Texas Instruments Corporation

E Ajith Amerasekera

Vikas I Gupta

Charvaka Duvvury

Alwin J Tsao

David B Spratt

Timothy Alan Rost

Gregory Charles Baldwin

Stanton Petree Ashburn

Mark Stephen Rodder

Amitava Chatterjee

Bernhard H Andresen

Richard Gene Burch

Sharad Saxena

Sridhar Ramaswamy

Zhiliang Julian Chen

Thomas A Vrotsos

Joseph C Davis

Raoul B Salem

Karthik Vasanth

Vincent Maurice McNeil

Shian-Wei Aur

The high current capabilities of a lateral npn transistor for application as a protection device against degradation due to electrostatic discharge (ESD) events are improved by adjusting the electrical resistivity of the material through which the collector current flows from the avalanching pn-junction to the wafer backside contact. As expressed in terms of the second threshold current improvements by a factor of 4 are reported. Two implant sequences are described which apply local masking and standard implant conditions to achieve the improvements without adding to the total number of process steps. The principle of p-well engineering is extended to ESD protection devices employing SCR-type devices.

Electrostatic discharge device and method

The invention comprises a system and method for providing electrostatic discharge protection. In one embodiment of the invention, an integrated circuit ( ) comprising at least one input element ( ) is protected by a protective circuit ( ). The protective circuit ( ) is operable to protect the integrated circuit ( ) from damage due to electrostatic discharge and may be coupled to the input element ( ). The protective circuit ( ) comprises a lateral NPN transistor (T ) coupled to the input element ( ) and operable to activate when the input element voltage exceeds threshold, the threshold greater than or equal to the ordinary operating voltage of circuitry coupled to the input element ( ). The protective circuit ( ) also may comprise a lateral PNP transistor (T ) coupled to the input element ( ) and to the lateral NPN transistor (T ). The lateral PNP transistor (T ) is operable to aid in raising a potential of the base of the lateral NPN transistor (T ). Alternatively, the protective circuit ( ) also may use a PMOS traisistor (P ), or a PMOS transistor (P ) in combination with the lateral NPN transistor (T ), coupled to the input element ( ) and to the lateral NPN transistor (T ). The PMOS transistor (P ) is operable to aid in raising the potential of the base of the lateral NPN transistor (T ).

System and method for electrostatic discharge protection using lateral PNP or PMOS or both for substrate biasing

An operational lifetime, and also performance characteristics, can be accurately predicted for an experimental transistor design ( ) and a specified set of fabrication process conditions ( ), without actually fabricating and testing a physical transistor made according to the particular design data and process conditions. With respect to the prediction of an operational lifetime, the operational lifetime can be expressed as a function of the size of a gate overlap ( ) of the transistor, and this relationship is valid throughout a selected semiconductor technology for which the transistor is designed. The size of the gate overlap is determined by selecting a combinations of values for two process conditions.

Method and apparatus for predicting an operational lifetime of a transistor

An ESD protection circuit ( ) and method is described herein. A lateral npn transistor ( ) is connected between an I/O pad ( ) and ground (GND). A substrate biasing circuit ( ) increases the voltage across a substrate resistance ( ) during an ESD event by conducting current through the substrate. This, in turn, triggers the lateral npn ( ) which clamps to voltage at the pad ( ) and dissipated the ESD current. The lateral npn ( ) is the primary protection device for dissipating ESD current.

Integrated ESD protection circuit using a substrate triggered lateral NPN

In a split gate process for dual voltage chips, the N-type high-voltage transistors which are part of the ESD protection circuit, and therefore have the thicker gate oxide of the high-voltage transistors, can receive channel doping and drain extender doping which is the same as the core transistors. This causes these transistors to develop a high substrate current during an ESD event, triggering the protection circuit.

