Conventional Optical Lithography Research Articles

Focused solar annealing for block copolymer fast self-assembly

Block copolymer (BCP) self-assembly has tremendous potential applications in next-generation nanolithography. It offers significant advantages, including high resolution and cost-effectiveness, effectively overcoming the limitations associated with conventional optical lithography. In this work, we demonstrate a focused solar annealing (FSA) technique that is facile, eco-friendly, and energy-efficient for fast self-assembly of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) thin films. The FSA principle involves utilizing a common biconvex lens to converge incident solar radiation into a high-temperature spot, which is directly used to drive the microphase separation of PS-b-PMMA thin films. As a result, PS-b-PMMA undergoes self-assembly, forming ordered nanostructures in a vertical orientation at seconds timescales on silicon substrates with a neutral layer. In addition, the FSA technique can be employed for grafting neutral polymer brushes onto the silicon substrate. Furthermore, the FSA's compatibility with graphoepitaxy-directed self-assembly (DSA) of BCP is also demonstrated in the patterning of contact holes. The results of contact hole shrinking show that contact hole prepatterns of ∼60.4 nm could be uniformly shrunk to ∼20.5 nm DSA hole patterns with a hole open yield (HOY) of 100 %. For contact hole multiplication, doublet DSA holes were successfully generated on elliptical templates, revealing an average DSA hole size of ∼21.3 nm. Most importantly, due to the direct use of solar energy, the FSA technique provides many significant advantages such as simplicity, environmental friendliness, solvent-free, low cost, and net-zero carbon emissions, and will open up a new direction for BCP lithography that is sustainable, pollution-free, and carbon-neutral.

Advanced optical nanolithography by enhanced transmission through bull’s eye nanostructured meta-mask

Abstract Plasmonic optical nanolithography using extraordinary optical transmission through a metallic nanohole mask has been actively applied to the high-resolution fabrication of nanostructures over a large area. Although there have been studies on improving the nanostructure fabrication performance in optical nanolithography, such as on adjustable external gap spacing, additional performance enhancement is required for practical applications and commercialization of large-area and high-resolution nanostructure array fabrication techniques. In this study, we design and apply a plasmonic bull’s eye nanostructured meta-mask to enhance the performance of optical nanolithography. Through simulation results and experimental verification, it is confirmed that advanced optical nanolithography using the bull’s eye nanostructured meta-mask has several merits compared to conventional Talbot lithography using nanoholes: (1) Optical nanolithography using the bull’s eye nanostructured meta-mask effectively fabricates nanopillar arrays even at a shorter exposure time than conventional optical lithography using nanoholes. (2) It is possible to create a large-area nanopillar array with various nanopillar diameters by exposure time control in optical nanolithography using the bull’s eye meta-mask. (3) Using water or objective immersion oil to increase the refractive index of the contact medium, light can be focused on smaller sizes, and large-area nanopillar arrays with smaller nanopillar diameters are established. With the upgradation of hardware for large-area fabrication, application of immersion media supplying techniques, and additional studies to establish complex nanostructures, optical nanolithography using the bull’s eye nanostructured meta-mask is an efficient modality to produce various nanostructure-based devices.

Optimization of plotter printing for sub-terahertz metallic metasurfaces fabrication on ultra-thin substrate

Additive manufacturing processes have emerged as a promising way to conceive terahertz and millimetric components. In this work, we discuss a printing process for sub-terahertz metallic metasurfaces fabrication on ultra-thin substrates. We demonstrate the use of a plastic substrate with a micrometric thickness which makes this printing method a promising and low cost alternative to conventional optical lithography for the fabrication of flexible terahertz 2D metasurfaces. After detailing the key parameters and limitations, we applied the optimized process to fabricate samples composed of periodic arrays of split ring resonators on 50 µm thick fused silica and 3 µm thick PET substrates. The optical response in transmission of the metasurfaces shows expected resonances in the 100 GHz range and demonstrates the use of microplotter system for rapid prototyping of low-loss terahertz passive components on ultra-thin substrate.

High-Resolution Colloidal Quantum Dot Film Photolithography via Atomic Layer Deposition of ZnO.

