Plasma induced damage on sub-0.5 μm MOSFETs using a CMOS driver as input protection

Analytic Model of Threshold Voltage Variation Induced by Plasma Charging Damage in High-k Metal–Oxide–Semiconductor Field-Effect Transistor

“…As mentioned below, recent studies showed that the interconnect connected to the active area even in some cases induces PCD. 14,23,24,57,58) Furthermore, it is expected that the effect of the width of the wiring interconnect on the antenna ratio -the difference in the width in terms of the wiring layers such as local, semi-global, and global interconnects -may be considered. However, owing to the stochastic phenomena for N ) 1 [some transistors are connected to wires in the global layers (larger r), and others, to the lower layer (smaller r) and vice versa], we can employ the overall trend of the r dependence in accordance with Rent's rule as a case study.…”

“…Regarding the antenna ratio, one may consider MOSFETs with protection diodes. In the case of interconnects longer than the limit value defined by the design rule, a protection diode 13,14,20,[23][24][25][26] is connected to the MOSFET (usually to the gate) to shunt the plasma charging current. The maximum allowed antenna ratio r max is dependent on the manufacturing process but it may range at approximately 100.…”

“…9,20,21) Note that the efficiency of the protection diode has been a source of controversy because the plasma stressing current is considered to be bidirectional and the polarity of diode characteristics is dependent on whether the structure is n/p or p/n. 14,23,24,58,59) It is imperative to consider the above efficiency of diode protection as well as the antenna design rule when routing the longer (violating) interconnect to the diode. Therefore, as the stochastic antenna ratio distribution, neglecting the detailed layout such as fanout or active-layer connection in an actual LSI circuit, we adopt f r ðrÞ in Fig.…”

“…[15][16][17][18][19] The damage is usually quantified by measuring the gate leakage current increase 16,17) and threshold voltage shift (ÁV th ). 15,19) Since this charging damage is considered to be inevitable in present-day plasma equipment, antenna design rules that limit the maximum antenna ratio in circuits [20][21][22] and protection diode schemes 13,14,20,[23][24][25][26] have been introduced to minimize the damage. Although various protection diodes have been proposed and introduced into the circuit, the ability to suppress charging damage is believed to be structure-and process-dependent.…”

“…Although various protection diodes have been proposed and introduced into the circuit, the ability to suppress charging damage is believed to be structure-and process-dependent. 8,[23][24][25]27) Therefore, even if protection diodes are employed in a large-scale integrated (LSI) circuit, the resultant charging damage should also be taken into account to evaluate the threshold voltage V th of MOSFETs.…”