Energy distribution extraction of negative charges responsible for positive bias temperature instability

Abstract

A new method is proposed to extract the energy distribution of negative charges, which results from electron trapping by traps in the gate stack of nMOSFET during positive bias temperature instability (PBTI) stress based on the recovery measurement. In our case, the extracted energy distribution of negative charges shows an obvious dependence on energy, and the energy level of the largest energy density of negative charges is 0.01 eV above the conduction band of silicon. The charge energy distribution below that energy level shows strong dependence on the stress voltage.

Influence of ultra-thin TiN thickness (1.4 nm and 2.4 nm) on positive bias temperature instability (PBTI) of high- k /metal gate nMOSFETs with gate-last process

“…In order to obtain the quantity and distribution of N OX in HK bulk, a new method is proposed, as described in Fig.2, based on PBTI recovery characteristics [12,13]. Figure5(a)shows that the larger trap density of the device with thinner capping TiN under both 90 • C and 160 • C. Figure5(b)shows the energy profile extraction for traps by using ramp recovery stress, which is described in detail below,[14] similar to that in our previous work [15]. (i) V th shift after completing discharge under each V discharge is converted into the effective charge density, i.e., N OX and plotted against V discharge , where N OX = ∆V th ε 0 ε r /dq, with ∆V th = V th (end of each discharge)-V th0 (T stress = 0);(ii) The next task is to convert V discharge into the energy level of E C , i.e., (E T − E C ), by the oxide band structure, the same as that of our previous work,[15] where E T − E C = q •V OX and V g = V OX +V S +V ms , with E T being the trap energy level and E C the conduction band of substrate silicon, and V S the surface potential drop;…”

“…[12,13] Figure 5(a) shows that the larger trap density of the device with thinner capping TiN under both 90 • C and 160 • C. Figure 5(b) shows the energy profile extraction for traps by using ramp recovery stress, which is described in detail below, [14] similar to that in our previous work. [15] (i) V th shift after completing discharge under each V discharge is converted into the effective charge density, i.e., N OX and plotted against V discharge , where N OX = ∆V th ε 0 ε r /dq, with ∆V th = V th (end of each discharge)-V th0 (T stress = 0);…”

“…(ii) The next task is to convert V discharge into the energy level of E C , i.e., (E T − E C ), by the oxide band structure, the same as that of our previous work, [15] where E T − E C = q •V OX and V g = V OX +V S +V ms , with E T being the trap energy level and E C the conduction band of substrate silicon, and V S the surface potential drop;…”

Influence of an ALD TiN capping layer on the PBTI characteristics of n-FinFET with ALD HfO2/TiN-capping/TiAl gate stacks

“…The determined E A values of both samples were less than 0.1 eV, indicating that the PBTI degradation was dominated by the pre-existing traps instead of the generated traps [6]. Furthermore, the energy distribution of the traps in the HfO 2 layer was also extracted from the recovery characteristics (not shown here) [7], as presented in Figure 1(d). The trap density peaks for the two samples were located near the edge of the conduction band (E c ).…”

Study on influences of TiN capping layer on time-dependent dielectric breakdown characteristic of ultra-thin EOT high- k metal gate NMOSFET with kMC TDDB simulations

“…It is concluded that the interface trap degradation is severe under such a high stress condition, which is different from PBTI characteristic in our previous work. [15,16] The charge pumping method is used to directly measure interface trap density in fresh devices. In charge pumping measurement, the pulse amplitude is constant and base level voltage sweep is applied.…”