A Solder Based Self Assembly Project In An Introductory IC Fabrication Course

Integrated circuit (IC) fabrication principles is an elective course in a senior undergraduate and early graduate student’s curriculum. Over the years, the semiconductor industry relies heavily on students with developed expertise in the area of fabrication techniques, learned in an IC fabrication theory and laboratory course. The theory course gives importance to the physics of manufacturing techniques and is often attached to a subsequent semester laboratory curriculum. The pre-requisite requirement of the theory component for a laboratory course requires students to enroll for two courses in separate semesters and is not an option for all students. Hence, an innovative student project is intended in the theory curriculum to give hands-on experience on the processes. The IC fabrication course is usually associated with high enrollment of students, leading to fewer laboratory experiments. The physics of IC fabrication techniques is important, but few students may perceive the theory as important with no laboratory experience. To improve the course and give students hands-on practice with existing state-of-the-art processing facilities, a tailored project was added to the syllabus. A solder-based self assembly (SBSA) project was introduced in the curriculum for the first time at the University of Alabama in Fall 2011. The student projects were designed in a way to provide an alternative to conventional time-intensive, high cost, and highly tool dependent IC fabrication lab experiments. SBSA forms three dimensional (3D) structures when applied to two dimensional (2D) patterns. The schedule was designed to accommodate theory classes aligned with the fabrication steps and completed by students. The project involved a brainstorming session, a design stage to develop 2D patterns using AutoCAD software, a deposition process, a lithography step, a dip soldering step, a reflow process, scanning electron microscope (SEM) imaging, and a final project presentation. Other processes required to complete the project were performed by the instructor. In general, students showed interest in working in teams, completing the project, and recommended to continuing the SBSA project in future IC fabrication course work. The SBSA project is cost effective and less tool dependent for incorporation in a semester long course. In addition, the project is time effective from both student and instructor perspectives.

Fabrication and characterization of a 0.14 μm CMOS device using ATHENA and ATLAS simulators

A 0.14 µm CMOS transistor with two levels of interconnection was designed and simulated to investigate its functionality and characteristics. ATHENA and ATLAS simulators were used to simulate the fabrication process and to validate the electrical characteristics, respectively. A scaling factor of 0.93 was applied to a 0.13 µm CMOS. The parameters being scaled are the effective channel length, the density of ion implantation for threshold voltage (Vth) adjustment, and the gate oxide thickness. In order to minimize high field effects, the following additional techniques were implemented: shallow trench isolation, sidewall spacer deposition, silicide formation, lightly doped drain implantation, and retrograde well implantation. The results show that drain current (ID) increases as the levels of interconnection increases. The important parameters for NMOS and PMOS were measured. For NMOS, the gate length (Lg) is 0.133 µm, Vth is 0.343138 V, and the gate oxide thickness (Tox) is 3.46138 nm. For PMOS, Lg is 0.133 µm, Vth is −0.378108 V, and Tox is 3.46167 nm. These parameters were validated and the device was proven to be operational