TWI670800B - Resistive memory cell structure - Google Patents

Abstract

The present invention provides a resistive memory cell structure comprising a substrate, a first electrode layer, a resistance change layer, a first ion collection layer, a second ion collection layer, and a second electrode layer. Wherein, the first electrode layer is disposed on the substrate, the resistance change layer is disposed on the first electrode layer, the first ion collection layer is disposed on the resistance change layer, the second ion collection layer is disposed on the first ion collection layer, and the second The electrode layer is disposed on the second ion collecting layer.

Description

Resistive memory cell structure

The invention relates to a resistive memory cell structure, in particular to a resistive memory cell structure which can improve reliability.

In today's electronic products, memory has been widely used in various electronic products, such as computers, mobile phones, and the Internet, and in various types of memory, resistive random access is recorded by changing the resistance to record data. Memory (RRAM) is one of the most attractive memory components. The resistive random access memory changes the state of the resistance change layer by applying a current or a voltage to set the state of the memory state "set state" and the memory state "1" (reset state) according to different resistance values. Switch between them to achieve the effect of storing data.

One of the objects of the present invention is to provide a resistive memory cell structure that enhances the reliability of a resistive memory cell structure through a stack structure design of a plurality of ion collecting layers.

One embodiment of the present invention provides a resistive memory cell structure comprising a substrate, a first electrode layer, a resistance change layer, a first ion collection layer, a second ion collection layer, and a second electrode layer. Wherein, the first electrode layer is disposed on the substrate, the resistance change layer is disposed on the first electrode layer, the first ion collection layer is disposed on the resistance change layer, and the second ion collection layer is disposed on the first ion collection layer Upper, and the second electrode layer is disposed on the second ion collecting layer.

The resistive memory cell structure of the present invention is provided with a first ion collecting layer and a second ion collecting layer, wherein the first ion collecting layer can be used to absorb most of the ions diffused from the variable resistance layer, the second ion The collection layer can be used not only to absorb ions diffused from the resistance change layer, but also to block the invasion of external ions and to block the escape of ions inside the resistive memory cell structure, thereby improving the reliability of the resistive memory cell structure. With manufacturing yield.

100‧‧‧Resistive memory cell structure

110‧‧‧Base

120‧‧‧First electrode layer

130‧‧‧resistive change layer

140‧‧‧First ion collection layer

150‧‧‧Second ion collection layer

160‧‧‧Second electrode layer

FIG. 1 is a schematic cross-sectional view showing a structure of a resistive memory cell element according to an embodiment of the present invention.

The present invention will be described in detail with reference to the embodiments of the present invention in detail, It should be noted that the drawings are simplified schematic diagrams, and therefore, only elements and combinations related to the present invention are shown to provide a clearer description of the basic architecture or implementation method of the present invention, and actual components and layouts may be more To be complicated. In addition, for convenience of description, the elements shown in the various drawings of the present invention are not drawn to the scale, shape, and size of the actual implementation, and the detailed ratios thereof may be adjusted according to the design requirements.

Please refer to FIG. 1. FIG. 1 is a cross-sectional view showing the structure of a resistive memory cell according to an embodiment of the present invention. It should be noted that at least one resistive memory cell structure of the present invention can be combined with other electronic components to form a resistive memory. As shown in Fig. 1, the resistive type of this embodiment The memory cell structure 100 includes a substrate 110, a first electrode layer 120, a resistance change layer 130, a first ion collection layer 140, a second ion collection layer 150, and a second electrode layer 160, wherein the first electrode layer 120 is disposed on the substrate 110, the resistance change layer 130 is disposed on the first electrode layer 120, the first ion collection layer 140 is disposed on the resistance change layer 130, the second ion collection layer 150 is disposed on the first ion collection layer 140, and the second electrode The layer 160 is disposed on the second ion collecting layer 150.

