WO2012070551A1

WO2012070551A1 - Device for manufacturing and method for manufacturing memory element

Info

Publication number: WO2012070551A1
Application number: PCT/JP2011/076851
Authority: WO
Inventors: 善明吉田; 小風　豊
Original assignee: 株式会社アルバック
Priority date: 2010-11-22
Filing date: 2011-11-22
Publication date: 2012-05-31
Also published as: JPWO2012070551A1; JP5437492B2

Abstract

Provided are a device for manufacturing and a method for manufacturing a memory element having a metal oxide layer with etching resistance. Anisotropic etching is performed by the metal oxide layer (14) reacting with etching gas containing chlorine in the chemical structure thereof and generating a chloride gas, which is eliminated by vacuum exhausting. Etching products (25) adhere to the side wall parts that have been etched and remain because the vapor pressure is low at the temperature during etching. These etching products (25) are water soluble; therefore, directly after etching, the etched surfaces are brought into contact with a washing fluid and the etching products (25) are eliminated by dissolution. Thus, a memory element (5) for which a pattern is formed by the metal oxide layer (14) can be obtained.

Description

Memory device manufacturing apparatus and manufacturing method

The present invention relates to a memory device manufacturing apparatus and manufacturing method, and more particularly to a memory device manufacturing apparatus and manufacturing method having a transition metal oxide layer.

In recent years, a resistance change memory (Resistance Random Access Memory, ReRAM) has attracted attention as a new nonvolatile memory using a transition metal oxide. The single cell structure of ReRAM is a simple capacitor structure in which a transition metal oxide exhibiting an insulator or semiconductor electrical property is sandwiched between metal electrodes, and can generate a huge resistance change by applying a pulse voltage. it can.

The ReRAM has a feature that a minimum cell area of 4F ² (F is a minimum processing dimension in a manufacturing process of a memory cell, so-called design rule) is possible, and multi-value can be made. In addition, since the ReRAM manufacturing process has good consistency with the CMOS process, the bit cost can be reduced by high integration, and it is expected as a universal memory that replaces and integrates DRAM and Flash memory.

In order to increase the memory capacity, it is necessary to process fine memory cells with good controllability, and from the viewpoint of compatibility with CMOS processes, reactive ion etching (Reactive Ion Etching) widely used in the semiconductor field , RIE) is required to develop a machining process.

Transition metals such as Co and Ni are used for the resistance change film used in ReRAM, and the vapor pressure of fluorides and chlorides of these materials is low, which is known as a difficult etching material. When such a material is etched, the etching product easily adheres to the side wall of the element pattern, and in the prior art, this product remains and becomes dust and contaminates the apparatus in the next process or the next process. There is a risk of disconnection or insulation failure in the wiring formation process.

With reference to FIGS. 2A to 2C, a conventional metal oxide pattern forming method will be described.
First, as shown in FIG. 2A, a processing target in which an insulating layer 112, a lower electrode 113, a metal oxide layer 114, and first and

second metal layers

116 and 117 are laminated in this order on a substrate 111. A mask 120 having a predetermined pattern is formed on the second metal layer 117 of the object. Here, the first and

second metal layers

116 and 117 constitute the upper electrode 118.

Next, as shown in FIG. 2B, the object to be processed is transferred to an etching chamber and etched with a chlorine-based gas such as Cl ₂ or BCl ₃ until the lower electrode 113 is exposed. At this time, the etching product 125 adheres to the etched side wall portion of the object to be processed.
Next, as shown in FIG. 2C, the object to be processed is carried into an ashing chamber while maintaining a vacuum atmosphere, and plasma ashing is performed using O ₂ gas to remove the mask 120. After ashing, a residue 126 is seen on the side wall of the object to be processed. The residue 126 cannot be removed in the subsequent steps and remains.

Republished Patent 2004/008535

The present invention was created to solve the above-mentioned disadvantages of the prior art, and its purpose is to remove etching products generated in reactive ion etching to form a pattern on a metal oxide satisfactorily. I will provide a.

