Chapter Four · failure evidence
What Photolithography & Microfabrication got wrong, from 65 dissertations
Microfabrication and photolithography investigations regularly encounter critical bottlenecks involving throughput constraints, optical diffraction limits, and chemical incompatibilities. Across diverse substrates and microdevices, processes suffer from film adhesion failures, mechanical collapse of delicate features, and stereolithographic resin defects. These records come from PhD theses at 22 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
High equipment costs, slow patterning speeds, and throughput limitations restrict fabrication scalability
Researchers frequently reject electron beam lithography, cleanroom photolithography, and direct laser writing because of excessive operational costs and long processing times. These top-down approaches also struggle with low manufacturing throughput and complex multistep alignment when scaling up array or chip fabrication.
Lost to a baseline
SLP negative-tone polymer printing rate is 35 times slower than commercial projection two-photon lithography (Saha et al., 2019)
Rapid and Affordable Nanoscale Printing via Projection of Superluminescent Light · Georgia Tech
Considered and rejected
Considered and rejected: Rejected microstereolithography and direct laser/e-beam writing due to high equipment cost and incompatibility with high-throughput array manufacturing.
Reactive ion etching techniques for uncooled pyroelectric detectors · Cranfield
Considered and rejected
Considered and rejected: Additively manufactured microfeatures via inkjet printing or FDM 3D printing, rejected for general sensor fabrication in favor of the polymer abrading technique due to high hardware complexity, cost, and specialized equipment requirements.
Considered and rejected
Considered and rejected: Rejected stereolithography 3D printing due to restriction to photo-curable resins which limits scalability to common mass-produced substrates.
Design automation and rapid prototyping of multi-component droplet microfluidic platforms · OpenBU
Considered and rejected
Considered and rejected: Rejected soft photolithography for fabricating small channels, choosing direct casting of PDMS over 3D-printed masters to improve fabrication speed and cost.
Considered and rejected
Considered and rejected: Rejected using electron beam lithography for patterning global alignment markers due to high cost and low throughput compared to photolithography.
Two-Dimensional Steep-Slope Transistors · DSpace at SUNY Buffalo
Considered and rejected
Considered and rejected: Rejected standard cleanroom photolithography/wet etching for scalable sleep patch manufacturing due to high cost, low yield, and radial over-etching across wafers in favor of femtosecond laser micromachining.
Study Of Soft Materials, Nano-Microfabrication, And Flexible Packaging For Developing Wearable Flexible Hybrid Electronics · Georgia Tech
Considered and rejected
Considered and rejected: Rejected PDMS dome combined with chrome-on-glass photolithography base (from 2019 baseline) due to high cost, time-consuming fabrication, and poor 3D scalability.
Considered and rejected
Considered and rejected: Rejected soft lithography for mold fabrication because the size and complexity of the chip geometry made it impractical, choosing 3D printing instead
Design and Testing of a Bubble Generator for Molten Salt Surrogate Fluid · Virginia Tech
Considered and rejected
Considered and rejected: Rejected top-down lithographic techniques (e-beam or polymer pen lithography) for substrate patterning due to high equipment cost, poor scalability, and substrate incompatibility.
Fabrications and Applications of Protein-based Bionanocomposites · Virginia Tech
Considered and rejected
Considered and rejected: Microscope projection photolithography (MPP) was rejected for micropatterning coverslips due to its small exposure area (~10^4 µm^2), making large cm-scale culture areas too labor-intensive.
Single Cell Transcriptomics and Spatial Localization in Mouse Neurons · Penn
Considered and rejected
Considered and rejected: Rejected lithographically patterned apertures on-chip for time-domain modulation due to microfabrication costs (>10¢/chip) and throughput limits (<5k drops/s)
Considered and rejected
Considered and rejected: Rejected PDMS channel microfabrication with cleanroom lithography for the final multiplexed diagnostic device due to high manufacturing cost, complexity, and electrode deposition hurdles.
Engineering DNA-based electrochemical diagnostics for translational applications · MIT
Considered and rejected
Considered and rejected: Rejected two-step electron-beam lithography for large-area hybrid graphene-metal antidots due to alignment complexity, choosing single-step self-aligned photolithography with AZ5214E undercut
Advanced Nanophotonics Resonator Designs for High-Performance Surface-Enhanced Vibrational Spectroscopy Sensing Applications · DSpace at SUNY Buffalo
Optical diffraction limits, proximity effects, and exposure dose errors distort fine features
Conventional contact, projection, and optical lithography fail to resolve sub-micron features because of diffraction limits, light spreading, and proximity effect broadening. Additionally, underexposure or narrow exposure dose windows produce feature rounding, distorted geometries, and merged adjacent structures.
