Ferroelectric-modulated Schottky non-volatile memory
10102898 ยท 2018-10-16
Assignee
Inventors
Cpc classification
H01L21/76897
ELECTRICITY
H01L29/66765
ELECTRICITY
H01L29/78678
ELECTRICITY
H01L29/495
ELECTRICITY
H01L29/16
ELECTRICITY
H01L29/78669
ELECTRICITY
H01L29/66643
ELECTRICITY
H01L29/517
ELECTRICITY
H01L21/76877
ELECTRICITY
H01L29/78391
ELECTRICITY
H01L29/40111
ELECTRICITY
H01L21/02148
ELECTRICITY
H01L21/02197
ELECTRICITY
International classification
H01L21/768
ELECTRICITY
H01L29/786
ELECTRICITY
H01L21/28
ELECTRICITY
H01L29/66
ELECTRICITY
H01L29/49
ELECTRICITY
H01L29/16
ELECTRICITY
H01L21/02
ELECTRICITY
Abstract
Ferroelectric-modulated Schottky non-volatile memory is disclosed. A resistive memory element is provided that is based on a semiconductive material. Metal elements are formed on a semiconductive material at two places such that two semiconductor-metal junctions are formed. The semiconductive material with the two semiconductor-metal junctions establishes a composite resistive element having a resistance and functions as a relatively fast switch with a relatively low forward voltage drop. Each metal element may couple a terminal to the resistive element. To provide a resistive element capable of being a resistive memory element to store distinctive memory states, a ferroelectric material is provided and disposed adjacent to the semiconductive material to create an electric field from a ferroelectric dipole. The orientation of the ferroelectric dipole changes the resistance of the resistive element to allow it to function as a resistive memory element.
Claims
1. A resistive memory element, comprising: a semiconductive material layer comprising a first portion and a second portion; a first metal element, positioned adjacent to the first portion, forming a first Schottky junction with the semiconductive material layer; a second metal element, spaced apart from the first metal element and positioned adjacent to the second portion, forming a second Schottky junction with the semiconductive material layer; and a ferroelectric material layer adjacent to the semiconductive material layer, the ferroelectric material layer being configured to generate an electric field into the semiconductive material layer, which is based on a voltage applied to the ferroelectric material layer, that changes a Schottky barrier height of the first or second Schottky junctions and changes a resistance associated with the semiconductive material layer.
2. The resistive memory element of claim 1, further comprising: a first metal terminal coupled to and proximate the first Schottky junction; a second metal terminal coupled to and proximate the second Schottky junction; and a third metal terminal coupled to and proximate the ferroelectric material layer.
3. The resistive memory element of claim 2, wherein the first, second, and third metal terminals comprise tungsten (W).
4. The resistive memory element of claim 2, wherein the first metal terminal is configured to provide a source line input; wherein the second metal terminal is configured to provide a bit line input; and wherein the third metal terminal is configured to provide a write input.
5. The resistive memory element of claim 4, further comprising a transistor coupled to the source line input, wherein the transistor comprises a gate and the gate is coupled to a word line input.
6. The resistive memory element of claim 1, wherein the first metal element and the second metal element comprise nickel (Ni).
7. The resistive memory element of claim 1, wherein the ferroelectric material layer comprises a Hafnium zirconium oxide (HfZrOx) material.
8. The resistive memory element of claim 1, wherein the ferroelectric material layer comprises a Hafnium aluminum oxide (HfAlOx) material.
9. The resistive memory element of claim 1, wherein the ferroelectric material layer comprises a Hafnium silicon oxide (HfSiOx) material.
10. The resistive memory element of claim 1, wherein the semiconductive material layer comprises a silicon (Si) semiconductor material.
11. The resistive memory element of claim 1, wherein the first metal element and the second metal element are both positioned on a first side of the semiconductive material layer and the ferroelectric material layer is positioned on a second side of the semiconductive material layer opposite the first side.
12. The resistive memory element of claim 1, wherein the semiconductive material layer forms a trench.
13. The resistive memory element of claim 1 integrated into a memory array.
14. The resistive memory element of claim 13, further comprising a shared write terminal coupled to two resistive memory elements of the memory array, wherein a write metal layer is configured to provide the shared write terminal.
15. The resistive memory element of claim 1 integrated into an integrated circuit (IC).
16. The resistive memory element of claim 1 integrated into a device selected from the group consisting of: a set top box; an entertainment unit; a navigation device; a communications device; a fixed location data unit; a mobile location data unit; a global positioning system (GPS) device; a mobile phone; a cellular phone; a smart phone; a session initiation protocol (SIP) phone; a tablet; a phablet; a server; a computer; a portable computer; a mobile computing device; a wearable computing device; a desktop computer; a personal digital assistant (PDA); a monitor; a computer monitor; a television; a tuner; a radio; a satellite radio; a music player; a digital music player; a portable music player; a digital video player; a video player; a digital video disc (DVD) player; a portable digital video player; an automobile; a vehicle component; avionics systems; a drone; and a multicopter.