The inventors examined the residue and found that the residue was an oxide of Co or Ni. Since the etching product is a chloride of Co or Ni, it is considered that the oxide is formed by oxidizing the chloride generated during the etching during the ashing. The oxide could not be removed in a later step, but the chloride could be dissolved by washing with water, thus completing the present invention.

In the present invention based on such knowledge, when a metal oxide layer is disposed between the upper electrode and the lower electrode and a DC voltage is applied between the upper electrode and the lower electrode, the DC voltage is reduced. Depending on the polarity, information can be stored by entering one of a high resistance state and a low resistance state, a sense current is passed in the film thickness direction, a resistance value is measured, and the high resistance state and the An apparatus for manufacturing a memory element capable of reading information by determining a low resistance state, an etching chamber having a gas supply unit for supplying an etching gas, and a plasma generating unit for converting the etching gas into a plasma A cleaning chamber connected to the etching chamber, and a transfer chamber for transferring an object to be processed from the etching chamber to the cleaning chamber, the etching chamber on the substrate. When a processing object in which an electrode, the metal oxide layer, and the upper electrode are stacked in this order is carried in, an etching gas containing chlorine in the chemical structure is turned into plasma, and the upper electrode and the metal oxide layer are The memory device manufacturing apparatus is configured to expose the lower electrode by etching, and the cleaning chamber is configured to contact a cleaning liquid with the etched surface of the processing object.
The present invention is a memory device manufacturing apparatus, wherein the metal oxide layer is selected from the group consisting of Al ₂ O ₃ , Y ₂ O ₅ , HfO ₂ , TiO ₂ , CoO, and NiO. This is an apparatus for manufacturing a memory element made of one metal oxide.
The present invention is an apparatus for manufacturing a memory element, wherein the etching gas is one of a gas selected from the group consisting of Cl ₂ , BCl ₃ , and SiCl ₄ , or a mixed gas of two or more. It is a manufacturing device.
According to the present invention, when a metal oxide is disposed between the upper electrode and the lower electrode, and a DC voltage is applied between the upper electrode and the lower electrode, a high resistance state and a low resistance are generated according to the polarity of the DC voltage. Information can be recorded by entering one of the resistance states, and a sense current is passed in the film thickness direction, and the resistance value is measured to discriminate between the high resistance state and the low resistance state. An apparatus for manufacturing a memory element that can be read, wherein the upper electrode is exposed on a processing object in which the lower electrode, the metal oxide layer, and the upper electrode are stacked in this order on a substrate. A mask process for disposing a mask having a predetermined pattern having an opening, and plasma etching of an etching gas containing chlorine in the chemical structure, etching the upper electrode and the metal oxide layer to expose the lower electrode And an etching step, a cleaning liquid is brought into contact with the etched surface of the processing object, a method of manufacturing a memory device having a cleaning process for removing metal chlorides generated in the etching step.
The present invention is a method of manufacturing a memory device, wherein the metal oxide layer is selected from the group consisting of Al ₂ O ₃ , Y ₂ O ₅ , HfO ₂ , TiO ₂ , CoO, and NiO. 1 is a method of manufacturing a memory element made of one metal oxide.
The present invention is a method of manufacturing a memory device, wherein the etching gas used for etching the metal oxide layer is one gas selected from the group consisting of Cl ₂ , BCl ₃ , and SiCl ₄ , or two or more. Is a method for manufacturing a memory element containing a mixed gas of

Since the etching product can be removed, the yield of ReRAM manufacturing can be improved without contaminating the devices after the next step or causing disconnection or insulation failure in the next wiring formation step.
Since the transition metal oxide can be stably patterned by reactive ion etching, high integration of ReRAM becomes possible.

