TW201440273A - Resistive random-access memory sensor element - Google Patents

Abstract

The Resistive random-access memory sensor element is provided, which includes a first electrode, an insulation layer has a first recess disposed in the first electrode, a resistance conversion layer is disposed on a surface of the insulation layer and on an inner surface of the first recess so as to form a second recess, a second electrode disposed on the insulation layer and disposed within the second recess, a sensing film disposed on the second electrode and a third recess is formed therein to expose the portion surface of the second electrode, and a photoresist layer disposed on the sensing film and a fourth recess is formed therein to expose the portion surface of the sensing film, and a fifth recess is formed to align the second recess and a portion of surface of the second electrode is to be exposed.

Description

Resistive memory sensing element

The invention relates to a memory component, in particular a resistive memory multi-ion sensing component, which achieves multi-ion selectivity and high-sensitivity by resistance conversion.

With the advancement of medical care and the popularization of the concept of eugenics education, the world has gradually entered an aging society, and the proportion of the elderly population has increased significantly. In view of this, health care and care have become one of the most important issues in the 21st century. In particular, the establishment of the "Home Care" real-time monitoring system has the greatest development potential and market value. The so-called medical real-time monitoring is to accurately observe the subtle changes in the human body, so as to prevent the occurrence of diseases or the early treatment of diseases. There are many parts that can be observed for subtle changes, including the pH and composition of sweat, urine, and saliva. To achieve this goal, a sensing platform that accepts human body information into accurate electronic signals must be established. This platform can be called a Transducer.

At present, there are many researches on sensing components, among which the converter platform developed includes: ion selective electrode (ISE), ion sensitive field-effect transistor (ISFET), optical addressing potential LAPS (light addressable potentiometric sensor), ion sensing organic ion field (ISOFET, ion sensitive organic field effect) Transistor, and sensing platforms such as GaN FETs. However, at present, these sensing platforms still have some parts to be improved, such as non-ideal effects such as time drift, hysteresis, temperature, etc., as well as packaging technology and reference electrode integration. Of the many types of sensors, ion-sensing field-effect transistors (ISFETs) have received the most attention and attention.

Ion-sensing devices (ISFETs) were proposed by P. Bergveld in 1970. After decades of research and improvement, they have the advantages of small size, fast response, long life and matching with advanced processes. The structure of the ion sensing element is similar to that of a metal oxide semiconductor field effect transistor (MOSFET), and only the portion of the metal gate is replaced by the solution to be tested and the reference electrode. The sensing mechanism of the ion sensing element is mainly that in different solutions to be tested, a different amount of acid, alkali or neutral ions and the surface of the sensing film are reacted and bonded to generate a bond on the surface of the sensing film. The surface potential formed by the layer causes a change in the flat band voltage (V _fb ), which also causes a change in its threshold voltage (V _th ). The sensitivity is calculated by changing the surface potential in different concentrations of the solution. . Among the ion sensing elements, EIS (Electrolyte Insulator Semiconductor) is its core sensing part, and its process is easier than ISFET ion sensing elements. Due to the wide application range of ion sensing field effect transistors, semiconductor technology can be used for mass production and miniaturization, and the reaction is fast and the structure is hard. Therefore, there are great opportunities and developments in the application of biosensors.

The sensing mechanism of the ion-sensing field-effect transistor is mainly that in different solutions to be tested, there are a number of different acid, alkali or neutral ions and the surface of the sensing film reacts and bonds to form a bonding layer on the surface. Forming the potential, and then using the change of the potential in different concentration solutions to calculate the sensitivity, and the sensing model is also called Site Binding Model. Ion-sensing field-effect transistors are currently available in a wide range of applications, including food testing, industrial waste, medical and medical testing, environmental, agricultural, and drinking water testing. At present, the bottleneck encountered in the development of ion-sensing transistor sensors can be summarized into three points: 1. It is difficult to miniaturize the reference electrode, 2. The stability of the package, and 3. The non-ideal effect of the sensing film. In view of the difficulty in miniaturizing the first reference electrode, a complete sensing system must contain many parts, in addition to the highly sensitive sensing elements and good signal processing wiring, a stable and robust reference electrode (Reference Electrode, RE) is quite necessary. Therefore, the miniaturization of the reference electrode has been the research that many scholars have been discussing, but it is also the most difficult problem in the sensor miniature technology. For the currently developed sensing system, the most common reference electrode is a silver chloride electrode (Ag/AgCl), but this electrode has a short lifetime and is difficult to miniaturize and integrate the sensing element on the same wafer. Shortcomings.

