Yuko Nozaki

Polymer Optimization of Pigmented Photoresists for Color Filter Production

The lithographic performance of pigmented photoresists for color filter production is affected by the structure of the employed polymer. Four polymers with acrylate backbones and pendant reactive acrylate/methacrylate groups were prepared, and the effects of their molecular weights and acid values on the pixel pattern quality, development time, sensitivity and development mode were elucidated. ECHIPTM, a statistical experimental design program was used for optimization studies revealing that the red resist performs best, when polymers with relatively low acid values ( 50,000 are used. The green and the blue resists yielded optimal patterns at molecular weights in the range of 20,000–30,000 with acid values of about 50–60 mg KOH/g polymer. The sensitivity of resists containing polymers with pendant acryloyl groups is in general higher than that of the corresponding methacryloyl derivatives. Polymers having butyl acrylate-methacrylic acid backbone units showed the highest sensitivity among the polymers investigated. When developed with an optimized tetramethyl ammonium hydroxide (TMAH) based developer, resists using polymers with methyl methacrylate units showed peeling type development, while butyl acrylate copolymers effected homogeneous dissolution yielding higher resolution.

High performance positive DUV photoresists AZ DX 1100P AZ, DX 1200P, AZ DX 1300P, AZ DX 2034P, AZ DX 2058p for advanced lithographic applications

An increasing number of DUV resists, which have taken considerable steps on the maturity curve, is available on the market these days. It becomes obvious that - similar to i-line application - there is not the universal resist giving the best fit for every aspect of DUV handling. Meanwhile this seems to find wide acceptance by the majority of the user community. Classifying major commercial PHS based resists according the protective group: acetal, t-BOC and acrylate type with the chemistry concept of low, medium and high activation energy may be distinguished. In order to satisfy specific customer needs Clariant have a commercially available family of AZ® DUV products. These recently developed products include on the positive resist side AZ® DX 1100P, AZ® DX 1200P, AZ® DX 1300P, AZ® DX 21134P and AZ® DX 2058P, all two component acetal-based systems. The details of this resist chemistry are described elsewhere 1 . Dose-to-print versus dose-to-clear ratio is about 2.4 indicating high contrast. Process parameters, as well as selected characteristics and performance items are highlighted in this contribution. AZ® DX 1100P is intended for use on weakly reflective substrates, such as bottom antireflective coatings (BARCs) of organic or inorganic nature. On AZ® BARLi, a BARC originally developed for i-line application, AZ® DX 1100P shows a lines and spaces resolution well below 0.2 μm. Depth of focus (DOF) amounts to 1.05 μm for 0.25 μm critical dimension (CD). Excellent post exposure bake (PEB) latitudes are found where CD change is below 1 nm/°C. Post exposure delay stability for CD 0.2 μm is better than 12 hours for amine concentrations at around 5 ppb. Good substrate compatibility is also found on TiN and Tungsten (W). AZ® DX 1200P is targeted for contact hole (C/H) printing. Besides an excellent sensitivity with the C/H dose to print at around 40 mJ/cm 2 for 0.96 μm resist thickness. C/H ultimate resolution goes down to < 0.2 μm. For CD 0.25 μm the DOF is determined to be greater than 1.2 μm. As far as the baking parameters are concerned, there is full processing compatibility with conventional diazonaphtoquinone/novolak based resists. This is also valid for AZ® DX 1300P, an allround resist, aimed for a wide range of applications on standard and highly reflective substrates. Evaluation highlights of AZ® DX 1300P include high sensitivity of around 20 mJ/cm 2 , excellent resolution down to 0.2 μm and a large DOF of 1.2 μm for 0.25 μm l/s. To respond to most advanced sub 0.2 μm CD needs AZ® DX 2034P comparable to AZ® DX 1100P addresses BARC and AZ® DX 2058P analogous to AZ®DX 1300P covers the remaining more general areas of use.

Structure-property relationship in acetal-based chemically amplified three-component DUV resist

AZ DX series are chemically amplified, three component resists based on a poly(4-hydroxystyrene-co-3-methyl-4-hydroxystyrene) matrix resin, a poly(N,O-acetal) dissolution inhibitor, and a bis(arylsulfonyl)diazomethane acid generator. The previously described AZ DX 46 is an environmentally and delay time stable, high performance resist capable of lineating structures down to 0.23 micrometers . The material contains a photoactive base to reduce the delay time effects. In this paper the influence of styrene units in the matrix resin, and some new polyacetals on the performance of the resist in comparison to the above mentioned standard formulation AZ DX 46.

Evaluation results for the positive deep UV resist AZ DX 46

This contribution emphasizes resist application site by communicating lithographic results for AZ DX 46, obtained using the GCA XLS 7800/31 stepper, NA equals 0.53, equipped with krypton fluoride excimer laser ((lambda) equals 248 nm), model 4500 D, as exposure source, delivered by Cymer Laser Technologies. As far as delay time experiments are concerned ASM-L PAS 5500/70 stepper, NA equals 0.42, was used in combination with Lambda Physik excimer laser, model 248 L.