Surface-energy triggered phase formation and epitaxy in nanometer-thick Ni1−xPtx silicide films

Abstract

The formation of ultrathin silicide films of Ni1−xPtx at 450–850 °C is reported. Without Pt (x=0) and for tNi<4 nm, epitaxially aligned NiSi2−y films readily grow and exhibit extraordinary morphological stability up to 800 °C. For tNi≥4 nm, polycrystalline NiSi films form and agglomerate at lower temperatures for thinner films. Without Ni (x=1) and for tPt=1–20 nm, the annealing behavior of the resulting PtSi films follows that for the NiSi films. The results for Ni1−xPtx of other compositions support the above observations. Surface energy is discussed as the cause responsible for the distinct behavior in phase formation and morphological stability.

Thermal Stability and Dopant Segregation for Schottky Diodes With Ultrathin Epitaxial $\hbox{NiSi}_{2 - y}$

“…1 is identical to that for the NiSi 2-y formation at different silicidation temperatures [2], [5]. For comparison, poly-Ni 1-x Pt x Si films of comparable thickness tend to agglomerate with a sharp resistance increase below 600 o C [2], [3]. Hence, the observed morphological stability as well as the ability of rapid lattice restoration is significant for implementation of the DS process for the epitaxial NiSi 2-y films.…”

“…It is worth noting that the temperature behavior in Fig. 1 is identical to that for the NiSi 2-y formation at different silicidation temperatures [2], [5]. For comparison, poly-Ni 1-x Pt x Si films of comparable thickness tend to agglomerate with a sharp resistance increase below 600 o C [2], [3].…”

“…Interaction of the 3-nm thick Ni film with Si(100) at 500 o C leads to epitaxial growth of NiSi 2-y , according to extensive XTEM, diffraction, pole-figure, resistance, and Raman analyses [2]- [5]. After B and As I/I, the resistance of the silicide films is rather high around 150 Ω/□ as shown in Fig.…”

“…Silicidation was carried out in a rapid thermal processing (RTP) chamber at 500 or 750 o C for 30 s, in N 2 atmosphere. The resultant epitaxial NiSi 2-y films were about 8 nm in thickness [2]. The wafers were then immersed in an H 2 SO 4 :H 2 O 2 (4:1) solution at 120 o C for 10 min to strip the unreacted Ni from the SiO 2 surface.…”

“…For these technology nodes, Ni-based silicide will most likely continue its dominance in the source/drain contact formation. Recent publications show that a NiSi 2-y film grows epitaxially on Si(100) if the initial thickness of Ni-Pt alloys is less than 4 nm and the Pt addition is restricted below 10% [2]- [5]. Polycrystalline Ni 1-x Pt x Si films will form for other thickness and/or composition combinations.…”