Photoresists positive

Miscellaneous Applications. PEIs and their derivatives ate used as cementation auxihaties in cmde oil exploration (459), and for breaking cmde oil emulsions (460) in cmde oil extraction. Seed coatings of water-soluble copolymers containing polyethyleneimine have been developed (461). Polyethyleneimine derivatives have positive photoresist properties (462) amidated polyethyleneimines improve the flow properties of cement (463) and with few exceptions, A/-acyla2iddines act as chemical sterilisers for insects (464). 

Fig. 6. Schematic illustration of the photohthographic patterning process used for defining features in siUcon dioxide using ( ) a positive photoresist that polymerizes light, where ( ) represents the mask (U) Si02 and ( ) Si. Development includes removal of the mask and undeveloped photoresist.

Carbonyl groups on the side chains also activate the dihalides. These particular dihalides were employed to prepare polyfarylenc ether)s containing pendent benzoyl groups.82 The polymers may be used as a positive photoresist for UV irradiation. 

Positive photoresists, by contrast, are based on water-soluble novolak resins with naphthalene diazoquinone sulfonate (NDS) as the photosensi-tiser. On photolysis the NDS causes a rearrangement in the polymer to yield nitrogen gas plus an indene carboxylic acid. This latter functional group considerably increases the solubility of the polymer, hence solubilising those areas of the polymer that had been exposed to light. 

Positive imaging techniques, 19 201 Positive ion spectroscopy, 24 107 Positive photochromism, 6 588 Positive photoresists, 20 280-281 Positive photosensitive polyimides,... 

Materials that exhibit enhanced solubility after exposure to radiation are defined as positive resists. The mechanism of positive resist action in most of these materials involves either main-chain scission or a polarity change. Positive photoresists that operate on the polarity change principle have been widely used for over three decades in the fabrication of VLSI devices and they exhibit high resolution and excellent dry etching resistance. Ordinarily, the chain scission mechanism is only operable at photon wavelengths below 300 nm where the energy is sufficient to break main chain bonds. 

While "conventional positive photoresists" are sensitive, high-resolution materials, they are essentially opaque to radiation below 300 nm. This has led researchers to examine alternate chemistry for deep-UV applications. Examples of deep-UV sensitive dissolution inhibitors include aliphatic diazoketones (61-64) and nitrobenzyl esters (65). Certain onium salts have also recently been shown to be effective inhibitors for phenolic resins (66). A novel e-beam sensitive dissolution inhibition resist was designed by Bowden, et al a (67) based on the use of a novolac resin with a poly(olefin sulfone) dissolution inhibitor. The aqueous, base-soluble novolac is rendered less soluble via addition of -10 wt % poly(2-methyl pentene-1 sulfone)(PMPS). Irradiation causes main chain scission of PMPS followed by depolymerization to volatile monomers (68). The dissolution inhibitor is thus effectively "vaporized", restoring solubility in aqueous base to the irradiated portions of the resist. Alternate resist systems based on this chemistry have also been reported (69,70). 

Chemistry associated with a typical conventional positive photoresist. 

Etching resistance = novolac based positive photoresists... 

Preparation of a Novel Silicone-Based Positive Photoresist and Its Application to an Image Reversal Process... 

We have developed a novel silicone-based positive photoresist (SPP) for two-layer resist systems. SPP is composed of an acetylated poly(phenylsilsesquioxane)... 

TANAKA ETAL. Novel Silicone-Based Positive Photoresist... 

HPR-206 Positive Photoresist (Olin-Hunt) Mixed Isomer Novolac + Diazonaphthoquinone Photoactive Compounds 120-140... 

Baking the polyester film at 200 C improved the planarity of the film profiles over the 20, 50 and 100 [Mi wide holes. These profiles were leveled better than those for the baked positive photoresist film. During baking, the polyester film shrinks less than the positive photoresist film and may also have either a lower viscosity and/or a longer, low viscosity flow period. 

Table IV lists the planarization of 20 - 400 [im wide holes achieved by unbaked and baked films of positive photoresist, ortho-cresol novolac and poly(o>-methylstyrene).

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