WO2017069772A1

WO2017069772A1 - Electrostatic discharge absorption using resistive random-access memory

Info

Publication number: WO2017069772A1
Application number: PCT/US2015/057107
Authority: WO
Inventors: Brent Buchanan; Richard James AULETTA; Ning GE
Original assignee: Hewlett Packard Enterprise Development Lp
Priority date: 2015-10-23
Filing date: 2015-10-23
Publication date: 2017-04-27

Abstract

In one example in accordance with the present disclosure an electrostatic discharge protection system is described. The system includes a number of electrostatic discharge absorption units coupled in parallel. An electrostatic discharge absorption unit includes a resistive random-access memory (RRAM) device switchable between multiple states to absorb an electrostatic discharge in the circuit by switching between states. Current is selectively passed through the RRAM device to manage a switching of a RRAM device state.

Description

ELECTROSTATIC DISCHARGE ABSORPTION USING RESISTIVE RANDOM-ACCESS MEMORY

BACKGROUND

[0001] Electrostatic discharge (ESD) is a phenomenon resulting in a release of static electricity when two objects at different electrical potentials come into contact with one another. For example an ESD event may occur as positively-charged particles on one object, for example human skin, come into contact with negatively-charged particles on another object, for example electronic components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The accompanying drawings illustrate various examples of the principles described herein and are a part of the specification. The illustrated examples are given merely for illustration, and do not limit the scope of the claims.

[0003] Fig. 1 is a diagram of an electrostatic discharge protection system using resistive random-access memory (RRAM), according to one example of the principles described herein.

[0004] Fig. 2 is a diagram of an electrostatic discharge protection system using resistive random-access memory (RRAM), according to another example of the principles described herein.

[0005] Fig. 3 is a diagram of an electrostatic discharge protection system using RRAM, according to one example of the principles described herein. [0006] Fig. 4 is a diagram of an electrostatic discharge protection device using RRAM, according to one example of the principles described herein.

[0007] Fig. 5 is a diagram of an electrostatic discharge protection system using RRAM, according to another example of the principles described herein.

[0008] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.

DETAILED DESCRIPTION

[0009] Electronic devices are ubiquitous in modern society. These electronic devices include integrated circuits to carry out particular functions. For example mobile phones, laptops, desktop computers, personal computing devices, and gaming systems to name a few include large circuit components to deliver different services and functionality to different users. Each of these integrated circuits, and other electrical components, are susceptible to electrostatic discharge (ESD) which is the swift discharge of electrical current through objects with different charges. For example, during manufacturing of electrical and electronic components of all types, human touch may result in an ESD event. Such an ESD event can, and often does, damage the component which either renders the component less effective or completely useless.

[0010] Accordingly, ESD protection devices have been developed in an attempt to alleviate the undesirable consequences of an ESD event. However, while certain ESD protection devices are available, their implementation has certain limitations. For example, such devices may be placed on the silicon next to other components in an electronic device. Accordingly, while an ESD protection device may dissipate the increased current flow, in this dissipation process, an ESD protection device may damage nearby circuitry. In other words these ESD protection devices are ineffective as, although they redirect ESD discharge, they still render the integrated circuit useless by harming other components of a circuit while attempting to redirect the ESD discharge.

Moreover, the circuitry included in an integrated circuit to dissipate the ESD discharge is large and bulky, taking up valuable space on an integrated circuit. Still further given the size constraints, there may be limits to the ability of these ESD protection devices to prevent ESD discharges, especially larger ESD discharges. As the capacity for an ESD protection device is exceeded, excessive joule heating can both damage the ESD protection device itself and also expel heat energy which can damage circuits near the ESD protection device.

[0011] The systems and devices of the present specification and appended claims address these and other issues. Specifically, the present application describes an ESD absorption system that includes a number of resistive random-access memory (RRAM) devices and in some cases, selectors, coupled together. A non-linear RRAM device or the selector prevents current flowing through a RRAM during non-ESD operation, but when a larger current is passed, i.e., during an ESD event, a breakdown voltage of the selector or non-linear RRAM device is surpassed, thus opening the current to flow through the RRAM device. In so doing, the current through the RRAM device causes the RRAM device to switch states via ion movement. This ion movement within the RRAM device absorbs the electrical energy generated during the ESD event. In other words, once current is allowed to flow through an RRAM device, the switching of the state of the RRAM device actually absorbs the energy from the ESD discharge, thus protecting the other components in the integrated circuit.

