A New Method of Photopatterning with LB Films Based on a Chemically Amplified Mechanism

A new approach to introducing a photoacid generator（PAG） into Langmuir-Blodgett （LB） films to draw photopatterns as a lithographic process is described here. The chemically amplified positive-tone resist system used here consists of two components ： a copolymer, poly （ dodecrylacrylamide-co-4-t-butyloxylvinyl-phenylcarbonate ） [ P （ DDA-t- BVPC53 ） ] and a PAG, tri （2,3-dibromopropyl） isocyanurate （ TDBPIC ）. In the two-component system, the acid generated by the PAG catalyzes the deprotection reaction of P（ DDA-t-BVPC53）, to remove the tert-butoxycarbonyl group（t-BOC） in the exposed region during the postexposure baking process, thus rendering the exposed region soluble to alkaline aqueous solvents to form a positive tone. Photolithographic properties of the LB films have been evaluated. The patterns can be resolved with a resolution of 1 μm line width by UV irradiation, followed by development with an alkaline solution. The LB films can be used to generate etched gold relief images on a glass substrate via an aqueous iodide, like ammonium iodide, in alcohol/water as the etchant. The etch resistance of such LB films is sufficiently good, allowing patterning of a gold film suitable for photomask fabrication.

Chemically Amplified Resist Based on Dendritic Molecular Glass for Electron Beam Lithography

A novel dendritic molecular glass(MG)containing adamantane core(AD-15)was synthesized and characterized.It exhibits good solubility in common organic solvents and a stable amorphous state at room temperature,which contributes to forming films with different thicknesses by spin-coating.The thermal analysis of AD-15 indicates that no apparent glass transition temperature(Tg)is observed before the thermal decomposition temperature(Td=160℃).The good thermal resistance suggests that it can satisfy the lithographic process and is a candidate for photoresist materials.The patterning properties of AD-15 resist were evaluated by electron beam lithography(EBL).By optimizing the lithographic process parameters,AD-15 resist can achieve 40 nm half-pitch patterns with a line-edge roughness of 4.0 nm.The contrast and sensitivity of AD-15 resist were 1.9 and 67µC/cm^(2),respectively.Compared with the commercial PMMA(950k)electron beam resist,the sensitivity of AD-15 resist increases by 6 times.This study provides a new example of molecular glass resist with high resolution and sensitivity for EBL.

Novel One-component Positive-tone Chemically Amplified I-Line Molecular Glass Photoresist Based on Tannic Acid

Molecular glass resist has been considered as one of the best choices for a new generation of lithography. In this work, a new type of photoaetive compound was obtained by the esterification of tannic acid with 2-diazo-1- naphthoquinone-4-sulfonyl chloride（2,1,4-DNQ-Cl） and ditertbutyl dicarbonate. The new obtained compound pos- sessed both a photosensitive group of diazonaphthoquinone sulfonate（2,1,4-DNQ） and a group of acidolytic protection. Upon the irradiation of the compound under 365 nm light, the former group was photolyzed and converted into indene carboxylic acid along with a small amount of sulfonic acid, which could lead to the deprotection of the latter group. As a result, a novel i-line molecular glass photoresist was formed with the chemical modification of tannic acid. The expe- rimental results show that the modificated compound had a fair solubility in many organic solvents. The lithographic performance of the resist was evaluated on an i-line exposure system with high photosensitivity and resolution as well.