Tried and failed
maskless photolithography of thick photoresist applied to large-area microfluidic master mold fabrication. Reason: failed to faithfully reproduce fine features across large wafers, resulting in inaccurate feature spacing and fluid leakage
Multi-Niche Human Bone Marrow On-A-Chip for Studying the Interactions of Adoptive Cell Therapies with Multiple Myeloma · Georgia Tech
Tried and failed
standard short UV exposure photolithography applied to photodegradable polymer micropatterning. Reason: insufficient photochemical degradation left polymer insoluble in aqueous developer
Single Cell Transcriptomics and Spatial Localization in Mouse Neurons · Penn
Tried and failed
contact aligner photolithography applied to sub-micron feature patterning. Reason: optical diffraction limits in contact printing prevented achieving sub-micron resolution
Simulation, Generation, and Detection of Low Emittance Electron Beams for Ultrafast Science · Cornell
Tried and failed
projection photolithography for direct metal photoreduction applied to arbitrary 2D metal micropatterning. Reason: reaction-diffusion of reactive species circularized sharp features and filled internal voids
Rapid and Affordable Nanoscale Printing via Projection of Superluminescent Light · Georgia Tech
Lost to a baseline
Visible meta-optics fabricated with laser direct-write (HiRes) exhibited lower resolution and patterned shell-like artifacts compared to electron beam lithography (JEOL JBX6300FS).
MEMS-integrated Alvarez Metalenses and Large-area Meta-optics · ResearchWorks
Considered and rejected
Considered and rejected: Conventional photolithography methods due to the diffraction limit when attempting large-area sub-10 nm 3D nanofabrication
Shift-Free Wide-Angle Optical Thin-Film Metamaterial Notch Filter for Visible Laser Protection Systems · Cranfield
Tried and failed
optical photolithography using positive photoresist applied to dense micron-scale line arrays. Reason: optical cross-talk and proximity effect broadening degraded resolution of densely spaced features
Tried and failed
low-dose electron-beam lithography applied to sub-micron optical waveguide couplers. Reason: underexposure caused distorted fine features, rough edges, and severe coupling transmission losses
Tried and failed
thick single-layer photoresist lithography applied to submicron channel patterning. Reason: narrow dose window led to underdevelopment at low exposure and feature rounding at high exposure
DECIPHERING BACTERIAL CELL ENVELOPE MECHANICS AND MECHANOSENSING: A MECHANICAL ENGINEERING APPROACH · Cornell
Tried and failed
dielectric nanopillar metasurface fabrication applied to optical linear polarizers. Reason: Feature oversizing during lithography caused adjacent nanopillars to merge, introducing unwanted optical phase retardance.
Metasurface-enhanced Multispectral and Polarization Filtering for SPAD imaging sensors · EPFL
Considered and rejected
Considered and rejected: Standard photolithography for contact patterning was rejected due to 2 μm resolution limit and unique flake geometries.
Transient Investigations of High-Field Conduction in Low-Dimensional Materials · DSpace at SUNY Buffalo
Considered and rejected
Considered and rejected: Rejected Ga+ or Au+ focused ion beam (FIB) lithography because limited ion penetration depth in thick PMMA (100 nm) reduces pattern fidelity and aspect ratio
Single Crystal Metal–Organic Framework Field–Effect Nanosensors · JScholarship
Considered and rejected
Considered and rejected: Rejected traditional optical interference lithography for fine gratings below 300 nm due to wavelength diffraction limits, switching to E-beam lithography.
Techniques for Reducing Beam-Induced Damage in Electron Microscopy · MIT
Chemical attack, solvent degradation, and resin leaching damage substrates and inhibit processing
Photoresists, developers, and stripping solvents chemically attack underlying polymer layers and cause oxidation or degradation in sensitive two-dimensional materials. In stereolithography applications, uncured resins and photoinitiators leach into cast materials to inhibit curing reactions or generate cytotoxicity concerns.
