# US 8,465,910 B2 · Hybrid lithographic method for fabricating complex multidimensional structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,910 B2 - Document ID: US8465910B2 - Status: Granted - Kind: B2 - Application number: 13/171,954 - Filed: 2011-06-29 - Published: 2012-06-28 - Granted: 2013-06-18 - Earliest claimed: 2010-07-06 - Assignees: Massachusetts Institute of Technology - Applicants: Jonathan Phillip Singer; Jae-Hwang Lee; Steven E. Kooi; Edwin Lorimer Thomas - Inventors: Jonathan Phillip Singer; Jae-Hwang Lee; Steven E. Kooi; Edwin Lorimer Thomas - Web page: https://patentgrep.com/patent/US8465910B2 ## CPC - G03F 7/203: {comprising an imagewise exposure to electromagnetic radiation or corpuscular radiation} - B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic - B82Y 40/00: Manufacture or treatment of nanostructures - G03F 1/20: Masks or mask blanks for imaging by charged particle beam [CPB] radiation, e.g. by electron beam; Preparation thereof - G03F 7/0002: {Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping} - G03F 7/70375: {Multiphoton lithography or multiphoton photopolymerization; Imaging systems comprising means for converting one type of radiation into another type of radiation} - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES ## Abstract Lithographic Method. The method fabricates complex structures and includes depositing a photoresist onto a substrate, the photoresist including a predominantly thermal band of optical absorption possibly due to the incorporation of a doping agent. A three-dimensional pattern is generated within the resist using a first wavelength of light to effect activation of a photoinitiator to produce a latently photostructured resist. Focused laser spike annealing of the photostructured resist with a second wavelength of light selected to be absorbed by the thermally absorbing band to accelerate the photoinduced reaction in the resist is provided. Three-dimensional direct writing may be performed within the resist to define features not part of the interference pattern and the resist is developed to produce the complex structure. ## Claims ### Claim 1 Lithographic method for fabricating a complex structure comprising: depositing a photoresist onto a substrate; generating a three-dimensional optical pattern within the resist using a first wavelength of light to effect activation of a photoinitiator in the resist to produce a latently photostructured resist; focused laser spike annealing of the photostructured resist with a second wavelength of light, selected to be absorbed by the photoresist accelerate the photoinduced reaction of the first exposure in the resist locally by production of heat and; developing the resist to produce the complex structure wherein the amount of time before performing the focused laser spike annealing is controlled to control the progression of the crosslinking reaction of the exposed areas. ### Claim 2 (depends on 1) The lithographic method of claim 1 wherein an additional absorbing dopant is incorporated. ### Claim 3 (depends on 2) The lithographic method of claim 2 wherein the optically absorbing doping agent comprises dyes, metallic or semiconductor nanoparticles or metallic shell particles. ### Claim 4 (depends on 1) The lithographic method of claim 1 wherein three-dimensional direct writing is subsequently performed within the resist to define features not part of the interference pattern using a writing process with disparate optical parameters of either the lithographic steps described in claim 1. ### Claim 5 (depends on 1) The lithographic method of claim 1 wherein the first and second wavelengths of light are different. ### Claim 6 (depends on 1) The lithographic method of claim 1 wherein the optically absorption arises from intrinsic absorption of one or more components of the photoresist. ### Claim 7 (depends on 1) The lithographic method of claim 1 wherein the three-dimensional optical pattern is generated by multiple exposures. ### Claim 8 (depends on 1) The lithographic method of claim 1 wherein the three-dimensional optical pattern is generated by phase mask or multibeam interference lithography. ### Claim 9 (depends on 8) The lithographic method of claim 8 wherein phase mask interference lithography is used and the mask contains multiple patterns and/or alignments. ### Claim 10 (depends on 1) The lithographic method of claim 1 wherein the beam power and/or dwell time of the second exposure is selected to variably control cross linking density, feature size, and subsequently fill fraction. ### Claim 11 (depends on 1) The lithographic method of claim 1 wherein the focused laser spike annealing uses a system of optics including a microscopic objective or multi-lens array of relatively high numerical aperture. ### Claim 12 (depends on 11) The lithographic method of claim 11 further providing switchable optics to allow for multiple feature sizes. ### Claim 13 (depends on 11) The lithographic method of claim 11 wherein the numerical aperture is greater than 0.4. ### Claim 14 (depends on 1) The lithographic method of claim 1 wherein the focused laser spike annealing uses non-Gaussian focused beams. ### Claim 15 (depends on 14) The lithographic method of claim 14 wherein the non-Gaussian beam has a toroidal beam shape. ### Claim 16 (depends on 1) The lithographic method of claim 1 wherein the complex structures are suspended above the substrate. ### Claim 17 (depends on 1) The lithographic method of claim 1 wherein the focused laser spike annealing uses continuous wave, pulse, or incoherent light sources. ### Claim 18 (depends on 17) The lithographic method of claim 17 further including providing a piezoelectric or mechanical stage or galvano or polygon mirrors to control lateral and axial position of focal points of the second wavelength light in a direct write process. ### Claim 19 (depends on 1) The lithographic method of claim 1 where the lateral and axial positioning of the focal points are controlled by a single mask optic such as a zone plate array to write in a single exposure. ### Claim 20 (depends on 1) The lithographic method of claim 1 wherein the complex structure is periodic or quasiperiodic. ### Claim 21 (depends on 1) The lithographic method of claim 1 wherein the photoresist is a positive or negative tone chemically amplified photoresist. ### Claim 22 (depends on 1) The lithographic method of claim 1 further including a variable shutter so that line and texture may be varied discretely or continuously allowing for three-dimensional filling fraction distributions. ### Claim 23 (depends on 1) The lithographic method of claim 1 further manipulating the thermal properties of the resist to affect the thermal distribution. ### Claim 24 (depends on 23) The lithographic method of claim 23 where manipulation is performed by changing the substrate, superstrate, immersion liquid or other sample features to manipulate the thermal conductivity surrounding the resist. ### Claim 25 (depends on 23) The lithographic method of claim 23 where the manipulation is performed by altering thermal conductivity of the resist with fillers such as carbon nanotubes. ### Claim 26 (depends on 23) The lithographic method of claim 23 where the manipulation is performed by heating or cooling the resist or substrate. ### Claim 27 (depends on 1) The lithographic method of claim 1 where the temperature is lowered to slow the rate of the crosslinking reaction. ### Claim 28 (depends on 1) The lithographic method of claim 1 where the temperature is raised to accelerate the rate of the crosslinking reaction. ### Claim 29 Lithographic method for fabricating a complex structure comprising: depositing a photoresist onto a substrate; generating a three-dimensional optical pattern within the resist using a first wavelength of light to effect activation of a photoinitiator in the resist to produce a latently photostructured resist; focused laser spike annealing of the photostructured resist with a second wavelength of light selected to be absorbed by the photoresist to accelerate the photoinduced reaction of the first exposure in the resist locally by production of heat and; developing the resist to produce the complex structure where the three-dimensional optical exposure is cleared by an additional step allowing for multiple cycles of exposure and annealing in the same deposited resist.