Thermal flow stability

The chemical structure of the acetal influences the thermal properties of the resin such as glass transition temperature, decomposition temperature and thermal flow stability (32-35). This paper describes the improved thermal properties by increasing the molecular weight via a transacetalization reaction. The polymers containing such crosslinking units were evaluated in two-component positive pWoresists. 

Figure 3. SEM micrographs illustrating the effect of the crosslinking degree X on thermal flow stability...

Photoresists with High Thermal Flow Stability.107... 

After the resist pattern has been delineated, it has to withstand processes like etching (wet or plasma) or ion implantation. A high thermal flow stability and low... 

Patterns of novolak-based resists can be chemically hardened by treatment with formaldehyde in an acidic medium The reaction that takes place is an inter-molecular condensation. The resin becomes highly crosslinked by reaction at its para positions. Although the method results in a high thermal flow stability (300 °C), it is not attractive for implementation in a production process because of the hazardous nature of the chemicals involved. 

Many polymers have been designed for the formulation of photoresists with special properties, e.g. high thermal flow stability, resistance to oxygen plasma and high sensitivity. As these polymers may become important in future resist applications, some of them are discussed below. 

Ordinary novolak, as discussed in Sect. 8.2, has a low thermal flow stability. During the bake treatment (120 °C), which is normally applied to developed resist patterns, thermal flow leads to deformation. Although this problem can be solved by hardening the pattern by chemical or physical means (see Sect. 3.2), many phenolic polymers with high T, have been studied as replacements for the novolak resin. For example poly (vinyl phenol) (T 160-180 °C) has been utilized in a commercially available... 

JET. The diameters of most jets used today are roughly 0.5 mm. This is because of the type of flame used. In a diffusion flame, as opposed to a flame in which the oxidizer and fuel are premixed, the rate of diffusion of the two gases controls the rate of burning. The velocity of the gas flow out the jet must be set to match the rate of diffusion. If the jet diameter is a little different from 0.5 mm, the detector can be optimized at a proportionately different flow. Much beyond a factor of two differences in diameter leads to some other effects, such as thermal transfer or flow stability problems. 

The first requirement of spinnability, thermal stability, has been discussed in Chap. 21. The other two requirements are closely related with the flow stability of fluid jets. 

Fig. 1 Scheme of apparatus for adsorption measurement. (1) Electromagnetic valve (2) flow stabilizer (3) needle valve (4), (6), (12) injector (5), (7) sorption pipe (8) thermal conductivity detector (9), (11) six-port valve (10) fteezing capillary (13) chromatography column (14) flame ionization detector (15) amplifier (16) electrometer (17) analog-to-digital converter (18) computer. 

Because it is based on well-established LWR technology and implements benchmarked thermal hydraulic safety analysis codes, and because each module is a relatively small reactor, it is possible that all of the information required for design certification may be obtained using a full-scale demonstration of a single module. Of significant interest for design certification would be the impact of neutronic feedback on flow stability, particularly during plant transients. 

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