Tried and failed
Casting PDMS in SLA 3D printed molds applied to Microfluidic device fabrication. Reason: Uncured resin components and photoinitiators leach into PDMS and inhibit platinum-catalyzed crosslinking
Design and development of cost-effective and portable 3D printed biomedical equipment · Iowa State
Tried and failed
SEBS elastomeric substrate photolithography applied to sub-micron multilayer stretchable microelectronics. Reason: SEBS elastomer is incompatible with sub-micrometer multilayer photolithography processing
Bioelectronics for Cellular Electrophysiology during Tissue Development · Harvard
Tried and failed
standard electron-beam lithography with polymer resists applied to air-sensitive thin 2D material flakes. Outcome: unstable. Reason: causes chemical degradation and oxidation of thin flakes even when using dry solvents
Probing Quantum Geometric Phenomena in Antiferromagnetic Topological Insulators · Harvard
Considered and rejected
Considered and rejected: Rejected photolithography and e-beam lithography for semiconductor patterning due to solvent/chemical degradation and steep edge angles increasing contact resistance.
Analysis of the Contact Resistance of Organic Thin-Film Transistors · EPFL
Considered and rejected
Considered and rejected: Rejected conventional photolithography with PMMA photoresist in favor of shadow masking to prevent polymer residue contamination and p-type doping on 2D transducers.
Wide- and zero-bandgap nanodevices for extreme biosensing applications · OpenBU
Considered and rejected
Considered and rejected: Rejected Glyseal for mounting wafers onto backing wafers during back-side photolithography due to contamination residues; unbaked, unexposed photoresist was used instead
High frequency thin-film bulk acoustic wave resonators for gas- and bio-analytical applications · Cranfield
Tried and failed
drop-casting unwashed polyurethane polymer matrices applied to photocatalytic membrane fabrication. Outcome: unstable. Reason: unwashed pristine polymer matrices leach unreacted material into aqueous solution during irradiation cycles
Light-activated materials for singlet oxygen generation and the degradation of pollutants · unevada
Considered and rejected
Considered and rejected: Rejected lift-off photolithography for patterning top gold electrodes on ferroelectric polymers because standard photoresist solvents (e.g., acetone) damage the polymer structure.
Ferroelectric and energy storage characterization of PVDF-based thin films and nanocomposites · DSpace-CRIS at TU Wien
Considered and rejected
Considered and rejected: Rejected photolithography lift-off on top of polymer thin films because resist solvent (PGMEA) and stripping solvents (acetone) chemically attack and crack the polymer.
Ferroelectric polymer thin films for MEMS applications : towards soft and high-speed AFM probes · DSpace-CRIS at TU Wien
Considered and rejected
Considered and rejected: Rejected stereolithography (SLA) 3D printing in favor of FDM due to toxicity and leaching of unreacted photoinitiators/resins.
A Multifaceted Approach to Preserve Effective Antibiotics Utilizing Antibiotic Susceptibility Testing, Antimicrobial Coatings or Glycomimetic Adjuvants · Publikationssystem UB Tuebingen
Considered and rejected
Considered and rejected: Solvent-based extrusion and SLA stereolithography for PCL bioscaffolds were rejected due to altered mechanical rigidity, bridging limits, and potential cytotoxicity/crosslinker biocompatibility concerns.
Additive Manufacture of Parametrically Modulated Porous Scaffold Architectures for Medical Device Applications · Research Repository UCD
Surface non-planarity, film stress, and poor adhesion cause resist pooling and lift-off defects
Non-planar topographies and deep trenches cause photoresist to pool unevenly, destroying coating uniformity and degrading lithographic patterning resolution. Film stress, incorrect resist thickness, and buried sacrificial structures trigger film peeling, delamination during stripping, and lift-off failures.