[0012] The present specification describes an electrostatic discharge protection system. The system includes a number of electrostatic discharge absorption units coupled in parallel. An electrostatic discharge absorption unit includes a resistive random-access memory (RRAM) device switchable between multiple states to absorb an electrostatic discharge in the circuit by switching between states. Current is selectively passed through the RRAM device to manage a switching of the RRAM device state.

[0013] The present specification also describes a device that includes a number of electrostatic discharge absorption units. An electrostatic discharge absorption unit includes a multi-state resistive random-access memory (RRAM) device to absorb energy from an electrostatic discharge event by switching between different states to move ions within the RRAM device. An electrostatic discharge absorption unit also includes a selector to manage the switching of a corresponding RRAM device by regulating current flow through the RRAM device.

[0014] The present specification also describes an electrostatic discharge protection system that includes a number of electrostatic discharge absorption units coupled in parallel between an input/output terminal of a circuit and core circuitry for the circuit. An electrostatic discharge absorption unit includes a non-linear memristor switchable between multiple states via ion movement within a switching layer of the non-linear memristor. The non-linear memristor device absorbs energy via the ion movement. The non-linear memristor also allows ion movement within the switching layer when an effective voltage across the non-linear memristor is greater than a threshold voltage for the non-linear memristor and 2) prevents ion movement within the switching layer when an effective voltage across the non-linear memristor is less than the threshold voltage for the non-linear memristor.

[0015] The electrostatic discharge units of the present systems and devices allow for energy absorption from an ESD event by moving ions within the RRAM devices of an electrostatic discharge unit. The movement of ions absorbs the energy from the ESD event.

[0016] Certain examples of the present disclosure are directed to systems and devices for protecting electrical components from electrostatic discharge that provides a number of advantages not previously offered including 1 ) absorbing the ESD energy via ion movement within a resistive random- access memory device; 2) moving the energy absorption mechanism away from other sensitive electrical components; and 3) providing a low cost solution to electrostatic discharge; and 4) realizing electrostatic discharge protection in a relatively small amount of space. However, it is contemplated that the devices and methods disclosed herein may prove useful in addressing other deficiencies in a number of technical areas. Therefore the systems and devices disclosed herein should not be construed as addressing just the particular elements or deficiencies discussed herein. [0017] As used in the present specification and in the appended claims, the term "core circuitry" refers to circuitry that is intended to be protected from ESD discharge. The core circuitry may be that circuitry of an electrical component that is intended to carry out a particular function.

[0018] Still further, as used in the present specification and in the appended claims, the term "a number of" or similar language is meant to be understood broadly as any positive number including 1 to infinity; zero not being a number, but the absence of a number.

[0019] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present systems and methods. It will be apparent, however, to one skilled in the art that the present apparatus, systems, and methods may be practiced without these specific details. Reference in the specification to "an example" or similar language indicates that a particular feature, structure, or characteristic described in connection with that example is included as described, but may not be included in other examples.

[0020] Fig. 1 is a diagram of an electrostatic discharge protection system (100) using resistive random-access memory (RRAM), according to one example of the principles described herein. The system (100) may be included in any electronic device that is capable of executing data processing operations. Examples of electronic devices include laptop computers, personal digital assistants (PDAs), mobile devices, notebooks, tablets, gaming systems, smartphones, mobile devices, printers such as laser printers, copiers, scanners, fax machines and other electronic devices.

[0021] The electrostatic discharge protection system (100) includes a number of electrostatic discharge absorption units (102-1 , 102-2, 102-3, 102-4). As used in the present specification, the identifier "-^*" refers to a specific instance of an element. For example (102-1 ) refers to a first electrostatic discharge absorption unit. By comparison, elements without the identifier "-Γ refer to a generic instance of an element. For example, (102) refers to electrostatic discharge absorption units in general. While Fig. 1 depicts four ESD absorption units (102), the system (100) may include any number of such units. For example, the system (100) may include hundreds or thousands of ESD absorption units (102). Specifically, in some examples, the system (100) includes a sufficient number of ESD absorption units (102) to protect against an anticipated electrostatic discharge value plus a safety margin. For example, if an anticipated ESD event, or the sum of multiple anticipated ESD events, is expected to generate a first current value, a sufficient number of ESD units (102) to absorb the first current value are used, plus a desired safety margin such as a safety factor of two or three. As a specific numeric example, an ESD current may have an oscillating or damped-pulse waveform that peaks at several amps (e.g., 5 amps) with a total duration of a nanosecond or two.