High-resolution patterning of quantum dot (QD) films is one of the preconditions for the practical use of QD-based emissive display platforms. Recently, inkjet printing and transfer printing have been actively developed; however, high-resolution patterning is still limited owing to nozzle-clogging issues and coffee ring effects during the inkjet printing and kinetic parameters such as pickup and peeling speed during the transfer process. Consequently, employing direct optical lithography would be highly beneficial owing to its well-established process in the semiconductor industry; however, exposing the photoresist (PR) on top of the QD film deteriorates the QD film underneath. This is because a majority of the solvents for PR easily dissolve the pre-existing QD films. In this study, we present a conventional optical lithography process to obtain solvent resistance by reacting the QD film surface with diethylzinc (DEZ) precursors using atomic layer deposition. It was confirmed that, by reacting the QD surface with DEZ and coating PR directly on top of the QD film, a typical photolithography process can be performed to generate a red/green/blue pixel of 3000 ppi or more. QD electroluminescence devices were fabricated with all primary colors of QDs; moreover, compared to reference QD-LED devices, the patterned QD-LED devices exhibited enhanced brightness and efficiency.

Comparison of Conventional and Maskless Lithographic Techniques for More than Moore Post-Processing of Foundry CMOS Chips

This article details and compares the technology options for post–processing foundry produced CMOS at chip-scale to enable More than Moore functionality. In many cases there are attractions in using chip-based processing through the Multi-Project Wafer route that is frequently employed in research, early-stage development and low-volume production. This article identifies that spray-based photoresist deposition combined with optical maskless lithography demonstrates sufficient performance combined with low cost and operational convenience to offer an attractive alternative to conventional optical lithography, where spin-coated photoresist is exposed through a patterned photomask. [2020-0249]

Direct Patterning of Metal Chalcogenide Semiconductor Materials

AbstractLithography is one of the most widely used methods for cutting‐edge research and industrial applications, mainly owing to its ability to draw patterns in the micro and even nanoscale. However, the fabrication of semiconductor micro/nanostructures via conventional electron or optical lithography technologies often requires a time‐consuming multistep process and the use of expensive facilities. Herein, a low‐cost, high‐resolution, facile, and versatile direct patterning method based on metal–organic molecular precursors is reported. The ink‐based metal–organic precursors are found to operate as negative resists, with the material exposed by different methods (electron‐beam/laser/heat/ultraviolet (UV)) to render them insoluble in the development process. This technical process can deliver metal chalcogenide semiconductors with arbitrary 2D/3D patterns with sub‐50 nm resolution. Electron beam lithography, two‐photon absorption lithography, thermal scanning probe lithography, and UV photolithography are demonstrated for the direct patterning process. Different metal chalcogenide semiconductor nanodevices, such as photoconductive selenium‐doped Sb2S3 nanoribbons, p‐type PbS single‐nanowire field‐effect transistors, and p‐n junction CdS/Cu2S nanowire solar cells, are fabricated by this method. This direct patterning technique is a versatile and simple micro/nanolithography technology with considerable potential for “lab‐on‐a‐chip” preparation of semiconductor devices.

Efficiency-enhanced and sidelobe-suppressed super-oscillatory lenses for sub-diffraction-limit fluorescence imaging with ultralong working distance.

Super-oscillatory lens (SOL) optical microscopy, behaving as a non-invasive and universal imaging technique, as well as being a simple post-processing procedure, may provide a potential application for sub-diffraction-limit fluorescence imaging. However, the low energy concentration, high-intensity sidelobes and micrometer-scale working distance of the reported planar SOLs impose unavoidable restrictions on the ground-state applications. Here, we demonstrate step-shaped SOLs based on the multiple-phase-modulated (MPM) method to improve the focusing efficiency. Two pivotal advantages are thus generated: (i) the fabrication complexity can be effectively reduced based on several conventional optical lithography steps; (ii) the focusing efficiency is much higher than that of the random MPM ones due to the efficient manipulation of the wavefronts, bringing about a stronger light concentration to the focal spot. Additionally, the ratio of the sidelobe intensity is flexibly tuned to meet the customized requirements, and a 2 mm-working-distance MPM SOL with the sidelobe intensity highly suppressed is finally exploited. For the first time, as far as we know, a SOL-based fluorescence microscopy without the pinhole filter to map the horizontal morphology of the dispersive fluorescent particles is established. Compared with the results achieved by the conventional wide-field microscopy, the sample details beating the diffraction limit can be reconstructed by simple imaging fusion. This research demonstrates the promising applications of SOLs for low-cost, simplified and highly customized sub-diffraction-limit fluorescence imaging systems free from photobleaching and an extremely short working distance.