Therefore, reference electrode field-effect transistor (REFET) elements have been designed to replace conventional reference electrodes. The main concept is to use a low-sensitivity sensing element with a quasi-reference electrode (qRE) that provides the system voltage. The ISFET with high sensitivity and the ISFET with low sensitivity get the output signal from qRE respectively. After the differential amplifier circuit, the output is the simple ion concentration obtained by deducting the noise.

The main object of the present invention is to provide a resistive memory sensing component, which utilizes the characteristics of high and low resistance switching of the resistive memory sensing component, so that different sensing ions can be added when the sensing transistor applies an electric field change. Selectivity.

According to the above object, the present invention discloses a method for forming a resistive memory sensing element, comprising: providing a germanium substrate; forming a first oxide layer on the substrate; forming a first patterned photoresist layer on the first oxide layer to define Resisting the memory device area; etching to remove a portion of the first oxide layer to form a first recess on the substrate and exposing a portion of the surface of the substrate; forming a second oxide layer on the surface of the first oxide layer And forming a second recess on the inner surface of the first recess; depositing a metal layer on the first oxide layer and filling the second recess; forming a third oxide layer on the metal layer; forming a second pattern a photoresist layer on the third oxide layer such that an electrode region of the resistive memory is defined on the third oxide layer; etching to remove a portion of the third oxide layer and exposing a portion of the surface of the metal layer; and forming The third patterned photoresist layer is on the third oxide layer to define a sensing element area, and expose a portion of the surface of the third oxide layer and expose a portion of the surface of the metal layer.

In addition, according to the above forming method, the present invention also discloses a resistive memory sensing element, comprising: a first electrode; an insulating layer having a first recess disposed on the first electrode; and a resistance conversion layer disposed on the insulating layer a surface and an inner surface of one of the first recesses to form a second recess; a second electrode disposed in the insulating layer and the second recess; and a sensing film disposed on the second electrode and having a a third recess to expose a portion of the surface of the second electrode; and a photoresist layer disposed on the sensing film and having a fourth recess to expose a portion of the surface of the sensing film and aligned with the second The recess and the fifth recess are aligned with the third recess to expose a portion of the surface of the second electrode.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

10‧‧‧Substrate

12‧‧‧First oxide layer

14‧‧‧First groove

16‧‧‧Second oxide layer

18‧‧‧second groove

20‧‧‧metal layer

22‧‧‧ third oxide layer

24‧‧‧ patterned second photoresist layer

26‧‧‧ third groove

28‧‧‧ patterned third photoresist layer

30‧‧‧fourth groove

32‧‧‧ fifth groove

Figure 1 is a diagram showing a technique on a substrate according to the disclosed technology A schematic diagram of a resistive switching layer; FIG. 2 is a schematic diagram showing the formation of a metal gate in the second oxide layer and the second recess according to the disclosed technology; and FIG. 3 is a technique according to the present invention. a schematic diagram showing the formation of a resistive switching layer on the metal layer; and FIG. 4 is a schematic view showing the formation of a patterned second photoresist layer on the third oxide layer according to the technique disclosed in the present invention; According to the technology disclosed in the present invention, a schematic diagram of removing a portion of a third oxide layer by etching is shown; and FIG. 6 is a schematic diagram showing formation of a third photoresist layer on a third oxide layer according to the disclosed technology. Figure 7A shows the CV curve at different pH values used to calculate the sensitivity of the sensing film for hydrogen ions; and Figure 7B shows the measurement curve.

The direction of the invention discussed herein is a resistive memory sensing element structure and method of forming the same. In order to thoroughly understand the present invention, detailed sensing elements and their manufacturing steps will be presented in the following description. Obviously, the practice of the invention is not limited to the specific details of those skilled in the art of the present invention. However, the preferred embodiment of the invention will be described in detail below. The present invention may be widely practiced in other embodiments, and the scope of the present invention is not limited thereto, and may be modified and modified without departing from the spirit and scope of the invention. Therefore, the scope of patent protection of the present invention is defined by the scope of the claims appended hereto.

1 to 6 are the resistive memory sensing disclosed in the present invention. A flow chart of the steps of forming the elements; and FIG. 7A shows the CV curve at different pH values to calculate the sensitivity of the sensing film to hydrogen ions; and FIG. 7B shows a schematic curve of the measurement curve.

