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A novel low-leakage diode string design using boosted diodes, in reference [3], snubber-clamped diode strings, separate diode objects in 0.18* im CMOS processes is proposed in reference [4], NMOS-controlled lateral SCR (NCLSCR) in this paper. Diode strings can be divided into two (or three) devices added into the stacked diode string, in reference [5] and groups with only a large shallow trench isolation (STI) used as T spacing. With STI used to separate the groups, the diode string Triple-Well diode strings in reference [6]. In reference [3]-[5] successfully prevents excessive current leakage. The turn-on additional circuits are implemented in order to overcome the voltage of the diode string can be derived from the equations excessive leakage issues, while reference [6] introduces a concluded from the experiments. technique applicable to RF-ESD using only an extra triple-well e-INTRODUCTION to avoid the vertical bipolar effect.While additional circuits or extra process masks were Diode strings have been used extensively in electrostatic necessary in previous studies, a brand new diode string structure discharge (ESD) protection for integrated circuits (ICs). is revealed in this paper. This new design can easily reduce the Under forward bias conditions, a diode can carry a large Darlington effect without the needs for extra circuits or masks. amount of current with predictable terminal voltages, thus I. EXIPERINENT protecting other circuits from permanent damage. To ensure there is no damage to the diodes themselves, they are usually A conventional 5-stage diode string (5D) in p-Substrate designed at sufficient area sizes. Theoretically, the turn-on CMOS is illustrated in fig. 1. Two new Sstage diode strings voltage of the diode string is equivalent to multiplying the with large STI spacing are divided into two groups (4-stage and turn-on voltage of a single diode by the number of diodes.1-stage) (4D1D) and three groups (3-stage, 1-stage and 1-stage)However, the Darlington effect [1] exists between the (3DIDID), and are shown in fig. 2 and fig. 3, respectively.diodes, and contributes to a lower than expected turn-on Three kinds of conventional diode strings with two new voltage for the diode strings. Equation (1) from reference [2] structures, which were built with large STI spacing, were taken indicates that the turn-on voltage decreases as the bipolar gain into consideration in our experiment. All the candidates are increases. In actuality, the value of * -should be greater than listed in table .! The items shown as ID, 3D and 5D are or equal to 1, which leads to the fact that the turn-on voltage conventional diode strings without large STI spacing. The items of the diode string does not increase in a linear fashion as the named mDnD are the first type of the new structure. A large STI number of diodes increases. spacing was implemented between two groups of diodes. The m (m -1) first group contained m diodes, while the other was composed of Vtotal = mVf-VO 2 log(. ±1)(1) n diodes. The mDnDpD items in tabl...

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