1.1: Invited Paper: TFT Backplane for Display

Thin Film Transistors (TFT) are being widely used as backplane to drive display components, such as LCD, OLED, and even u‐LCD. A‐Si, poly Si, oxide, and organic are common materials for TFT. Mobility, scale‐up and long term stability are among the key concern for TFT. Vertical channel thin film transistors (VTFTs) are proposed as an effective approach to reduce driving voltage and power consumption for achieving high speed and high resolution displays. Considering that oxide semiconductors have large‐area compatible processes, it will be better to find a method for achieving low driving voltages with conventional optical lithography machines used for large area display panels. In this talk, we will review the state of art of the vertical TFTs and explore the major fabrication issues. In addition, we will examine amorphous indium gallium zinc oxide (a‐IGZO) vertical channel TFT fabricated at low temperature to evaluate the impact of gate dielectric on electric characteristics of the vertical vis‐à‐vis planar TFTs. VTFTs employing vertical amorphous a‐IGZO channel of 500 nm have been fabricated without additional photolithography process. The various issues related to the improved device performance will be addressed. Solution based organic TFT will also be examined to explore its feasibility for backplane to drive display and other components.

High-performance axicon lenses based on high-contrast, multilayer gratings

Axicon lenses are versatile optical elements that can convert Gaussian beams to Bessel-like beams. In this letter, we demonstrate that axicons operating with high efficiencies and at large angles can be produced using high-contrast, multilayer gratings made from silicon. Efficient beam deflection of incident monochromatic light is enabled by higher-order optical modes in the silicon structure. Compared to diffractive devices made from low-contrast materials such as silicon dioxide, our multilayer devices have a relatively low spatial profile, reducing shadowing effects and enabling high efficiencies at large deflection angles. In addition, the feature sizes of these structures are relatively large, making the fabrication of near-infrared devices accessible with conventional optical lithography. Experimental lenses with deflection angles as large as 40° display field profiles that agree well with theory. Our concept can be used to design optical elements that produce higher-order Bessel-like beams, and the combination of high-contrast materials with multilayer architectures will more generally enable new classes of diffractive photonic structures.

Multiple Patterning Layout Decomposition Considering Complex Coloring Rules and Density Balancing

Multiple patterning lithography has been recognized as one of the most promising solutions, in addition to extreme ultraviolet lithography, directed self-assembly, nanoimprint lithography, and electron beam lithography, for advancing the resolution limit of conventional optical lithography. Multiple patterning layout decomposition (MPLD) becomes more challenging as advanced technology introduces complex coloring rules. Existing works model MPLD as a graph coloring problem; nevertheless, when complex coloring rules are considered, layout decomposition can no longer be modeled accurately by graph coloring. Therefore, in this paper, for capturing the essence of layout decomposition with complex coloring rules, we model the MPLD problem as an exact cover problem. We then propose a fast and exact MPLD framework based on augmented dancing links. Our method is flexible and general: it can consider the basic and complex coloring rules simultaneously, can maintain density balancing, and can handle quadruple patterning and beyond. Experimental results show that our approach outperforms state-of-the-art works on reported conflicts and stitches and is promising for handling complex coloring rules and density balancing as well.

Design and fabrication of low power GaAs/AlAs resonant tunneling diodes

A very low peak voltage GaAs/AlAs resonant tunneling diode (RTD) grown by molecular beam epitaxy (MBE) has been studied in detail. Excellent growth control with atomic-layer precision resulted in a peak voltage of merely 0.28V (0.53V) in forward (reverse) direction. The peak current density in forward bias is around 15.4kA/cm2 with variation of within 7%. As for reverse bias, the peak current density is around 22.8kA/cm2 with 4% variation which implies excellent scalability. In this work, we have successfully demonstrated the fabrication of a GaAs/AlAs RTD by using a conventional optical lithography and chemical wet-etching with very low peak voltage suitable for application in low dc input power RTD-based sub-millimetre wave oscillators.

Large area nanoimprint by substrate conformal imprint lithography (SCIL)

Abstract Releasing the potential of advanced material properties by controlled structuring materials on sub-100-nm length scales for applications such as integrated circuits, nano-photonics, (bio-)sensors, lasers, optical security, etc. requires new technology to fabricate nano-patterns on large areas (from cm2 to 200 mm up to display sizes) in a cost-effective manner. Conventional high-end optical lithography such as stepper/scanners is highly capital intensive and not flexible towards substrate types. Nanoimprint has had the potential for over 20 years to bring a cost-effective, flexible method for large area nano-patterning. Over the last 3–4 years, nanoimprint has made great progress towards volume production. The main accelerator has been the switch from rigid- to wafer-scale soft stamps and tool improvements for step and repeat patterning. In this paper, we discuss substrate conformal imprint lithography (SCIL), which combines nanometer resolution, low patterns distortion, and overlay alignment, traditionally reserved for rigid stamps, with the flexibility and robustness of soft stamps. This was made possible by a combination of a new soft stamp material, an inorganic resist, combined with an innovative imprint method. Finally, a volume production solution will be presented, which can pattern up to 60 wafers per hour.

