Joo Hyeon Park

Chemically Amplified Resists based on the Norbornene Copolymers with Steroid Derivatives

In order to develop a new series of chemically amplified photoresists for 193-nm lithography, norbornene substituted with a steroid derivative was copolymerized with maleic anhydride by free radical polymerization. The resulting polymers have excellent transmittance at 193 nm and possess good thermal stability up to 260 degrees C. The resist formulated with the polymers showed better dry-etching resistance than the conventional poly(hydroxystyrene) resist for Cl2/O2 plasma. With the standard developer, the resists from 0.15-0.20 micrometers patterns at doses of 5-18 mJ/cm2 using an ArF excimer laser stepper.

Novel single-layer photoresist containing cycloolefins for 193 nm

New matrix resins containing maleic anhydride and cycloolefin units for ArF excimer laser resist have been developed. Several series of these matrix resins having good dry-etching durability were prepared by free radical polymerization using AlBN as free radical initiator. All of the resists using the matrix resins revealed good coating uniformity and adhesion to silicon wafer, and were readily soluble in a variety of resist solvents such as MMP, EEP, PGMEA and EL. In preliminary 193 nm testing a resist formulated with the matrix resins sulfonium triflate as photoacid generator afforded positive images with 0.14 micrometers L/S resolution. In this paper, we will discuss the polymerization results and lithographic properties for 193 nm exposure tool.

The noble resists composed of cationic and anionic polymerizable PAGs

A recent new class of resists referred to as polymer-bound PAG resists, which have slightly increased PAG loading and reduced photo acid diffusion relative to tranditional blended CAR systems have shown promise in improving resolution, faster photospeed, higher stablility and LER. we have developed two kinds of PAG, which are cationic and anionic polymerizable PAGs. One is that the polymer backbone is directly connected with cationic part in PAG and the other is that the polymer backbone is directly connected with anionic part in PAG. In this study we described the synthetic process of polymerizable PAGs and the polymerization process to make PAG-bound polymers and then, the lithography properties of resists composed of PAG-bound polymer were reffed to.

Terpolymer of maleic anhydride and cycloolefin derivatives as an ArF photoresist

A number of single layer ArF resist systems based on acrylic polymer have been reported. However, the resist systems generally have poor dry etch durability and unusual developing condition. To overcome these problems, in this work, we have developed a novel alkaline soluble polymer through deprotection. The polymer was prepared by free radical polymerization of maleic anhydride, norbornene, and t-butyl 3- bicyclo-(2,2,1)-hept-5-en-2-yl 3-hydroxypropionate. Since our polymer system contains large amount of alicyclic carbon and hydroxy group in the polymer chain, the system shows good adhesion, thermal stability, and high transmittance at 193 nm. The resist based on the polymer shows positive tone image of 0.17 micrometer L/S in the presence of photoacid generators such as onium salts. We describe this resist system together with the synthese of monomer and polymer, their characterizations and some of results of lithographic performance.

High-performance 193-nm photoresist materials based on ROMA polymers: sub-90-nm contact hole application with resist reflow

There are numerous methods being explored by lithographers to achieve the patterning of sub-90nm contact hole features. Regarding optical impact on contact imaging, various optical extension techniques such as assist features, focus drilling, phase shift masks, and off-axis illumination are being employed to improve the aerial image. One possible option for improving of the process window in contact hole patterning is resist reflow. We have already reported the resist using a ring opened polymer of maleic anhydride unit(ROMA) during the past two years in this conference. It has several good properties such as UV transmittance, PED stability, solubility and storage stability. The resist using ROMA polymer as a matrix resin showed a good lithographic performance at C/H pattern and one of the best characteristics in a ROMA polymer is the property of thermal shrinkage. It has a specific glass transition temperature(Tg) each polymers, so they made a applying of resist reflow technique to print sub-90nm C/H possible. Recently, we have researched about advanced ROMA polymer(ROMA II), which is composed of cycloolefine derivatives with existing ROMA type polymer(ROMA I), for dry etch resistance increasing, high resolution, and good thermal shrinkage property. In this paper, we will present the structure, thermal shrinkage properties, Tg control, material properties for ROMA II polymer and will show characteristics, the lithographic performance for iso and dense C/H applications of the resist using ROMA II polymer. In addition, we will discuss resist reflow data gained at C/H profile of sub-90nm sizes, which has good process window.

ArF photoresist system using alicyclic polymer

We have developed a chemically amplified photoresist for use in ArF lithography based on alicyclic polymer. 3- Bicyclo(2,2,1)hept-2-yl-3-(2-methyl allyoxy)-propionic acid tert-butyl ester (BHPE) was prepared as a new kind of protected acid-labile monomer. Terpolymer, poly(BHPE-NBO-MAL), was prepared with BHPE, 5-norbornen-2-ol (NBO), and maleic anhydride (MAL) monomers by radical polymerization. Photoresist of poly(BHPE-NBO-MAL) displayed good adhesion, dry-etch resistance, and development. As a result, we obtained 0.16 micrometer line-and-space positive patterns with 2.38 wt% TMAH aqueous solution using an ArF exposure system.

