The fabrication of integrated circuits (ICs) in a semiconductor manufacturing environment is governed by two main categories: Front End of the Line (FEOL) processing and Back End of the Line (BEOL) processing. Transistors are formed in active regions in FEOL while BEOL processing focuses on creation of metal interconnects and interlevel dielectrics (ILDs). These dielectrics patterned in BEOL are required to have low permittivity or k values in order to mitigate parasitic capacitance. This reduction in capacitance between metal layers diminishes dynamic power dissipation, crosstalk noise, and interconnect delay issues as IC technology nodes continue to scale down in size. Dielectric constants between 2.0 to 2.7 are required for sub 90nm CMOS technology. Organosilicate glass (OSG) has been chosen as a candidate in this thesis study due to its k value being within the required range. OSG film was deposited on pilot wafers via Plasma Enhanced Chemical Vapor Deposition (PECVD) using a reaction between organosilane and oxygen gases. A challenge that has been identified in patterning OSG as an interlevel dielectric film occurs during the photoresist removal or ash process. Two types of plasma ash chemistries have been used to test OSG film integrity: O2 and H2Ar. The quality of OSG film is compromised due to plasma damage observed by carbon depletion or hydrogen species. Pre- and post-resist removal of OSG film composition has been characterized using materials analytic methods such as Fourier Transform Infrared (FTIR) spectrometry, X-ray Photoelectron Spectroscopy (XPS), Dynamic Secondary Ion Mass Spectrometry (DSIMS), and Surface Photovoltage (SPV). Wafer test chips were also fabricated and probed at Metal 1 and Metal 2 levels for serpentine line resistances and comb capacitances to characterize the performance of the OSG film as an ILD. The H2Ar plasma chemistry has been proven to be a better candidate for maintaining OSG composition.
Library of Congress Subject Headings
Metal oxide semiconductors, Complementary--Materials; Dielectrics; Metal oxide semiconductors, Complementary--Design and construction
Department, Program, or Center
Center for Materials Science and Engineering
Huang, Amy, "On the plasma induced degradation of organosilicate glass (OSG) as an interlevel dielectric for sub 90 nm CMOS" (2007). Thesis. Rochester Institute of Technology. Accessed from
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