(A)-(e): The figure explaining the manufacturing method of the memory element of this invention (A)-(c): The figure explaining the metal oxide pattern formation method by a prior art The internal block diagram of the memory device manufacturing apparatus of this invention Schematic diagram of a memory device having a memory element formed in the present invention

FIG. 1E shows the structure of the memory element 5 formed according to the present invention, and FIG. 4 shows a schematic diagram of the memory device 1 having a plurality of memory elements 5.
As illustrated in FIG. 4, the storage device 1 includes a storage unit 6 and a control unit 7. A plurality of memory elements 5 are arranged in the storage unit 6.

As shown in FIG. 1E, the memory element 5 has a lower electrode 13, a metal oxide layer 14, and first and

second metal layers

16 and 17, and the

layers

13, 14, 16, and 17 are insulated. They are stacked on the substrate 11 in this order via the layer 12. The first and

second metal layers

16 and 17 constitute the upper electrode 18. That is, the metal oxide layer 14 is disposed between the upper electrode 18 and the lower electrode 13.

The substrate 11 is made of a semiconductor or the like, and Si is used here, and the insulating layer 12 is made of an insulator, and here is SiO ₂ . The lower electrode 13 and the first and

second metal layers

16 and 17 are made of a conductive material. Here, a TiN film is used for the lower electrode 13 and the second metal layer 17, and the first metal layer 16 is an Al film.
The metal oxide layer 14 is made of one metal oxide selected from the group consisting of Al ₂ O ₃ , Y ₂ O ₅ , HfO ₂ , TiO ₂ , CoO, and NiO.

When a DC voltage is applied between the upper electrode 18 and the lower electrode 13, the memory element 5 is either in a high resistance state or a low resistance state having a resistance value lower than that in the high resistance state depending on the polarity of the DC voltage. It comes to be in one state.
In this embodiment, when a positive pulse voltage is applied with the upper electrode 18 as an anode and the lower electrode 13 as a cathode, the memory element 5 is in a low resistance state, and a negative pulse voltage is applied. Although it is configured to be in a high resistance state, it is configured to be in a high resistance state when a pulsed positive voltage is applied, and to be in a low resistance state when a pulsed negative voltage is applied. May be.

The surface of the lower electrode 13 is partially exposed, and first and second connection terminals are electrically connected to the second metal layer 17 and the lower electrode 13, respectively.

Reference numerals

71a and 71b in FIG. 4 indicate first and second connection terminals.

When a DC voltage is applied from the control unit 7 to the first and

second connection terminals

71a and 71b of the one memory element 5, the one memory element 5 has a high resistance state and a low resistance depending on the polarity of the DC voltage. One of the resistance states is entered. By associating the low resistance state and the high resistance state with 1 and 0, respectively, 1/0 information can be recorded.

In addition, a sense current is passed from the control unit 7 in the film thickness direction of the one memory element 5 via the first and

second connection terminals

71a and 71b, and the resistance value of the one memory element 5 is measured. By discriminating between the high resistance state and the low resistance state, the information stored in the one memory element 5 can be read out.

FIG. 3 shows a memory device manufacturing apparatus 50 according to the present invention.
The memory element manufacturing apparatus 50 includes an etching chamber 30 that forms a predetermined pattern on a processing target, a cleaning chamber 52 that removes etching products, and a transfer chamber that transfers the processing target from the etching chamber 30 to the cleaning chamber 52. 51.

The etching chamber 30 includes a vacuum chamber 39, a gas supply unit 31 that supplies an etching gas into the vacuum chamber 39, a plasma generation unit 42 that converts the supplied etching gas into plasma, and a vacuum that evacuates the vacuum chamber 39. The exhaust part 32 and the temperature control part 38 which controls the temperature of the process target object arrange | positioned in the vacuum layer 39 are provided.

Inside the vacuum chamber 39, a stage 36 for placing a processing object is provided.
The temperature control unit 38 is connected to the stage 36, and can control the temperature of the processing object placed on the stage 36 by flowing a temperature-controlled heat medium through a cooling pipe (not shown) provided on the stage 36, for example. Has been.