Tried and failed
photolithography over deep pre-etched topographical trenches applied to heater electrode patterning on semiconductor chips. Reason: Photoresist pooled unevenly into trenches, degrading spin-coating uniformity and destroying photolithographic resolution
InGaAs/InP chip-based mid-infrared optical phased arrays for communications and sensing · UT Austin
Tried and failed
metal deposition on under-exposed negative photoresist applied to flexible thin-film electrode fabrication. Reason: sub-optimally exposed photoresist led to weak adhesion causing metal delamination during stripping
Organic electrochemical transistors for neurotechnology · Imperial
Tried and failed
deep ultraviolet lithography with negative photoresists applied to microstructure patterning. Outcome: unstable. Reason: optical incompatibility and high film stress causing poor substrate adhesion
Programmable Magnetics for Microscopic Assembly, Metamaterials, and Robots · Cornell
Tried and failed
additive lithography with wet etching applied to thin-film metal patterning on substrates. Reason: film peeling and unwanted metal-resist bridges occurred when resist thickness matched film thickness
Superconducting Coplanar Waveguides for High Fidelity Operation of Quantum Repeaters · Harvard
Tried and failed
two-step aerosol-assisted chemical vapor deposition applied to photoanode thin film fabrication. Outcome: unstable. Reason: poor substrate adhesion and mechanical instability caused low photocurrent
Interface engineering for photoelectrochemical water oxidation · Imperial
Considered and rejected
Considered and rejected: Lift-off process using photoresist spin-coating on patterned 50 µm SU-8 microdisks was rejected due to severe non-planarity and non-uniform resist coating; stencil lithography was used instead.
Laser-Induced Forward Transfer of Functional Microdevices · EPFL
Tried and failed
nanosphere lithography lift-off patterning applied to thick multilayer thin-film deposition. Reason: deposited material thickness buried etched mask spheres, preventing solvent access and lift-off removal
Tried and failed
multi-scale feature etching with uniform resist mask applied to photonic crystal cavity nanofabrication. Reason: Resist thickness could not clear small features without failing to protect large features during multi-step etching.
Diamond Nanostructures with Color Centers for Quantum Technology Experiments · Harvard
Resin entrapment, demolding peel forces, and resolution limits impair stereolithography
Additive microfabrication suffers from uncured liquid resin becoming trapped within microscale cavities and clogging fine negative features. Furthermore, separation peel forces tear delicate low-modulus elastomeric structures during vat printing, while resolution limits cause channel defects and fluid leakage.
Tried and failed
3D printing microfluidic channels applied to acoustofluidic device fabrication. Reason: insufficient printing precision and material acoustic incompatibility with the transducer
Design and development of cost-effective and portable 3D printed biomedical equipment · Iowa State
Tried and failed
stereolithography 3D printing of negative microcavity features applied to micropatterned mold fabrication. Reason: uncured liquid resin remained trapped and clogged within microscale negative hole features during printing
Programming Complex Alignment in Engineered Cardiac Tissue · Harvard
Tried and failed
3D-printed and milled molds for soft lithography applied to microfluidic channel fabrication. Reason: Molds produced via stereolithography, FDM, and CNC milling failed to yield functional PDMS channels
Tried and failed
stereolithography at extreme layer resolutions applied to fluidic manifolds. Reason: High resolution caused thread defects and excessive print time; low resolution lacked precision, causing leaks.
Extending human interaction capabilities with soft robotics · EPFL
Tried and failed
stereolithography 3D printed molds for elastomer casting applied to miniature soft structural components. Reason: printer resolution limits and small feature sizes rendered printed molds unusable
Manipulating Stiffness of Biomechanical Systems to Train Muscle · MIT
Tried and failed
stereolithography printing with low-modulus elastomeric resin applied to cellular lattice structures. Reason: vat adhesion peel forces during separation tore delicate low-stiffness layers apart during printing
Development and mechanical characterisation of additively manufactured lattice structures · Imperial
High aspect ratio collapse, microgap electrical shorting, and mechanical rupturing cause device failure
High-aspect-ratio resist bridges collapse during development, and small electrode gaps produce severe microfabrication shorting defects. Weakly crosslinked polymer matrices and bent conductive traces also suffer mechanical tearing and microcracking under applied fluidic or physical strain.
Tried and failed
planar conductive ink deposition prior to substrate deformation applied to flexible sensor fabrication. Reason: Bending induced mechanical microcracking, drastically increasing electrical resistance and introducing non-smooth voltage fluctuations.