[0022] Returning to the ESD absorption units (102), the units may be coupled in parallel to one another and may be placed between an input/output terminal of a circuit and the core circuitry for the circuit. The input/output terminal may be a component of the integrated circuit that interacts with other components of an integrated circuit. The input/output terminal may be an input/output pin. The core circuitry may be the circuitry that carries out an intended function for the integrated circuit and that is intended to be protected from an ESD discharge. For example, the core circuitry may include random logic circuitry, output from a microprocessor, or a clock reference, among other circuit components. As depicted in Fig. 1 , current may come from an

input/output terminal as indicated by the arrow (104-1 ). During non-ESD operation, this current may pass to or from the core circuitry as indicated by the arrow (104-2). However, during an ESD event, the current is re-directed, and absorbed by the number of ESD absorption units (102) as indicated by the dashed arrows (104-3).

[0023] Each electrostatic discharge absorption unit (102) includes a resistive random-access memory (RRAM) device (106-1 , 106-2, 106-3, 106-4). An RRAM device (106) is a memory device that is switchable between multiple states, specifically between multiple resistive states. An RRAM device (106) is non-volatile, meaning that it retains its state even after electrical energy, i.e., a voltage or a current is removed from the device. For example, if charge flows in one direction through a circuit, the resistance of that component of the circuit will increase. If charge flows in the opposite direction in the circuit, the resistance will decrease. If the flow of charge is stopped by turning off the applied voltage, the component will "remember" the last resistance that it had, and when the flow of charge starts again the resistance of the circuit will be what it was when it was last active.

[0024] One example of a RRAM device (106) is a memristor. Memristors take many forms. One example is a metal-insulator-metal structure where the memristor includes a first conductive electrode a second conductive electrode and a switching layer placed between the conductive electrodes. The first and second conductive electrodes may be formed of an electrically conductive material such as AICu, AlCuSi, AlCuSi, TaAI, TiN, HfN, AIN, Pt, Cu, and WSiN. In some examples the first and second electrode are formed of the same material, and in other examples the second electrode is formed of a different material than the first electrode.

[0025] The switching layer may be formed of a switching oxide, such as a metallic oxide. Specific examples of switching oxide materials may include magnesium oxide, titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, iron oxide, cobalt oxide, copper oxide, zinc oxide, aluminum oxide, gallium oxide, silicon oxide, germanium oxide, tin dioxide, bismuth oxide, nickel oxide, yttrium oxide, gadolinium oxide, and rhenium oxide, among other oxides. In addition to the binary oxides presented above, the switching oxides may be ternary and complex oxides such as silicon oxynitride. The oxides presented may be formed using any of a number of different processes such as sputtering from an oxide target, reactive sputtering from a metal target, atomic layer deposition (ALD), oxidizing a deposited metal or alloy layer, etc.

[0026] The state of the memristor is changed in response to various programming conditions. For instance, the memristor may be programmed to have one of a plurality of distinct states. Particularly, the resistance level of the switching layer may be changed through application of an electrical field, e.g., through application of a current or voltage, in which the current or voltage cause mobile ions in the switching layer to move and/or change the status of conducting channel(s) in the switching layer, which may alter the resulting electrical operation of the memristor. That is, for instance, the distinct resistance levels of the switching layer, and thus the state of the memristor, may correspond to different programming current levels or voltage amplitudes applied to the switching layer. By way of example, the switching layer may be programmed to have a higher resistance level through application of an earlier current or voltage level. After removal of the current or voltage, the locations and characteristics of the ions or conducting channels are to remain stable until the application of another programming electrical field. That is, the switching layer remains at the programmed resistance level following removal of the current or voltage.