The plasma generation unit 42 includes an RF antenna 33, a plasma matching box 37a, and a plasma high-frequency power source 34. The RF antenna 33 is installed above the vacuum chamber 39 and is electrically connected to the plasma high frequency power supply 34 via the plasma matching box 37a. When a high frequency voltage is applied from the plasma high frequency power supply 34 to the RF antenna 33, The etching gas supplied into the vacuum chamber 39 can be converted into plasma by inductive coupling.

A high frequency power supply 35 for bias is electrically connected to the stage 36 via a bias matching box 37b. When a high frequency voltage is applied to the stage 36 from the high frequency power supply 35 for bias, an electric field is formed on the stage 36. Thus, ions in the plasma are drawn toward the stage 36 and collide with the object to be processed, so that the object to be processed can be anisotropically etched.

The gas supply unit 31 is installed outside the vacuum chamber 39 and is connected to the inside of the vacuum chamber 39 so that an etching gas can be supplied into the vacuum chamber 39.
The evacuation unit 32 is installed outside the vacuum chamber 39 and connected to the inside of the vacuum chamber 39 so that the inside of the vacuum chamber 39 can be evacuated.

The transfer chamber 51 is hermetically connected to the vacuum chamber 39 of the etching chamber 30 via the first gate valve 55a, and the cleaning chamber 52 is hermetically connected to the transfer chamber 51 via the second gate valve 55b. Yes.
The transfer chamber 51 has an evacuation unit (not shown), and is configured so that the transfer chamber 51 can be evacuated while the first and

second gate valves

55a and 55b are closed.

A method for manufacturing a memory element according to the present invention will be described.
The first and

second gate valves

55a and 55b are closed, and the inside of the vacuum chamber 39 and the transfer chamber 51 of the etching chamber 30 are evacuated in advance to maintain a vacuum atmosphere. Further, an inert gas not containing oxygen is introduced into the cleaning chamber 52 to keep the atmospheric pressure.

As shown in FIG. 1A, a processing target in which an insulating layer 12, a lower electrode 13, a metal oxide layer 14, and first and second metal layers 16 and 17 are stacked in this order on a substrate 11. Use things.
First, as a mask process, as shown in FIG. 1B, a photoresist is applied on the second metal layer 17, a predetermined pattern is exposed and developed, and a mask 20 having an opening is formed. The second metal layer 17 is exposed on the bottom surface of the opening of the mask 20.

Alternatively, an imprint resist is applied onto the second metal layer 17 and an original plate having irregularities of a predetermined pattern is pressed to form a mask 20 having an opening, and the second metal layer 17 is formed on the bottom surface of the opening. It may be exposed.
Next, as an etching process, the object to be processed 10 is carried into the vacuum chamber 39 of the etching chamber 30 while maintaining the vacuum atmosphere with reference to FIG. 36.

The temperature control unit 38 is operated, a temperature-controlled heat medium is passed through a cooling pipe (not shown) of the stage 36, and the temperature of the processing object 10 during etching is maintained in the range of 20 ° C to 80 ° C.
A first etching gas is supplied from the gas supply unit 31, and the inside of the vacuum chamber 39 is maintained at a pressure of 0.1 Pa to 2.0 Pa. A gas containing chlorine in the chemical structure is used as the first etching gas, for example, a gas containing one gas or a mixed gas of two or more selected from the group consisting of Cl ₂ , BCl ₃ , and SiCl _4. is there. When BCl ₃ is used, a rare gas (He, Ne, Ar, Kr, Xe) may be added to dilute the polymerizability.

The high frequency power supply for plasma 34 is activated, an alternating current is passed through the RF antenna 33, radio waves are emitted from the RF antenna 33 into the vacuum chamber 39, the first etching gas is excited and turned into plasma, and chlorine ions and chlorine radicals are produced. And so on. In addition, the bias high-frequency power source 35 is activated, a bias voltage is applied to the object 10 to be processed, and the generated chlorine ions are incident on the object 10 to perform an anisotropic etching process.

