Abstract:The self-development characteristics of Si containing polymers were investigated with the objective of applying these polymers to the surface-imaging process in x-ray lithography. Polymers containing Si atoms in their backbones or substitutents were studied in detail; UV and Fourier transform infared spectra were used to study their reaction to soft xrays. The polymers exhibited postive-tone characteristics when exposed to x-rays. Their self-development sensitivity and oxygen reactive ion etching (02-RIE) resi… Show more
“…Polysilanes are well‐known precursor materials for SiC ceramics . Strong absorption of polysilanes in UV region makes these materials suitable for application to photo and X‐ray lithography …”
“…Polysilanes are well‐known precursor materials for SiC ceramics . Strong absorption of polysilanes in UV region makes these materials suitable for application to photo and X‐ray lithography …”
“…The bottom layer acts as an antireflective layer as shown in Figure . One of the silicon-containing polymers, polysilane, has been investigated extensively as the photosensitive top layer. − 1 Difference between the polysilane bilayer resist process and polysilane antireflective layer process.…”
Fundamental aspects for a novel LSI pattern fabrication process employing polysilanes as an antireflective layer (ARL) are discussed. The multilayer is composed of an organic resist, a polysilane layer, and a substrate. The polysilane avoids reflections from the substrate when the resist is exposed to 248-nm light emitted from a KrF excimer laser. It also acts as a pattern transfer layer. The polysilane layer is etched faster than the resist when the etching is carried out with reactive ions by employing Cl 2 gas. Therefore, the resist pattern is transferred to the polysilane layer precisely. The relationship between the structure of the polysilane and its physical properties, namely, the UV absorbance at 248 nm and etching selectivity toward the organic resist, is discussed and the best polysilane structure for this application identified.
“…Polysilane resists have been investigated extensively as a bilayer polysilane resist necessary in LSI devices. , Resist patterns are fabricated by UV exposure, followed by development. A KrF excimer laser (248 nm), a ArF excimer laser (193 nm), and X-rays have been reported to be useful light sources for polysilane lithography. − Miller et al have reported that certain halogenated additives, such as a chlorinated triazine (EA5), enhance the photosensitivity of certain polysilanes, so that the needed dose approximates that in LSI production lines. ,− , …”
A likely mechanism of especially large photosensitization for a base-developable poly-(phenylhydrosilane) resist (1) in the presence of 3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone (EA1) is discussed in terms of photolysis rates and dissolution rates. The increase in the photolysis rate occurs through photoinduced electron transfers from polysilanes to electron acceptors. The fluorescence quenching rate of 1 in the presence of EA1 is almost the same as that in the presence of benzophenone (EA2). However, EA1 does increase both photolysis rates and resist sensitivities, but EA2 does not. The difference between EA1 and EA2 is discussed in terms of back-electron transfer in order to explain the importance of the presence of peroxide moieties. In the case of EA2, photoinduced electron transfers as well as back-electron transfers occur. In case of EA1, the cleavage of peroxide bonds on the benzophenone moiety would effectively inhibit the back-electron transfer to the 1 radical cation. The same phenomena are observed for C-60. EA1 photodecomposes to form compounds bearing carboxylic acids which also facilitate the dissolution of photolysis products of 1 into basic aqueous solutions.
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