[0027] The ions in the switching layer of the RRAM device (106) have significant mass and moving them consumes energy. Moreover, the ions in the RRAM device (106) are attached to other atoms in the switching layer and movement of these ions first includes breaking of these bonds, and the breaking of these bonds also consumes energy. Accordingly the switching between states of the RRAM device (106) absorbs energy, specifically the energy generated during an ESD event. In other words, during an ESD event, ESD discharge is allowed to pass through the RRAM devices (106) which discharge initiates a change in state of the RRAM device (106). While changing state, i.e., moving ions within the switching layer, the RRAM absorbs the ESD discharge present in the circuit during an ESD event.

[0028] The ESD absorption units (102) also include a current regulating component. The current regulating components selectively allow current flow through the RRAM device (106), thus controlling whether or not current passes through, and is absorbed, by the corresponding RRAM device (106).

[0029] In some examples, current is regulated through an RRAM device (106) when the RRAM device is a non-linear RRAM device (106). A non-linear RRAM device (106) is an RRAM device (106) wherein a certain change in voltage seen by the RRAM device (106) results in a disproportionate change in current passing through the RRAM device (106). For example, a RRAM device (106) may see an effective voltage of a first value resulting in a first current level. As the voltage seen by the RRAM device (106) is increased to a second value, a second current level passes through the non-linear RRAM device (106), where the difference between the first and second current levels is greater than the difference between the first and second voltage values. Put another way, a current-voltage curve for a non-linear RRAM device (106) has a non-linear relationship, and may be exponential.

[0030] The non-linearity of a RRAM device (106) may serve as a selector in that it prevents current flow through the RRAM device (106) at low levels, i.e., during non-ESD operation. For example, low current flow through a non-linear RRAM device (106) directs the current from the input/output terminal as indicated by the line (104-1 ) through to the core circuitry as indicated by the line (104-2). However, when a larger voltage is seen, such as during an ESD event, the non-linear RRAM device (106) directs more current through the

corresponding ESD absorption unit (102) as indicted by the lines (104-3 thereby absorbing the ESD energy. Accordingly, the non-linear RRAM device (106) such as a memristor has a threshold voltage and when an effective voltage is greater than the threshold voltage, ion movement within the switching layer is allowed (i.e., the RRAM device (106) switches state). By comparison, when the threshold voltage for the non-linear RRAM device (106) such as the memristor is less than the effective voltage, ion movement within the switching layer is prevented.

[0031] One example of a non-linear RRAM device (106) is an RRAM device (106) that uses titanium oxide as a switching layer. These so-called TiOx RRAM devices (106) are highly non-linear. A non-linear RRAM device (106) may simplify an ESD absorption unit (100) in that it does not implement a separate selector.

[0032] In some examples, the current regulating component is a separate selector component as depicted in Fig. 2. In this example, similar to a nonlinear RRAM device (106), the selector (208-1 , 208-2, 208-3, 208-4) directs current to a corresponding ESD absorption unit (102) when current is greater than a specified value. In this example, each ESD absorption unit (102) includes a selector (208) serially coupled to an RRAM device (106) in that same ESD absorption unit (102). In these examples, the selector (208) has a breakdown voltage. When an effective voltage seen by the selector (208) is less than the breakdown voltage, no current is passed through the selector (208) or other components in series with the selector (208). By comparison, when an effective voltage seen by the selector (208) is greater than the breakdown voltage of the selector (208), current is allowed to pass through the selector (208) and other components in series with the selector (208).

[0033] In other words, the selector (208) may be a reverse-biased diode. The breakdown voltage may be such that during non-ESD operation, the breakdown voltage is not overcome. Then during an ESD event, an effective voltage seen by the selector (208) is greater than the breakdown voltage, which opens up the corresponding arm of the circuit for current, which current alters the state of the RRAM device (106). Put another way, a selector (08) such as a reverse-biased diode prevents current flow through the RRAM device (106) when an effective voltage seen by the selector (208) is less than a break down voltage of the selector (208), i.e., during non-ESD operation, and allows current flow through the RRAM device (106) when an effective voltage seen by the selector (208) is greater than the breakdown voltage of the reverse-biased diode, i.e., during an ESD event.

