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The thermal and electron activated properties of CCl4 on Si(100), with and without adsorbed hydrogen, have been investigated in the temperature range 100–1100 K using temperature programmed desorption (TPD), electron stimulated desorption, and x-ray photoelectron spectroscopy. Dosed at 100 K but not exposed to electrons, molecular CCl4 desorbs from both surfaces between 120 and 170 K with coverage-dependent monolayer and multilayer peaks. An etching product, SiCl2 desorbs from Si(100), but not H–Si(100). Electron irradiation of CCl4 on both surfaces at 100 K drives reactions with ejection and retention of products. Compared to thermal activation, SiCl2 TPD is enhanced on Si(100), while on H–Si(100), the SiCl2 TPD channel opens and HCl peaks appear at 610 and 820 K in TPD. Ejection of neutral CClx (x⩽4) and Cl is observed on both Si(100) and H–Si(100), and the CCl+ ion signal decays with a cross section of (1.3±0.1)×10−16 on Si(100) and (2.8±0.5)×10−17 cm2 on H–Si(100). On both surfaces, the electron activated cross section describing the decay of the CCl4 TPD peak area is 9×10−17 cm2. C2Clx (x=2, 4, and 6) appear in post-irradiation TPD.

Most organosilicate glass 1 (OSG), low dielectric constant (low-) films contain Si-R groups, where R is an organic moiety such as -CH 3 . The organic component is susceptible to the chemically reactive plasmas used to deposit cap layers, etch patterns, and ash photoresist. This study compares a spin-on, mesoporous OSG film with a completely connected pore structure to both its nonmesoporous counterpart and to another low-density OSG film deposited by plasma-enhanced chemical vapor deposition. The results show that the film with connected pores was much more susceptible to integration damage than were the nonmesoporous OSG films.As integrated circuit device and interconnect dimensions continue to scale smaller, low dielectric constant () interlayer dielectric (ILD) materials will become necessary to mitigate RC (product of resistance and capacitance) propagation delay and reduce power consumption and crosstalk. 1 Lowering the -value of a material requires either altering the chemical bonding to reduce the bond polarizability or decreasing the number of bonds (density) in a material. 2 To reduce the -value below 2.2, most dielectric materials will require a density decrease by introducing free volume (micropores < 2 nm in diameter) or mesoporosity (2-50 nm diameter pores). Unfortunately, lowering the density also compromises the mechanical strength and other properties of the material. 2 The material properties of mesoporous dielectric films, such as connected pores and low mechanical strength, create a host of integration problems including integration damage to the film. 3,4 The Si-R groups make organosilicate glass (OSG) films hydrophobic and they lower the density by breaking up the tetrahedral Si-O bonding. However, the carbon component is susceptibleto degradation when exposed to the reactive plasmas used for capping, etching, and ashing processes, especially oxidizing plasmas that induce silanol formation. Such plasma-induced chemical modifications can cause film densification, dangling bonds and defects, and moisture uptake. 5,6 Recently, International SEMATECH monitored several OSG films for change in caused by integration damage (ID) while integrating the films into SEMATECH's Cu/Damascene test chip using their standard processing flow (Table I). 7 Mesoporous OSG films with connected pores exhibited a large increase in due to ID during integration. In contrast, nonmesoporous OSG films showed much smaller changes in . Thus, connected mesoporosity appears to facilitate film damage during processing by allowing reactive species to more easily penetrate the film.Various plasma pretreatments (PPT) have been reported to form densified and chemically modified interface layers on OSG films, and these skin layers can prevent film damage by photoresist ash processes. [8][9][10] This study reports the effects of oxygen and nitrogenbased plasmas on one mesoporous and two nonmesoporous blanket films. To our knowledge, this is the first direct demonstration that a mesoporous film is more susceptible to ID than its nonm...

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Dosed on oxidized Si(100) at 100 K, carbon tetrachloride adsorbs and desorbs without dissociation. The monolayer desorbs at 135 K, 10 K lower than the multilayer. This unusual behavior is attributed to stronger interactions between condensed CCl4 molecules than between CCl4 and SiO2. Irradiation with either low-energy (⩽50 eV) electrons or Mg Kα x rays causes C–Cl cleavage. For 50 eV incident electrons, the decay of the CCl4 temperature programmed desorption peak area occurs with an effective cross section of (2.0±0.1)×10−16 cm2. The same cross section characterizes the ejection of CCl (CCl+) during electron irradiation. After low electron fluences, C2 and C3 molecules desorb reflecting both electron-induced C–Cl bond dissociation and C–C bond formation. At 2.5 eV incident electron energy, the cross section is still high—10−17 cm2. Electron activation is attributed to a combination of impact ionization and electron attachment mechanisms.

Acetone, (CH3)2CO and (CD3)2CO, adsorbed on Ag(111) at 95 K was studied using using thermal, photon, and electron activation. Adsorption and desorption involve no dissociation. The temperature-programmed desorption (TPD) spectra exhibit three resolvable peaks, two of which (146 and 134 K) are assigned to the first layer and the third (127−134 K) to multilayers. TPD, after sequentially dosing 1 ML of (CD3)2CO followed by 1 ML of (CH3)2CO, shows extensive mixing of the two adsorbates throughout the full width of the desorption peaks. This suggests rapid motion, on the TPD time scale, below the onset of desorption (120 K). RAIRS analysis at 95 K indicates that the orientation of adsorbed acetone is coverage-dependent, but the CO bond remains nearly parallel to the Ag(111) surface at all coverages. At the lowest coverages the average C−C−C plane position is 50° from the surface normal; at higher coverages (up to monolayer) this plane tilts toward the surface normal (22°). Dissociation and desorption of adsorbed (CH3)2CO are initiated by 100 eV electrons; TPD products include ketene, methane, and high-temperature (CH3)2CO derived from acetone enolate. RAIRS after electron irradiation provides evidence for electron-induced reorientation in which the CO bond moves away from the surface plane. The cross section for loss of parent was of order 10-16 cm2. Photon irradiation at 248 and 193 nm produced no effects with cross sections higher than 10-21 cm2.

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