17. A method of operating a resistive memory element, the method comprising: determining a datum to be written to the resistive memory element having a first Schottky junction and a second Schottky junction at a first terminal and a second terminal, respectively, of the resistive memory element; selecting an orientation of a ferroelectric dipole of a ferroelectric material in the resistive memory element to write the datum to the resistive memory element; writing the datum to the resistive memory element by providing voltages through the first terminal, the second terminal, and a write terminal of the resistive memory element that change a Schottky barrier height of the first Schottky junction or the second Schottky junction, and change a resistance of the resistance memory element by changing the orientation of the ferroelectric dipole to the orientation selected by the selecting; and determining the resistance of the resistive memory element to read the datum stored therein.
18. The method of claim 17, wherein changing the orientation of the ferroelectric dipole to the orientation selected by the selecting comprises changing the orientation to a first selected orientation based on a first voltage and changing the orientation to a second selected orientation based on a second voltage.
Description
BRIEF DESCRIPTION OF THE FIGURES
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
DETAILED DESCRIPTION
(12) With reference now to the drawing figures, several exemplary aspects of the present disclosure are described. The word exemplary is used herein to mean serving as an example, instance, or illustration. Any aspect described herein as exemplary is not necessarily to be construed as preferred or advantageous over other aspects.
(13) Aspects disclosed in the detailed description include ferroelectric-modulated Schottky non-volatile memory. In exemplary aspects disclosed herein, a resistive memory element is provided that is based on a semiconductive material. Metal elements are formed on the semiconductive material at two places such that two semiconductor-metal junctions are formed. These junctions are also known as Schottky junctions and form Schottky barriers. The semiconductive material with the two semiconductor-metal junctions establishes a composite resistive element having a resistance and functions as a relatively fast switch with a relatively low forward voltage drop. Each metal element may be used to couple a terminal to the resistive element. To provide a resistive element capable of being a resistive memory element to store distinctive memory states, a ferroelectric material is provided and disposed adjacent to the semiconductive material to create an electric field from a ferroelectric dipole. The orientation of the ferroelectric dipole changes the resistance of the resistive element to allow it to function as a resistive memory element. Controlling the orientation of the ferroelectric dipole controls in which of two or more resistive states the semiconductive material exists. A third terminal is provided to the ferroelectric material. To write to the resistive memory element, the orientation of the ferroelectric dipole created by the ferroelectric material can be changed by providing a voltage to the ferroelectric material through the third terminal while holding the two metal terminals of the resistive element at fixed voltages. To read from the resistive memory element, the third terminal is held at zero volts (0 V or a fixed voltage), and a small voltage can be applied to one metal terminal of the resistive element to determine the stored memory state as a function of its resistance. Such a structure formed with Schottky junctions can provide a suitably fast memory element with an acceptable on current (I.sub.on) to off current (I.sub.off) ratio (I.sub.on/I.sub.off ratio) and an acceptably low write-energy requirement. Additionally, the ease of manufacturing may justify any area penalty imposed by the third terminal
(14) In this regard,
(15) With continued reference to
(16) With continued reference to
(17)
(18)
(19) To write a one value (1) to the memory cell 400, the BL 402 is held at 0.0 V, the WL 408 has a pulsed voltage of Vdd, the SL 414 has a pulsed voltage of 0 V, and the write line at the node 128 is elevated to Vp (e.g., 3-4 V). While providing a high voltage at the node 128 and holding the voltages at the nodes 130 and 132 low, an electrical field crosses the ferroelectric material 120, which causes the ferroelectric dipole 202 (
(20) To write a zero value (0) to the memory cell 400, the BL 402 has a pulsed voltage of Vp, the WL 408 has a pulsed voltage of Vdd, the SL 414 has a pulsed voltage of 0V, and the write line at the node 128 is held at 0.0 V. By putting a high voltage at the nodes 130 and 132 and a low voltage at the node 128, an electrical field crosses from the nodes 130 and 132 through the semiconductive material 102 into the ferroelectric material 120. This electrical field causes the ferroelectric dipole 206 (
(21) Exemplary aspects of the present disclosure allow the construction of the resistive memory element 100 through patterning and deposition processes. Deposition processes, such as an atomic layer deposition (ALD) process, allow precise control over the thicknesses of the various elements. Such precision is important as node sizes of integrated circuits continue to shrink. Further, relatively few masks may be used in patterning processes. Reuse of masks makes manufacturing easier as well.
