Electron-microscope investigations of the Pt-Si system during its rapid thermal treatment

The paper is dedicated to investigation of the influence of rapid thermal treatment on the microstructure of platinum silicide. The Pt films 43.7 nm thick were applied on the substrates of the monocrystal silicon by means of the magnetronic sputtering of platinum with the purity of 99.95 % on the МРС 603 set-up with the cryogenic pumping to the pressure not worse than 5*10-5 Pa. As an operating medium, argon was used with the purity of 99.933 %. Rapid thermal treatment of samples was performed in the thermal balance conditions by irradiating the non-working side of the wafer with the incoherent light flow in the nitrogen atmosphere during 7 s at the temperatures of 200-550 °C. The irradiation source in the set-up was represented by the quartz halogen incandescent lamps. The comparative analysis was done through the traditional long thermal treatment of the platinum films at a temperature of 550оС for 30 min in the nitrogen atmosphere. Investigations of the platinum silicide microstructure were performed by means of the transmission electron microscopy which demonstrated that the increase in the RTT temperature initiates first the annealing of defects on the inter-grain boundaries, which is evident from the more distinct contrast from the grains, and then one can observe their growth reflecting the forming of the new phase (silicide one). Such progress of changes of the platinum silicide microstructure and of the size of the grains with the increase in treatment temperature is determined by the heat of its forming. As the Pt2Si phase forming heat is minimum and constitutes 10.4-16.8 Kkal/atom of metal, and for PtSi - 15.7-25.5 Kkal/atom of metal, then the forming of a stable PtSi structure requires a higher temperature. The authors carried out calculations of the activation energy of the diffusion synthesis of platinum silicide during rapid thermal treatment. The calculations show that it is 0.37 eV smaller, than during the long thermal treatment. This means that in this case this process is subject to acceleration related to the rupture of the silicon-silicon bonds and electron excitation in silicon under the influence of the photon flow.

1. Tabolkin A. [Ensuring the National Security of Russia in the Sphere of the Radiation Hardened IC]. Jelektronnye Komponenty = Electronic Components. 2011;8:86-89. (In Russ.)

2. Belous A.I., Efimenko S.A., Turtsevich A.S. [Semiconductor Power Electronics]. Moscow: Technosphere; 2013:216. (In Russ.)

3. Mewrarka Sh.P. [Silicides for VLSIs]. Moscow: Mir; 1986:176. (In Russ.)

4. Turtsevich A.S., Soloviev Ya.A., Anufriev D.L., Milchanin O.V. [Structural - Morphological Peculiarities of the Separation Boundary of Si/PtSi in the Schottky Diodes for Power Microelectronics]. Vakuumnaja tehnika i tehnologija = Vacuum Electronics and Technology 2006;.16(4):271-275. (In Russ.)

5. Turtsevich A.S., Soloviev Ya.A., Anufriev D.L., Milchanin O.V. [Formation Peculiarities of the Si/PtSi Separation Boundary in the Schottky Diodes for Power Electronics]. Doklady BGUIR = Doklady BGUIR. 2006;4(16):53-58. (In Russ.)

6. Electron Microscopy. Under Edition of A.A. Lebedev. Moscow: GITT; 1954:636. (In Russ.)

7. Thin Films Mutual Diffusion and Reactions. Under Edition of J. Pouta, K. Tu, J. Meira, Moscow: Mir; 1982:576. (In Russ.)

8. Mazel E.Z., Press F.P. [Planary Technology of Silicon Devices]. Moscow: Energy; 1974:384. (In Russ.)

9. Pilipenko V.A., Gorushko V.A., Ponomar V.N., Pilipenko I.V. [Phase Composition and Structure of Titanium Disilicide, Obtained with Application of the Rapid Thermal Treatment]. Vestnik BGU = Bulletin of BSU, 2001;1(1):43-47. (In Russ.)

10. Robert T. Fryer, Robert J. Lad. Synthesis and thermal stability of Pt3Si, Pt2Si and PtSi films grown by e-beam co-evaporation. Journal of Alloys and Compounds. 2016; Vol. 682:216-224.