Measurements of Ultra-Shallow Junction (USJ) Sheet Resistance with a Non-Penetrating Four Point Probe

Abstract

An accurate method to measure the four point probe (4PP) sheet resistance (R s ) of USJ Source-Drain structures is described. The new method utilizes Elastic Material probes (EMprobe) to form non-penetrating contacts to the silicon surface. The probe design is kinematic and the force is controlled to ensure elastic deformation of the probe material. The probe material is selected so that large direct tunneling currents can flow through the native oxide thereby forming a low impedance contact. Sheet resistance measurements on USJ implanted P+/N structures with SIMS junction depths as shallow as 15 nm have been measured. The sheet resistance values obtained with the new EM-probe 4PP method were found to be consistent with expectations. In this paper, the method will be demonstrated on a variety of implanted USJ structures.

Implementation of Electrochemical Methods for Metrology and Analysis of Nano Electronic Structures of Deep Trench DRAM

“…This can lead to false results of the µ-4PP measurements. To avoid such mistakes a non-penetrating µ-4PP or non-damaging elastic material probe (EMprobe) was developed by Hillard et al [6].…”

“…From the current density the charge Q, capacity C and sheet resistance R can be obtained. From these physical quantities one obtained the layer thickness, layer resistance, the roughness, the dielectric constant, the thickness of space charge, surface area and doping concentration [6]. In potentiodynamic methods, the potential increases with time, when oxidation at the anode electrode takes place and vice versa, when reduction at the cathode electrode occurs.…”

“…The charges versus potential can be plotted by a numerical integration of the measured current. Potentiodynamic methods also enable a simultaneous measurement of a one frequency capacity with the lockin-amplifier parallel to a cyclic voltammetry measurement [6]. The surface area of the specimen can be converted by calculating the ratio of the well known oxide layer growth current density 100 µA/cm 2 [11], derived from the high field mechanism law of SiO 2 and the amount of current which fluxed during the experiment of cyclic voltammetry, which could be obtained from such cyclic voltammogramme depicted in Fig.…”

Ultra low energy (ULE) implant dose and activation monitoring

“…The USJ junction depths and level of dopant activation depend strongly on processing [5]. The best method for monitoring the USJ structure is with Four Point Probe (4pp) Sheet Resistance (Rs) measurements [6,7,8].…”