Electrical behaviour of arsenic implanted silicon wafers at large tilt angle

Abstract

Two sets of silicon wafers were implanted with 60 keV arsenic ions at a dose of 5×1015 cm-2, using an Applied Materials SWIFT implanter. The first batch consisted of five silicon pre-amorphised wafers, whilst the second batch was implanted under the same conditions into <100> single crystal wafers. The tilt angle was varied over the range 0° - 45°. After implantation the samples were cut into smaller pieces and annealed in the range 800 to 1000°C for times up to 60 seconds in flowing nitrogen. Van der Pauw measurements of the Hall effect and resistivity were made to obtain values of the sheet resistance (RS), Hall mobility (μH) and sheet carrier concentration (NS) as a function of the tilt angle. Electrical profiles were obtained from differential Hall effect measurements, whilst the retained dose was determined by Rutherford Back Scattering (RBS). The results show that the sheet resistance and the sheet carrier concentration are a function of the tilt angle and that preamorphisation results in a higher degree of electrical activation. A comparison of atomic and carrier concentration profiles as a function of tilt angle in conjunction with simulations are used to explain the observed results.