(22) In this regard,
(23) The process 600 continues by using photo process patterning in the diffusion barrier layer 504 (block 608). The diffusion barrier layer 504 is etched and photoresist stripped to expose the metal write line 502 (block 610). Having exposed the metal write line 502, a first metal layer 508 is deposited and chemical mechanical polished (CMP) to form a first pattern (block 612). The first metal layer 508 is electrically coupled to the metal write line 502, effectively forming the node 128 of
(24) The process 600 continues by depositing a second IDL 506 and CMP, patterning the vias 518 and 520 and a metal trench, and depositing or plating metal into the metal trench and CMP (block 626), coupling a source line via 518 to the first metal terminal (block 628) and then coupling a bit line via 520 to the second metal terminal (block 630).
(25) While the process 600 provides a simple structure that is relatively easy to manufacture even at small node sizes, there are other three-terminal aspects which also fall within the scope of the present disclosure. Thus, a trenching process could also be used. Trenching may allow the ferroelectric material to have a larger area of the ferroelectric dipole in the semiconductive material and thus may provide a more robust write function. In this regard,
(26)
(27) TABLE-US-00001 TABLE 1 Selected Memory Cell Voltages Operation Write 1 Write 0 Read WL Vdd Vdd Vdd BL 0 V Vp (3-4 V) Vread or Vdd SL 0 V 0 V 0 V Write Line Vp (3-4 V) 0 V 0 V
(28) TABLE-US-00002 TABLE 2 Unselected Memory Cell Voltages Unselect Unselect (same Unselect (diff Operation write line) write line) Remark WL Vdd 0 V BL Vdd or 0 V Vdd or 0 V Use half select to avoid switching SL Vdd or 0 V Vdd or 0 V Use half select to avoid switching Write Line Vp (3~4 V) or 0 V 0 V or Vdd
(29)
(30)
(31) The ferroelectric-modulated Schottky non-volatile memory according to aspects disclosed herein may be provided in or integrated into any processor-based device. Examples, without limitation, include a set top box, an entertainment unit, a navigation device, a communications device, a fixed location data unit, a mobile location data unit, a global positioning system (GPS) device, a mobile phone, a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a tablet, a phablet, a server, a computer, a portable computer, a mobile computing device, a wearable computing device (e.g., a smart watch, a health or fitness tracker, eyewear, etc.), a desktop computer, a personal digital assistant (PDA), a monitor, a computer monitor, a television, a tuner, a radio, a satellite radio, a music player, a digital music player, a portable music player, a digital video player, a video player, a digital video disc (DVD) player, a portable digital video player, an automobile, a vehicle component, avionics systems, a drone, and a multicopter.
(32) In this regard,
(33) Other master and slave devices can be connected to the system bus 1108. As illustrated in
(34) The CPU(s) 1102 may also be configured to access the display controller(s) 1120 over the system bus 1108 to control information sent to one or more displays 1126. The display controller(s) 1120 may include one or more RMEs 100. The display controller(s) 1120 sends information to the display(s) 1126 to be displayed via one or more video processors 1128, which process the information to be displayed into a format suitable for the display(s) 1126. The display(s) 1126 can include any type of display, including, but not limited to, a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, a light emitting diode (LED) display, etc.
(35) Those of skill in the art will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithms described in connection with the aspects disclosed herein may be implemented as electronic hardware, instructions stored in memory or in another computer readable medium and executed by a processor or other processing device, or combinations of both. The devices described herein may be employed in any circuit, hardware component, integrated circuit (IC), or IC chip, as examples. Memory disclosed herein may be any type and size of memory and may be configured to store any type of information desired. To clearly illustrate this interchangeability, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. How such functionality is implemented depends upon the particular application, design choices, and/or design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
(36) The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).
(37) The aspects disclosed herein may be embodied in hardware and in instructions that are stored in hardware, and may reside, for example, in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer readable medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a remote station. In the alternative, the processor and the storage medium may reside as discrete components in a remote station, base station, or server.
(38) It is also noted that the operational steps described in any of the exemplary aspects herein are described to provide examples and discussion. The operations described may be performed in numerous different sequences other than the illustrated sequences. Furthermore, operations described in a single operational step may actually be performed in a number of different steps. Additionally, one or more operational steps discussed in the exemplary aspects may be combined. It is to be understood that the operational steps illustrated in the flowchart diagrams may be subject to numerous different modifications as will be readily apparent to one of skill in the art. Those of skill in the art will also understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
(39) The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.