energetically expensive [16,154].	Capable of producing over 40 wafers of 300 nm per hour with a defect rate less than 9 pcs/cm2 [171].	Short time for pattern. E.g., 150-300-mm wafers per hour and 40-nm two-dimensional pattern resolution of a scanner with pixel throughput of 1.8T pixels per second approximately [144].
	low-temperature vapor phase deposition process cuts costs and improves environmental sustainability [21,137].
Wastes generated	Solvents, excess inorganic precursor for metal infiltration, excess polymer during deposition stage.		Solvents are typically volatile and flammable. Polymer matrix, photoactive compounds and cross-linkers in polymer photoresist are toxic and non-degradable [149,172].
Tool complexity	Thickness and pattern formation control can be achieved with simple chambers consisting of temperature and gas flow systems [124,125]. Predicted low cost of ownership. These techniques do not require the use of photoresists and avoids acquisition costs.		Expensive and complex multilayer optics, hot plasma or acceleration technology and high vacuum. Cost of tool > $30 million [137,144,154].	Depends: TE-NIL uses heat and pressure. SFIL uses capillary forces, pressure, and light exposure. Improved tool performance required [173,174,176].	Acquisition cost of photolithographic resist coat system is $950,000 [139].
Disadvantages	High defect density of BCPs [138]. Poor etch contrast of polymer blocks [14].	Improved range of metals that can be deposited [18].	Obtaining high reflectivity [144], improved etch and deposition defect mitigation and repair of mask, installation and power costs [16,142,162,166,170].	Needs reduced process steps and improved mould material, fabrication quality, mass production capacity, reduced overlay and defectivity [16,33,171].	Photolithography can no longer be further optimised as it has an intrinsic resolution limit [51,137].
	Standardised methodology and further research required [7,138].
Advantages	No diffraction limit in resolution [137], directly pattern functional materials [137], efficient for 3D patterning [137].	Reduction of processing steps [133]. self-aligned patterning with capability of extending to 3D [17].	Improved: cycle time, increased number of patterning levels, line edge roughness, high etch resistance, increased sensitivity [33,138].	Facilitates change in flash memory from scaling horizontally to vertically. Simple processing steps, high throughput, low cost and high resolution [51].	Established technology being the dominate patterning technique since the beginning of IC production [51].