Effect of Entrapped Solvent on the Evolution of Lateral Order in Self-Assembled P(S-r-MMA)/PS-b-PMMA Systems with Different Thicknesses.

Block copolymers (BCPs) are emerging as a cost-effective nanofabrication tool to complement conventional optical lithography because they self-assemble in highly ordered polymeric templates with well-defined sub-20-nm periodic features. In this context, cylinder-forming polystyrene-block-poly(methyl methacrylate) BCPs are revealed as an interesting material of choice because the orientation of the nanostructures with respect to the underlying substrate can be effectively controlled by a poly(styrene-random-methyl methacrylate) random copolymer (RCP) brush layer grafted to the substrate prior to BCP deposition. In this work, we investigate the self-assembly process and lateral order evolution in RCP + BCP systems consisting of cylinder-forming PS-b-PMMA (67 kg mol-1, PS fraction of ∼70%) films with thicknesses of 30, 70, 100, and 130 nm deposited on RCP brush layers having thicknesses ranging from 2 to 20 nm. The self-assembly process is promoted by a rapid thermal processing machine operating at 250 °C for 300 s. The level of lateral order is determined by measuring the correlation length (ξ) in the self-assembled BCP films. Moreover, the amount of solvent (Φ) retained in the RCP + BCP systems is measured as a function of the thicknesses of the RCP and BCP layers, respectively. In the 30-nm-thick BCP films, an increase in Φ as a function of the thickness of the RCP brush layer significantly affects the self-assembly kinetics and the final extent of the lateral order in the BCP films. Conversely, no significant variations of ξ are observed in the 70-, 100-, and 130-nm-thick BCP films with increasing Φ.

Subdiffraction plasmonic lens lithography prototype in stepper mode

In this paper, the authors present a low-cost and high-resolution lithography prototype by utilizing surface plasmons. In the surface plasmon lithography (SPL) prototype, a metal-photoresist-metal plasmonic cavity lens is adopted to amplify evanescent waves, thereby addressing the issues of poor fidelity, low contrast, and short working distance suffered from the conventional near-field optical lithography. The authors achieved the photoresist patterns with high resolution, high contrast, and high exposure depth experimentally by using an Hg lamp with 365 nm wavelength. Hole array patterns with radius of 50 nm and period of 160 nm were realized. Moreover, the grating array patterns with line width of 32(60) nm and period of 64(120) nm were successfully achieved. Furthermore, the authors introduced a step exposure method to fabricate a 5 × 5 array of grating patterns with a step length of 300 μm and the uniform patterns cover the whole area of about 2 × 2 mm2. Step exposure is valuable, which makes SPL have the ability to obtain a large-area pattern exposure, especially in the condition that the mask area is far smaller than the exposure region. It is believed that this prototype provides a low-cost, high-throughput, and high-resolution nanofabrication route for fabricating nanostructure devices.

(Invited) Vertical Channel Amorphous Indium Gallium Zinc Oxide Thin Film Transistors

Vertical channel thin film transistors (VTFTs) are proposed as an effective approach to reduce driving voltage and power consumption for achieving high speed and high resolution displays. VTFTs with amorphous silicon (a-Si) technology have severe problems related to low on/off current ratio (Ion/off), high drain-leakage current, and absence of saturation behavior at high drain voltages. In this concern, thin gate insulator plays a key role to result well behaved a-Si VTFT characteristics such as clear saturation behavior at high drain voltage, low leakage current and good device performance with high Ion/off. However, poor mobility and contact resistance due to space charge limited current a-Si VTFT become increasingly noticeable, when the channel length is scaled down to nanometer dimensions. In contrast, the oxide semiconductor can be scaled to a very short channel without deteriorating the device performances. Considering that oxide semiconductors have large-area compatible processes, it will be better to find a method for achieving low driving voltages with conventional optical lithography machines used for large area display panels. In this talk, we will review the state of art of the vertical TFTs and explore the major fabrication issues. In addition, we will examine amorphous indium gallium zinc oxide (a-IGZO) vertical channel TFT fabricated at low temperature to evaluate the impact of gate dielectric on electric characteristics of the vertical vis-à-vis planar TFTs. VTFTs employing vertical amorphous a-IGZO channel of 500 nm have been fabricated without additional photolithography process. The various issues related to the improved device performance will be addressed. Figure 1