Ring opened maleic anhydride and norbornene copolymers (ROMA) have a good character in resist flow process for 193-nm resist technology

We have already reported the resist using a ring opened polymer of maleic anhydride unit (ROMA). The synthesis of the ROMA polymer is as follows: 1)copolymerization of cycloolefin derivatives and maleic anhydride 2)ring opening reaction of maleic anhydride unit. 3)substitution reaction of pendant group. The ROMA Polymer has several good properties such as UV transmittance, pattern profile, PED stability and storage stability. Especially, we have been known that the resist using a ROMA polymer has a good character for application of Resist Flow Process(RFP), recently. The ROMA polymer has shown various Tg value ranging from 100°C to 170°C in accordance with substituents and substituted degree. The resist made by ROMA polymer as a matrix resin showed a good lithographic performance at direct C/H pattern. We also got a good C/H pattern profile by resist flow process at sub-100nm hole size. In this study we will discuss about it and illustrate about various Tg value of ROMA polymers and data gotten by means of resist flow process.

Correlation between polymer platform of ArF photoresist and defect in the track nozzle of manufacturing process line

As the minimum feature size of electronic devices continues to shrink, the industry is moving from wavelength of 248-nm KrF excimer laser sources to shorter wavelength of 193-nrn ArF excimer laser and ArF immersion to achieve required higher resolution. As minimum feature sizes are reduced, the ability to minimize defects is getting more important, because they have a close connection with yield. With the replacement of laser source, 248-nm with 193-nm, the platform of polymer was also converted from phenolic polymer into acrylic polymer. With this platform changes unexpected various defect problems had been occurred. Although KrF process causes not much of defect, ArF process causes more serious defect problems. One of those major defect source is solidification of polymer in track nozzle. The solidified polymer at track nozzle needs to be removed periodically, unless it causes significant throughput loss in mass production. The amount of this type of defect relies on physical properties of polymer platform such as hydrophilicity, solubility or structural rigidity. The hydrophilic phenol based KrF polymer shows minor defects, contrarily hydrophobic acryl based ArF polymer causes serious defects. The solidification of acrylate type polymer was caused by poor solubility. In order to improve solubility, olefinic moieties such as norbornylene, norbornyl devertives and opened maleic anhydride monomers were adopted in acrylate polymer. Those inserted olefins and opened maleic anhydride in acrylic polymer changed overall structure such as rigid helix structure into flexible structure. With the increase of solubility, particle defect was dramatically reduced. Conclusively, insertion of cycloolefin and opened maleic anhydride moiety releases rigid acrylic structure and it improves solubility. As solubility improves, crystallization at nozzle has been decreased and the particle defect is reduced. Moreover this flexible structure allows the resist reflow at the moderate temperature which is one of the resolution enhancement techniques.

Cycloolefin copolymer containing hindered hydroxyl group for 193nm photoresist

The basic requirements for polymer design rule in photoresist are as following. The performances of the photoresist relate to transmittance, adhesion on BARC material, dry etch resistance and process margin as a function of the exposure tool. However, it is very difficult for us to find the polymer that has good performance for 193 nm ArF photoresist, because it has many limitations as target feature size of photoresist become smaller. One of the most important properties in it is adhesion. Researchers usually introduce functional group, as an adhesion promoter, such as carboxylic acid group, hydroxyl group and lactone group at the side chain of the polymer. Carboxylic acid group represents the highest adhesive property, but it has poor dark erosion because of affinity with developer, 2.38 wt% TMAH solution. Lactone group has a limit for introduction as a functional group because it can cause low dry etch resistance and pattern slope. On the other hand, in case of primary alcohol, the hydroxyl group occurs cross-link with carbonyl unit of a neighboring unit. We have recently synthesized cycloolefin copolymer, which has a secondary hindered alcohol in its side chain. And they showed good performances in adhesion, resolution, PED stability, processing window, dry etch resistance, and good pattern profile in both L/S and C/H pattern profile. In this paper we will discuss the properties and the evaluation results.

New approach for 193-nm resist using modified cycloolefin resin

We have investigated new photoresist materials based on modified cycloolefin-maleic anhydride resin for 193nm lithography. Compared to COMA resin, the new resin offers several good properties such as UV transmittance, taper in pattern profile, PED stability and storage stability. The resist using the new resin showed good lithographic performances on ArF exposure tool. So, we obtained good hole patterns below 90nm with condition of exposure: PAS 5500/900 full field scanner, resist thickness: 320nm, development: 2.38% TMAH, for 40sec., Illumination: 0.61NA, conventional SOB: 110 degree(s)C/90sec, PEB:130 degree(s)C/90sec, on BARC. In this paper we will report on the properties of new polymer and will show the contact hole pattern that demonstrate progress in these areas.