In the present invention, the substrate 110 is used to carry the other film layers of the resistive memory cell structure 100. The substrate 110 may be a hard substrate such as a germanium substrate, a glass substrate, a plastic substrate or a quartz substrate, or may comprise polythene. A flexible substrate of polyimide (PI) or polyethylene terephthalate (PET). In some embodiments, the substrate 110 may comprise a conductive material or a metal layer having a conductive effect. For example, when the resistive memory cell structure 100 is fabricated in a process of an integrated circuit, the substrate 110 may include an integrated circuit. The metal layer in the middle, such as M1 or M2, but not limited thereto, for example, the substrate 110 is a semiconductor substrate, and the surface or the inside thereof is provided with electronic components (such as but not limited to CMOS transistors), conductive materials or lines, and can be electrically Connected to a resistive memory cell structure 100. In accordance with the present invention, any material, film or structure that can be used to carry the resistive memory cell structure 100 can be the substrate 110 of the present embodiment. The first electrode layer 120 and the second electrode layer 160 serve as a lower electrode and an upper electrode of the resistive memory cell structure 100, respectively, for conducting current or voltage applied to the resistive memory cell structure 100. In this embodiment, the materials of the first electrode layer 120 and the second electrode layer 160 may include titanium (Ti), titanium nitride (TiN), tantalum (Ta), tantalum nitride (TaN), tungsten nitride (TaW). ), tungsten (W), aluminum (Al), platinum (Pt) or a combination thereof, such as titanium aluminum nitride (TiAlN), but the material is not limited thereto.

The resistance change layer 130 is used as a film layer for providing a significant resistance change in the resistive memory cell structure 100. In this embodiment, the resistance change layer 130 may include hafnium oxide (HfO _x ), tantalum oxide (TaO _x ), Titanium oxide (TiO _x ), nickel oxide (NiO _x ), niobium oxide (NbO _x ), alumina (AlO _x ), lanthanum oxide (LaO _x ), tungsten oxide (WO _x ), zinc oxide (ZnO _x ), oxidation At least one of zirconium (ZrO _x ) or a composition thereof, wherein the cerium oxide may be cerium oxide (HfO ₂ ), and the cerium oxide may be tantalum pentoxide (Ta ₂ O ₅ ), but the material of the variable resistance layer 130 is Not limited to this. The first ion collecting layer 140 and the second ion collecting layer 150 may be used to absorb ions (for example, oxygen ions) in the resistance change layer 130 or may ion (eg, oxygen) in the first ion collecting layer 140 and the second ion collecting layer 150. The ions are supplied to the resistance change layer 130. In the embodiment, the first ion collection layer 140 may include a metal oxide material, and the metal oxide material may include, for example, hafnium (Hf), magnesium (Mg), aluminum (Al), and antimony ( a metal oxide of Nb), lanthanum (La), zirconium (Zr), tantalum (Ta), and titanium (Ti) or a combination thereof, and the first ion collecting layer 140 may have an oxygen content less than that of the variable resistance layer 130 The amount of oxygen is favorable to absorb oxygen ions in the resistance change layer 130. On the other hand, the second ion collecting layer 150 may include a metal material or a metal nitride material, wherein the metal material may be a metal material that is easily bonded to oxygen, and may include, for example, hafnium (Hf), tantalum (Ta), and titanium (Ti). ), zirconium (Zr), platinum (Pt) and aluminum (Al), magnesium (Mg), lanthanum (La), copper (Cu) or a combination thereof (such as titanium aluminum alloy (TiAl)) metal materials, but the materials are Not limited to this. A barrier material may also be doped in the metal material contained in the second ion collecting layer 150 to form a metal nitride material.