Template-free fabrication of Ag nanowire arrays/Al2O3 assembly with flexible collective longitudinal-mode resonance and ultrafast nonlinear optical response

We utilized a co-sputtering technique without any templates, featuring growing and etching synchronously, to delicately fabricate dense and ultrafine Ag nanowire arrays/alumina matrix composite films. Both the diameter and separation distance of the Ag nanowire arrays in the composites are not only within the scope of sub-10 nm but also tunable, which is very hard to accomplish for the conventional optical lithography- or template-based method. It is exhibited that the collective longitudinal plasmon resonance of the composite films, covering a wide range from visible to the near infrared region, is extremely sensitive to the geometrical parameters of the Ag nanowires, owing to the strong plasmonic coupling among neighboring nanowires. The experimental observations were also theoretically supported by the near-field electromagnetic numerical simulation. More interestingly, the fabricated composite films demonstrated ultrafast nonlinear optical response in the visible light region under femtosecond laser excitation, possessing a short relaxation time of 1.45 ps for the longitudinal mode (L mode) resonance. These results indicate that the proposed composite films as a building block with exotic optical properties could provide an opportunity to construct integrated nanodevices for plasmonic optical applications.

Frequency Dependence of Electrical Parameters of an Organic-Inorganic Hybrid Composite Based Humidity Sensor

The present study highlights the interdependence of ambient humidity levels on the electrical parameters of organic-inorganic hybrid composite based humidity sensor at varied AC frequencies of input signal. Starting from the bottom, the layer stack of the fabricated humidity sensor was 200-nm silver (Ag) thin film and 4 μm spun-coated PEPC+NiPC+Cu2O active layer. Silver thin films were deposited by thermal evaporator on well cleaned microscopic glass slides, which served as a substrate. Conventional optical lithography procedure was adapted to define pairs of silver-silver surface electrodes with two sorts of configurations, i.e., interdigitated and rectangular. Humidity-sensitive layers of organic-inorganic composite were then spun-cast upon the channel between the silver electrodes. The changes in relative humidity levels induced variation in capacitance and impedance of the sensors. These variations in electrical parameters of sensors were also found to be highly dependent upon frequency of input AC signal. Our findings reveal that the organic-inorganic composite shows higher humidity sensitivity at smaller orders of frequency. This finding is in accordance with the established fact that organic semiconductors-based devices are not applicable for high frequency applications due to their lower charge carrier mobility values. Two distinct geometries of semiconducting medium between the silver electrodes were investigated to optimize the sensing parameters of the humidity sensor. Furthermore, the effect of temperature change on the resistance of organic composite has also been studied.

Micrometer-Scale Ordering of Silicon-Containing Block Copolymer Thin Films via High-Temperature Thermal Treatments.

Block copolymer (BCP) self-assembly is expected to complement conventional optical lithography for the fabrication of next-generation microelectronic devices. In this regard, silicon-containing BCPs with a high Flory-Huggins interaction parameter (χ) are extremely appealing because they form high-resolution nanostructures with characteristic dimensions below 10 nm. However, due to their slow self-assembly kinetics and low thermal stability, these silicon-containing high-χ BCPs are usually processed by solvent vapor annealing or in solvent-rich ambient at a low annealing temperature, significantly increasing the complexity of the facilities and of the procedures. In this work, the self-assembly of cylinder-forming polystyrene-block-poly(dimethylsiloxane-random-vinylmethylsiloxane) (PS-b-P(DMS-r-VMS)) BCP on flat substrates is promoted by means of a simple thermal treatment at high temperatures. Homogeneous PS-b-P(DMS-r-VMS) thin films covering the entire sample surface are obtained without any evidence of dewetting phenomena. The BCP arranges in a single layer of cylindrical P(DMS-r-VMS) nanostructures parallel-oriented with respect to the substrate. By properly adjusting the surface functionalization, the heating rate, the annealing temperature, and the processing time, one can obtain correlation length values larger than 1 μm in a time scale fully compatible with the stringent requirements of the microelectronic industry.