Modular Robots Morphology Transformation And Task Execution · Penn
Tried and failed
fluid evacuation combined with bulk photopolymerization applied to granular hydrogel scaffold fabrication. Outcome: unstable. Reason: polymerized scaffold ruptured mechanically upon re-exposure to fluid flow
Tried and failed
photopolymerization with low precursor or initiator concentration applied to hydrogel fabrication. Reason: insufficient crosslinking led to hydrogels that were too mechanically weak to handle
POLYMERIZATION AND VOLUMETRIC PRINTING OF SOFT COMPOSITES · Cornell
Tried and failed
low-voltage electron-beam lithography for high-aspect-ratio nanogaps applied to coupled nanophotonic waveguides. Outcome: unstable. Reason: resist bridges collapsed during development due to high aspect ratio and low beam energy
Enhanced infrared sensing with plasmonic metasurfaces and undetected light · Imperial
Tried and failed
Hole-based photonic crystal polarization reflectors applied to optical state transfer fidelity. Reason: Extreme fabrication intolerance where nanometer-scale feature deviations cause severe fidelity loss
Techniques for Deployed Quantum Networks with Solid-State Defect Centers · MIT
Tried and failed
Non-faradaic impedance spectroscopy on microgap interdigitated electrodes applied to bacterial cell detection. Outcome: unstable. Reason: High microfabrication shorting defects and unrepeatable impedance spectra at small interelectrode spacings
The impact of mass transport and surface charging on the performance of field effect transistor biosensors · Georgia Tech
Left open by the authors
Problems the authors named and did not get to.
Left open
Increase 3D printing resolution to fabricate thinner microfluidic channels and denser micropillar arrays for improved processing throughput. Blocker: Requires a physical wet lab, specialized high-resolution 3D printing hardware, and microfabrication materials.
Negative Enrichment of Circulating Tumor Cells Via 3D Printed Microfluidic Device · Georgia Tech
Left open
Investigate faster and cheaper deposition alternatives to ALD or alternative dielectrics like SiO2 for photonic crystal cavity filling. Blocker: Requires cleanroom fabrication facilities, wet lab chemistry, and thin-film deposition equipment.
Left open
Develop microfabricated small-scale well plates on microscope slides using two-photon polymerisation for single-FOV imaging with acoustic droplet dispensing. Blocker: Requires a physical microfabrication wet lab, two-photon polymerisation equipment, and acoustic droplet dispensers.
Parallel synthesis and screening of optical probes for G-quadruplex DNA · Imperial
Left open
Fabricate polymer interdigitated pillar electrostatic actuators scaled to micrometer dimensions using two-photon 3D printing or deep reactive-ion etching. Blocker: Requires cleanroom microfabrication equipment, two-photon 3D printers, or DRIE silicon etching apparatus
HIGH VOLTAGE PYROELECTRIC GENERATION, ELECTROSTATIC ACTUATORS, AND SENSING IN MICROSYSTEMS · Cornell
Left open
Design cost-effective integration of on-chip optical interconnects on PCBs to replace electrical traces. Blocker: Requires specialized hardware fabrication, optical engineering lab equipment, and physical prototyping facilities.
Physical Layer Data Integrity Attacks and Defenses in Cyber-Physical Systems · Virginia Tech
Left open
Replicate perovskite solar cell fabrication at larger scale using scalable techniques like inkjet printing, doctor blade printing, or slot-die coating. Blocker: Requires a wet-lab setup and physical deposition equipment (e.g., slot-die coater, inkjet printer).
Efficient planar formamidinium-based perovskite solar cells · Imperial
Left open
Develop glaucoma microshunt prototypes using alternative non-biodegradable gelatin copolymer materials and fabrication methods. Blocker: Requires a wet lab and specialized microfabrication equipment (e.g., projection micro-stereolithography) for polymer synthesis and prototype fabrication
A Novel Squid Glaucoma microShunt for Controlled Release of Aqueous Humor · DSpace at UTSWMED
Left open
Fabricate complex 3D microstructures using direct-write printing across alternative material systems beyond simple glasses. Blocker: Requires a physical high-temperature direct-write microfabrication apparatus and material synthesis lab.
MOLTEN-BASED 3-D DIRECTWRITE FABRICATION OF MICRO STRUCTURES · Georgia Tech
Left open
Design and fabricate nanoscale 3D-printed filters with parametric pores via two-photon lithography to maximize pathogen-SERS nanostructure apposition. Blocker: Requires advanced physical fabrication hardware (two-photon lithography system) and specialized materials/lab facilities.
Raman spectroscopy for point of care urinary tract infection diagnosis · Imperial
Left open
Optimize electrode geometry, impedance frequency, and polyaniline layer thickness for the printed root-monitoring sensors. Blocker: Requires wet lab fabrication facilities for screen printing and electrochemical sensor testing
Plant-on-a-chip: monitoring chemical responses in living plants with printed sensors · Imperial
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