Positive tone process

Figure 4. Positive tone process for MAGME-polymers.

Fig. 26. SEM micrographs illustratiag the effects of airborne basic chemical contamination, (a) This image was formed when a positive-tone CA resist was processed without any delay after coating, (b) This image was formed when an identical film was stored after coating for 15 minutes in an atmosphere containing 10 parts per billion on A/-methylpyrrohdone, and then processed identically to the first film.

Fig. 35. Process flow for thin-film imaging lithography (a) bilayer process and (b) top surface imaging. The bilayer process shown here employs a positive-tone imaging layer. The TSI process illustrated refles on preferential silicon incorporation in the exposed regions of the imaging layer to give a...

Positive-tone photoresists, 15 161-163 acid-catalyzed chemistry in, 15 169-170 Positive-working dye processes, 19 284... 

Figure 22. Schematic plasma-development process showing exposure, fixing, and both negative and positive tone plasma development. (Reproduced by...

One final example of the application of onium salt photochemistry in positive resist materials should be mentioned, because it does not include any postexposure acid-catalyzed processes and therefore does not encompass the principle of chemical amplification (79). Interestingly, Newman (79) has determined that onium salts themselves can inhibit the dissolution of novolac in aqueous base and that irradiation of such an onium salt-novolac resist restores the solubility of the resin in developer and leads to a positive-tone image. In this application, the onium salt behaves like diazonaphthoquinone in a typical positive resist. Recently, Ito (80) has reported also the use of onium salts as novolac dissolution inhibitors. 

M.A. Hartney, R.R. Kunz, L.M. Eriksen, and D.C. LaTulipe, Comparison of liquid and vapor phase silylation processes for 193 nm positive tone hthography, Proc. SPIE 1925, 270 (1993). K. H. Baik, L. Van den Hove, and B. Roland, Comparative study between gas and liquid phase silylation for the diffusion enhanced silylated resist process, J. Vac. Set Technol. B 9, 3399 (1991) K. H. Baik, K. Ronse, L. Van den Hove, and B. Roland, Liquid phase silylation for the DESIRE process, Proc. SPIE 1672, 362 (1992). 

M.A. Hartney, R.R. Kunz, L.M. Eriksen, and D.C. LaTulipe, Comparison of liquid and vapor phase silylation processes for 193 nm positive tone lithography, Proc. SPIE 1925, 270 (1993). 

Figure 17.10 shows the process sequence of the hydrophilic overlayer (HOL) process. First, a chemically amplified or non-chemically amplified positive-tone photoresist comprising hydrophobic polymer and appropriate PAG is coated to a nominal thickness on an appropriate substrate such as a silicon wafer, followed by a soft bake to dry out the nonaqueous solvent. Next, the photoresist film is exposed to radiation of appropriate wavelength to generate photoacid from the PAG. Then the exposed film is again baked (called PEB) at the standard temperature to enhance the diffusion of the photoacid and thermolysis of the acid-labile protecting groups of the polymers. 

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