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 (<40 mg KOH/g polymer) and high molecular weights >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.

A novel pigment dispersed resist system (red, green and blue), which consists of a crosslinkable acrylate copolymer, a photoinitiator, and selected pigment dispersions has been developed. The materials combine excellent resistance to solvents, acids and alkalis, good thermal stability, light fastness, high transparency, chromaticity, contrast and film uniformity with adequate sensitivity (200 mJlcm2), high resolution (<_ 10 µm) and large process margins. As the photospeed of conventional acrylate-based photopolymerizable resist systems is deteriorated in air due to oxygen induced inhibition reactions, the acrylate group was directly attached to the polymer, yielding high sensitivity even in the presence of oxygen. The application of a proprietary surfactant containing developer eliminated the formation of pigment residues after development.

A negative resist system composed of a phenolic resin, an azide, a crosslinker and a pigment dispersion has been developed for black matrix formation of color filters (CF). The novel pigmented photoresist (PPR), which consists of poly(4-hydroxystyrene), hexamethoxymethyl melamine, 4,4'diazidostilbene-2,2'-disulfonic-N,N-diethyleneoxyethylamide and a dispersion of carbon black combines superior opacity (OD = 3. S tm 1), adequate resistance to solvents, acids and alkalis, good thermal stability, and film uniformity with excellent lithographic performance, such as high sensitivity (120 mJlcm2), high resolution (<_ 10 µm) and wide process margins. The investigation of the dissolution behavior of the film via backside exposure and the reaction ratio of the azide indicates that the pattern formation mechanism occurs mainly via insolublilization of the resist surface in the exposed areas and subsequent etching of the resist layer by the alkaline developer.

Bottom anti-reflective coatings (BARC) provide a production proven solution to improve linearity, depth-of-focus, CD control and process latitudes of photoresists. A series of BARCs compatible with chemically amplified deep ultra-violet (DUV) photoresists exhibiting different k values ranging from 0.1 to 0.6 at the DUV wavelength (248 nm) has been developed. The relationship between the k values and the etch rates of the BARC polymers with different dye concentrations in the polymer has been investigated. As a result, BARCs with targeted k values and etch rates can be provided. Formulation aspects of the BARC materials including edge bead remover (EBR) compatibility and evaluation results of these BARCs with different DUV resists are also discussed.

Distribution of photosynthetic photon flux density (PPFD) in a culture vessel was estimated using a sensor film for measuring the integrated solar radiation. A plantlet model whose leaves were constructed from sensor film was used to simulate a potato plantlet. The plantlet model was put into a culture vessel and, after exposure to culture conditions for 20 days, PPFD was estimated for each individual model leaf based on the degree of fading of the sensor film. The method was able to demonstrate the light intensity distribution patterns inside a small test tube under downward lighting conditions. This technique allows for the estimation of light intensity distribution patterns inside a small culture vessel, which was previously difficult to measure by conventional methods.Abbreviations: PPFD -photosynthetic photon flux density