Effect of Rapid Thermal Treatment Теmperature on Electrophysical Properties of Nickel Films on Silicon

Abstract

Present work is devoted to determination the regularity of change of specific resistance and Schottky barrier height of nickel films on n-type silicon (111) at their rapid thermal treatment in the temperatures range from 200 to 550 °C. Nickel films of about 60 nm thickness were deposited by magnetron sputtering onto the silicon substrates having a resistivity of 0.58 to 0.53 Ohms×cm. The rapid thermal treatment was carried out in the range of 200 to 550 °C under heat balance mode by irradiating the backside of the substrates with non-coherent light flux in nitrogen ambient for 7 seconds. The thickness of the nickel films was determined by scanning electron microscopy. The sheet resistance of the samples was measured by a four-probe method. The Schottky barrier height was determined from I-V plots. It is shown that at a temperatureы of rapid thermal treatment of Ni/n-Si (111) 200–250 °C nickel will be transformed to Ni2Si, increasing in thickness by 1.15–1.33 times, specific resistance increases to 26–30 μOhm×cm, and Schottky barrier height decreases from 0.66 to 0.6 V. At a rapid thermal treatment temperature of 300°C the initial nickel film thickness increases by 1.93 times, the resistivity and Schottky barrier height decrease to 26–30 μOhm×cm and 0.59 V respectively due to the conversion of the Ni2Si into NiSi and the fixation of the barrier height by surface states at the silicidesilicon interface. Rapid thermal treatment of 350–550 °C transforms the original nickel film into NiSi, increases its thickness by 2.26–2.67 times, reduces its resistivity to 15–18 μOhm×cm and increases the Schottky barrier height to 0.62–0.64 V. The minimum defects and better reproducibility of electrophysical properties are characterized by NiSi films formed by rapid thermal treatment of nickel films on n-type silicon at a temperature of 400–450 °C. The results obtained can be used in the technology of integrated electronics products containing rectifying contacts.

Microstructure and Properties of Thin-Film Submicrostructures Obtained by Rapid Thermal Treatment of Nickel Films on Silicon

“…The change in film thickness (Figure 1) is also explained by a change in the phase composition, as well as solid-phase interaction of nickel with silicon throughout the entire heat treatment temperature range [15]. At RTT 200-250 • C, the film thickness remains virtually unchanged, but the grain size increases (visible in the cross section, Figure 1b).…”

“…Formation of nickel silicide thin films is mainly carried out by a solid-phase reaction of a nickel film with silicon. Nickel is applied by physical vapor deposition [5][6][7][9][10][11][12][13][14][15][16][17] or chemical deposition [8,18] onto a previously prepared silicon wafer. After this, the Ni/Si system is subjected to heat treatment, during which the phases Ni 2 Si, NiSi and NiSi 2 are sequentially formed [8].…”

“…The resulting silicides differ in their formation temperatures and the value of their surface-specific resistance [5,6]. Formation of the Ni 2 Si phase occurs within a temperature range from 175 • C to 300 • C [5,10,14,15,[17][18][19]. According to [5,9,15], the transition from the Ni 2 Si phase to NiSi occurs at temperatures of 275-350 • C, and at a temperature of 700 • C [6,8,14,18], the NiSi 2 phase is formed.…”

“…Formation of the Ni 2 Si phase occurs within a temperature range from 175 • C to 300 • C [5,10,14,15,[17][18][19]. According to [5,9,15], the transition from the Ni 2 Si phase to NiSi occurs at temperatures of 275-350 • C, and at a temperature of 700 • C [6,8,14,18], the NiSi 2 phase is formed. Heat treatment is carried out by steady-state annealing in a vacuum [5,7,[10][11][12], in an atmosphere of argon [8] and nitrogen [9], and rapid thermal annealing (RTA) in an atmosphere of argon [16] and nitrogen [6,7,9,11,[13][14][15]17,18].…”

“…According to [5,9,15], the transition from the Ni 2 Si phase to NiSi occurs at temperatures of 275-350 • C, and at a temperature of 700 • C [6,8,14,18], the NiSi 2 phase is formed. Heat treatment is carried out by steady-state annealing in a vacuum [5,7,[10][11][12], in an atmosphere of argon [8] and nitrogen [9], and rapid thermal annealing (RTA) in an atmosphere of argon [16] and nitrogen [6,7,9,11,[13][14][15]17,18]. RTT with lamp heating makes it possible to form nickel silicides within a time frame of 5 to 7 s [9,15,17], while steady-state annealing takes at least 30 min [5,[7][8][9][10][11][12].…”