(Keynote) Challenges of 10 Nm and 7 Nm CMOS for Server and Mobile Applications

CMOS scaling has served the semiconductor industry and transformed the world exceedingly successfully over the past several decades. In recent times, the transition to hi-K dielectric interfaces enabled CMOS to shrink circuits to below the 32nm node. The advent of fully depleted devices (FDSOI, FINFETs) have enabled CMOS scaling to the limits of conventional 193nm optical immersion lithography. Over the past decade, CMOS scaling has transformed mobile technologies. The cell phone and smartphone have become ubiquitous as increased performance has been garnered to increase functionality on the form factor at constant power (Watt regime). The resulting boom in data has transformed industries and fueled the social network and the "app" world. 14nm FINFET technology is now available on cutting edge mobile devices. The 10nm node will see various incarnations across the major semiconductor fabricators. The pressure on density to reduce cost will result in the adoption of multiple patterning techniques for the FIN, Gate and various MIddle Of Line (MOL) and Back End Of Line (BEOL) wiring levels. The need to reduce doping in the FINFETs will result in Multi-Workfunction-Gates. Novel materials will be needed to reduce parasitic capacitance and resistance in the MOL and BEOL levels. Some incarnations of the 10nm node will be called "7nm", but the true "7nm" node circuit densities will require the next generation of lithography -- Extreme Ultra Violet (EUV) at 13.6nm wavelength. The key to adoption in the commodotized mobile space is thus the cost of the chip which is challenged by the need for novel cost intensive patterning techniques and new materials. While power and form factor are key to the mobile world, Server applications have required performance at much higher power (100+ Watt regime). CMOS scaling has served this market very well over the decades as improved transitors have always been utilized for increased performance (high end servers run > 5 GHz). The growth in the server market has migrated to large datacenters for cloud applications and away from standard transaction processing (which still remains important in many areas). Parasitic components on FINFETs are thus much more critical in this market and has thus driven early adoption of "next generation" materials and processes. The adoption of 10nm and 7nm nodes in this space will be determined less by cost than by ability to get better performance at constant chip power given the increased parasitics in the MOL and BEOL. This drives the need for introduction of new novel materials for improved performance and reliability.

Surface plasmon lithography beyond the diffraction limit

Due to the light’s diffraction feature, conventional optical lithography methods have been suffering from the diffraction limit of resolution, which imposes great obstacles for obtaining nano patterns with ultra-violet and deep ultra-violet light source. Surface plasmons (SPs) are the free electron density waves confined at the interface of metal and dielectric medium, which exhibits unique sub-diffraction optical characteristic in SP propagation, focusing and imaging performances. In recent years, benefiting from SPs’ features beyond the diffraction limit, researchers have proposed a variety of SP lithography methods in the manner of interference, imaging and direct writing, demonstrating both in theoretical simulations and experiments that the sub-diffraction resolution could be readily obtained in SP lithography just using ultra-violet light source and single exposure process. The SPs interference lithography is simple and easy to realize nano periodic patterns with short wavelength of SPs, but usually deliver some shortcomings, like greatly restricted interference area size and complex fabrications of exciting structures. Bulk plasmon polaritons formed by greatly coupled SPs was proposed and demonstrated in our work for deep subwavelength large area interference lithography without the necessity of subwavelength exciting structures. SPs lithography in direct writing manner mainly originates from localized surface plasmon resonance behaviors of nano particles or metallic tips, further investigations of bow-tie structure and SP focusing lens with specific nano structures deliver enhanced resolution and intensity efficiency and help to realize point to point writing lithography with much more flexibility. Plasmonic lens imaging lithography seems to be particular interesting for applications as projecting nano irregular patterns in one exposure step. Superlens, as a simplified version of perfect lens, provides the physical prototype of SP imaging lithography. Further, the contributions of metal-dielectric-metal cavity lens and SP wave front engineering methods, like off axis illumination and near field proximity corrections, deliver great quality improvement of lithography patterns, including resolution, aspect ratio and fidelity. Half pitch resolution down to 22 nm (~1/17 light wavelength) has been obtained in SP imaging lithography experiments. Also some functional devices, like meta-lens and polarizer, have been successfully fabricated by plasmonic lens imaging lithography. It shows that SP helps to give a potentially promising access for high resolution, efficient, large area and low cost nano lithography tools. Besides the review and analysis of research progress, representative achievements of SP lithography, the remained problems and outlook of further developments are presented as well in this review.