In the present embodiment, when the resistive memory cell structure 100 is applied with a specific voltage, the resistance change layer 130, the first ion collection layer 140, and the second between the first electrode layer 120 and the second electrode layer 160 are disposed. The ion collecting layers 150 act on each other to change the resistance of the resistance change layer 130. In detail, when the resistive memory cell structure 100 of the present embodiment is applied with a first voltage, part of ions (eg, oxygen ions) in the resistance change layer 130 may be transferred or diffused to the first ion collecting layer 140 or The second ion collecting layer 150, that is, the first ion collecting layer 140 and the second ion collecting layer 150 may absorb or combine part of the ions in the variable resistance layer 130, so that the ions are separated from the original position in the variable resistance layer 130. The vacancy generates a conductive path such as a filament, thereby reducing the resistance of the variable resistance layer 130 to a low resistance state (LRS). Conversely, when this embodiment When the resistive memory cell structure 100 is applied with a second voltage, some ions (eg, oxygen ions) in the first ion collecting layer 140 or the second ion collecting layer 150 are driven to be transferred or diffused to the resistance change layer 130. The vacancies in the resistance change layer 130 are recombined (that is, the vacancies are filled) to break the conductive path such as a filament, thereby increasing the resistance of the resistance change layer 130 to become a high resistance state (HRS). ). Accordingly, when the resistive memory cell structure 100 is applied with the first voltage, the first ion collecting layer 140 and/or the second ion collecting layer 150 temporarily stores ions that leave the resistance changing layer 130; when resistive memory When the second voltage is applied to the somatic cell structure 100, such ions temporarily stored in the first ion collecting layer 140 and/or the second ion collecting layer 150 are driven back into the resistance change layer 130. It can be seen that when ions in the resistance change layer 130 are transferred from the resistance change layer 130 to the first ion collection layer 140 or the second ion collection layer 150, or when in the first ion collection layer 140 or the second ion collection layer 150 When the ions are transferred from the first ion collection layer 140 or the second ion collection layer 150 to the resistance change layer 130, the resistance value of the resistance change layer 130 changes. In this embodiment, one of the high resistance state and the low resistance state can be used as the digital data “0”, and the other as the digital data “1”, for example, the high resistance state is used as the digital data “0”, and the low resistance state is low. As the digital data "1", that is, the resistance change layer 130 is in the low resistance state as the memory state "1" via the set operation, and the first voltage can be referred to as a set voltage, via reset (reset) The operation causes the resistance change layer 130 to be in the high resistance state as the memory state "0", and the second voltage may be referred to as a reset voltage, and therefore, when a read voltage is applied to the resistive memory cell structure 100 The resistance value of the resistance change layer 130 can be read, and the data stored in the resistive memory cell structure 100 can be known.

It is worth mentioning that when the resistive memory cell structure 100 of the present embodiment is applied with a first voltage to drive partial oxygen ion transfer or diffusion in the resistance change layer 130, the transferred oxygen ions first pass through the first The ion collecting layer 140 is such that at least a portion of the oxygen ions are combined and absorbed in the first ion collecting layer 140, and the remaining oxygen ions not absorbed by the first ion collecting layer 140 are collected by the second ion. The layer 150 is bonded without escaping the resistive memory cell structure 100, that is, the second ion collecting layer 150 has a function of blocking oxygen ions from escaping from the resistive memory cell structure 100, and conversely, when resistive When the memory cell structure 100 is applied with the second voltage, the oxygen ions of the first ion collecting layer 140 and the second ion collecting layer 150 are still driven by the second voltage to return to the resistance change layer 130, so even if the resistance changes After several states of layer 130, the amount of oxygen ions in the resistive memory cell structure 100 can remain relatively constant, thereby increasing the reliability of the resistive memory cell structure 100. On the other hand, when the resistive memory cell structure 100 is applied with a second voltage, the energy required to return oxygen ions from the first ion collecting layer 140 back to the resistance change layer 130 is less than that from the second ion collecting layer 150. The energy required to reach the resistance change layer 130, therefore, in the present embodiment, in order to enable the first ion collection layer 140 to absorb more diffused oxygen ions, the oxygen ion absorption capacity of the material contained in the first ion collection layer 140 The oxygen ion absorbing ability of the material of the second ion collecting layer 150 may be greater than that of the first ion collecting layer 140, and the first ion collecting layer 140 may be thicker than the second ion collecting layer. The thickness of the layer 150 is increased to increase the probability of oxygen ions being absorbed by the first ion collecting layer 140. In other words, the oxygen ion absorbing ability of the first ion collecting layer 140 is designed to be larger than that of the second ion collecting layer 150, but Not limited to this. In addition, in the embodiment, the second ion collecting layer 150 can be a pure metal layer, which can not only improve the ability of preventing oxygen ions from escaping from the resistive memory cell structure 100, but also can not be greatly provided in the case of providing the film layer. The resistance of the resistive memory cell structure 100 is increased, but not limited thereto.

