Resist pattern profiles

The resist pattern profiles were evaluated using a JEOL JSM-T200 scanning electron microscope. 

Figure 3. Schematics of developed resist pattern profiles.

Figure 4. SEM micrographs showing inorganic resist pattern profiles developed by (a) RIE and (b) wet chemical method. ...

To improve the thermal properties of resists and prevent thermal deformation of resist pattern profiles during the dry etching process, where the temperature of the wafer often exceeds the deformation temperature of untreated resist, UV radiation curing that results in cross-linking is sometimes used. DNQ/ novolac, poly (hydroxy styrene), acrylate, alicyclic, and a whole host of other... 

Resist Pattern Profiles. Figure 8 shows 0.24 pi m line-and-space patterns fabricated in a resist on a Si substrate treated with TMSP or HMDS for 30 sec. at lOO C. Figure 9 shows 0.3 pi m line-and-space patterns fabricated in the resist on a TiN substrate. For TMSP, as same as for HMDS, hi aspect ratio and precise resist patterns were successfully achieved without any peeling off. 

As for negative deep UV resist, O Toole et al. have exhibited half-micron pattern resolution in 0.5 micron film thickness using the new resist and PIE process (10). The pattern profiles, however, were re-entrant, due to the large photo absorption and the applications to single-layer-resist system have not been presented (11). 

In this paper, the material characteristics and lithographic evaluation of this new resist are demonstrated. The resist meets the requirements for KrF excimer laser lithography, which exhibits high sensitivity, high resolution and high aspect ratio pattern profiles. 

The UV spectra for this resist film, before and after exposure to KrF excimer laser irradiation for 100 mJ/cm2, are shown in Figure 6. The absorbance of the azide renders the reist film of l.o micron thickness essentially opaque at 248 nm. After exposure of 100 mJ/cm2, the absorbance bleaches from 0.5 to 6.0% at 248 nm. Intense absorption by this resist at 248 nm closely relates to the pattern profile of the resist, which will be discussed in the last section. 

Figure 1. Cross sections of films etched with liquid or plasma etchants. The isotropic profile is the result of zero overetch and can be generated with liquid or plasma etch techniques. The anisotropic (vertical) profile requires plasma or dry-etch processes. W is the width of the resist pattern. (Reproduced from reference 2. Copyright 1983 American Chemical Society.)...

F.A. Vollenbroek, E.J. Spiertz and H.J.J. Kroon, "Profile modification of resist patterns in optical lithography," Polym. 

For the pattern profile evaluation, KrF resist was coated to a thickness of 0.7 m on a Si or TiN substrate treated with an each adhesion promoter. After e osure, PEB and the alkaline development, we observed SEM of line-and-space pattern profiles. A 0.7 pt m thick KrF excimer laser positive chemically amplified resist with acid-labile protecting group was used. 

Pattern profiles of chemical amplification resists. T-top images appear strongly for the longer interval 1. 

Metallization by a lift-ofP procedure involves the generation of resist patterns with undercut profiles. A metal is evaporated over the entire surface in such a way that a discontinuity exists between metal on the substrate and metal on top of the resist (see Fig. 8). Then the resist is dissolved and the metal on top of the resist thus lifts off. 

Fig. 8a-c. Schematic representation of the lift-off procedure a a resist pattern with negatively sloping profiles is made either by the soak procedure or by image reversal b metal is deposited on the patterned resist, so that a discontinuity exists between metal on the substrate and metal on the resist c the metal on, the resist has been lifted off by dissolution of the resist pattern... 

Antibiotic resistance While genot) ic techniques identify organisms on the basis of their genetic makeup, antibiotic-resistance testing employs the fact that different kinds of antibiotics are used in humans and animals. As a result, patterns of resistance to a variety of antibiotics in the natural bacterial populations symbiotic with these organisms will differ in the environmental isolates that are human derived and those that are farm-animal or wildlife derived. In the case of antibiotic-resistance methodology, profiles of antibiotic resistance of fecal coliform bacteria from known sources are obtained and banked. The sources of new fecal coliform bacteria isolated from surface water are identified based on the degree of similarity and differences of their antibiotic-resistance characteristics to those from known sources [150]. 

IMPROVEMENT OF RESIST PERFORMANCES Improvement in pattern profile... 

As the minimum VLSI pattern size is now in the sub-half micron region, conventional singlelayer resists can no longer satisfy all VLSI fabrication requirements. Due to the excessive absorbance or the light reflected from the patterned substrates, controlling the pattern profile and line width is difficult with a singlelayer resist. 

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. 

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