Effects of electrical and temperature stress on polysilicon resistors for CMOS technology applications

A Temperature- and Aging-Compensated RC Oscillator With ±1030-ppm Inaccuracy From40 °C to 85 °C After Accelerated Aging for 500 h at 125 °C

“…Various resistors are available in standard CMOS technology, including poly, diffusion, and metal resistors, each governed by distinct aging mechanisms. The primary factor responsible for the shift in poly resistance is the depassivation of hydrogen at grain boundaries, coupled with hydrogen migration within an electric field [26], [27], [28], [29], [30], [31]. On the other hand, the alteration in metal resistance predominantly stems from electromigration (EM), a phenomenon that propels the migration of metal atoms and consequently leads to the formation of voids within the resistor's structure [31], [32], [33].…”

“…where A is an empirically determined constant, J is current density (A/cm 2 ), n is the empirically determined current density factor, E a is the activation energy (eV), k is Boltzmann's constant, and T is the absolute junction temperature of the resistor during the aging stress. The TTF estimation can be achieved through Black's approach, as demonstrated by (1) [29], [31], [32], [33], or by employing an alternate model, as depicted in (2) [26], [29], [31] to accommodate low current density (J ) scenarios. E a represents a vital aging-associated parameter obtained by fitting aging experimental data with (1) or (2).…”

“…These equations illustrate that a resistor's TTF experiences exponential growth as E a becomes larger. The p-poly resistors have a low E a of 0.477 eV and suffer from higher degradation caused by aging stress [26], [27]. Compared with p-poly resistors, n-poly resistors have a higher E a of 0.68 eV and longer TTF, making them more suitable for the better long-term stability of the oscillators [26].…”

“…Resistor aging is the primary contributor to long-term frequency drift in RC oscillators, and p-poly resistors, commonly used as reference resistors in RC oscillators for their high sheet resistance, small area, and relatively low-temperature coefficient of resistance (TCR), are particularly prone to aging [25], [26]. Accelerated aging tests on standalone p-poly resistors have shown that their resistivity can change by over 0.5% after 1000 h at 150 • C [27].…”

Evaluation of stability and robustness of poly-Si resistors with different dopant concentrations

“…4) For example, in regulator circuits, the stability and reliability of resistors directly affect the accuracy of voltage supplied to the electrical circuit. 5,6) A poly-Si thin film is the most ideal choice for embedded resistors in CMOS integrated circuit because of its low and stable voltage and temperature coefficients. 7) Many factors influence the electrical properties of the poly-Si resistors during the deposition process, such as process temperature, dopant concentrations, and the overall thermal budget.…”