A new isolation technology for mixed-mode and general mixed-technology SOC chips

• Published in: 2000 Semiconductor Manufacturing Technology Workshop (Cat. No.00EX406) pp. 124 - 132
• Main Authors: Liao, C.P., Juang, K.C., Huang, T.H., Duh, D.S., Yang, T.T., Liu, M.N.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2000
• Subjects: Circuit simulation; Circuit synthesis; Circuit testing; Coupling circuits; Crosstalk; Frequency; Isolation technology; Protons; System-on-a-chip; Very large scale integration
• ISBN: 0780363744; 9780780363748
• DOI: 10.1109/SMTW.2000.883093

With higher levels of integration in VLSI, the importance of limiting undesirable interactions (i.e. crosstalk) between different circuits fabricated on a common Si substrate is increasing. Such interaction, known as substrate coupling, is more significant in mixed-mode or mixed-technology ICs, particularly in the high frequency regime. In commercial operations, the procedure for mixed-mode (or mixed-technology) device development has always become a laborious cycle of circuit design/simulation, layout, pilot run, and testing, before a final compromised (not necessarily optimized) result is reached. Consequently, the whole process of mixed-technology IC production is very time-consuming, costly and may lead to poor market timing. In this paper, a new isolation method is proposed in which penetrating protons are applied at selected locations on each IC prior to packaging. Experimental results indicated that a 25-30 dB improvement could be achieved by applying a low-fluence proton bombardment to the isolation-intended region of a metal pad pattern on a /spl sim/10 /spl Omega/-cm Si substrate. In addition, a proton-enhanced alternative-SOI structure from initially lightly doped wafers may be achieved for all SOC (system-on-a-chip) purposes. This option fully exploits the proton treatment, since the resistivity enhancement is most effective in lightly doped silicon. This proton isolation technology should be of interest to any mixed-technology SOC producer longing for the opportunity to break the aforementioned development cycle from the outset into a more familiar development sequence, while still leading to as-designed, optimum products.