In addition, when a conventional resistive memory is subjected to a high temperature state, for example, in a high temperature environment or when a high temperature test is performed on a resistive memory, inevitably, for example, ions escape from the resistive memory or external ions are diffused to The phenomenon of the resistive memory further affects the reliability of the resistive memory, but since the resistive memory cell structure 100 of the present embodiment is provided with the second ion collecting layer 150 having the function of blocking ions, it can be prevented from being heated at a high temperature. Other ions diffuse from the outside to the resistive memory In the cell structure 100, or the ions in the resistive memory cell structure 100 escape the resistive memory cell structure 100 to improve the reliability and manufacturing yield of the resistive memory cell structure 100. For example, when the resistive memory cell structure 100 is operated or tested at a high temperature, although the oxygen ions in the resistance change layer 130 are easily diffused away from the resistance change layer 130 at a high temperature, the second ion collection layer 150 is present. In the arrangement, the free oxygen ions are absorbed by the second ion collecting layer 150, so that the amount of oxygen ions in the resistive memory cell structure 100 can be maintained constant, thereby improving the reliability at high temperatures.

In addition, for example, when in a high temperature state (for example, high temperature operation), external ions are intended to be from the outside of the second ion collecting layer 150 (ie, opposite to the side of the resistance change layer 130 or the upper side of the second ion collecting layer 150) When diffused to the resistance change layer 130 (diffusion from top to bottom in FIG. 1), external ions are blocked by the second ion collection layer 150, so that external ions cannot affect the composition of the resistance change layer 130, thereby protecting the resistive type. Memory cell structure 100. In addition, in order to enhance the effect of blocking external ions, the second ion collecting layer 150 may optionally include a barrier material such as nitrogen or other suitable material to make it, for example, a metal nitride material, and a barrier material. It may be disposed in the second ion collecting layer 150 or the surface of the second ion collecting layer 150 by means of a plasma or a doping process, but is not limited thereto.

In summary, the resistive memory cell structure of the present invention is provided with a first ion collecting layer and a second ion collecting layer, wherein the first ion collecting layer can be used to absorb most of the ions diffused from the variable resistance layer. The second ion collecting layer can be used not only to absorb ions diffused from the variable resistance layer, but also to block the intrusion of external ions and block the escape of ions in the structure of the resistive memory cell structure, thereby improving the resistive memory cell. The reliability of the meta-structure and the manufacturing yield.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

Claims (9)

A resistive memory cell structure comprising: a substrate; a first electrode layer disposed on the substrate; a resistance change layer disposed on the first electrode layer; a first ion collecting layer disposed on the substrate a second ion collecting layer disposed on the first ion collecting layer; and a second electrode layer disposed on the second ion collecting layer, wherein when the resistive memory cell structure is When a first voltage is applied, at least one of the first ion collecting layer and the second ion collecting layer temporarily stores ions that are separated from the resistance change layer; when the resistive memory cell structure is applied with a second At a voltage, the ions temporarily present in at least one of the first ion collecting layer and the second ion collecting layer are returned to the resistance change layer. The resistive memory cell structure of claim 1, wherein the first ion collecting layer comprises a metal oxide material. The resistive memory cell structure according to claim 2, wherein the metal oxide material comprises hafnium (Hf), magnesium (Mg), aluminum (Al), niobium (Nb), hafnium (La), zirconium (Zr). Metal oxides of tantalum (Ta) and titanium (Ti) or combinations thereof. The resistive memory cell structure according to claim 1, wherein the second ion collecting layer comprises a metal material or a metal nitride material. The resistive memory structure of claim 4, wherein the metal material comprises hafnium (Hf), tantalum (Ta), titanium (Ti), zirconium (Zr), platinum (Pt), aluminum (Al), magnesium ( A metal material of Mg), lanthanum (La), copper (Cu), or a combination thereof. The resistive memory cell structure of claim 1, wherein the second ion collecting layer comprises a barrier material. The resistive memory cell structure of claim 6, wherein the barrier material comprises nitrogen. The resistive memory cell structure according to claim 1, wherein the resistance change layer comprises hafnium oxide (HfO _x ), tantalum oxide (TaO _x ), titanium oxide (TiO _x ), nickel oxide (NiO _x ), and oxidation. At least (NbO _x ), alumina (AlO _x ), tungsten oxide (WO _x ), zinc oxide (ZnO _x ), cobalt oxide (CoO _x ), lanthanum oxide (LaO _x ), zirconia (ZrO _x ) One or a combination thereof. The resistive memory cell structure according to claim 1, wherein the ions in the resistance change layer are transferred from the resistance change layer to at least one of the first ion collection layer and the second ion collection layer. Or when the ions temporarily present in at least one of the first ion collecting layer and the second ion collecting layer are transferred from the first ion collecting layer or the second ion collecting layer to the resistance change layer The resistance value of the resistance change layer changes.