Document Type
Thesis
Date of Award
5-31-1990
Degree Name
Master of Science in Electrical Engineering - (M.S.)
Department
Electrical and Computer Engineering
First Advisor
Marek Sosnowski
Second Advisor
Roy H. Cornely
Third Advisor
Armen K. Jermakian
Abstract
This thesis describes a study of a unique deposition technique known as Ionized Cluster Beam (I.C.B.) deposition. According to I. Yamada and T. Takagi, the inventors of the I.C.B. concept, the beam of deposited material contains clusters as large as thousands of atoms. To study the mass distribution of the ionized species, an I.C.B. source was designed and built by the author. The design provided temperature control along the axis of the crucible by using electron beam heating with two independently controlled emission filaments. Special attention was given to minimizing the background of charged particles generated in various sections of the I.C.B. system.
The operational characteristics of the system were experimentally determined using gallium as the deposition material. A deposition rate as high as 51 A/sec. was achieved at a crucible temperature of 1900°C. The maximum ionization efficiency was 0.2% at a deposition rate of 1.4 A/sec.
Ion energy spectra were measured by a retarding potential method at crucible temperatures of 1400°C, 1500°C, 1700°C and 1800°C. At 1700°C and 1800°C, the measurements indicated that 0.16% of the ions had kinetic energy greater than that which could be explained by acceleration in the electric potential of the ionizer. This high energy tail observed in the ion spectra consisted of particles with energies up to 200eV.
Interpretation of the data includes discussion of the energy spread due to electric potential nonuniformities in the ionizer, the thermal velocity distribution of the particles and an ionization cross section which is a function of cluster size. A computer program was used to simulate the energy spread due to the particles thermal velocity distribution and that introduced by the nonuniformities in the ionizer potential. Based on this simulation, it was concluded that the high energy tail of the ion energy distribution for a crucible temperature of 1700°C could be the result of the presence of clusters, consisting of about 850 atoms, and making up 0.23% of the ionized beam.
Recommended Citation
Krommenhoek, Steven K., "Design of an ionized cluster beam system for thin film deposition and cluster size measurement" (1990). Theses. 2803.
https://digitalcommons.njit.edu/theses/2803
