Flood exposure

A 0.3 fin thick SPP layer was exposed to a 20 kV electron beam followed by a flood exposure using near UV radiation with an integrated dose of over 500 mJ/cm2. Such a dose was sufficient to convert the remaining DNQ to indenecarboxylic acid. The resist was then dip-developed In an aqueous TMAH solution for 60 s at 25°C. 

A 0.4 m thick SPP layer was exposed to X-rays followed by a flood exposure using near UV radiation. The resist was then dip-developed in a 0.8 wt% TMAH solution for 60 s at 25 °C. We used two x-ray exposure systems to evaluate the characteristics of the SPP resist. One is SR-114 which has a source composed of a molybdenum rotating anode with a 0.54 nm Mo-La characteristic line. The exposure was carried out in air. The other has a synchrotron radiation source with a central wavelength of 0.7 nm (KEK Photon Factory Beam Line, BL-1B). The exposure was carried out in vacuum (<10-4 Pa). A positive resist, FBM-G,15) was used as a standard, because its sensitivity only weakly depends on the ambient. 

Figure 3. Sensitivity curves of SPP image reversal (solid line) after 20kV EB exposure compared with a novolac-based resist (dashed line). A 0.3 //m thick resist layer was exposed to EB followed by a flood exposure using near UV radiation and then dip-developed in an aqueous THAH solution for 60 s at 25°C. TMAH concentration A 0.65 wt%, B 0.70 wt%, C 0.80 wt%, D 1.2 wt%.

Figure 4. SEM photograph of 0.3 izm line and 0.5 m space pattern using an SPP two-layer resist system. A 0.3 m thick SPP layer was exposed to a 20 kV EB at 5 tzC/cm2 followed by a flood exposure and then dip-developed in a 0.65wt% TMAH solution for 60 s at 25 XI. The pattern formed in the top SPP layer was transferred to a 1.0 izm thick bottom layer by O2 RIE.

Figure 5. Sensitivity curve of SPP Image reversal to X-rays compared with that of FBM-G. A 0.4 /ui thick SPP layer was exposed to X-rays both In air and In vacuum followed by a flood exposure and then dip-developed In a 0.8 wt% TMAH solution for...

Flood exposure with other types of radiation... 

Exposure tools Gamma radiation from 60Co source Flood exposure to 50 keV electrons Pattern exposure to 20 keV electrons... 

DNQ from regions of high concentration to regions of low concentration at the edges of the exposed areas (5). The application of a deep-UV flood exposure during a postbake step can increase contrast, again by the formation of a less base-soluble surface skin (35). 

Although DNQ sensitizers react with X-rays, very little ICA is formed. This observation was made even when exposure was conducted under ambient conditions in which water vapor was present. The net result is that the irradiated areas of the resist have very poor solubility in aqueous base. In fact, if a UV flood exposure is used after imagewise X-ray irradiation, the areas exposed only to the UV can be selectively removed with a developer, a process that leads to an image-reversal scheme. 

Figure 4.5 The dual response of Dylux material. (Top) Nagative image formation by imagewise exposure to UV light. (Bottom) Positive image formation with initial imagewise exposure to visible light followed by flooding exposure with UV light.

Solomon, S. D., Smith, E. M. (1994). Social support and perceived control as moderators of response to dioxin and flood exposure. In R. J. Ursano, B. G. McCaughey, C. S. Fullerton (Eds.), Individual and community responses to trauma and disaster The structure of human chaos (pp. 179-200). Cambridge, UK Cambridge University Press. 

Resist films of approximately 0.5ym thickness were spun on silicon wafers and cross inked by baking either in an oven or on a hotplate. Incremental exposures were made by a JEOL JBX6A2 electron beam machine at 20 keV. The UV flood exposures were carried out under nitrogen using a 185nm UV lamp. UV dosimetry was carried out on the basis of exposure time which had previously been correlated with the equivalent electron beam exposure by measuring dissolution rates. 

The type of feature requiring the greatest exposure to destroy the gel is an isolated line, because it receives less backscattered energy than any other type of feature. From the results of section (a) it is known that the required dose, Q., is 85yC/cm2 in the absence of flood exposure. For a flood exposure dose, Qf, the new patterning dose, Qp, required to clear the line is... 

Other methods of reducing the crosslink density have also led to sensitivity improvements, of which the most promising is the uneven copolymer mixtures with a potential 60-70% reduction in operating dose. However, the solutions must be aged after mixing in order to obtain reproducible performance. This technique also requires work on a developer system. Flood exposure yields a 50% improvement in sensitivity but creates additional processing difficulties due to double exposure effects. 

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. 

Currently two methods are utilized for transfer of the relief image from the top resist layer to the bottom planarizing layer oxygen reactive ion etching (RIE), and optical flood exposure (1). Oxygen RDE systems have not found widespread acceptance due to the high cost and low throughput of RIE equipment. Optical... 

Figure 3. UV spectra of the carbonate protected phenolic, after surface irradiation with 500 fjJ/220 nm light, and after reaction with phenyl isocyanate. Note the extreme absorptivity at the flood exposure wavelength of 254 nm.

Figure 5. Sensitivity to x-rays (flood exposure through berylium window) for same materials as in figure 4. The slope for the blend is 2.7 times that for PMMA. Polydispersity for PMMA ranges from 1.9 to 2.3 at all doses.

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