[0034] In some examples, the RRAM devices (106) may initially be in a low resistance state such that when the breakdown voltage of a corresponding selector (208), or a threshold voltage for a non-linear RRAM device (106), is surpassed, the RRAM device (106) readily conducts. Then as the RRAM device (106) receives enough current, it switches to a high resistance state and stops conducting. However, the remaining RRAM devices (106) that have not yet switched to a high resistance state, and are thus still in a low resistance state, continue to conduct and absorb the ESD energy. Thus, one-by-one the RRAM devices (106) switch from a low resistance state to a high resistance state, each absorbing a portion of the ESD energy during switching until all the ESD energy is absorbed by the number of RRAM devices (106). In other words, during an ESD event, one RRAM device (106) at a time is switched state so as to sequentially absorb a portion of the energy generated during the electrostatic discharge event.

[0035] The number of ESD units (102) may be sufficient to handle an anticipated ESD event(s) plus a safety margin. In some examples, the number of ESD units (102) may satisfy industry standards such as Joint Electron Device Engineering Counsel (JEDEC) tests using the Human Body Model (HBM), Charged Device Model (CDM), and the Machine Model (MM).

[0036] An ESD absorption system (100) as described herein may allow for greater amounts of energy to be absorbed in a smaller physical space. Moreover as the movement of ions, including the breaking of the atomic bonds of the ions with other atoms, consumes a lot of energy, RRAM devices (106) have a large capacity for energy absorption.

[0037] Fig. 3 is a diagram of an electrostatic discharge protection system (100) using resistive random-access memory (RRAM), according to one example of the principles described herein. As described above, the number of ESD absorption units (102) are connected in parallel between an input/output terminal of a circuit and core circuitry for the circuit. The ESD absorption units (102) include RRAM devices (Fig. 1 , 106) to absorb the energy of an ESD event. Specifically, the RRAM devices (Fig. 1 , 106) may be memristors (330-1 , 330-2, 330-3, 330-4). As described above in connection with Fig. 1 , a memristor (330) is a non-volatile memory device, meaning that it retains its state even after electrical energy, i.e., a voltage or a current, is removed from the memristor. If the flow of charge is stopped by turning off the applied voltage, the component will "remember" the last resistance that it had, and when the flow of charge starts again the resistance of the circuit will be what it was when it was last active. As it switches state, ions within the memristors (330) move, which movement absorbs energy, specifically the energy generated during an ESD event.

[0038] The memristors (330) may be non-linear memristors. A non-linear memristor (330) is a memristor (330) wherein a certain change in voltage seen by the memristor (330) results in a disproportionate change in current passing through the memristor (330). For example, a memristor (330) may see an effective voltage of a first value resulting in a first current level. As the voltage seen by the memristor (330) is increased to a second value, a second current level passes through the non-linear memristor (330), where the difference between the first and second current levels is greater than the difference between the first and second voltage values. Put another way, a current- voltage curve for a non-linear memristor (330) has a non-linear relationship, and may be exponential.

[0039] The non-linearity of a memristor (330) may further prevent current flow at low levels, i.e., during non-ESD operation. For example, low current flow through a non-linear memristor (330) directs the current from the input/output terminal as indicated by the line (104-1 ) through to the core circuitry as indicated by the line (104-2). However, when a larger voltage is seen, the non-linear memristor (330) directs more current through the corresponding branch as indicated by the lines (104-3). As described and illustrated in Fig. 1 , when using a memristor (330) with non-linearity, a selector (Fig. 2, 208), such as the reverse-biased diodes (332) may be eliminated from the system (100), thus simplifying the system (100) layout.

[0040] Still to this point, the memristor (330) may be in a low resistance state when the effective voltage across a reverse-biased diode (332) is less than a breakdown voltage for the reverse-biased diode and may be switched to a high resistance state when the effective voltage across the reverse-biased diode (332) is greater than the breakdown voltage for the reverse-biased diode.

[0041] While in some examples, a memristor (330) may have sufficient non-linearity to be used without a selector (Fig. 2, 208), Fig. 3 illustrates the use of a memristor (330), which may or may not be non-linear, in coordination with a selector (Fig. 2, 208). The selector (Fig. 2, 208) of the EDS absorption unit (102) may be a reverse-biased diode (332-1 , 332-2, 332-3, 332-4). A reverse- biased diode (332) prevents current flow in one direction, unless an effective voltage seen by the reverse-biased diode (332) is greater than a breakdown voltage for the reverse-biased diode (332). For example, the breakdown voltage may have a value between 3.3 volts (V) to 5 volts (V). For example, the breakdown voltage for a reverse-biased diode (332) may be 3.3 V. In another example, the breakdown voltage for the reverse-biased diode (332) may be 5 V. A voltage less than this breakdown voltage results in no current being seen by that arm of the system (100).