Here, a shield 41 is provided so as to surround the stage 36, and adhesion of etching products to the inner wall of the vacuum chamber 39 is prevented.
When the metal oxide layer 14 is exposed by the anisotropic etching process, the operations of the plasma high-frequency power source 34 and the bias high-frequency power source 35 are stopped, and the supply of the first etching gas from the gas supply unit 31 is stopped. To do.

After the first etching gas is evacuated and the pressure in the vacuum chamber 39 decreases, the supply of the second etching gas from the gas supply unit 31 is started. The inside of the vacuum chamber 39 is maintained at a pressure of 0.1 Pa to 10 Pa according to the selection ratio with the resist (mask 20). Using a gas containing chlorine to the composition in the chemical structure in the second etching gas, for example, Cl _2, and BCl _3, the gas containing one gas or more of the mixed gas selected from the group of SiCl ₄ It is. When BCl ₃ is used, a rare gas (He, Ne, Ar, Kr, Xe) may be added to dilute the polymerizability.

Next, the high frequency power source for plasma 34 and the high frequency power source for bias 35 are operated, and the exposed metal oxide layer 14 is reacted with the second etching gas by chlorine ions in the plasma to generate a chloride gas. Then, anisotropic etching is performed by removing chloride gas by evacuation.

At this time, as shown in FIG. 1C, an etching product 25 made of a metal chloride contained in the metal oxide layer 14 adheres and remains on the etched side wall portion of the processing object 10. This is because the metal chloride contained in the metal oxide layer 14 generally has a high melting point and boiling point and a low vapor pressure at the temperature during etching.

When the lower electrode 13 is exposed, the operations of the plasma high-frequency power source 34 and the bias high-frequency power source 35 are stopped, and the supply of the second etching gas from the gas supply unit 31 is stopped.
Here, a transfer robot 65 is provided in the transfer chamber 51. After the transfer chamber 51 is evacuated and the pressure in the vacuum chamber 39 decreases, the first gate valve 55a is opened to move the processing object 10 from the vacuum chamber 39 into the transfer chamber 51, and One gate valve 55a is closed. Next, an inert gas not containing oxygen is introduced into the transfer chamber 51 to raise the pressure in the transfer chamber 51 to atmospheric pressure.

In the cleaning chamber 52, a cleaning stage 61 on which a processing target can be placed and a shower nozzle 62 for injecting a cleaning liquid onto the processing target placed on the cleaning stage 61 are arranged.
The second gate valve 55 b is opened, the processing object 10 is carried into the cleaning chamber 52 from the transfer chamber 51, and placed on the cleaning stage 61.

Next, as a cleaning process, a cleaning liquid is sprayed from the shower nozzle 62 onto the etched surface of the processing object 10, and the etching surface of the processing object 10 is brought into contact with the cleaning liquid to perform a cleaning process.
Here, the shower method is described as the cleaning method, but the present invention is not limited to this, and the cleaning process is performed by bringing the etched surface of the processing object 10 into contact with the cleaning liquid by another cleaning method such as an ultrasonic dip method. May be.

As the cleaning liquid, one kind or a mixture of two or more kinds of water such as pure water, ion exchange water, micro / nano bubble water, and organic solvents such as ethanol, methanol, acetone, isopropyl alcohol, and ethyl ether are used.
The etching product 25 is, for example, a water-soluble and alcohol-soluble metal chloride such as CoCl ₂ or NiCl _{2. As} shown in FIG. 1D, the etching product 25 is dissolved in the cleaning liquid by the cleaning process using the cleaning liquid. And removed.

Here, it is desirable that the time required from the time when the processing object 10 is brought into contact with the atmosphere in the transfer chamber 51 to the start of the cleaning in the cleaning chamber 52 is within 5 minutes. This is because when the object to be treated 10 is put into the atmosphere, chlorine remaining on the surface of the object to be treated 10 reacts with moisture in the atmosphere to form HCl. This is because if a material (for example, Al) that is corroded by HCl is used for the object 10 to be processed, corrosion (corrosion) may occur there.

