光可飽和遷移を経由してパターニング - 作製と特性評価
Summary
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.
Abstract
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.
Introduction
光リソグラフィは、ナノスケール構造およびデバイスの製造において極めて重要である。増加した小説リソグラフィ技術の進歩は、新規のデバイスの新世代を可能にする機能を備えています。この記事では8-11、レビューは小説photoswitchable分子を用いたディープサブ波長分解能を達成光学リソグラフィ技術のクラスで提示されている。このアプローチは、光学-可飽和トランジションズ（POST）を介してパターニングと呼ばれている。1-3
POST一意フォトクロミック分子の光学遷移を飽和のアイデアを組み合わせた新規なナノ加工技術、特に（1,2-ビス（5,5'-ジメチル-2,2'-ビチオフェンイル））perfluorocyclopent -1-エンである。口語的に、この化合物は、それラーグのための強力なツールとなる干渉リソグラフィを用いて、そのような誘導放出枯渇（STED）顕微鏡12で使用されるようなBTE、 図1と呼ばれ2位と3次元への潜在的な拡張子を持つ多様な表面の上に深いサブ波長機能の電子面積並列ナノパターニング。
フォトクロミック層はもともと1均一な状態である。この層は、λ1の一様な照明に曝されると、第2の異性体の状態（1c）は 、 図2に変換する。次いで、サンプルは、最初の異性体の状態にサンプルを（変換λ2、に集中ノードにさらされている1O）どこでもノードの近く付近で除く。露光量を制御することにより、未変換領域の大きさは任意に小さくすることができる。異性体の1つのその後の定着工程は、選択的かつ不可逆的にパターンをロックする（黒で）3 番目の状態（ロック状態）に変換することができる。次に、層は、元の状態に戻しロックされた領域以外のすべてを変換するλ1、一様にさらされている。ザ·ステップの順序は、その間隔が遠視野回折限界以下の2つのロックされた領域で、その結果、光学系に対する試料の変位を繰り返してもよい。したがって、任意の幾何学的形状は、「ドットマトリックス」方式でパターニングしてもよい。1-3
Protocol
Representative Results
Discussion
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…
Disclosures
The authors have nothing to disclose.
Acknowledgements
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.
Materials
| 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 |
References
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