Imaging Liquid photoresists

Taff, L, and Benron, H., Liquid Photoresist for Thermal Laser Direct Imaging, Board Authority supplement to CircuiTree, Vol. 1, No. 3, October 1999, p. 66. 

Liquid Photoresist Liquid resists work well in a print-and-etch process. They have excellent adhesion and a tolerance for surface flaws and are relatively low in cost. The disadvantage of a liquid photoresist is the need to produce a perfect coating. Foreign material, skips, thin spots, and dewetting all cause serious image problems. The use of a wet coating can also cause problems due to resist contamination of the transport system. 

OPVs are suitable for various applications in materials science Organic light emitting diodes (OLED), field-effect transistors (FET), semiconductors (doped), photoconductors, solar cells, photovoltaic devices, optical brighteners, laser dyes, nonlinear optics (NLO), optical switching, imaging techniques, photoresists and liquid crystals [la-e, Ij-o, Ir, Iv, 27, 120]. Among these applications, two fields will be selected here, namely NLO and electroluminescence studies. 

Adhesion has been achieved on these oxides through a variety of silane precoat treatment processes. Solutions of y-aminopropyltriethoxysilane, y-methacryloxytrimethoxysilane, and y-glycidoxytrimethoxysilane applied to thermal oxide substrates all improved resist image adhesion for conventioanl positive photoresists Mallinckrodt Multisurf also works well. Conventional liquid-phase application of HMDS, however, was not adequate for the latter three tougher substrates listed above it did provide adequate photoresist adhesion for thermal oxides, however. For the last three substrates, a double... 

The double promoter process involves the successive application of liquid promoter solutions of vinyltrichlorosilane (VTS) and 3-chloropropyltrimethoxy-silane followed by successive cure cycles in dry N2 at 90°C after each application and before photoresist application. The double promoter process evolved because it was felt that the silane reaction with the SiOH surface groups of low temperature oxides was incomplete for a single promoter application, and because vapor silane equipment did not exist at that time. Interestingly, a double HMDS liquid promoter process failed to yield adequate adhesion as well. Later in time, the successful but somewhat complex double promoter process was replaced by the vapor phase HMDS process in the Star 1000 (or 2000) then superior resist image adhesion was obtained on all four oxide substrates with all the photoresists tested. Before the advent of the HMDS vapor priming in standalone or wafer track equipment module chambers, liquid priming solutions were widely used, especially in development areas. 

CARS microscopy has emerged as a highly sensitive analytical tool for vibrational bioimaging, predominantly, of lipids in membrane model systems [69, 81-84], live unstained cells [85-95, 43], and both ex vivo and in vivo tissues [26, 96-103, 43]. Examples of CARS imaging applications in the physical and material sciences include the study of fracture dynamics in drying silica nanoparticle suspensions [104], patterned polymeric photoresist film [105], drug molecules in a polymer matrix [106], and liquid crystals [107, 108],... 

FIGURE 4.13 Electrochemical overoxidation techniques for use with polythiophenes, (a) A plotter pen modified to be used in an electrochemical cell, (b) Screen-printing electrochemical cell, (c) Photoresist patterned on a PEDOT PSS film protects areas of the film from overoxidation whereas the rest is patterned when wet by the liquid electrolyte. (Images from Tehrani, P., Remonen, T., Hennerdal, L.-O., Hall, J., Malmstrom, A., Leenders, L., Kugler, T., Robinson, N.D., Crispin, X., Fahlman, M., and Berggren, M., Smart Mater Struct 14, N21-N25. Copyright 2005, Institute of Physics Publishing. With permission.)... 

The relative ease with which relief images can now be produced has led to the introduction of microlithography in many other applications. These include the production of liquid crystal displays, liquid crystal television, and solid state cameras. These applications are reviewed only briefly. Finally the impact of polymers on photoresists is discussed more explicitly. 

Apart from the applications discussed above, there are several other products where microlithography is involved. Among these products are liquid crystal displays, liquid crystal television and colour filters for image sensors. The manufacture of most of these products does not require resist properties additional to those which already exist in most conventional photoresists. Accordingly, a selection of these resists is normally made. 

Initially, liquid solvent-based photoresists were used as the primary imaging medium in printed circuit board manufacturing, and application... 

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