Referring first to Figure 1, there is shown a schematic diagram of a resistive switching layer on a substrate in accordance with the teachings of the present invention. In Fig. 1, a substrate 10 is provided first. The material of the substrate 10 may be a germanium substrate used as a lower electrode (or first electrode) of the resistive memory sensing element. Next, a first oxide layer 12 is formed on the substrate 10 by a general deposition method such as low pressure chemical vapor deposition (LPCVD). Next, using a semiconductor technique, a first patterned photoresist layer (not shown) is first formed on the first oxide layer 12 for the purpose of defining a resistive memory device on the first oxide layer 12. area. Then, by etching, and using the surface of the substrate 10 as an etching stop layer, etching is performed to remove a portion of the first oxide layer 12, and a first recess is formed in the first oxide layer 12. The groove 14 exposes a portion of the surface of the substrate 10.

Then, referring to FIG. 1 again, the second oxide layer 16 having a thin thickness is formed in a blanket manner on the surface of the first oxide layer 12 and on the exposed substrate by deposition. On the surface of the surface 10, a second recess 18 is formed between the first oxide layer 12 and the second oxide layer 16, and the second recess 18 is aligned with the first recess 14.

Next, please refer to FIG. 2, which is a schematic view showing the formation of a metal gate in the second oxide layer and the second recess. In FIG. 2, after the first oxide layer 16 is formed, a metal layer 20 of a material such as platinum or tungsten is deposited on the second oxide layer 16 and the second recess 18 is filled. This metal layer 20 serves as the metal gate of the resistive memory sensing element. Here to explain In the embodiment of the present invention, the metal layer 20 serves as an upper electrode (or a second electrode) of the resistive memory sensing element.

Next, please refer to FIG. 3, which shows a schematic diagram of forming a resistance conversion layer on the metal layer. In the third figure, the third oxide layer 22 is deposited on the metal layer 20 by deposition, and the third oxide layer 22 is used as a sensing film of the resistive memory sensing element. The purpose of the film (third oxide layer) 22 is mainly to: react and bond the surface of the sensing film 22 with a different amount of acidic ions, basic ions or neutral ions in different solutions to be tested. The surface is generated with a potential formed by a bonding layer, and the change in the concentration of the potential is used to calculate the sensitivity.

Next, please refer to FIG. 4, which is a schematic view showing the formation of a patterned second photoresist layer on the third oxide layer. In Fig. 4, a patterned second photoresist layer 24 is formed on the third oxide layer 22 for the purpose of defining an upper electrode region of the resistive memory. It should be noted that the first oxide layer 12, the second oxide layer 16, and the third oxide layer 22 may be an oxide layer having a high dielectric constant of about 20 to 200, such as a germanium oxide (Ge ₂ O ₃ ) layer. Or a layer of cerium oxide (SiO ₂ ).

Next, please refer to FIG. 5, which is a schematic view showing the removal of a portion of the third oxide layer by etching. In FIG. 5, according to the patterned second photoresist layer 24 disclosed in FIG. 4, the metal layer 20 is used as an etch stop layer, and etching is performed to remove a portion of the third oxide layer 22 to form a The third recess 26 is exposed within the third oxide layer 22 and will serve as a metal gate 20 of the metal gate. In the embodiment of the invention, the third recess 26 is disposed at a position that is not aligned with the second recess 16.

Next, please refer to FIG. 6 to show that a third photoresist is formed on the third oxide layer. Schematic diagram of the layer. In Fig. 6, a patterned third photoresist layer 28 is formed on the third oxide layer 22 to define the sensing element area. Next, referring also to FIG. 6, an etching process is performed to remove a portion of the third photoresist layer 28 to form a fourth recess 30 and a fifth recess 32, wherein the fourth recess 30 exposes the third oxide layer. A portion of the surface of 22 is aligned with the second recess 18, and the fifth recess 32 is aligned with the third recess 26 and also exposes a portion of the surface of the metal layer 20, and remains unremoved. The third photoresist layer 28 is formed to form a resistive memory sensing element.

According to the technology disclosed by the present invention, it is known that a general ion sensing element calculates the ion sensitivity by using a capacitance-voltage curve (CV) to cause a drift of a CV curve at different ion concentrations, as shown in FIG. 7A. The hydrogen ion sensing uses the CV curve at different pH values to calculate the sensitivity of the sensing film to hydrogen ions. However, the CIM curve cannot be measured by the IMIM structure, so we will use the current-voltage curve (JV). The ion sensibility is calculated by causing a drift of the JV curve at different ion concentrations.

