Photoresist systems

Photopolymerizable coatings relief-image-forming systems, 6,125 Photoreactivity environmental effects, 1, 394 Photoredox properties bipyridyl metal complexes, 2, 90 Photoresist systems, 6,125 Photosensitive materials, 6, 113 Photosynthesis anoxygenic, 6, 589 magnesium and manganese, 6, 588 water decomposition models, 6, 498... 

New positive-type photoresist systems based on enzymatically synthesized phenolic polymers were developed. The polymers from the bisphenol monomers... 

Under UV-laser irradiation, photosensitive multifunctional acrylate resins become rapidly cross-linked and completely insoluble. The extent of the reaction was followed continuously by both UV and IR spectroscopy in order to evaluate the rate and quantum yield of the laser-induced polymerization of these photoresist systems. Two basic types of lasers emitting in the UV range were employed, either a continuous wave (C.W.) argon-ion laser, or a pulsed nitrogen laser. 

A negative working photoresist system is obtained using a oligocarbodiimide derived from 2,4-TDI and a phospholene oxide catalyst. m-Tolylisocyanate is used as the chain stopper. To this soluble linear polycarbodiimide a photoamine is added, which generates... 

We have used the sensitizer system of Michler s ketone/ azidosulphonylphenylmaleic imide, which was first developed by Siemens, for the fundamental study of photocrosslinking in a wide range of layer thickness. The absolute values of the radiation dose necessary in these studies are high as this is not a very sensitive system. However, based on Siemens fundeimental technology new photoresist systems which are significantly more photosensitive are now commercially available The fundamental studies discussed here apply in principle also to these new systems. 

The Photoresist systems now commercially available require a dose of 50 - 70 mJ/cm for thin layers of up to about 6 im and approximately 500 - 750 mJ/cm for thick layers of 100 im. These dose values account for highly crosslinked patterns which show no reduction in film-thickness after developing. 

These results are also valid for the commercially available photoresist system based on polyamic acid methacrylate ester, which have an improved photospeed for technical applications. 

In humans the cross-linked thymine moieties create a kink in our DNA. An excision enzyme recognizes this kink and that portion of DNA is cut out and repaired. Skin cancer has been linked to the failure of this mechanism. Another repair mechanism is found in some microbes which have an enzyme called DNA photolyase. DNA photolyase functions by recognizing the thymine dimers and un-zipping them (79). We have found methods to use DNA photolyase as an enzyme for regenerating thymine polymer photoresists, allowing re-use of the photoresist systems (20). 

BPHT and other phenothiazine derivatives have been widely applied as photosensitizers to the development of photoresist technology [30,96,110]. Photoresist systems have been established to achieve the differential solubility of thin polymer films [30]. A key element in these photoresist systems is represented by the so-called photosensitive acid generator (PAG). The PAG can be defined as a compound that, under UV irradiation, liberates an acid (HX) and yields other photolysis photoproducts, according to the following reaction [30] ... 

The photoresists have very strong absorption even for thin films. The latter gives a possibility to use the photoresists as thin top layers in the bilayer photoresist systems. 

MacDonald, S.A. Schlosser, H. Ito, H. Clecak, N. Willson, C.G. Plasma developable photoresist systems based on chemical amplification. Chem. Mater. 1991, 3, 435-442. 

In addition, eight aromatic-like novolac resin containing first and second generation photoresist systems have been evaluated. 

New positive-type photoresist systems based on enzymatically synthesized phenolic polymers were developed [55]. The polymers from the bisphenol monomers exhibited high photosensitivity, comparable with a conventional cresol novolak. Furthermore, this photoresist showed excellent etching resistance. The oxidative polymerization of bisphenol-A proceeded by fungal peroxidase from Coprinus cinereus (CiP) in aqueous isopropanol [56]. CiP also catalyzed the oxidative... 

An alternative approach to the complicated photoresist systems could be the application of APD (ablative photodecomposition), where a strong absorbance at the irradiation wavelength is one of the conditions for successful ablation. A logical approach to the use of APD as a dry etching technique in microlithography is the development of polymers designed for APD. This is especially true for photolithographic applications that do not require a submicron resolution, such as thin film transistor (TFT) fabrication for liquid crystal displays (LCD) which require a resolution around 1 pm. 

Many polymers are used in the fabrication of multilayer, high-density electronic circuitry consisting of silicon chips containing large numbers of integrated circuits. However, most of the polymers function in a temporary role in photoresist systems that are removed before the devices are completed. 

An alternative to encapsulating OFETs with parylene is to use an aqueous photoresist system which does not induce the destructive phase transformation which is observed when metastable oligomeric semiconductors are exposed to other solvents. Since the resist is developed in pure water, exposure to strong bases or solvent developers is also avoided. The process shown is based on Kane, et al. [57]. 

DeSimone, Z. Guan, and C.S. Elsbernd, Synthesis of fluoropolymers in supercritical carbon dioxide, Science 257, 945 (1992) C.L. McAdams, D. Flowers, E.N. Hoggan, R.G. Carbonell, and J.M. DeSimone, All CO2 processed 157 nm fluoropolymer containing photoresist systems, Proc. SPIE 4345, 327 (2001). 

Wallow, F.M. Houlihan, O. Nalamasu, E.A. Chandross, T.X. Neenan, and E. Reichmanis, Evaluation of cycloolefin maleic anhydride alternating copolymers as single layer photoresists for 193 nm photolithography, Proc. SPIE 2724, 355 (1996) F.M. Houlihan, T.I. Wallow, A. Timko, E. Neria, B. Hutton, R. Cirelli, O. Nalamasu, and E. Reichmanis, Recent advances in 193 nm single layer photoresists based on alternating copolymers of cycloolefins, Proc. SPIE 3049, 84 (1997) J. H. Park, S. J. Kim, S. Y. Park, and H. Lee, ArF photoresist system using alicyclic polymer, Proc. SPIE 3049, 485 (1997). 

Figure 17.22 Catalytic deprotection reaction of a photoresist system based on copolymer poly(4-hydroxystyrene-co-4-t-butyloxycarbonyloxystrene).

The recent technological evolution requires ecologically safe processing In the field of photoresists systems. Within this scope It Is worthwhile to mention the use of 1-azldopyrene as an Interesting sensitizer to reduce the solubility of novolacs t3rpe phenolic resins In alkaline developers (79). 

Photo-cross-linking polymeric materials are basically used as photoresists systems in which a layer is coated on a surface and then exposed to light through a master image or pattern so that a change in the solubility properties of the layer occurs (80). 

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