On-chip ESD protection in dual voltage CMOS

A protection device for trench isolated technologies. The protection device includes a lateral SCR (100) that incorporates a triggering MOS transistor (120) with a first gate electrode (116) connected to the cathode (112) of the SCR (100). The anode (110) of the lateral SCR (100) is separated from the nearest source/drain region (122) of the triggering MOS transistor (120) by a second gate electrode (132) rather than by trench isolation. By using the second gate electrode (132) for isolation instead of trench isolation, the surface conduction of the lateral SCR (100) in unimpeded.

Lateral SCR structure for ESD protection in trench isolated technologies

A method for achieving improving ESD protection in integrated circuits. Capacitance associated with a power supply plays an important role in ESD protection and increasing Vcc.sub.-- c capacitance by integrating distributed capacitors as junction capacitors, or MOS capacitors along Vcc and grounded n+ diffusion parallel runs improves protection against ESD and EOS. Additionally, at least a pair of antiparallel diodes interposed between the periphery voltage source and internal core circuitry voltage provides an added noise margin.

EOS/ESD protection for high density integrated circuits

An ESD protected semiconductor circuit and the ESD protection circuit. The protected circuit includes a terminal, a semiconductor device coupled to the terminal and an ESD protection circuit. The ESD protection circuit includes a substrate of a first conductivity type and has a surface. A first well of conductivity type opposite to the first conductivity type is disposed within the substrate and extends to the surface. A second well of the first conductivity type is disposed within the first well and is spaced from the substrate and extending to the surface. A third region of the opposite conductivity type is disposed within the second well and is spaced from the first well and extending to the surface. At least one of the substrate or the third region is coupled to the terminal.

ESD protection for high density DRAMs using triple-well technology

Bias circuits which define control terminal voltages in a cascoded nMOS ESD protection circuit, such that the circuit is in high impedance state (OFF) during normal operation, and low impedance (ON) during an ESD event. G1 and G2 are the driver circuits which define V3 and V4 during an ESD event at the pad. During normal operation, V3 and/or V4 are high and no current flows between the pad and V.sub.SS. During an ESD event, V3 and V4 are high and both devices conduct MOS current as the lateral NPNs turn on. Diode D1 conducts current to charge C.sub.c, the chip capacitance, raising V.sub.DD, enabling G1 and G2 to turn on and raise V3 and V4 to levels greater than the nMOS threshold voltage.

Cascoded-MOS ESD protection circuits for mixed voltage chips

One embodiment of the instant invention is an electrostatic discharge protection device (10) which includes a field-effect transistor, the field-effect transistor comprising: a substrate (12) of a first conductivity type and having a surface and a backside; a gate structure (18) insulatively disposed on the substrate; a blocking region (30) disposed on the substrate and adjacent to the gate structure; a lightly-doped region (32) of a second conductivity type opposite the first conductivity type and disposed within the substrate and beneath the blocking region; a channel region (14) disposed within the substrate, under the gate structure, and adjacent the lightly-doped region; a first doped region (38) of the second conductivity type and disposed within the substrate and adjacent to the lightly doped region, the first doped region spaced away from the channel region by the lightly-doped region; and a second doped region (22) of the second conductivity type and disposed within the substrate, the second doped region spaced away from the first doped region by the channel region. Preferably, a first bipolar transistor (210) is integrated into the electrostatic discharge device and is formed by the substrate, the lightly-doped region and the second doped region and a second bipolar transistor (212) is integrated into the electrostatic discharge device and is formed by the substrate, the first doped region and the second doped region, the first bipolar transistor becoming conductive at a lower voltage during an ESD event than the second bipolar transistor but the second bipolar transistor able to carry more current during the ESD event.

Integrated lateral structure for ESD protection in CMOS/BiCMOS

A technique for providing a design window for scaled technologies in which good electrostatic discharge/electrical over stress damage and optimum transistor operation can be achieved without the use of additional masks or design steps. The M, beta, and R.sub.sub parameters of the NMOS transistor 13 and associated parasitic npn transistor 10 are selected to provide the design window.

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Plano, TX, United States of America

E Ajith Amerasekera