As shown in the schematic diagram of the measurement curve of FIG. 7B, when the concentration of the hydrogen ions changes, the work function of the electrode is shifted, and the JV curve is changed, thereby calculating the sensitivity of the sensing film to hydrogen ions. Since the IMIS component contains the MIS resistive memory portion, when the resistive memory is operated, the MIS device has two states of high impedance (HRS) and low impedance (LRS) (not shown in the figure). When the resistive memory is set to a low impedance, the voltage drop across the MIS resistive memory is small, and the equivalent effective field of the IMIS component is large; if the resistive memory weight is set (Reset When the impedance is high, the voltage drop across the MIM resistive memory is large, and the equivalent electric field of the opposite IMIM component becomes small, by changing across the IMIM component. With the equivalent electric field, we will be able to adjust the condition of the IMIM ion sensing element for different ion sensing. Therefore, the resistive memory sensing element can be utilized to have high and low resistance switching characteristics, so that when the sensing transistor is applied with an electric field change, the selectivity to different ion sensing can be increased.

10‧‧‧Substrate

12‧‧‧First oxide layer

14‧‧‧First groove

16‧‧‧Second oxide layer

18‧‧‧second groove

20‧‧‧metal layer

22‧‧‧ third oxide layer

26‧‧‧ third groove

28‧‧‧ patterned third photoresist layer

30‧‧‧fourth groove

32‧‧‧ fifth groove

Claims (13)

A method for forming a resistive memory sensing device, comprising: providing a substrate; forming a first oxide layer on the substrate; forming a first patterned photoresist layer on the first oxide layer to define the resistor An area of the memory device; etching to remove a portion of the first oxide layer to form a first recess on the substrate and exposing a portion of the surface of the substrate; forming a second oxide layer in the first oxide a surface of one of the layers and on an inner surface of the first recess, and a second recess is formed on the first recess; depositing a metal layer on the first oxide layer and filling the second Forming a third oxide layer on the metal layer; forming a second patterned photoresist layer on the third oxide layer, thereby defining an electrode region of the resistive memory on the third oxide layer Etching to remove a portion of the third oxide layer to form a third recess and expose a portion of the surface of the metal layer; forming a third patterned photoresist layer on the third oxide layer to define a sense Component area; and etching to remove portions of the third patterned photoresist layer Forming a fourth recess and a fifth recess, wherein the fourth recess exposes a portion of the surface of the third oxide layer and the fifth recess is aligned with the third recess and exposes the metal Part of the surface of the layer. The method of claim 1, wherein the substrate is a germanium substrate. The method of claim 1, wherein the first oxide layer, The second oxide layer and the third oxide layer are oxide layers having a high dielectric constant. The method of claim 1, wherein the material of the first oxide layer, the second oxide layer and the third oxide layer is selected from the group consisting of cerium oxide and cerium oxide. The method of claim 1, wherein the third groove is not aligned with the second groove. A resistive memory sensing component comprising: a first electrode; an insulating layer having a first recess disposed on the first electrode; a resistive switching layer disposed on the insulating layer and in the first recess a second groove is formed on the surface of the groove; a second electrode is disposed on the resistance conversion layer and the second groove; and a sensing film has a third groove disposed on the second electrode And exposing a portion of the surface of the second electrode; and a protective layer disposed on the sensing film and having a fourth recess corresponding to the second recess to expose a portion of the surface of the sensing film and A fifth groove is aligned with the third groove to expose a portion of the surface of the second electrode. The resistive memory sensing element of claim 6, wherein the first electrode is a germanium substrate. The resistive memory sensing element of claim 6, wherein the insulating layer is an oxide layer having a high dielectric constant. The resistive memory sensing element of claim 6, wherein the material of the insulating layer is selected from the group consisting of cerium oxide and cerium oxide. A resistive memory sensing element according to claim 6 of the patent application, The resistance conversion layer is an oxide layer having a high dielectric constant. The resistive memory sensing element of claim 6, wherein the second electrode is a metal layer. The resistive memory sensing element of claim 11, wherein the material of the metal layer is selected from the group consisting of platinum and tungsten. The resistive memory sensing element of claim 6, wherein the sensing film is an oxide layer.