Multilayer resists technology

Multilayer resist technology offers a number of advantages in the generation of relief images but carries the burden of process complexity. We wish to report a novel process that greatly simplifies the optical MLR sequence. This concept is based on selective surface modification of the resist with a reactive dye which masks selected areas toward later flood exposure and solvent development. 

Electron beam resists to be used in direct wafer writing for submicron devices need significant improvement in sensitivity, resolution and dry etching durability. Multilayer resist (MLR) systems are now regarded as the most important technology to perform practical submicron lithography for VLSI fabrication (1-3). Many advantages in MLR compared with one layer resists (1LR) are listed here ... 

Dekempeneer, E., Van Acker, K., Vercammen, K., Meneve, J., Neerinck, D., Eufinger, S., Pappaert, W., Sercu, M., and Smeets, J., Abrasion Resistant Low Friction Diamond-Like Multilayers," Surface and Coatings Technology, Vol. 142-144,2001,pp. 669-673. 

Another route to protect polymers from oxygen, light and UV is to encapsulate the part with a continuous film of another, more-resistant polymer to provide a barrier to oxygen. This technology is also used for decoration of plastic parts (in mould decoration or IMD, painting, multilayer sheets for thermoforming. ..). There is no protection against heat. 

Figure 17.10. GMR value versus longitudinal magnetic field in electrochemically grown Co/Cu multilayers (a) resistivity measured using direct current (b) resistivity measured using alternating current (1 kHz). (From M. Schlesinger, Chapter 14 in Electrochemical Technology, T. Osaka, ed., with permission from Kodansha Ltd.)...

Several nanoscale multilayered materials have been prepared. Techniques of Rutherford backscatteiing, electron microscopy and microanalysis and other metallurgical tools have been used to investigate wear resistant, scratch resistant, microhardness, and spark erosion properties of these nanoscale multilayered materials. Preliminary results indicate that nanoscale multilayered materials with improved thermomechanical, properties can be synthesized for application in the EM gun system. Application of ion beam technology for the synthesis of gradient materials appears to have great potential for design of new materials with improved properties to be used in fabrication of many armament materials. 

Figovsky, O., and Dubrovsckaya-Vinokurova, G. Shock Resistance of Monolithic Multilayer Flooring, Scientific Israel Technological Advantages 5, no. 2 (2003) 165-169. 

The other change in resist processing involves the use of multilayer schemes in place of a simple photoresist coating. Microimaging using multilayer materials and technology has revolutionized the electronics industry. Many silicon chips used in calculators and computers are produced in some variation of the following sequence of operations ... 

Predesigned particles of impact modifiers are based on core-shell technology. Core is involved in impact modification and shell improves adhesion between PVC and impact modifier particles.Three major combinations are used methacrylate-butadiene-styrene, MBS, which has a core made out of butadiene-styrene copolymers and shell made out of methylmethacrylate-styrene copolymer, acrylic impact modifiers, AIM, which have a core made out of acrylic and shell from polymethylmethacrylate, and silicone-acrylic have multilayer structures with silicone-acrylic in the core. MBS has excellent compatibility with PVC, similar to ABS, which is used as an impact modifier of PVC, as well. In both cases of ABS and MBS, weather resistance is lacking, therefore they are used for indoor applications only. At the same time, MBS gives translucent to crystal clear products, whereas with AIM, only translucent products are possible. In order to improve optical properties of AIM, it has to be reformulated. For transparent products, the core is made out of acrylic-styrene copolymers. Comparing silicone and all acrylic impact modifiers, PVC containing silicone-based products has superior low temperature impact properties. The incorporation of silicone into an acrylic impact modifier provides excellent weatherability, and thermal stability. It has shown improved retention of impact after outdoor weathering in PVC. ... 

Bottles and containers are the major products of blow molding. The major novelties in this technology are probably due to application of multilayered products to improve mechanical performance, barrier properties, and weathering resistance. These are products of different polymer layers and as such they are not discussed here. 

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