| AVS 62nd International Symposium & Exhibition | |
| Electronic Materials and Processing | Monday Sessions |
| Session EM+NS+PS-MoM |
| Session: | More Moore! Materials and Processes to Extend CMOS Another Decade |
| Presenter: | Mary Edmonds, University of California at San Diego |
| Authors: | M. Edmonds, University of California at San Diego T. Kent, University of California at San Diego S. Wolf, University of California at San Diego J. Kachian, Applied Materials N. Yoshida, Applied Materials M. Chang, Applied Materials D. Alverez, Rasirc, Inc R. Droopad, Texas State University A.C. Kummel, University of California at San Diego |
| Correspondent: | Click to Email |
A broader range of channel materials allowing better carrier confinement and mobility could be employed if a universal control monolayer (UCM) could be ALD or self-limiting CVD deposited on multiple materials and crystallographic faces. Si-OH is a leading candidate for use as the UCM, as silicon uniquely bonds strongly to all crystallographic faces of InGa1-xAs, InxGa1-xSb, InxGa1-xN, SiGe, and Ge enabling transfer of substrate dangling bonds to silicon, which may then subsequently be functionalized with an oxidant such as HOOH(g) in order to create the UCM terminating Si-OH layer. This study focuses on depositing a saturated Si-OH seed layer on InGaAs(001)-(2x4) at a substrate temperature of 350°C. XPS in combination with STS/STM were employed to characterize the electrical and surface properties of the saturated Si-OH seed layer on InGaAs(001)-(2x4).
The 350°C self-limiting CVD procedure includes a decapped In0.53Ga0.47As(001)-(2x4) surface dosed with total 87.6 MegaLangmuir Si2Cl6 followed by 210.55 MegaLangmuir total anhydrous HOOH(g). Complete saturation of silicon coverage is determined to occur once further dosing with Si2Cl6 leads to no further increase in the silicon 2p or further decrease in the substrate gallium 3p peak areas. Complete surface saturation of Si-Ox on InGaAs(001)-(2x4) was determined to occur once no further increase in the O 1s peak was seen with additional anhydrous HOOH(g) doses. Following Si-OH surface saturation, 300,000 L TMA was dosed at 250°C, and XPS shows the emergence of Al 2p and C 1s peaks indicative of TMA surface nucleation. The surface was then dosed with 500 L atomic H at 250°C to remove the methyl groups on the surface aluminum and replace with -H termination as well as remove any residual chlorine left on the surface. The surface was then exposed to air for 30 minutes, dosed with an additional 500 L atomic H at 250°C, and then STS measurements were performed. STM measurements of the Si-Ox surface show uniform surface coverage. STS measurements show the surface Fermi level position moves towards midgap due to a surface dipole formation from –OH groups and oxygen bonding to the surface. TMA dosed on the Si-Ox surface shifts the Fermi level back towards the conduction band, consistent with unpinning and the -OH induced surface dipole being lessened through surface bonding with dimethylaluminum groups. Following hydrogen dosing and air exposure, the surface Fermi level remains near the conduction band edge consistent with the surface being stable and unreactive in air. Preliminary MOSFET studies on InGaAs(001) show equivalent performance with Si2Cl6 predosing compared to in-situ cleaning with atomic H.