After the cleaning process is completed, the object to be processed is dried by centrifugal force drying or high-temperature gas blowing, and then the object to be processed is carried into an ashing chamber (not shown), and plasma ashing is performed using O ₂ gas. Do. Oxygen ions and oxygen radicals generated from the excited O ₂ gas oxidize and decompose the mask 20 to remove the mask 20.
The etching product 25 on the side wall portion of the object to be processed is removed before ashing, and no oxide residue remains on the side wall portion after ashing.
Thus, the memory element 5 in which the pattern is formed on the metal oxide layer 14 as shown in FIG. 1E is obtained.

5 ... Memory element 13 ... Lower electrode 14 ... Metal oxide layer 18 ... Upper electrode 20 ... Mask 30 ... Etching chamber 31 ... Gas supply part 42 ... Plasma generation part 50 ... Manufacturing of memory element Equipment 51 …… Transport chamber 52 …… Cleaning chamber

Claims

When a metal oxide layer is disposed between the upper electrode and the lower electrode, and a DC voltage is applied between the upper electrode and the lower electrode, the high resistance state and the low resistance state are changed according to the polarity of the DC voltage. Information can be stored by entering either state, and information is read by flowing a sense current in the film thickness direction and measuring the resistance value to distinguish between the high resistance state and the low resistance state An apparatus for manufacturing a memory device,
An etching chamber having a gas supply section for supplying an etching gas, and a plasma generation section for converting the etching gas into a plasma;
A cleaning chamber disposed in connection with the etching chamber;
A transfer chamber for transferring a processing object from the etching chamber to the cleaning chamber;
Have
When the processing object in which the lower electrode, the metal oxide layer, and the upper electrode are stacked in this order is loaded on the substrate, the etching chamber converts the etching gas containing chlorine into plasma into plasma, Etching the metal oxide layer to expose the lower electrode;
The apparatus for manufacturing a memory element, wherein the cleaning chamber is configured to bring a cleaning liquid into contact with an etched surface of the processing object.
The metal oxide layer, Al 2 O 3, and Y 2 O 5, and HfO 2, and TiO 2, and CoO, consists of a metal oxide selected from the group consisting of NiO claim 1, wherein Memory device manufacturing apparatus.
3. The memory according to claim 1, wherein the etching gas contains one gas or two or more mixed gases selected from the group consisting of Cl 2 , BCl 3 , and SiCl 4. Device manufacturing equipment.
When a metal oxide is disposed between the upper electrode and the lower electrode and a DC voltage is applied between the upper electrode and the lower electrode, either a high resistance state or a low resistance state is selected depending on the polarity of the DC voltage. Information can be recorded by entering one of the states, and information can be read by flowing a sense current in the film thickness direction and measuring the resistance value to distinguish between a high resistance state and a low resistance state. A device for manufacturing a memory element,
A mask process of disposing a mask having a predetermined pattern having an opening exposing the upper electrode on a processing object in which the lower electrode, the metal oxide layer, and the upper electrode are laminated in this order on a substrate. When,
An etching process that plasmaizes an etching gas containing chlorine in a chemical structure, etches the upper electrode and the metal oxide layer, and exposes the lower electrode;
A method of manufacturing a memory device, comprising: a cleaning step of bringing a cleaning liquid into contact with an etched surface of the object to be processed to remove a metal chloride generated in the etching step.
The metal oxide layer is made of one metal oxide selected from the group consisting of Al 2 O 3 , Y 2 O 5 , HfO 2 , TiO 2 , CoO, and NiO. Method for manufacturing the memory element.
The etching gas used for etching of the metal oxide layer, and Cl 2, and BCl 3, claim 4 or claim containing one gas or more of the mixed gas selected from the group consisting of SiCl 4 Metropolitan 6. A method for manufacturing a memory element according to any one of items 5 to 6.