Two-dimensional profiling in silicon using conventional and electrochemical selective etching

Abstract

Articles you may be interested inTwo-dimensional dopant concentration profiles from ultrashallow junction metal-oxide-semiconductor field-effect transistors using the etch/transmission electron microscopy method One of the methods to delineate a two-dimensional dopant profile in Si devices is the selective etching technique combined with imaging of the doping dependent topography by atomic force microscopy. A major problem of the etching procedures reported so far is the critical control of the etch duration of only a few seconds as well as a limited sensitivity and dynamic range. We report further improvements of the conventional technique and compare it to an alternative approach. Etching experiments were carried out in an electrolytic cell, whereby the etching is controlled potentiostatically. Better control of the dissolved volume is achieved through current integration. Buffered HF as the electrolyte replaces the difficult nitrogen related chemistry of the classical approach. The etch rates thereby decrease by a factor of 10-100 thus allowing for a longer etch duration. The basic mechanisms, the sensitivity, and the dynamic range of the two techniques have been studied by using homogeneous samples and special test structures for calibration and ultrashallow profiling. Two-dimensional profiling has been carried out on cross sections of 0.25 m complementary metal-oxide-semiconductor devices with the classical and the electrochemical approaches. Problems of preparation, etching procedure, and imaging techniques are discussed in order to improve the quantification of the selective etching technique.

Probing resistivity and doping concentration of semiconductors at the nanoscale using scanning microwave microscopy

“…32,33 It consists of several 5 µm wide layers of silicon with varying donor dopant density ranging between 1 × 10 15 atoms per cm 3 and 1 × 10 19 atoms per cm 3 grown on a silicon wafer. 32,33 It consists of several 5 µm wide layers of silicon with varying donor dopant density ranging between 1 × 10 15 atoms per cm 3 and 1 × 10 19 atoms per cm 3 grown on a silicon wafer.…”

Electrical Scanning Probe Microscopy: Investigating the Inner Workings of Electronic and Optoelectronic Devices

“…2 AFM on its own can be used to characterize semiconductor devices beyond simple topographic mapping. For example, selective chemical etching can be used 3 to remove materials of certain composition or doping concentration and the resulting topography can be measured by AFM, from which the doping and composition is inferred over the device surface.…”

One- and two-dimensional dopant/carrier profiling for ULSI

“…The use of AFM imaging originated from the idea to determine the topography in a quantitative manner as one then could convert the topography to concentration levels by the use of appropriate calibration curves [74]. Despite several attempts and the use of more controlled etching procedures (such as the etching within an electrolytical cell [75]) the latter concept has not materialized to a routine technique as the etching turns out to be fairly irreproducible. Variations in etch rates are observed related to different lighting conditions, size of the doped regions, dopant gradients and equally well local stress and defect levels in the sample [76].…”