We report that the diffraction limit of conventional optical lithography can be overcome by exploiting the transitions of organic photochromic derivatives induced by their photoisomerization at low light intensities.1-3 This paper outlines our fabrication technique and two locking mechanisms, namely: dissolution of one photoisomer and electrochemical oxidation.
This protocol describes the fabrication and characterization of nanostructures using a novel nanolithographic technique called Patterning via Optical Saturable Transitions (POST). In this technique the chemical properties of organic photochromic molecules that undergo single-photon reactions are exploited, enabling rapid top-down nanopatterning over large areas at low light intensities, thereby, allowing for the circumvention of the far-field diffraction barrier.4 Simple, cost-effective, high throughput and resolution alternatives to nanopatterning are being explored, such as, two-photon polymerization5,6, beam pen lithography (BPL)7, scanning electron beam lithography (SEBL), and focused ion beam (FIB) patterning. However, multi-photon approaches require high light intensities, which limit their potential for high throughput and offer low image contrast. Although, electron and ion beam lithographic processes offer increased resolution, the serial nature of the process is limited to slow writing speeds, which also prevents patterning of features over large areas. Beam-pen lithography is an approach towards parallel near-field optical lithography. However, the gap between the source of the beam and the surface of the photoresist needs to be controlled extremely precisely for good pattern uniformity and this is very challenging to accomplish for large arrays of beams. Patterning via Optical Saturable Transitions (POST) is an alternative optical nanopatterning technique for patterning sub-wavelength features1-3. Since this technique uses single photons instead of electrons, it is extremely fast and does not require high light intensities1-3, opening the door to massive parallelization.
광학 리소그래피는 나노 구조 및 장치의 제조에 대단히 중요하다. 새로운 리소그래피 기술의 향상 발전은 새로운 장치의 새로운 세대를 가능하게하는 기능이있다. 8 ~ 11이 글에서 검토가 새로운 환성 분자를 사용하여 깊은 파장 이하의 해상도를 달성 광 리소그래피 기술의 클래스 표시됩니다. 이 방법은 광학 – 가포 전환 (POST)를 통해 패턴 화라고합니다. 1-3
POST 고유 즉, (1,2- 비스 (5,5'- 디메틸 -2,2'- bithiophen 일))의 광 변색 성 분자 천이 포화의 사상을 겸비한 신규 한 나노 기술 perfluorocyclopent -1- 엔이다. 놓고,이 화합물을 그 larg의 강력한 도구하게 간섭 리소그래피와 같은 유도 방출 핍층 (STED) 현미경 (12)에 사용되는 것과 같은 BTE,도 1이라2 및 3 차원의 잠재적 인 확장과 다양한 표면 위에 깊은 서브 파장 기능의 전자 영역 병렬 나노 패터닝.
광 변색 층은 원래 하나의 균질 한 상태입니다. 이 층은 λ (1)의 균일 한 조명에 노출되는 경우, 제 2 이성체 상태 (도 1c),도 2로 변환한다. 그 후 샘플은 제 이성체 상태로 샘플 (변환 λ (2)에 포커싱 된 노드에 노출 1O) 사방 노드의 근처 부근에서 제외. 노광량을 제어함으로써, 전환되지 않은 영역의 크기는 임의로 작게 만들어 질 수있다. 이성체 중 하나의 후속 정착 단계는 선택적으로 패턴을 비가 역적으로 잠글 (블랙) 3 차 상태 (잠금) 변환 될 수있다. 이어서, 층을 다시 원래의 상태로 락 영역을 제외한 모든 변환 한 λ, 균일 노출된다.단계들의 시퀀스는 그 간격 원방 회절 한계보다 작은 두 잠긴 영역 결과적으로 광학 샘플의 상대 변위로 반복 될 수있다. 따라서, 임의의 형상은 "도트 매트릭스"방식으로 패턴 화 될 수있다. 1-3
The fabrication, experimental setup and related operational procedures of Patterning via Optical Saturable Transitions (POST) have been described. By exploiting the linear switching properties of thermally stable photochromic molecules, POST offers new perspectives on circumventing the far-field diffraction limit.1-2,4
Previously long-term storage requirement of the samples was solved by storing the samples under N2, directly after the initial evaporation.2 How…
The authors have nothing to disclose.
Thanks to Michael Knutson, Paul Hamric, Greg Scott, and Chris Landes for helpful discussions and assistance related to the custom inert atmosphere sample holder and assistance in the University of Utah student machine shop. P.C. acknowledges the NSF GRFP under Grant No. 0750758. P.C. acknowledges the University of Utah Nanotechnology Training Fellowship. R.M. acknowledges a NSF CAREER Award No. 1054899 and funding from the USTAR Initiative.
Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
Isopropanol | Fisher Scientific | P/7500/15 | CAUTION: flammable, use good ventilation and avoid all ignition sources. |
Buffered Oxide Etch | |||
Methanol | Ricca Chemical | 48-293-2 | CAUTION: flammable, use good ventilation and avoid all ignition sources. |
Ethylene Glycol | Sigma-Aldrich | 324558 | CAUTION: Harmful if swallowed |
Silicon wafer | |||
Diamond Scribe | |||
Glass Beakers | |||
Tweezers | Ted Pella | 5226 | |
Reactive Ion Etching System | Oxford | Plasma Lab 80 Plus | |
Inert Atmosphere Sample Holder | Proprietary In-house Designed | ||
Polarizing beamsplitter cube | Thorlabs | PBS052 | |
HeNe Laser | Melles Griot | 25-LHP-171 | CAUTION: Wear safety glasses |
Half-wave plates | Thorlabs | WPH05M-633 | |
Thermal Evaporator | Proprietary In-house Designed | ||
TMV Super | TM Vacuum Products | TMV Super | |
Voltammograph | Bioanalytical Systems | CV-37 | |
Shortwave UV lamp 365nm | UVP Analytik Jena Company | UVGL-25 | CAUTION: Wear UV safety glasses |