Resist imaging

A.irbome Basic Chemical Contamination. A critical, and at-first pu22ling problem, was encountered during early manufacturing trials of CA resists. Sporadically, severely distorted resist profiles would be formed in positive-tone CA resists, displaying what seemed to be a cap on the upper surface of the resist image (Fig. 26). In severe cases this cap or T-top would appear as a kin or cmst over the entire wafer surface that prevented development of the pattern. The magnitude of the effect varied dramatically between laboratories and appeared to grow more severe as the time interval between exposure and post-exposure bake was increased. 

Unlike DNQ—novolac resists, CA-resist imaging characteristics are determined to a significant extent by thermally activated bimolecular chemistry taking place during postexposure processing. Since the polymer serves here as the reaction medium, its properties and state induence the course and... 

Fig. 37. Resist images obtained with a cross-linking monocomponent TSI resist (PHOST polymer), cross-linked by photo-oxidation using light at 193-nm wavelength. After exposure, the film was treated with a vapor of dimethyl silyl dimethyl amine and then plasma developed using O2—RIE (122).

The etching resistance of a resist is simply a function of how well the material withstands the pattern transfer processes used in device manufacturing. Its resistance must be sufficiently high to allow precise transfer of the resist image into the underlying substrate with < 10% linewidth change. This is not an easy... 

Figure 8. (a) Resist images at different stages of development. 0.5 pm of... 

Figure 13a shows the resist in a three-layer Al-RIE-PCM system by Havas et al. The dry etching conditions were similar to those of plasma etching. Therefore, an undercut was produced under the Al PCM to facilitate lift-off. Figure 13b shows the resist image in a three-layer siloxane RIE PCM system. The dry etching process was sufficiently anisotropic to eliminate the undercut. 

Figure 14. Resist images of the two-layer copolymer wet-etch PCM system. A 0.4-jjLm thick copolymer layer was spun on 1.4 pm of PMMA. (Reproduced with permission from Ref. 19.)...

Figure 15. Uncapped resist image obtained with a two-layer deep-UV PCM system. The 0.85-um wide PMMA lines were 1.9-fim thick separated by 2.4 ixm. A 0.2-um AZ1350J PCM was used.

Figure 16. Capped resist image obtained with an identical two-layer deep-UV PCM system as in Figure 13. The AZ layer was 0.3-fim thick on...

Figure 17. Resist images delineated with a GCA DSW 4800 mask aligner. The Ag2Se/Geo.iSeo.9/// Pi two-layer inorganic RIE PCM system was used. The HPR planarizing layer was 2.5 in thickness. ((Reproduced with permission from Ref. 27 J...

Figure 26. A one-layer novolak-based resist image after chlorobenzene...

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