A method of surface functionalization of ceramics with monolayers and surface grafted polymer layers is described. A phenylsilane monolayer is created on the substrate's oxide surface by using phenyltrichlorosilane as the silane coupling agent. To control the formation of the monolayer and ensure the growth of a dense, homogeneous layer, the ceramic surface is first dried and then a controlled amount of water is adsorbed onto it, and a hindered organic base is added to the phenyltrichlorosilane solution to absorb acid generated in the reaction of the silane coupling agent with hydroxyl groups on the ceramic surface. This procedure results in dense homogeneous phenylsilane monolayers on a variety of surfaces, including silicon, Pt/PtO, and quartz. These layers can now be functionalized by addition of triflic acid, which removes the phenyl ring as benzene, and introduction of a nucleophile. Monolayers of −C⋮CH, −OCH2CF3, [(OCH2CH2)2O], −OCH2CF2CF3, and −O(CH2)6NH2 were generated in this fashion, all proving to be continuous and homogeneous. In addition, the cationic silyl triflate site generated by the removal of the phenyl ring is capable of initiating polymerization to form covalently bound polymer layers on the surface. Polymer layers of poly(methyl methacrylate), poly(propylene oxide), and poly(dimethylsiloxane) were generated in this manner; in the case of poly(dimethylsiloxane), layers up to 300 Å thick were formed. Anionic initiation of polymerization is also possible, using a bromopropyl trichlorosilane coupling agent to form the initial monolayer, followed by lithiation with lithium di-tert-butylbiphenyl. Acrylonitrile can be anionically polymerized to films of up to 2450 Å in thickness. The monolayers and polymer layers were characterized by XPS, AFM, contact angle measurements, and profilometry and were found to be continuous. The initial phenylsilane monolayer can be lithographically patterned by using 193 nm light to cleave the surface phenyl groups; the remaining groups can then be functionalized as discussed above to create surface-grafted patterned polymer layers.

No abstract

As lithography is extended to 157 nm, the molecular absorptivity becomes high for most organic polymers. Polymer photochemistry depends on photon absorption, and the higher energy associated with 157 nm light should lead to higher quantum yields of photoproducts. Polymers representative of those commonly employed in 193 or 248 nm resists were selected for this study. A gel permeation chromatography based method was developed to determine quantum yields for chain scission and crosslinking on thin polymers films coated on silicon wafers. This method was applied to determine the ΦS and ΦX of a number of lithographically significant homopolymers and copolymers at both the 157 and 248 nm wavelengths. It was found that polymers containing hydroxystyrene only undergo crosslinking while acrylate and methacrylate polymer only undergo chain scission. The film loss of 157 nm exposed poly-t-butyl acrylate and polymethyl methacrylate was found to be very high and attributed primarily to side chain cleavage of the esters, while no film loss of polyhydroxystyrene was detected. The analysis of outgassing materials showed that ester elimination in poly-t-butyl acrylate was responsible for all outgassed products and that the sum of the quantum yields of all outgassed products exceeded one, implying a reaction mechanism that recycled the initially produced radical. Direct polymer photolysis is significant at 157 nm and must be considered in resist design given the relatively high absorbance of most organic molecules at 157 nm.

Electron beam induced surface nucleation and low temperature thermal decomposition of metal carbonyls AIP Conf.The k~netics of low-energy electron beam induced metal film nucleation have been investigated. Expen~lents performed were the deposition of Fe and Cr from Fe(CO)s and Cr(CO)", respectIvely. It was found that the activation energy for the autocatalytic thermal decomposition of these compounds was lower than the activation energy for decomposition on Si surface. The autocatalytic activation energies were measured as 0.14 eV for Fe(CO)s and 1.02 eV for Cr(CO)6' The electron beam induced nucleation, together with the rapid autocatalytic decomposition, allowed for selective area metal film growth. A qualitative model based on classical nucleation theory describes well the effect of electron irradiation in induCing film growth. The electron beam induced nucleation step has been modeled in more detail and shows a t 4 dependence for the early stages of film growth, in agreement with the observed data.