[0042] By comparison, if an effective voltage seen by the diode (332) is greater than that breakdown voltage then current is allowed to pass through that arm. In other words, a reverse-biased diode (332) serially-coupled to the memristor (330) allows ion movement within a corresponding memristor (330) when an effective voltage across the reverse-biased diode (332) is greater than a breakdown voltage for the reverse-biased diode (332) and prevents ion movement within the corresponding memristor (330) when an effective voltage across the reverse-biased diode (332) is less than the breakdown voltage for the reverse-biased diode (332). Put yet another way, the reverse-biased diode (332) maintains the RRAM device (Fig. 1 , 106), i.e., the memristor (330), in a first resistance state when the effective voltage is less than the breakdown voltage for the diode (332) and switches the RRAM device (Fig. 1 , 106) to a second resistance state when the effective voltage is greater than the breakdown voltage for the diode (332). In some examples, the selector (Fig. 1 , 108) may be a Zener-type or avalanche type reverse-biased diode (332).

[0043] Fig. 4 is a diagram of an electrostatic discharge protection device (434) using resistive random-access memory (RRAM), according to one example of the principles described herein. The device (434) may include a substrate (436). The substrate (436) of the device (434) may include componentry of an integrated circuit such as transistors and diodes, among other components. The device (434) is made up of a stack (412) of alternating metal layers and vias that form different components of an electrical device (434). In some examples, the memristor (330) may be removed from the substrate (436) with its corresponding circuitry. For example, the memristor (330) or other RRAM device (Fig. 1 , 106) may be higher on the stack (412) than the substrate (436), i.e., vertically removed from the substrate (436), where other components of the device (434) reside. Other ESD protection devices may be formed on the substrate (436) which as described above, has the potential to damage other components, i.e., transistors and diodes that are on the substrate (436). Accordingly, removing the RRAM device (Fig. 1 ,106), and specifically the memristor (330), allows for any heat generated by the memristor (330) during ESD energy absorption to be spatially removed from the other components and therefore is less likely to cause damage to those components.

[0044] In some examples, the device (434) that includes the ESD system (Fig. 1 , 100) may be an input/output device to couple different components within an electronic system together.

[0045] While Fig. 4 depicts the memristor (330) being vertically-removed from the substrate (436) in some examples, the memristor (330) may be nearer the bottom of the stack (412). In still further examples different memristors (330) that make up the ESD protection system (Fig. 1 , 100) may be positioned near different vias of the stack (412). Doing so may allow more memristors (330) per unit area of the device (434).

[0046] Fig. 5 is a diagram of an electrostatic discharge protection system (100) using resistive random-access memory (RRAM), according to another example of the principles described herein. In this example, the system (100) may include a switching unit (538) to switch the RRAM devices (106) back into a first, or low, resistance state. For example, after an ESD event a number of the RRAM devices (106) may be in a high resistance state due to the absorption of ESD energy. If left in this state, during a subsequent ESD event, the RRAM devices (106) in a high resistance state would not be able to receive current and switch state to absorb ESD energy. In other words, the RRAM devices (106) would be one-time use devices. Accordingly, after an RRAM device (106) has been switched to a high resistance state, the switching unit (538) may switch the RRAM devices (106) back into a low resistance state, thus rendering them able to absorb ESD energy via a transition from low resistance to high resistance. Such a switching unit (538) may include hardware that passes a voltage of a certain level to the RRAM device (106) to return them to a low resistance state.

