arameter fit is shown in fig. 29, where the symbols refer to experimental data, and the solid line refers to this simple model fit with the case of the 80 nm "thin" SIMOX oxide. A very good agreement is shown here for SIMOX oxides of different thicknesses. The complete set of trap parameters (i.e., those extracted for large positive and negative fields) is given next in table 7. Hole Traps Electron Traps Oxide Type Oxide thickness [cm-2] [cm2] [cm-2] [cm2] 2.7 + 0.3 2.9 + 0.3 7.1 + 0.1 SIMOX x1012 x10-1 x1011 x10-15 Medium 4.3 + 0.2 2.8 + 0.2 2 = 0.2 15 1 10 SIMOX x1012 x10-13 x1012 x10-15 Medium 5.6 2.2 3.7 + 1.7 2.4 + 0.3 7.9 3.3 SIMOX 121.5 x1012 x10-13 x1012 x10-15 Thick 1.3 + 0.4 5.2 1.3 2.5 + 0.3 5.4 + 3.2 SIMOX x1013 x10-14 x1012 x10-15 Table 7. Summary of trap densities and capture cross sections extracted from Vot VS dose data using the exponential fit method [Pail95b]. III-47 4. NUMERICAL MODELING OF TRAPPING 4.1. BACKGROUND Since the mid-70's, a series of modeling efforts have been pursued to numerically account for the trapping of charges in oxide. These stages of development have the following ideas and assumptions in common: - In most of low to moderate dose cases, oxide degradation is dominated by charge trapping whereas interface state contribution is less important. Anyway, the charge separation technique [McWh-86] has been widely applied and accepted for 15 years and a device response can most of the time be separated into oxide-trapped and interface-states contributions, which makes sense of separate modeling of Vot and Vit. - Whereas interface states physics is still a matter of debate, trapped charge equation is to first order better known, as far as several assumptions can be accepted. And, moreover, the charge trapping component is known to be the major component in parasitic medium to thick oxides such the lateral isolation edge in bulk-MOS and MOS/SOI, the field oxide in bulk-CMOS, and the buried oxide in CMOS/SOI. However, we shall point out that analytical solutions are not tractable in