Interfacial reactions and Schottky barriers of Pt and Pd on epitaxial Si1−xGex alloys

Abstract

The evolution of interfacial reactions during the deposition of Pt and Pd on epitaxial Si1−xGex alloys was studied using x-ray photoelectron spectroscopy (XPS) for metal coverage up to 10 Å. Auger electron depth profiling was performed on a thicker metal overlayer before and after in vacuo annealing to study the redistribution of composition in the reactions. We have found that Pt and Pd react mainly with Si to form silicides at 350 °C, leaving some Ge to segregate at the surface. These results were correlated with Schottky barrier height measurements. We found that the Schottky barrier heights of Pt/n-Si0.8Ge0.2 and Pd/n-Si0.8Ge0.2 are about the same, pinned at 0.68 eV, which is much smaller than those of n-Si. These barrier heights are quite stable up to 550 °C.

Rectifying characteristics of sputter-deposited SiGe diodes

“…2 However, experimental results of Schottky contacts on epitaxial SiGe showed some exceptions to this rule. For example, SBH of Pt contact on n-Si 0.80 Ge 0.20 was measured to be 0.69 eV, 16 significantly lower than that of Pt/n-Si, and SBH of Pd 2 Si/p-Si 0.80 Ge 0.20 was measured to be 0.70 eV, significantly higher than that of Pd 2 Si/p-Si ͑0.42 eV͒. 17 In addition, Guliants et al measured SBHs of Pd/n-poly-Si ͑0.925 eV at 300 K͒ and Al/p-poly-Si ͑0.959 eV at 300 K͒, 27 substantially different from SBHs of those metals on c-Si.…”

“…For example, Schottky barrier height ͑SBH͒ of metal/poly-SiGe contact is not available though there are some reports on SBH of metal/epitaxial SiGe contact. [15][16][17][18][19][20][21][22][23] But the knowledge of SBH may be important for poly-SiGe's application in some cases, such as the elevated source/drain MOS device. This work presents the preparation of poly-SiGe Schottky barrier diode ͑SBD͒ and pn junction by IBS technique.…”

Schottky contact properties of Ni/n-poly-Si0.87Ge0.13/n-Si(100) heterostructure

“…Furthermore, formation and characterization of metal/ semiconductor interface have attracted considerable attention because of the scientific and technological significance [3]. In recent years, interfacial reaction and properties of Schottky contacts on Si 1 À x Ge x film for Pt, Pd, Ni, Ti, W, Al, Zr and Ir have been studied [4][5][6][7][8][9][10][11]. Most Si 1 À x Ge x films used in these research works are epitaxial and grown by molecular beam epitaxy (MBE) or chemical vapor deposition (CVD).…”

Interfacial reactions of Co/Si0.76Ge0.24 and Co(Si0.76Ge0.24)/Si0.76Ge0.24 by pulsed KrF laser annealing

“…1,2 The formation of metal-Si 1−x Ge x ohmic or rectifying contacts is required for the device applications. Recently, the interfacial reactions of metals such as Ni, 3 Pt, 4,5 Pd, [5][6][7] Ti, [8][9][10][11][12][13] Co, [14][15][16][17] W, 18 Cr, 19 and Cu 20 with Si 1−x Ge x films by conventional furnace annealing have been studied. In these reactions, the formation of a ternary phase, e.g., M(Si 1−x Ge x ) 2 , Ge segregation out of the germanosilicide, strain relaxation of the unreacted Si 1−x Ge x film, and the occurrence of agglomeration structure at higher annealing temperatures were generally observed.…”

“…The superior annealing condition was searched to effectively suppress or improve the phenomena, i.e., Ge segregation out of the germanosilicide, the formation of agglomeration structure, and the occurrence of strain relaxation in the unreacted Si 1−x Ge x film, which were generally observed on vacuum annealing. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In addition, to alleviate the constitutional supercooling phenomenon occurring during laser annealing, the Co(Si 0.76 Ge 0.24 )/Si 0.76 Ge 0.24 system was simultaneously studied because it was reported 23 that interfacial instability and cell formation can be suppressed by melting monosilicide or disilicide films.…”