[0047] While Fig. 5 depicts a single switching unit (538) for all RRAM devices (106), any number of switching units (538) may be used. For example, each ESD absorption unit (102) may include a separate switching unit (538). [0048] Certain examples of the present disclosure are directed to systems and devices for protecting electrical components from electrostatic discharge that provides a number of advantages not previously offered including 1 ) absorbing the ESD energy via ion movement within a resistive random- access memory device; 2) moving the energy absorption mechanism away from other sensitive electrical components; and 3) providing a low cost solution to electrostatic discharge; and 4) realizing electrostatic discharge protection in a relatively small amount of space. However, it is contemplated that the devices and methods disclosed herein may prove useful in addressing other deficiencies in a number of technical areas. Therefore the systems and devices disclosed herein should not be construed as addressing just the particular elements or deficiencies discussed herein. However, it is contemplated that the devices and methods disclosed herein may prove useful in addressing other deficiencies in a number of technical areas. Therefore the systems and devices disclosed herein should not be construed as addressing just the particular elements or deficiencies discussed herein.

[0049] The preceding description has been presented to illustrate and describe examples of the principles described. This description is not intended to be exhaustive or to limit these principles to any precise form disclosed. Many modifications and variations are possible in light of the above teaching.

Claims

CLAIMS WHAT IS CLAIMED IS:

1 . An electrostatic discharge protection system comprising:

a number of electrostatic discharge absorption units coupled in parallel, wherein:

an electrostatic discharge absorption unit comprises a resistive random-access memory (RRAM) device switchable between multiple states to absorb an electrostatic discharge in the circuit by switching between states, wherein current is selectively passed through the RRAM device to manage a switching of a state of the RRAM device.

2. The system of claim 1 , wherein the electrostatic discharge absorption unit further comprises a selector serially-coupled to the RRAM device to manage current flow through the RRAM device based on an effective voltage seen by the selector.

3. The system of claim 2, wherein the selector is a reverse-biased diode to: prevent current flow through the RRAM device when an effective voltage seen by the reverse-biased diode is less than a breakdown voltage of the reverse-biased diode; and

allow current flow through the RRAM device when an effective voltage seen by the reverse-biased diode is greater than the breakdown voltage of the reverse-biased diode.

4. The system of claim 1 , wherein during an electrostatic discharge event, the number of electrostatic discharge absorption units are sequentially switched from a low resistance state to a high resistance state to absorb energy generated during the electrostatic discharge event.

5. The system of claim 1 , wherein the electrostatic discharge absorption units are vertically removed from an input/output terminal of a circuit and core circuitry for the circuit.

6. The system of claim 1 , wherein the RRAM device is a non-linear memristor.

7. A device comprising:

a number of electrostatic discharge absorption units, wherein an electrostatic discharge absorption units comprises:

a multi-state resistive random-access memory (RRAM) device to absorb energy from an electrostatic discharge event by switching between different states to move ions within the RRAM device; and

a selector to manage the switching of a corresponding RRAM device by regulating current flow through the RRAM device.

8. The device of claim 7, wherein the selector is a zener diode or avalanche diode having a breakdown voltage wherein effective voltages less than the breakdown voltage maintain the RRAM device in a first resistance state and effective voltages greater than the breakdown voltage switch the RRAM device from the first resistance state to the second resistance state.

9. The device of claim 8, further comprising a switching unit to return a number of RRAM devices to the first resistance state.

10. The device of claim 7, wherein the device is an input/output device to couple different components within an electronic system to one another.

1 1 . The device of claim 7, wherein the number of electrostatic discharge absorption units is sufficient to protect against an anticipated electrostatic discharge value plus a safety margin.

12. The device of claim 7, wherein an RRAM device comprises moveable ions within the RRAM device to move during the switching of the resistance state to absorb energy of the electrostatic discharge event.

13. An electrostatic discharge protection system comprising:

a number of electrostatic discharge absorption units coupled in parallel between an input/output terminal of a circuit and core circuitry for the circuit, wherein an electrostatic discharge absorption units comprises:

a non-linear memristor switchable between multiple states via ion movement within a switching layer of the non-linear memristor, the nonlinear memristor to:

absorb energy via the ion movement;

allow ion movement within the switching layer when an effective voltage across the non-linear memristor is greater than a threshold voltage for the non-linear memristor; and

prevent ion movement within the switching layer when an effective voltage across the non-linear memristor is less than the threshold voltage for the non-linear memristor.

14. The system of claim 13, wherein the non-linear memristor is in a low resistance state when the effective voltage across the non-linear memristor is less than the threshold voltage for the non-linear memristor.

15. The system of claim 14, wherein the non-linear memristor switches to a high resistance state when the effective voltage across the non-linear memristor is greater than the threshold voltage for the non-linear memristor.