Ion Implantation.

This is the method of doping of a slice or an epitaxial layer by bombarding it with impurity ions accelerated to an energy enough to enable the ions to penetrate rather deep into the slice bulk. The depth of the penetration of ions depends on their energy and mass. The larger the energy of ions, the greater the thickness of the implanted layer. The increased ion energy, however, produces more radiation defects, which impair the electrophysical properties of a crystal.

The impurity concentration in the implanted layer depends on the current density in the ion beam and the process duration, or what is called the exposure time. The time of exposure ranges from a few seconds to 3 to 5 min and over, sometimes to 1 or 2 h, depending on the current density and the desired impurity concentration. It stands to reason that the longer exposure of a slice to the ion beam leads to a greater number of radiation defects.

Since the area of the ion beam is merely 1 or 2 mm, which is much smaller than the area of a slice, the ion implantation setup must have a special deflection system to scan the beam, that is to deflect it smoothly or stepwise and in an adequate sequence along all the lines of the slice containing integrated circuits.

After completion of the doping process, the slice should be subjected to annealing at 500 to 800 C to ensure ordering of the silicon crystal lattice and eliminate the inevitably present radiation induced defects, if only partially. At the annealing temperature, the diffusion processes change somewhat the profile of distribution.

Ion implantation, like diffusion, can be overall and local (selective). In the latter, more typical case, the irradiation (ion bombardment) is performed through masks in which the free path of ions must be much shorter than that in silicon. The materials of masks can be silicon oxide and aluminum which find extensive uses in IC fabrication. An important merit of ion implantation is that ions, travelling along the straight line, penetrate only into the slice bulk at right angles to the surface and do not affect the regions under the mask.

The Kaluga Branch of the Bauman Moscow State Technical University

The Kaluga Branch of the Bauman Moscow State Technical University was founded in 1959.

It has six faculties: Faculty of Mechanical Engineering Technologies; Machine Designing Faculty; Electronics, Informatics and Control System Faculty; Fundamental Sciences Faculty; Social-Economic Faculty and Pre-University Training Faculty.

The students of the Kaluga Branch are trained in eighteen specialties. Each faculty is headed by the Dean and has a number of specialized chairs. The academic year is divided into two terms and the students take examinations twice a year, in winter and in summer.

The University has good libraries, well-equipped laboratories and computer centers.

The first- and second- year students study many subjects: Higher Mathematics, Technical Drawing, Strength of Materials, Physics, Chemistry, as well as History, Philosophy, Russian and foreign languages and so on.

The students begin to master their speciality in the third year. The course of studies at the University lasts 5 years and 10 months and leads to the Diploma of Engineering.

Undergraduates of all specialities have an opportunity to receive the second higher education in Economics, Computers or Foreign languages.

The Kaluga Branch has the post-graduate course to raise scientific and professional level of young lecturers.