Recent progress in semiconductor technology includes the utilization of advanced metallization schemes and low k dielectrics in integrated circuit (IC) design. 1,2 As critical dimensions decrease, intermetal dielectrics (IMD) with low dielectric constant (k < 3) play an increasingly important role in developing and producing high speed, high performance ICs. Low k dielectrics reduce interconnect RC [resistance (R) ϫ capacitance (C)] delay, power consumption, and offer many advantages such as reduced line-to-line capacitance and interconnnect cross-talk noise.Hydrogen silsesquioxane (HSQ), commercially available in solution as FOx ® flowable oxide, is one of the most intensively studied low k spin-on dielectrics (SOD) concerning both its basic properties as well as integration-related issues. 3-12 Used as gap-filling dielectric in advanced metallization, HSQs built-in microporosity results in reduced dielectric constant and thus lowers coupling capacitance between tightly pitched metal lines. The successful integration of HSQ into IC interconnnects requires a careful choice of materials together with heat-treatment optimization. However, properties of HSQ films, particularly dielectric properties are strong function of curing parameters, i.e., time, temperature, etc. It is therefore of current research interest to carry out an in-depth study of the curing characteristics of this SOD, to achieve a better understanding of how thermal curing affects the properties of HSQ.HSQ is a subset of polyhedral oligomeric silsequioxane (POSS) macromers, a family of ordered three-dimensional polymers whose structure resembles a cage (Fig. 1a). 3 With the empirical formula of (HSiO 3/2 ) 2n (n ϭ 2, 3, 4, etc.), there are one and one-half (sesqui) stoichiometry of oxygen bound to silicon in a caged structure of HSQ. The structure of HSQ resin, however, is composed of mixture of Si-O network and cage-like network (Fig. 1b), i.e., a random structure of partially formed cages of various sizes as the chemical reactions which produce the resin do not produce completely formed cages. HSQ has no terminal Si-OH or Si-OR groups and it polymerizes after bake and cure by opening of the cages. Therefore, HSQ is cured from a near cage-like structure to a three-dimensional network which provides mechanical integrity to the film for subsequent wafer processing. 4 ExperimentalThin film characterization.-HSQ films (about 4,000 Å) were prepared by spin-coating Dow Corning FOx ® solution onto 8 in. Si wafers followed by heating on three hot plates at 150, 200, and 335ЊC for 1 min each. After that, these films were cured in a furnace at different curing temperature for different durations. The curing conditions used for this study are listed in Table I. The thickness of HSQ films was measured using ellipsometer prior to and after thermal curing. Recent studies reported the importance of an inert environment during the HSQ cure at around 400ЊC in order to prevent oxidation. 4,5 Hence, in this study the HSQ cure employs double ramp rates to prevent tem...

This is the unspecified version of the paper.This version of the publication may differ from the final published version. between charge packet formation and propagation, and electroluminescence. Although the two phenomena are observed in the same field range, it is found that the onset of continuous EL follows the formation at the electrodes of positive and negative space charge regions that extend into the bulk prior to the propagation of charge packets. Charge recombination appears to be the excitation process of EL since oppositely charged domains meet in the material bulk. To gain an insight into specific light excitation process associated with charge packet propagation, electroluminescence has been recorded for several hours under fields at which charge packet dynamics were evidenced. It is shown that current and luminescence oscillations are detected during charge packet propagation, and that they are in phase. Mechanisms underlying EL and charge packets are further considered on the basis of these results. Permanent repository link2

The formation of space charge packets in XLPE (Cross-linked polyethylene) tapes from unaged cable insulation has been studied utilising the pulsed electro-acoustic (PEA) technique.The 150 m thick sheets were studied under constant applied dc field of 120 kV/mm at a temperature of 20 C for a period of 48 hours. After an inception period of about 3.5 hours, during which heterocharge accumulates at the anode and increases the local field there, a sequence of positive charge packets were observed to transit the sample starting from near the anode. This is shown as a moving image at the following web site: . Calculation of the internal field showed that the packets required a field of 140 kV/mm for their initiation. Reduction of the applied field step-wise from 120 kV/mm to 80 kV/mm indicated that the charge packet would keep moving as long as the local field at its front exceeded 100 kV/mm, but with a reducing magnitude. A return to an applied field of 120 kV/mm confirmed that the local field required to initiate a new packet was in excess of 135 kV/mm. The results are discussed in terms of current theories of charge packet formation. The first packet appears to be a moving front of field ionisation. The generation of subsequent packets is governed by the field at the anode and the balance of charge See, Dissado and Fothergill 9/16/08 2:31 PM 2 injection and extraction process, which occur there. The nature of the negative charges produced at the ionisation front is not clear, but they are unlikely to be electrons.

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