This study assesses the use of selective LPCVD tungsten as a contact barrier in VLSI circuits. Measurements of the contact resistance and leakage current are evaluated as a function of variations in W deposition parameters, implant type, implant dosage, and metallization heat‐treatment. Addition of SiF4 to alter the equilibrium of the displacement reaction is seen to cause minimal erosion and encroachment of the Si contacts as well as produce low and thermally stable contact resistances to both n+ and p+ diffusions. For surface doping concentrations of 1.44×1020 cm−3 normalAs and 0.62×1020 cm−3B , measured values of the contact resistance for 2.0 μm sized vias are near 30Ω. Such values are quite compatible with high performance CMOS device requirements. Further reductions in these values are achieved with use of a self‐aligned normalPtSi/W contact barrier metallization. The contact resistance for 2.0 μm sized vias are, in this case, near 4 and 15OHgr; for the n+ and p+diffusions, respectively. Sporadic leakage across shallow n+/P‐Tub junctions remains, however, a serious problem associated with this selective LPCVD W process. Understanding the origin of this leakage and eliminating it can lead to numerous applications of this technology in VLSI manufacturing.

No abstract

THIN POLYMER FILMS 2285 metal-containing materials having optimal properties for use in high resolution lithography. AcknowledgmentWe are grateful to several members of the Polymer Science and Technology staff at the Almaden Research Center for their many helpful suggestions. ABSTRACTIn this paper, we present data on the formation and structure of CVD W films deposited by the Si reduction of WF~. Although the great majority of CVD W films deposited for IC applications are ostensibly deposited by H~ reduction, the Si reduction of WF~ always occurs first, even in the presence of copious amounts of H2. Therefore, it is the Si reduction reaction that determines the nature of W/St interface, and, in turn, such important properties as contact resistance and leakage current. We have found that Si reduced W films deposited between 210 ~ and 700~ are porous and discontinuous, and are probably not effective barriers to the further diffusion of WF,~. The discontinuous structure of the films provides a simple mechanism for the growth of thick W films by Si reduction; such thick films have been observed with increasing frequency as of late and have been enigmatic, because the reaction between WF6 and Si was thought to be self-limiting. An unusual temperature dependence of W film growth is reported. Films deposited below 310~ self-limit at about 0.3 • 1017 atom/cm 2 coverage (-60A of full dense W). In the temperature range 320 -450~ film coverages up to 6.1 • 1017 atom/cm 2 (-950A, at 340~ are observed. In the higher temperature range, 500~176 film covera es of about 1.5 • 10 I7 atom/cm 2 (200A) are observed. The temperature dependence and the self-limiting behavior of film gg~wth (regardless of the ultimate film thickness at which the film self-limits), are believed to be controlled by some surface-catalyzed reaction. Thus, the temperature dependence of the sticking coefficient of a reactive intermediate probably controls the reaction. This kind of model has the potential to explain why minor changes in the Si surface due to cleaning variations, for example, can result in radically different W film growth behavior.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.239.1.230 Downloaded on 2015-03-13 to IP

The wet and dry etch rates of Ga-doped ZnO and MgxZn1-xO deposited on r-plane sapphire by metalorganic vapor phase epitaxy (MOVPE) were studied for magnesium content 0 ≤ x ≤ 0.3 using dilute phosphoric acid and halogen–based inductively coupled plasma reactive ion etching (ICP-RIE) respectively. A decrease in the dry etch rates with increasing magnesium content was observed along with relatively low thermal activation energies of 21, 25, and 55 meV corresponding to n-ZnO, n-Mg0.1Zn0.9O, and n-Mg0.3Zn0.7O films respectively. Conversely, wet etch rates increased with increasing magnesium content with corresponding thermal activation energies of 8.4, 5.5, and 4.3 kCal/mol for n-ZnO, n-Mg0.05Zn0.95O, and n-Mg0.1Zn0.9O epilayers respectively. The dominant rate-limiting step was determined to be ion-assisted desorption of the etch products including (Mg, Zn) Cl2 during ICP-RIE etching and the wet etch process transitioned from reaction rate-limited to diffusion rate-limited etching with increasing magnesium content.

Articles you may be interested inResidual and intentional n-type doping of ZnO thin films grown by metal-organic vapor phase epitaxy on sapphire and ZnO substrates Effects of substrate treatment and growth conditions on structure, morphology, and luminescence of homoepitaxial ZnTe deposited by metalorganic vapor phase epitaxy